Red Meat and trimethylamine N-oxide - Kresser

Red Meat and TMAO: Cause for Concern, or Another Red Herring?

By Chris Kresser on April 10, 2013 

 

 

I’m sure many of you have seen reports on a recent study published in the journal Nature suggesting a possible mechanism linking red meat consumption to heart disease. The day after one such report was published in the New York Times, I received numerous emails and numerous Facebook and Twitter messages from concerned red meat enthusiasts. This is understandable, but rest assured it’s not yet time to switch over to soy burgers.

 

The researchers in this study published a paper a while back proposing that a chemical called TMAO (trimethylamine N-oxide) increases the risk of heart disease. In this study, they hypothesized that eating red meat may increase levels of TMAO in the bloodstream, which would intern ramp up your chances of having a heart attack. Sounds plausible, right?

 

There’s another hypothesis that also seemed plausible for why red meat increases the risk of heart disease (if we even accept that, which I do not; more on this in a moment). It’s called the “diet-heart hypothesis”, and you’re all very well aware of it whether you know it by name or not. It holds that eating cholesterol and saturated fat increase cholesterol levels in the blood, and high cholesterol levels in the blood cause heart disease. This theory became so widely accepted that few people even question it anymore. The problem is it’s simply not true. Recent research has shown that dietary saturated fat and cholesterol are not associated with heart disease after all, and even if they were, high cholesterol levels in the blood are not the culprit. I’ve written about this extensively in the past, and I will be starting a brand new series with updated information this month.

 

The mistaken blame of saturated fat and cholesterol as drivers of heart disease led to a decades-long campaign to encourage low-fat, high-carbohydrate diets. Unfortunately, the effects of this campaign were not harmless. Not only did it unnecessarily deprive people of nutrient-dense, nourishing (and delicious!) foods like meat, butter and eggs, it may have indirectly contributed to the epidemics of obesity, heart disease and diabetes. Studies have shown that when people replace saturated fat with carbohydrates, the risk of heart disease doesn’t go down—it goes up. (1) This is not because of the carbohydrates, per se, but because 85% of the grain consumed in the U.S. is in the highly refined form. (2)

 

The diet-heart hypothesis should be a cautionary tale that prevents us from jumping to rash conclusions based on limited evidence. Alas, the almost complete lack of criticism or scrutiny in the popular media reports on this study indicate that caution has been thrown to the wind. Let’s now examine three reasons why I’m not yet ready to take the conclusions of this study (i.e. red meat causes heart disease via TMAO) at face value.

Epidemiological evidence is inconsistent

If red meat consumption elevates TMAO, and elevated TMAO increases the risk of heart disease, we’d expect to see higher rates of heart disease in people that eat more red meat. The epidemiological evidence examining this question is mixed. A large meta-analysis published in Circulation by Micha et al. covering over 1.2 million participants found that consumption of fresh, unprocessed red meat is not associated with increased risk of coronary heart disease (CHD), stroke or diabetes. (3) On the other hand, a smaller prospective study including about 121,000 participants from the Nurses Health Study and Health Professionals Follow-up Study did find an association between red meat consumption (both fresh and processed) and total mortality, cardiovascular disease (CVD) and cancer. (4)

 

If eating meat increases heart disease risk we might expect lower rates in vegans and vegetarians. Early studies suggested this was true, but later, better-controlled studies suggest it’s not. The early studies were poorly designed and subject to confounding factors (i.e. vegetarians tend to be more health conscious on average than general population, so there could be other factors explaining their longevity, such as more exercise, less smoking, etc.). Newer, higher quality studies that have attempted to control for these confounding factors haven’t found any survival advantage in vegetarians. For example, one study compared the mortality of people who shopped in health food stores (both vegetarians and omnivores) to people in the general population. They found that both vegetarians and omnivores in the health food store group lived longer than people in the general population. (5) This suggests, of course, that eating meat in the context of a healthy diet does not have the same effect as eating meat in the context of an unhealthy diet. (Hold this thought: we’ll be coming back to it shortly.) A very large study performed in the U.K. in 2003 including over 65,000 subjects corroborated these results: no difference in mortality was observed between vegetarians and omnivores. (6)

 

Taken together, these data do not suggest a strong relationship between red meat and heart disease. It’s also crucial to remember that epidemiological evidence does not prove causality. Even if red meat intake is associated with a higher risk of CVD (or any other health problem), such studies don’t tell us that red meat is causing the problem. If you’re new to this concept, I suggest reading these excellent articles by Denise Minger and Chris Masterjohn.

The “healthy user bias” strikes again

The healthy user bias is the scientific way of explaining the phenomenon I described above, where people that engage in one behavior that is perceived as healthy (whether it is or not) are more likely to engage in other behaviors that are healthy. (7, 8) Of course the flip-side is also true: those that engage in behaviors perceived to be unhealthy are more likely to engage in other unhealthy behaviors. The healthy user bias is one of the main reasons it’s so difficult to infer causality from epidemiological relationships. For example, say a study shows that eating processed meats like bacon and hot dogs increases your risk of heart disease. (9) Let’s also say, as the healthy user bias predicts, that those who eat more bacon and hot dogs also eat a lot more refined flour (hot dog and hamburger buns), sugar and industrial seed oils, and a lot less fresh fruits, vegetables and soluble fiber. They also drink and smoke more, exercise less and generally do not take care of themselves very well. How do we know, then, that it’s the processed meat that is increasing the risk of heart disease rather than these other things—or perhaps some combination of these other things and the processed meat? The answer is, we don’t. Good studies attempt to control for some of these confounding factors, but inevitably some will not be controlled for. And one of the most important potential confounding factors that is never controlled for is the gut microbiome.

 

Numerous studies, which I’ve written about on this blog and spoken about on my podcast, suggest that the balance of bacteria in our gut may be one of the most important factors—if not the most important—that determines our overall health. Gut dysbiosis (an imbalance between healthy and unhealthy bacteria in the gut) and small intestine bacterial overgrowth (SIBO, a condition involving an inappropriate overgrowth of bacteria in the gut) have been linked to health problems as diverse as skin disease, depression, anxiety, autoimmunity, and hair loss.

 

The study we’re discussing here found that those who eat red meat produce TMAO, whereas vegans and vegetarians who hadn’t eaten meat for at least a year do not. The researchers claimed that this means eating red meat must alter the gut flora in a way that predisposes toward TMAO production. However, there’s another explanation that I believe is much more plausible: the red meat eaters are engaging in unhealthy behaviors that have led to dysbiosis and/or SIBO. This could include eating fewer fruits and vegetables and less soluble fiber, and more processed and refined flour, sugar and seed oils. All of these behaviors have been shown to be more common in the “average” red meat eater, and all of them have been associated with undesirable changes in the gut microbiota. (10, 11, 12) In other words, the problem isn’t the red meat, it’s the gut bacteria. This is supported by the finding in the study that the red meat eaters did not produce TMAO after a course of antibiotics. It is also supported by data indicating that a breakdown in the intestinal barrier, which occurs in dysbiosis and SIBO, may increase heart disease risk by elevating the number of circulating LDL particles in the bloodstream. (13) I will be covering this (i.e. the connection between LDL particles and heart disease) in my updated series on heart disease.

 

In the last section I presented evidence suggesting that eating meat in the context of a healthy diet does not have the same effect as eating it in the context of an unhealthy diet. This study is likely yet another example. In order to know whether red meat is really to blame for changes in the gut flora that increase TMAO production, we’d have to do another study with two groups: one that follows a Paleo diet rich with fruits, vegetables and soluble fiber, as well as red meat; and another vegan/vegetarian diet with equivalent amounts of plant matter and no meat. If the Paleo diet followers still had higher levels of TMAO, this hypothesis would be a lot stronger.

The jury is still out on TMAO

The evidence linking TMAO production to eating red meat, and serum TMAO levels to heart disease, is not as cut-and-dry as the study authors suggest. For example:

• The Nature paper on TMAO contained data from two studies: an epidemiological study on humans, and a clinical study on mice. The human study compares a single vegan that they managed to convince to eat a steak to a single “representative” meat-eater. A single person in each group is not an adequate sample size, and is hardly convincing given the wide variation in the response to carnitine (see next bullet) among meat-eaters.

• The mouse study used a carnitine supplement. While it is well established that free carnitine increases TMAO production, previous studies have not shown that carnitine-rich foods like red meat increase TMAO. In fact, in one 1999 study, out of 46 different foods tested, including red meat, only one food elevated TMAO levels in the participants: seafood (see graph to right, from Chris Masterjohn’s article referenced below). This makes perfect sense since trimethylamine occurs naturally in seafood. Does this mean we should cut back on fish and shellfish because they’re going to give us a heart attack?(15)

Another obvious question we should ask is whether there are alternative explanations for why we see elevated TMAO levels in meat or seafood eaters (if indeed we do see them in a wide sample of meat eaters, which at least one earlier study didn’t support)? According to a 2011 article by Chris Masterjohn touching on TMAO in a different context: (16)

Elevated TMAO could reflect dietary trimethylamine or TMAO from seafood, but it could also reflect impaired excretion into the urine, or enhanced conversion of trimethylamine to TMAO in the liver.

The enzyme Fmo3 carries out this conversion, mainly in the liver, as reviewed here. There are a number of genetic variants affecting the activity of this enzyme, some of which appear only in certain ethnicities, and the enzyme also processes a number of drugs used to treat psychoses, infections, arthritis, gastro-esophageal reflux disease (GERD), ulcers, and breast cancer. Iron or salt overload may also increase the activity of the enzyme. TMAO could, then, be a marker for ethnicity, drug exposure, genetically determined drug efficacy, or other conditions.

As you can see, it’s overly simplistic to suggest that eating red meat causes elevated TMAO; there are many other factors at work.

But even if Paleo meat eaters have higher TMAO levels than vegans and vegetarians, we still don’t have evidence proving a causal relationship between TMAO and CVD. Once again, the supposed link between cholesterol and saturated fat and heart disease should serve as a reminder not to jump to hasty conclusions that unnecessarily deprive people of nutrient-dense, healthy foods. It is virtually impossible to control for all of the possible confounding factors, and the study we’re discussing in this article only further highlights this problem.

Conclusions

I’d like to end with an observation from the discussion section of the TMAO paper. The authors state:

Numerous studies have suggested a decrease in atherosclerotic disease risk in vegan and vegetarian individuals compared to omnivores; reduced levels of dietary cholesterol and saturated fat have been suggested as the mechanism explaining this decreased risk. Notably, a recent 4.8-year randomized dietary study showed a 30% reduction in cardiovascular events in subjects consuming a Mediterranean diet (with specific avoidance of red meat) compared to subjects consuming a control diet.

This might sound like damning evidence against red meat. However, when you look at Table One in Mediterranean Diet trial, you’ll find that the Mediterranean diet allowed more red meat than the control diet (a low-fat diet)! The Mediterranean Diet allowed for “one serving or less of red or processed meat per day“, whereas the low-fat diet only permitted “one serving or less of red or processed meat per week“. (You can see this for yourself. Click here to access the PDF version of the study, then scroll down to Table One.) Clearly this paper does not support the authors’ conclusion that red meat increases the risk of heart disease.

They also claim that vegan and vegetarian diets reduce the risk of atherosclerotic disease compared to omnivorous diets; but the studies they reference fail to adequately control for the “healthy user bias”.

The study I mentioned in the beginning of this article compared heart disease risk amongst omnivores and vegetarians that shop at health food stores (which is a big step toward reducing healthy user bias), and did not find a difference in deaths from heart disease, stroke or all causes.
If you read the media reports and full-text of this study, you might have noticed something interesting. The study itself, and even most of the media article about it, quite simply and without much fanfare stated that saturated fat and cholesterol have little to do with the supposed increase in heart disease observed with red meat consumption. Hold the press! Shouldn’t THAT be front-page news?!? Apparently not. Of course, they’re only willing to admit this publicly in the context of an article where they’re proposing yet another mechanism for how red meat will kill you.

Finally, the most remarkable and sad part of this for me is seeing just how deep most people’s fear and distrust of red meat is, even if they’ve been following a Paleo diet for a long time. The day after the TMAO study was published, I woke up to no fewer than 20 emails and the same number of Facebook messages and Tweets from people expressing concern that their choice to eat red meat might be killing them. It really is a testament to the power of brainwashing. Most of us grew up with the idea that red meat is harmful, and it’s perhaps not so easy to leave that behind—even when you think you have.

Chris Masterjohn is working on a detailed analysis of the data from this paper, which should be ready soon. I believe we may be seeing more “red meat is bad because of TMAO” studies in the near future, so as always, when you see a media report on such a study, take it with a heavy grain of salt (which, by the way, doesn’t cause high blood pressure in most people!).
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10 Lies and Misconceptions Spread by Mainstream Nutrition - Mercola

10 Lies and Misconceptions Spread by Mainstream Nutrition

by Joseph Mercola February 27, 2013

Story at-a-glance

• Many mainstream nutritionists are guilty of spreading dietary myths and misconceptions that lead to poor health outcomes. Here, I review 10 of the most widespread lies that have been refuted by science
• The National Academies’ Institute of Medicine recommends adults to get 45–65 percent of their calories from carbohydrates, 20–35 percent from fat, and 10–35 percent from protein. This is an inverse ideal fat to carb ratio that is virtually guaranteed to lead you astray and result in a heightened risk of chronic disease.
• Most people likely benefit from 50-70 percent of calories as healthful fats in their diet for optimal health, whereas you need very few carbohydrates to maintain good health. Although that may seem like a lot, fat is much denser and consumes a much smaller portion of your meal plate
• The low-fat myth may have done more harm to the health of millions than any other dietary recommendation as the resulting low-fat craze led to increased consumption of trans-fats, which we now know increases your risk of obesity, diabetes and heart disease – the very health problems wrongfully attributed to saturated fats
• Most people use artificial sweeteners to lose weight and/or because they’re diabetic and need to avoid sugar. Ironically, nearly all the studies that have carefully analyzed artificial sweeteners show that those who use artificial sweeteners actually gain more weight than those who consume caloric sweeteners. Studies have also revealed that artificial sweeteners can be worse than sugar for diabetics
• Fructose, soy, eggs, whole grains, milk, lunch meats, and genetically engineered foods are also victims of widespread misconceptions that threaten your health unless you get it “right”

There's no shortage of health myths out there, but I believe the truth is slowly but surely starting to seep out there and get a larger audience. For example, two recent articles actually hit the nail right on the head in terms of good nutrition advice.
Shape Magazine features a slide show on "9 ingredients nutritionists won’t touch,"¹ and authoritynutrition.com listed “11 of the biggest lies of mainstream nutrition."²
These health topics are all essential to get "right" if you want to protect your health, and the health of your loved ones, which is why I was delighted to see both of these sources disseminating spot-on advice. I highly recommend reading through both of them.
Here, I will review my own top 10 lies and misconceptions of mainstream nutrition – some of which are included in the two featured sources, plus a few additional ones I believe are important.

Lie # 1: 'Saturated Fat Causes Heart Disease'

As recently as 2002, the "expert" Food & Nutrition Board issued the following misguided statement, which epitomizes this myth:
"Saturated fats and dietary cholesterol have no known beneficial role in preventing chronic disease and are not required at any level in the diet."
Similarly, the National Academies’ Institute of Medicine recommends adults to get 45–65 percent of their calories from carbohydrates, 20-35 percent from fat, and 10-35 percent from protein. This is an inverse ideal fat to carb ratio that is virtually guaranteed to lead you astray, and result in a heightened risk of chronic disease.
Most people benefit from 50-70 percent healthful fats in their diet for optimal health, whereas you need very few, if any, carbohydrates to maintain good health... Although that may seem like a lot, fat is much denser and consumes a much smaller portion of your meal plate.
This dangerous recommendation, which arose from an unproven hypothesis from the mid-1950s, has been harming your health and that of your loved ones for about 40 years now.
The truth is, saturated fats from animal and vegetable sources provide the building blocks for cell membranes and a variety of hormones and hormone-like substances, without which your body cannot function optimally. They also act as carriers for important fat-soluble vitamins A, D, E and K. Dietary fats are also needed for the conversion of carotene to vitamin A, for mineral absorption, and for a host of other biological processes.
In fact, saturated is the preferred fuel for your heart! For more information about saturated fats and the essential role they play in maintaining your health, please read my previous article The Truth About Saturated Fat.

Lie # 2: 'Eating Fat Makes You Gain Weight'

The low-fat myth may have done more harm to the health of millions than any other dietary recommendation as the resulting low-fat craze led to increased consumption of trans-fats, which we now know increases your risk of obesity, diabetes and heart disease – the very health problems wrongfully attributed to saturated fats...
To end the confusion, it's very important to realize that eating fat will not make you fat!
The primary cause of excess weight and all the chronic diseases associated with it, is actually the consumption of too much sugar – especially fructose, but also all sorts of grains, which rapidly convert to sugar in your body. If only the low-fat craze had been a low-sugar craze... then we wouldn't have nearly as much chronic disease as we have today. For an explanation of why and how a low-fat diet can create the very health problems it's claimed to prevent, please see this previous article.

Lie # 3: 'Artificial Sweeteners are Safe Sugar-Replacements for Diabetics, and Help Promote Weight Loss'

Most people use artificial sweeteners to lose weight and/or because they’re diabetic and need to avoid sugar. The amazing irony is that nearly all the studies that have carefully analyzed their effectiveness show that those who use artificial sweeteners actually gain more weight than those who consume caloric sweeteners. Studies have also revealed that artificial sweeteners can be worse than sugar for diabetics.
In 2005, data gathered from the 25-year-long San Antonio Heart Study showed that drinking dietsoft drinks increased the likelihood of serious weight gain, far more so than regular soda.³ On average, each diet soft drink the participants consumed per day increased their risk of becoming overweight by 65 percent within the next seven to eight years, and made them 41 percent more likely to become obese. There are several potential causes for this, including:

• Sweet taste alone appears to increase hunger, regardless of caloric content.
• Artificial sweeteners appear to simply perpetuate a craving for sweets, and overall sugar consumption is therefore not reduced – leading to further problems controlling your weight.⁴
• Artificial sweeteners may disrupt your body's natural ability to "count calories," as evidenced in studies such as this 2004 study at Purdue University,⁵ which found that rats fed artificially sweetened liquids ate more high-calorie food than rats fed high-caloric sweetened liquids.

There is also a large number of health dangers associated with artificial sweeteners and aspartame in particular. I've compiled an ever-growing list of studies pertaining to health problems associated with aspartame, which you can find here. If you're still on the fence, I highly recommend reviewing these studies for yourself so that you can make an educated decision. For more information on aspartame, the worst artificial sweetener, please see my aspartame video.

Lie # 4: 'Your Body Cannot Tell the Difference Between Sugar and Fructose'

Of the many health-harming ingredients listed in the featured article by Shape Magazine – all of which you're bound to get in excess if you consume processed foods – fructose is perhaps the greatest threat to your health. Mounting evidence testifies to the fact that excess fructose, primarily in the form of high fructose corn syrup (HFCS), is a primary factor causing not just obesity, but also chronic and lethal disease. In fact, I am convinced that fructose is one of the leading causes of a great deal of needless suffering from poor health and premature death.
Many conventional health "experts," contend that sugar and fructose in moderation is perfectly okay and part of a normal "healthy" diet, and the corn industry vehemently denies any evidence showing that fructose is metabolically more harmful than regular sugar (sucrose). This widespread denial and sweeping the evidence under the carpet poses a massive threat to your health, unless you do your own research.
As a standard recommendation, I advise keeping your total fructose consumption below 25 grams per day. For most people it would also be wise to limit your fructose from fruit to 15 grams or less. Unfortunately, while this is theoretically possible, precious few people are actually doing that.
Cutting out a few desserts will not make a big difference if you're still eating a "standard American diet" – in fact, I've previously written about how various foods and beverages contain far more sugar than a glazed doughnut. Because of the prevalence of HFCS in foods and beverages, the average person now consumes 1/3 of a pound of sugar EVERY DAY, which is five ounces or 150 grams, half of which is fructose.
That's 300 percent more than the amount that will trigger biochemical havoc. Remember that is the AVERAGE; many actually consume more than twice that amount. For more details about the health dangers of fructose and my recommendations, please see my recent article Confirmed – Fructose Can Increase Your Hunger and Lead to Overeating.

Lie # 5: 'Soy is a Health Food'

The meteoric rise of soy as a "health food" is a perfect example of how a brilliant marketing strategy can fool millions. But make no mistake about it, unfermented soy products are NOT healthful additions to your diet, and can be equally troublesome for men and women of all ages. If you find this recommendation startling then I would encourage you to review some of the many articles listed on my Soy Index Page.
Contrary to popular belief, thousands of studies have actually linked unfermented soy to malnutrition, digestive distress, immune-system breakdown, thyroid dysfunction, cognitive decline, reproductive disorders and infertility – even cancer and heart disease.
Not only that, but more than 90 percent of American soy crops are genetically modified, which carries its own set of health risks.⁶ I am not opposed to all soy, however. Organic and, most importantly, properly fermented soy does have great health benefits. Examples of such healthful fermented soy products include tempeh, miso and natto. Here is a small sampling of the detrimental health effects linked to unfermented soy consumption:

Breast cancer	Brain damage	Infant abnormalities
Thyroid disorders	Kidney stones	Immune system impairment
Severe, potentially fatal food allergies	Impaired fertility	Danger during pregnancy and breastfeeding

Lie # 6: 'Eggs are a Source of Unhealthy Cholesterol'

Eggs are probably one of the most demonized foods in the United States, mainly because of the misguided idea implied by the lipid hypothesis that eating egg yolk increases the cholesterol levels in your body. You can forget about such concerns, because contrary to popular belief, eggs are one of the healthiest foods you can eat and they do not have a detrimental impact on cholesterol levels. Numerous nutritional studies have dispelled the myth that you should avoid eating eggs, so this recommendation is really hanging on by a very bare thread...
One such study⁷, conducted by the Yale Prevention Research Center and published in 2010, showed that egg consumption did not have a negative effect on endothelial function – a measure of cardiac risk – and did not cause a spike on cholesterol levels. The participants of the Yale study ate two eggs per day for a period of six weeks. There are many benefits associated with eggs, including:

One egg contains 6 grams of high quality protein and all 9 essential amino acids	Eggs are good for your eyes because they contain lutein and zeaxanthin, antioxidants found in your lens and retina. These two compounds help protect your eyes from damage caused by free radicals and avoid eye diseases like macular degeneration and cataracts	Eggs are a good source of choline (one egg contains about 300 micrograms), a member of the vitamin B family essential for the normal function of human cells and helps regulate the nervous and cardiovascular systems. Choline is especially beneficial for pregnant mothers as it is influences normal brain development of the unborn child
Eggs are one of the few foods that contain naturally occurring vitamin D (24.5 grams)	Eggs may help promote healthy hair and nails due to their high sulphur content	Eggs also contain biotin, calcium, copper, folate, iodine, iron, manganese, magnesium, niacin, potassium, selenium, sodium, thiamine, vitamin A, vitamin B2, vitamin B12, vitamin E and zinc

Choose free-range organic eggs, and avoid “omega-3 eggs” as this is not the proper way to optimize your omega-3 levels. To produce these omega-3 eggs, the hens are usually fed poor-quality sources of omega-3 fats that are already oxidized. Omega-3 eggs are more perishable than non-omega-3 eggs.

Lie # 7: 'Whole Grains are Good for Everyone'

The use of whole-grains is an easy subject to get confused on especially for those who have a passion for nutrition, as for the longest time we were told the fiber in whole grains is highly beneficial. Unfortunately ALL grains, including whole-grain and organic varieties, can elevate your insulin levels, which can increase your risk of disease. They also contain gluten, which many are sensitive to, if not outright allergic. It has been my experience that more than 85 percent of Americans have trouble controlling their insulin levels – especially those who have the following conditions:

• Overweight
• Diabetes
• High blood pressure
• High cholesterol
• Protein metabolic types

In addition, sub-clinical gluten intolerance is far more common than you might think, which can also wreak havoc with your health. As a general rule, I strongly recommend eliminating or at least restricting grains as well as sugars/fructose from your diet, especially if you have any of the above conditions that are related to insulin resistance. The higher your insulin levels and the more prominent your signs of insulin overload are, the more ambitious your grain elimination needs to be.
If you are one of the fortunate ones without insulin resistance and of normal body weight, then grains are fine, especially whole grains – as long as you don’t have any issues with gluten and select organic and unrefined forms. It is wise to continue to monitor your grain consumption and your health as life is dynamic and constantly changing. What might be fine when you are 25 or 30 could become a major problem at 40 when your growth hormone and level of exercise is different.

Lie # 8: 'Milk Does Your Body Good'

Unfortunately, the myth that conventional pasteurized milk has health benefits is a persistent one, even though it’s far from true. Conventional health agencies also refuse to address the real dangers of the growth hormones and antibiotics found in conventional milk. I do not recommend drinking pasteurized milk of any kind, including organic, because once milk has been pasteurized its physical structure is changed in a way that can actually cause allergies and immune problems.
Important enzymes like lactase are destroyed during the pasteurization process, which causes many people to not be able to digest milk. Additionally, vitamins (such as A, C, B6 and B12) are diminished and fragile milk proteins are radically transformed from health nurturing to unnatural amino acid configurations that can actually worsen your health. The eradication of beneficial bacteria through the pasteurization process also ends up promoting pathogens rather than protecting you from them.
The healthy alternative to pasteurized milk is raw milk, which is an outstanding source of nutrients including beneficial bacteria such as lactobacillus acidophilus, vitamins and enzymes, and it is, in my estimation, one of the finest sources of calcium available. For more details please watch the interview I did with Mark McAfee, who is the owner of Organic Pastures, the largest organic dairy in the US.
However, again, if you have insulin issues and are struggling with weight issues, high blood pressure, diabetes, cancer or high cholesterol it would be best to restrict your dairy to organic butter as the carbohydrate content, lactose, could be contribute to insulin and leptin resistance. Fermented organic raw dairy would eliminate the lactose issue and would be better tolerated. But if you are sensitive to dairy it might be best to avoid these too.

Lie # 9: 'Genetically Engineered Foods are Safe and Comparable to Conventional Foods'

Make no mistake about it; genetically engineered (GE) foods may be one of the absolute most dangerous aspects of our food supply today. I strongly recommend avoiding ALL GE foods. Since over 90 percent of all corn grown in the US is GE corn, and over 95 percent all soy is GE soy, this means that virtually every processed food you encounter at your local supermarket that does not bear the "USDA Organic" label likely contains one or more GE components. To avoid GE foods, first memorize the following list of well-known and oft-used GE crops:

Corn	Canola	Alfalfa (New GM crop as of 2011)
Soy	Cottonseed	Sugar derived from sugar beets

Fresh zucchini, crookneck squash and Hawaiian papaya are also commonly GE. It’s important to realize that unless you're buying all organic food, or grow your own veggies and raise your own livestock, or at the very least buy all whole foods (even if conventionally grown) and cook everything from scratch, chances are you're consuming GE foods every single day... What ultimate impact these foods will have on your health is still unknown, but increased disease, infertility and birth defects appear to be on the top of the list of most likely side effects. The first-ever lifetime feeding study also showed a dramatic increase in organ damage, cancer, and reduced lifespan.

Lie # 10: 'Lunch Meats Make for a Healthy Nutritious Meal'

Lastly, processed meats, which includes everything from hot dogs, deli meats, bacon, and pepperoni are rarely thought of as strict no-no’s, but they really should be, if you’re concerned about your health. Virtually all processed meat products contain dangerous compounds that put them squarely on the list of foods to avoid or eliminate entirely. These compounds include:

• Heterocyclic amines (HCAs): a potent carcinogen, which is created when meat or fish is cooked at high temperatures.
• Sodium nitrite: a commonly used preservative and antimicrobial agent that also adds color and flavor to processed and cured meats.
• Polycyclic Aromatic Hydrocarbons (PAHs): Many processed meats are smoked as part of the curing process, which causes PAHs to form.
• Advanced Glycation End Products (AGEs): When food is cooked at high temperatures – including when it is pasteurized or sterilized – it increases the formation of AGEs in your food. AGEs build up in your body over time leading to oxidative stress, inflammation and an increased risk of heart disease, diabetes and kidney disease.

This recommendation is backed up by a report commissioned by The World Cancer Research Fund⁸ (WCRF). The review, which evaluated the findings of more than 7,000 clinical studies, was funded by money raised from the general public, so the findings were not influenced by vested interests. It's also the biggest review of the evidence ever undertaken, and it confirms previous findings: Processed meats increase your risk of cancer, especially bowel cancer, and NO amount of processed meat is "safe." A previous analysis by the WCRF found that eating just one sausage a day raises your risk of developing bowel cancer by 20 percent, and other studies have found that processed meats increase your risk of:

• Colon cancer by 50 percent
• Bladder cancer by 59 percent
• Stomach cancer by 38 percent
• Pancreatic cancer by 67 percent

Processed meats may also increase your risk of diabetes by 50 percent, and lower your lung function and increase your risk of chronic obstructive pulmonary disease (COPD). If you absolutely want or need a hot dog or other processed meats once in awhile, you can reduce your risk by:

• Looking for "uncured" varieties that contain NO nitrates
• Choosing varieties that say 100% beef, 100% chicken, etc. This is the only way to know that the meat is from a single species and does not include byproducts (like chicken skin or chicken fat or other parts)
• Avoiding any meat that contains MSG, high-fructose corn syrup, preservatives, artificial flavor or artificial color

Ideally, purchase sausages and other processed meats from a small, local farmer who can tell you exactly what's in their products. These are just some of the health myths and misconceptions out there. There are certainly many more. The ones listed above are some of the most important ones, in my view, simply because they’re so widely misunderstood. They’re also critical to get "right" if you want to protect your health, and the health of your loved ones. For more great advise, please review the two featured sources.

Sources and References

• ¹ Shape Magazine, 9 Ingredients Nutritionists Won’t Touch
• ² Authoritynutrition.com February 11, 2013
• ³ UT Health Science Center June 14, 2005
• ⁴ Journal of the American Dietetic Association 1991 Jun;91(6):686-90.
• ⁵ International Journal of Obesity and Related Metabolic Disorders 2004 Jul;28(7):933-5
• ⁶ Huffington Post April 20, 2010
• ⁷ Nutrition Journal 2010 Jul 2;9:28
• ⁸ The World Cancer Research Fund (WCRF) Report

Copyright © 2013 Dr. Joseph Mercola

The Best of Joseph Mercola

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Three more studies that should make you skeptical of mainstream health advice - Kresser

Three more studies that should make you skeptical of mainstream health advice

 

 

For the last 50 years mainstream medical “authorities” have been hammering it into our heads that high cholesterol levels are dangerous and low cholesterol levels are desirable; that eating saturated fat is bad for us; and that a low-fat, high carbohydrate diet is healthy and helps people lose weight.

If you’re a new reader, you might be surprised to learn that there’s very little evidence to support these recommendations and plenty of evidence that contradicts them. Long ago I learned that if I wanted to live a long, healthy life it was in my best interest to ignore the dietary advice of the medical mainstream. And of course that’s why I started this blog – to share this information with all of you so you can make educated, and informed choices about your health.

Lately I’ve been encouraged by the number of studies being published that undermine the anti-fat, anti-cholesterol dogma we’ve been brainwashed with for so long. This is good news.

The bad news is that paradigm shifts do not happen overnight. It took half a century for researchers and doctors to convince people that eating toxic, highly processed, nasty-tasting vegetable oils was somehow better for them than eating traditional animal fats like butter and lard; that eating dry bagels, boneless-skinless chicken breast and salad with fat-free dressing was a path to good health; and that the best way to lose weight was to eat a highly unnatural diet high in processed, refined carbohydrates and low in fat.

So I don’t expect these ideas to disappear anytime soon, in spite of the solid evidence being published that contradicts them. It’s going to take time. But my sense is that it will take less time to convince people that eating traditional, nutrient-dense, whole foods that have been minimally processed is better for them than eating what the industrial food conglomerates have been selling us.
Here are the three studies.

The first is yet another study that associates low cholesterol with an increase in the risk of death (total mortality). It showed increased death rates in hospitalized patients with low cholesterol levels.

CONCLUSIONS: In our cohort, lower LDL-cholesterol at admission was associated with decreased 3-year survival in patients with NSTEMI.

This shouldn’t be a surprise. There’s already plenty of evidence suggesting low cholesterol increases the risk of death – as well as contributing to other conditions such as cancer and depression. For more on this see my previous article Cholesterol Doesn’t Cause Heart Disease.

The second study shows (once again) that cutting carbs is the best way to lose weight and fight obesity.

No surprise here either. Countless studies, trials and reviews have demonstrated that low-carb diets are superior for weight loss, managing diabetes and preventing many of the other modern diseases which plague us. How long will it take until doctors and the media get the message? For more on one such recent review, see Low-carb Diet Best for Weight Loss.

The last study I want to share with you was performed by a Swedish PhD student. It demonstrates that children who eat saturated fat and full-cream dairy products are healthier than those who do not.

Conclusions: BMI correlated strongly to fat mass and leptin was the best marker of overweight and fat mass in 8-year-olds. Food choice was similar to that at 4 years of age. An intake of fat fish once a week was associated with higher serum concentrations of n-3 fatty acids. Saturated fat and intake of full fat milk were inversely associated with BMI. Serum phospholipid fatty acids were associated with bone mineralisation. The results for metabolic markers may provide preliminary reference intervals in healthy children.

If you’re surprised by this, read my recent post Have Some Butter with Your Veggies as well as Whole Fat Milk: Benefits for Moms and Kids.

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Read the complete article here.

The most important thing you probably don’t know about cholesterol

Summary:

• The simplified view of cholesterol as “good” (HDL) or “bad” (LDL) has contributed to the continuing heart disease epidemic
• Not all LDL cholesterol is created equal. Only small, dense LDL particles are associated with heart disease, whereas large, buoyant LDL are either benign or may protect against heart disease.
• Replacing saturated fats with carbohydrates – which has been recommended by the American Heart Association for decades – reduces HDL and increases small, dense LDL, both of which are associated with increased risk of heart disease.
• Dietary cholesterol has a negligible effect on total blood LDL cholesterol levels. However, eating eggs every day reduces small, dense LDL, which in turn reduces risk of heart disease.
• The best way to lower small, dense LDL and protect yourself from heart disease is to eat fewer carbs (not fat and cholesterol), exercise and lose weight.

Read the full article here

Krauss is in the HOUSE: 'Low-fat Message Was a MISTAKE'

"Everybody I know in the field -- e v e r y b o d y -- recognized that a simple low-fat message was a mistake," says Dr. Krauss, as interviewed in the latest Men's Health magazine, see below. Why is Men's Health interviewing Krauss?! What is this revolutionary MH reporter saying? Don't. S-W-A-L-L-O-W . . . ! ? ? *haa!!* Men's Health, Your Unstoppable Heart: Before you swallow what your doctor prescribes, we suggest you read this article By: Paul Scott CHOLESTEROL IS A NATURAL SUBSTANCE your body produces for a variety of uses. It is carried through the body in three containers -- LDL, HDL, and VLDL -- that deliver it to cells along with triglycerides. The average man reasons that the cholesterol in his scrambled eggs must surely end up in his arteries somehow, and this makes him do things like order egg-white omelets for breakfast. There is indeed a link between the cholesterol you eat and the cholesterol in your arteries. It's just not the "eat more, have more" worry that's been drummed into you for years. In fact, your body's production and uptake of cholesterol is highly regulated; eat a six-egg omelet and your body simply produces less cholesterol because of the dietary onslaught. "There is a very weak connection between the LDL cholesterol we measure and dietary cholesterol," Dr. Krauss says. "I spend a lot of time talking to reporters and trying to explain that dietary cholesterol is not the same as blood cholesterol." He adds that the 200 milligrams of cholesterol most people eat every day is NOTHING compared with the 800 milligrams their bodies produce [my EMPHASIS]. But you don't have to take his word for it. "It is now acknowledged that the original studies purporting to show a linear relation between cholesterol intake and coronary heart disease may have contained fundamental study design flaws," wrote the author of a recent review in the International Journal of Clinical Practice. [ HERE . Jones PJ citing Hu et al] The author suggests to lower small dense LDL, the actual heart disease culprit Targeting the Killer LDL Small changes, fewer small particles "Small, dense particles of LDL are much more inflammatory than larger particles," says Paul Ziajka, M.D., Ph.D., a clinical lipidologist with the Southeast Lipid Association. Here's how to snuff the little devils. Crack an egg Down an omelet every morning and you may lower your small-particle count, University of Connecticut researchers recently found. People who ate three whole eggs a day for 12 weeks dropped their small-LDL levels by an average of 18 percent. Choose your meds wisely A class of drugs known as fibrates, which includes Tricor, specifically targets small, dense LDL, says Dr. Ziajka. The effect is significant only when your triglycerides are also elevated, he says. [Note: no statin mentioned...*haa*; actually low carb, sat fats and fish oil omega-3 work far FAR better than fibrates, PPAR drugs] Pop some niacin "Most drugs shift particle size after the cholesterol is made," Dr. Ziajka says. "Niacin causes the liver to produce larger particles." Try a no-flush variety (Dr. Ziajka recommends Slo-Niacin) starting with 500 milligrams a day and building to 2,000. There are side effects, so talk to your doctor first. [Note: no-flush doesn't work; slo-niacin is a lower-flush type of niacin] Lighten your load Deflating your spare tire may reduce your small, dense LDL cholesterol, say scientists at Children's Hospital Oakland Research Institute. The majority of overweight men who were pattern B (mostly small LDL) switched to pattern A (mostly large LDL) after they lost an average of 19 pounds. Have a glass That nightly beer does more than relax you -- it may also lower your small, dense LDL, a recent Journal of Clinical Endocrinology Metabolism study found. Men who drank 7 to 13 alcoholic drinks a week had 20 percent fewer small-LDL particles than men who didn't drink at all. [Note: beer aint paleo] Previous animal pharm: Men's Health interview with Mozzafarian MD on benefits of dietary saturated fats Read more about Krauss et al's newest research that redeems the role of saturated fats at my fave peeps and playgrounds: Tourgeman, holymoly ur so funny Nephropal Seth Roberts my Berkeley bud... Animal Fat Peter Hyperlipid Stephan WholeHealthSource Don Primal Wisdom Chris Masterjohn Daily Lipid Dr. Mike Eades THANKGODFORYOURSANENESS

No-Bologna Facts from Tom Naughton

No-Bologna Facts

• There’s never been a single study that proves saturated fat causes heart disease.
• As heart-disease rates were skyrocketing in the mid-1900s, consumption of animal fat was going down, not up. Consumption of vegetable oils, however, was going up dramatically.
• Half of all heart-attack victims have normal or low cholesterol. Autopsies performed on heart-attack victims routinely reveal plaque-filled arteries in people whose cholesterol was low (as low as 115 in one case).
• Asian Indians - half of whom are vegetarians - have one of the highest rates of heart disease in the entire world. Yup, that fatty meat will kill you, all right.
• When Morgan Spurlock tells you that a McDonald’s salad supplies almost a day’s allowance of fat, he’s basing that statement on the FDA’s low-fat/high-carbohydrate dietary guidelines, which in turn are based on … absolutely nothing. There’s no science behind those guidelines; they were simply made up by a congressional committee.
• Kids who were diagnosed as suffering from ADD have been successfully treated by re-introducing natural saturated fats into their diets. Your brain is made largely of fat.
• Many epileptics have reduced or eliminated seizures by adopting a diet low in sugar and starch and high in saturated animal fats.
• Despite everything you’ve heard about saturated fat being linked to cancer, that link is statistically weak. However, there is a strong link between sugar and cancer. In Europe, doctors tell patients, “Sugar feeds cancer.”
• Being fat is not, in and of itself, bad for your health. The behaviors that can make you fat - eating excess sugar and starch, not getting any exercise - can also ruin your health, and that’s why being fat is associated with bad health. But it’s entirely possible to be fat and healthy. It’s also possible to be thin while developing Type II diabetes and heart disease.
• Saturated fat and cholesterol help produce testosterone. When men limit their saturated fat, their testosterone level drops. So, regardless of what a famous vegan chef believes, saturated fat does not impair sexual performance.

My Thanks To The Dietary Guidelines Committee

This is not about heart disease (or maybe it is indirectly?) I believe there is a strong connection between heart disease (and other diseases as well ) and diet. This article is about diet! Thanks Tom!

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My Thanks To The Dietary Guidelines Committee from Fat Head by Tom Naughton




Dear Members of the USDA Dietary Guidelines Committee:


I’m writing to thank you and all the members of the previous committees for your tireless work on the USDA’s dietary guidelines. You’ve made my job as a parent quite a bit easier.


I came to that conclusion yesterday when my wife and I joined our seven-year-old for lunch in her school cafeteria. My wife sends our girls to school with lunches she packs at home … usually some kind of meat or meaty stew accompanied by cheese sticks, carrots, apple slices, or olives. She also puts small bottles of water in their lunchboxes.


Most of the other kids eat lunches prepared in the cafeteria, which of course is required to follow the USDA guidelines. Yesterday’s government-approved lunch consisted of chicken nuggets (battered and deep-fried in vegetable oil), macaroni and cheese, mandarin oranges in some kind of syrup, and a drink. Some kids chose juice boxes for their drinks, others chose 1% or 2% milk, but the most popular choice was the 1% chocolate milk.


Naturally, I was horrified to see kids eating a meal consisting primarily of processed grains and sugar, and only slightly less horrified to realize that the meal was nearly devoid of natural fats. When I observed how many kids seemed to prefer the chocolate milk, my wife informed me that since the new USDA guidelines call for restricting fat even more, the school will soon limit its milk offerings to 1% white milk, skim white milk, and skim chocolate milk.


That’s when I realized what a huge favor you’ve done me.


Like any other father, I want my kids to succeed in life. I want them to win scholarships, attend the best colleges, and excel in whatever fields they choose to study. According to their teachers, they’re both bright girls. However, their school district is the highest-ranked in Tennessee and also one of the higher-ranked districts in the country, which means there are a lot of other bright kids in their classes. The competition to win scholarships some years from now ought to be fierce — but I don’t think it will be, at least not by the time my girls are in high school.


In an otherwise equal competition, there are two ways to gain an advantage: make yourself stronger, or find a way to weaken your opponents. We’re helping our daughters become as strong and as smart as we possibly can, but that may not be enough. Luckily for us, your dietary guidelines will simultaneously weaken the competition … sort of like a federally-funded Tonya Harding conspiring to give a whack to Nancy Kerrigan’s knees.


A growing human brain needs plenty of natural saturated fat and cholesterol, which is why Mother Nature was smart enough to put rather a lot of both in breast milk. Unlike their classmates, my girls have no idea what skim milk tastes like, because we never buy any. In fact, my daughters sometimes ask for extra cream in their whole milk, and we give it to them. They also eat lots of Kerry Gold butter, egg yolks, bacon fat, and marrow fat whenever my wife makes a stew.


Your committee and the previous committees have scared most parents away from serving kids these amazingly nutritious foods, which means my girls will have an advantage in cognitive development — especially now that you’ve instructed schools to remove what little natural fat was left in the milk. It may take some time for the difference in cognitive development to manifest, but the high concentrations of grains and fructose in the government-approved meals are already working to our benefit. While my girls are both alert and calm in class, other kids are already exhibiting signs of hyperactivity or difficulty concentrating.


When my seven-year-old was a toddler, she had occasional play dates with a boy her age who struck me as bright at the time. The boy’s mother served him fruit-spread sandwiches and juice for lunch and proudly informed us that she kept the boy on a low-fat diet. We learned recently that the boy — now a seven-year-old — is in a special class at school because he’s been diagnosed with attention deficit disorder. Multiply him by several million, and you can see why I’m confident your dietary guidelines are giving my daughters a leg up on the academic competition. I don’t expect all kids who follow your recommended diet to be quite so hampered, but frankly, even a minor deceleration in cognitive growth will push my girls that much higher on the curve.


And if for some reason my daughters don’t reach the top academically, I think it’s possible they’ll nonetheless surpass their peers physically and win some kind of athletic scholarship. The kids in my daughter’s second-grade class are all lean at this point, but when I looked over to where the fifth-graders were eating, I saw several examples of what just a few extra years of a government-approved diet can accomplish. It’s kind of depressing to see 11-year-old girls with pretty faces and protruding bellies, but when I reminded myself that young women with fatty livers aren’t going to beat my daughters out of starting positions on the college track or basketball teams, my spirits were lifted.


So again, my sincere thanks for all the work you put into the 2010 Dietary Guidelines. I don’t know how much interaction you have with similar committees in other countries, but I urge you to do whatever you can to promote these guidelines around the world. After all, my girls will someday need to compete in a global economy.
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Please visit Tom's web site if you like what you read here. He's got lots of insite.
http://www.fathead-movie.com/

European Heart Journal on "Low Fat/Low Cholesterol"

I came across this article from the European Heart Journal with evidence from clinical trials about the so called heart healthy diet. It can be found on line at http://www.omen.com/corr.html. I reduced the text size of the 'Reference' section not because that information is less important rather to save some space. In fact the #1 principal to defend against junk science (as found in "The Junk Science Self-Defense Manual" by Anthony Colpo) is to 'Check the research yourself!'.

Here's a quote from that publication.

"I’ve lost count of the number of times I’ve checked studies that were cited in support of a specific stance, and found they either did not support that stance or even contradicted it!

A striking example of this phenomenon can be found in a joint statement by the American Heart Association and the NIH's National Heart, Lung, and Blood Institute entitled The Cholesterol Facts, where one finds the following claim: "The results of the Framingham study indicate that a 1% reduction…of cholesterol [corresponds to a] 2% reduction in CHD risk"[1].

Incredibly, one of the papers cited in support of the above statement was a thirty-year follow-up report from Framingham that flatly contradicts any claim that cholesterol reduction is beneficial. This report found that those whose cholesterol levels decreased during the study experienced an increase in both total and cardiovascular mortality! To quote the Framingham researchers themselves: "There is a direct association between falling cholesterol levels over the first 14 years and mortality over the following 18 years…". So don’t be satisfied with the fact that someone has posted a bunch of scientific-looking citations at the end of their article. Check those citations for yourself! Doing so will often paint a very different picture to the one the original author wants you to see!"

Well enough intro - on to the article that prompted this post.
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The low fat/low cholesterol diet is ineffectiveReprinted with permission from: European Heart Journal (1997) 18, 18-22
L.A. Corr, Guy's and St. Thomas' Hospitals, London, U.K. M.F. Oliver, National Heart and Lung Institute, London, U.K.
Correspondence: Dr. Laura A. Corr, MB, BS, MRCP, PhD, FESC,Consultant Cardiologist, Guys and St. Thomas' Hospitals, St. Thomas Street, London SE1 9RTAsk almost member of the general public about a diet which would reduce their chance of heart disease and the reply is the same: "a low fat diet". On closer questioning, this means a diet with a reduction in cholesterol and saturated 'animal' fats, i.e. less meat, butter, milk and cheese. Most national and international recommendations for the prevention of heart disease, whether for primary prevention of or for patients who have developed the clinical manifestations of coronary heart disease, have made dietary restriction of total and saturated fats and of cholesterol the primary advice and often the sine qua non in relation to all other forms of management. To this extent they are to be congratulated that the message seems to be so universally accepted. Unfortunately, the available trials provide little support for such recommendations and it may be that far more valuable messages for the dietary and non-dietary prevention of coronary heart disease are getting lost in the immoderate support of the low fat diet.

The origin of the 'low fat' diet

The international bodies which developed the current recommendations based them on the best available evidence[1-3]. Numerous epidemiological surveys confirmed beyond doubt the seminal observation of Keys in the Seven Countries Study of a positive correlation between intake of dietary fat and the prevalence of coronary heart disease[4] although recently a cohort study of more than 43,000 men followed for 6 years has shown that this is not independent of fiber intake[5] or risk factors. The prevalence of coronary heart disease has been shown to be correlated with the level of serum total and low density lipoprotein cholesterol (LDL) as well as inversely with high density lipoprotein. As a consequence of these studies, it was assumed that the reverse would hold true: reduction in dietary total and especially saturated fat would lead to a fall in serum cholesterol and a reduction in the incidence of coronary heart disease. The evidence from clinical trials does not support this hypothesis.

The evidence from clinical trials

It can be argued that it is virtually impossible to design and conduct an adequate dietary trial. The alteration of any one component of a diet will lead to alterations in others and often to further changes in lifestyle so it is extremely difficult to determine which, if any, of these produce an effect. Dietary trials cannot generally be blinded and changes in the diet of the 'control' population are frequently seen: they may be so marked as to render the study irrevocably flawed. It is also recognized that adherence to dietary advice over many years by large population samples, as for most people in real life, is poor and that the stricter the diet, the worse the compliance. Nonetheless, the evidence for a reduction in saturated fat from dietary trials for both primary and secondary prevention merits closer scrutiny.

Trials of low fat diets in primary prevention

There have been six randomized, controlled trials with the long-term follow-up designed to modify the development of coronary heart disease in healthy subjects [6-11]. Remarkably, no primary prevention trial of sufficient size or sensitivity to examine the effect of a low total and saturated fat diet alone has ever been conducted. All six primary prevention trials involved alteration of one or more other risk factors such as cigarette smoking, blood pressure and exercise.

Of the three smallest trials(approximately 300-600 subjects per group), two suggested a significant reduction in coronary events. In the Oslo Study[7], men at high risk were given dietary advice aimed at reducing saturated fat intake and modestly increasing polyunsaturated fat intake, and counseled to stop smoking. General advice was given to increase fish, whale meat, vegetable and fruit intake. Over 5 years the mean difference in serum cholesterol between the two groups was relatively large for a dietary trial - 13% and tobacco consumption was lower in the intervention group. There were fewer coronary events in the control group (P<0.028)Trials of low fat diets in secondary prevention
There have been two trials of the effect of a low saturated fat diet alone in patients with coronary heart disease. The MRC study[13] followed 252 men randomized to a very low fat diet or no change in diet over three years: the low fat diet was poorly tolerated but achieved a 10% reduction in cholesterol. There was no difference in the rate of reinfarction or death and the researchers concluded that the low fat has no place in the treatment of myocardial infarction. An Australian trial of 458 men substituted polyunsaturated margarine for butter and found a slightly lower 5 year survival in the intervention group (3.3% deaths per year) than in the control group (2.4% deaths per year) although multivariate analysis showed that none of the dietary factors was significantly related to survival[14]. Following the negative results of these trials, no further studies of a low saturated fat diet alone have been conducted.

Should we be recommending diet at all?

The overwhelming importance of coronary heart disease in terms of morbidity, mortality and economic cost in the Western world made dietary advice, which was perceived to be cheap and safe, very attractive to Governments and their Health Departments. Vast sums of money have been invested in nutritional programs, dietary advice and nurse counseling to promote low saturated fat, low cholesterol diet--yet the trials to date for both primary and secondary prevention suggest that these diets do not work. However, this does not mean that all dietary interventions are futile. Other trials of secondary prevention have to a greater or lesser extent tried to alter the quality of the dietary fat intake and other components in patients with coronary heart disease, rather than restrict the quantity of saturated and total fat, and the results are more encouraging.

Trials of diets not dependent on fat reduction

Vegetable oil supplements were used in four of these trials[15-18]. In the LA Veterans Administration study, increasing ingestion of corn, safflower, soyabean and cottonseed oils significantly reduced total cardiovascular events after eight years[15]. The study by Rose et al, found no evidence of clinical benefit in patients given a low fat diet and supplements of olive or corn oil[16]. Similarly, the MRC group added soyabean oil as a supplement to the diet and found no difference in the incidence of death or myocardial infarction compared to men taking their normal diet[17], but a similar study from Oslo did show a significant reduction in pooled coronary heart disease relapses after 5 years and fewer fatal myocardial reinfarctions by 11 years[18]. However, none of these produced a significant difference in total mortality.

Saturated fat reduction, vegetable oil supplements and lifestyle changes in keeping with the current recommendations of the American Heart Association were advised for both the intervention and control groups in a study of Indian patients randomized within 48 h of a suspected myocardial infarction, but in addition the intervention group received a diet high in dietary fiber, omega-3 fatty acids (from fish and nuts), antioxidant vitamins and minerals[19]. The intervention group achieved remarkable wide-ranging and sustained changes in their nutrient intake associated with a modest reduction in serum cholesterol and weight loss. Cardiovascular events were reduced in the intervention group after only 6 weeks and after 1 year there was a significant reduction in myocardial infarction, a 42% reduction in cardiac deaths and a 45% reduction in total mortality compared to the control group on the standard 'low fat' diet. The study does not seem to have been continued beyond on year.

The first successful dietary study to show reduction in overall mortality in patients with coronary heart disease was the DART study reported in 1989[20]. The three-way design of this 'open' trial compared a low saturated fat diet plus increased polyunsaturated fats, similar to the trials above, with a diet including at least two portions of fatty fish or fish oil supplements per week, and a high cereal fibre diet. No benefit in death or reinfarctions was seen in the low fat or the high fibre groups. In the group given fish advise there was a significant reduction in coronary heart disease deaths and overall mortality was reduced by about 29% after 2 years, although there was a non-significant increase in myocardial infarction rates. The reduction in saturated fats in the fish advice group was less than in the low fat diet group and there was no significant change in their serum cholesterol.

Finally, the more recent Lyon trial[21] used a Mediterranean-type of diet with a modest reduction in total and saturated fat, a decrease in polyunsaturated fat and an increase in omega-3 fatty acids from vegetables and fish. As in the DART study there was little change in cholesterol or body weight, but the trial was stopped early following a 70% reduction in myocardial infarction, coronary mortality and total mortality after 2 years.

The most effective diet for secondary prevention is therefore not reduction of saturated fats and cholesterol but appears to be an increase in polyunsaturates of both omega-6 and omega-3 fatty acids. Unfortunately, the design and conduct of these trials are insufficient to permit conclusions about which polyunsaturates and other elements of these diets are the most beneficial. The long term effects of these trials[20,21] and the compliance with the dietary regimes remain to be seen. But the mechanism of any benefit of the omega diets would appear not to be associated with reduction in the total or LDL cholesterol levels and may be more related to reduction of a thrombotic tendency.

The case for recommending similar changes in diet in primary prevention is less clear cut. Although the benefit of olive oil receives strong epidemiological support from several Mediterranean countries, particularly Crete, and short-term studies of diets rich in oleic acid (the principle monounsaturate in our diet) have demonstrated a reduced LDL susceptibility to oxidation, no formal randomized long-term trial of monounsaturates has yet been attempted. There is no consensus from population or cohort follow up surveys about the protective effects of increased fish consumption on coronary mortality. The recently published report from the physicians Health study[22] found no evidence of an inverse association between the intake of fish or fish oils and the risk of myocardial infarction and, while the highest coronary mortality was found among men who ate no fish, the risk did not decrease with increasing fish intake. At present, there does not appear to be any dietary advice which is effective in primary prevention.

Is drug treatment better?

An important aspect of the lipid-lowering dietary trials is that on average they were only able to achieve about a 10% reduction in total cholesterol. The results of recent drug trials have demonstrated that there is a linear relation between the extent of the cholesterol, or LDL, reduction and the decrease in coronary heart disease mortality and morbidity, and a significant effect seen only when these lipids are lowered by more than 25%[23].

Until 1994, the trials with lipid lowering therapy for primary and secondary prevention had been as disappointing and confusing as the trials with diet. They tended to show a reduction in coronary events, including deaths from myocardial infarction, but no reduction in overall mortality. Even though an excess of deaths from cancer and suicide was not shown to have any casual relationship with the treatment, there was no widespread acceptance of lipid lowering therapy.
This changed in 1994 with the publication of the seminal 4S study on secondary prevention of coronary heart disease in 4444 patients with cholesterol levels greater than 5.5 mmol . 1-1 who were randomized to treatment with simvastatin or placebo in addition to 'usual care' including dietary advice[24]. The 4S study showed highly significant (30%) reduction in cardiac events and deaths from myocardial infarction and, for the first time, in overall mortality. The benefits were apparent after 18 months and the difference between the treated and the control groups continued to increase over the five years of follow-up. The more recent CARE study showed a similar outcome with a 28% reduction in reinfarction using pravastatin in 4159 patients following myocardial infarction despite the fact their cholesterol levels before treatment were not high (mean 5.4 mmol . 1-1)[25]. As part of their usual care, patients in this study also received high levels of antiplatelet agents and beta-blockers and 55% had undergone revascularization with angioplasty or bypass surgery. There was no change in coronary heart disease deaths or in all-cause mortality. Over 5 years of follow-up in both these statin trials the treatment was extremely well tolerated with around 90% compliance and no serious effect, indeed there was almost no difference in the side-effect profiles between the statins and the placebo.

With primary prevention the results of treatment with the statins appears equally encouraging. The West of Scotland Coronary Prevention study treated over 6000 healthy men (aged 44-65 years) who had total cholesterol levels greater than 6.5 mmol . 1-1 with either pravastatin or placebo[26]. Again the trial was continued for 5 years, and normal advice was given to both the intervention and the control groups. The risks of death from coronary heart disease and non-fatal myocardial infarction were reduced significantly in the pravastatin group by 31%, and there was a non-significant but favourable trend for all-cause mortality (-22%) with no adverse effect on non-cardiovascular mortality.

The cost effectiveness of treatment with the statins has been assessed at current prices for both primary and secondary care. It varies greatly according to the risk, being obviously more efficient for those at the highest risk, but has been shown to be greater than drug treatment for mild-to-moderate hypertension which is widely endorsed and used in general practice. For those at lower risk, diet should be able to provide a cheaper regimen but at present none has proved sufficiently beneficial.

Conclusions

The commonly-held belief that the best diet for the prevention of coronary heart disease is a low saturated fat, low cholesterol is not supported by the available evidence from clinical trials. In the primary prevention, such diets do not reduce the risk of myocardial infarction or coronary or all cause mortality. Cost-benefit analyses of the extensive primary prevention programmes, which are at present vigorously supported by Governments, Health Departments and health educationalists, are urgently required.

Similarly, diets focused exclusively on reduction of saturated fats and cholesterol are relatively ineffective for secondary prevention and should be abandoned. There may be other effective diets for secondary prevention of coronary heart disease but these are not yet sufficiently well defined or adequately tested. The circumstantial evidence of benefit from oils, particularly olive oil, vegetables, fruit and fish is strong.

For those at high risk, drug therapy, with the statins provides effective primary and secondary prevention and should be considered, with or without a diet, in the same way as drug treatment for mild or moderate hypertension.L.A. Corr, Guy's and St. Thomas' Hospitals, London, U.K.
M.F. Oliver, National Heart and Lung Institute, London, U.K.

References
[1] Diet and cardiovascular disease (COMA Report) 1984, Report on health and social subjects-28, DHSS, HMSO.
[2] National Cholesterol Education Program Expert Panel on detection, evaluation and treatment of high blood cholesterol in adults. First report - Arch Int Med 1988: 148:36-39, Second report - Circulation 1994: 89: 1329-445.
[3] Pyorala K, De Backer G, Poole-Wilson P, Wood D. Prevention of coronary heart disease in clinical practice. Recommendations of the Task Force of the European Society of Cardiology, European Atherosclerosis Society and European Society of Hypertension. Eur Heart J 1994: 15: 1300-331
[4] Keys A. Seven Countries, A multivariate analysis of diet and coronary heart disease. Cambridge and London: Harvard University Press, 1980.
[5] Ascherio A, Rimm EB, Giovannucci EL, et al. Dietary fat and risk of coronary heart disease in men: cohort follow up study in the United States, BMJ 1996: 313: 84-90.
[6] Turpenien O, Karvonen MJ, Pekkarinen M, et al. Dietary prevention of coronary heart disease: the Finnish Mental Hospital Study, Int J Epidemiol 1979: 8: 99-118.
[7] Hjermann I, Velve Byre K, Holme I, Leren P. Effect of diet and smoking in the incidence of coronary heart disease. Lancet 1981: ii: 1303-10
[8] Strandberg TE, Salomaa VV, Naukkarinen VA, et al. Longterm mortality after 5 year multifactorial primary prevention of cardiovascular diseases in middle-aged men. JAMA 1991: 266: 1229-9.
[9] Franz D, Dawson EA, Ashman PL, et al. Test of effect of lipid lowering by diet on cardiovascular risk. The Minnesota Coronary Survey, atherosclerosis 1989: 9: 129-35.
[10] World Health Organization European Collaborative Group, European collaborative trial of multifactorial prevention of coronary heart disease. Lancet 1986: 1: 869-72.
[11] Neaton JD, Blackburn H, Jacobs D, et al. Serum cholesterol level and mortality: findings for men screened in the Multiple Risk Factor Intervention Trial. Arch Int Med 1992: 152: 1490-500.
[12] The Multiple Risk Factor Intervention Trial Research Group. Mortality after 16years for participants randomized to the Multiple Risk Factor Intervention Trial. Circulation 1996: 94: 946-51.
[13] Research Committee to the Medical Research Council. Low fat diet in myocardial infarction. A controlled trial Lancet 1965: ii: 501-4.
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