This is an article from a well respected, articulate and intelligent blogger from the Paleosphere, Chris Kresser. I have several issues with the content and as such I decided to reply as noted. I do not pretend to be on the same level as Chris Kresser. All I wish is to keep the argument based on the facts. If I am wrong I will gladly accept it, since my only desire is to find the best dietary pattern that fits most of us. I respect Chris Kresser and continue to keep an open mind to anything he says. I am in no way trying to attack him in any way shape or form! Accuracy of facts is the only goal. I will not get caught up in blogosphere drama! That is not conducive to anything positive or of benefit to anyone! My comments are in red.
It’s hard to overstate the impact that cardiovascular disease (CVD) has in the U.S.. Consider the following:
- Cardiovascular disease affects 65 million Americans.
- Close to one million Americans have a heart attack each year.
- In the U.S., one person dies every 39 seconds of cardiovascular disease.
- 1 of 3 deaths that occurs in the U.S. is caused by cardiovascular disease.
- 1 in 3 Americans have metabolic syndrome, a cluster of major cardiovascular risk factors related to overweight/obesity and insulin resistance.
- The total cost of cardiovascular disease in 2008 was estimated at $300 billion.
To put that last statistic in perspective, the World Health Organization has estimated that ending world hunger would cost approximately $195 billion. One might argue that the $300 billion we spend on treating cardiovascular disease in the U.S. is a necessary expenditure; however, a recent study which looked at the relationship between heart disease and lifestyle suggested that 90% of CVD is caused by modifiable diet and lifestyle factors. (1)
Unfortunately, cardiovascular disease is one of the most misdiagnosed and mistreated conditions in medicine. We’ve learned a tremendous amount about what causes heart disease over the past decade, but the medical establishment is still operating on outdated science from 40-50 years ago.
In this 4-part series, I’m going to debunk 3 common myths about heart disease:
- Eating cholesterol and saturated fat raises cholesterol levels in the blood.
- High cholesterol in the blood is the cause of heart disease.
- Statins save lives in healthy people without heart disease.
In the fourth and final article in the series, I’ll discuss strategies for naturally protecting yourself against heart disease.
Myth #1: Eating cholesterol and saturated fat raises cholesterol levels in the blood.
Most of us grew up being told that foods like red meat, eggs and bacon raise our cholesterol levels. This idea is so deeply ingrained in our cultural psyche that few people even question it. But is it really true?
The diet-heart hypothesis—which holds that eating cholesterol and saturated fat raises cholesterol in our blood—originated with studies in both animals and humans more than half a century ago. However, more recent (and higher quality) evidence doesn’t support it. What evidence is that?
On any given day, we have between 1,100 and 1,700 milligrams of cholesterol in our body. 25% of that comes from our diet, and 75% is produced inside of our bodies by the liver. Much of the cholesterol that’s found in food can’t be absorbed by our bodies, and most of the cholesterol in our gut was first synthesized in body cells and ended up in the gut via the liver and gall bladder. The body tightly regulates the amount of cholesterol in the blood by controlling internal production; when cholesterol intake in the diet goes down, the body makes more. When cholesterol intake in the diet goes up, the body makes less. True!
This explains why well-designed cholesterol feeding studies (where they feed volunteers 2-4 eggs a day and measure their cholesterol) show that dietary cholesterol has very little impact on blood cholesterol levels in about 75% of the population. The remaining 25% of the population are referred to as “hyper-responders”. In this group, dietary cholesterol does modestly increase both LDL (“bad cholesterol” and HDL (“good cholesterol”), but it does not affect the ratio of LDL to HDL or increase the risk of heart disease. (2) “Although higher plasma levels of low-density lipoprotein cholesterol are associated with an increased risk of coronary disease and lipid-lowering therapy has been shown to reduce the risk of cardiovascular disease, the relation between dietary cholesterol and the risk of CHD is not clearly understood. This article reviews the current evidence on the association between dietary cholesterol and the risk of CHD.” This is from the citation. I could not find it online however I do not see anywhere in the abstract anything to indicate what the author so convincingly states.
In other words, eating cholesterol isn’t going to give you a heart attack. You can ditch the egg-white omelettes and start eating yolks again. That’s a good thing, since all of the 13 essential nutrients eggs contain are found in the yolk. Egg yolks are an especially good source of choline, a B-vitamin that plays important roles in everything from neurotransmitter production to detoxification to maintenance of healthy cells. (3) This citation is from an article not a study. Eggs are the richest source of choline but not the only one. There are vegetarian sources such as wheat germ, quinoa, beets, legumes, etc. Studies show that up to 90% of Americans don’t get enough choline, which can lead to fatigue, insomnia, poor kidney function, memory problems and nerve-muscle imbalances. (4) This is another article 2 years earlier from one of the same authors as before. It clearly states that our bodies produce choline and the problem is when we are deficient. You don’t need to eat more choline unless there is a deficiency and a problem.
What about saturated fat? It’s true that some studies show that saturated fat intake raises blood cholesterol levels. But these studies are almost always short-term, lasting only a few weeks. (5) This study was a cohort of 60 studies.
“The studies included in our meta-analysis lasted between 13
and 91 d. This raises the question of whether the effects observed
are transitory. However, long-term epidemiologic findings support
our findings. For example, a life-long high intake of carbohydrates
is associated with increased triacylglycerol concentrations (110),
whereas the effects on total cholesterol of fatty acids in observa-
tional studies also agree with the trials analyzed here (111). This
gives us confidence that the effects seen in our present meta-analysis
are not transient.”
It is not conclusive but shows a constant association. If it quacks like a duck and walks like a duck then it might be a duck! Not conclusive either way but strongly associated against Chris Kresser’s argument. And yes it was short term!
Longer-term studies have not shown an association between saturated fat intake and blood cholesterol levels. In fact, of all of the long-term studies examining this issue, only one of them showed a clear association between saturated fat intake and cholesterol levels, and even that association was weak. (6) This is a link to a blog post by Whole Health source written by Stephan Guyenet. It is not a study but an opinion by another blogger. Whether it has merit or not would be too lengthy now. However the lone wolf syndrome comes to mind. Why rely on a blogger although a researcher as well, instead of more established scientists?
Moreover, studies on low-carbohydrate diets (which tend to be high in saturated fat) suggest that they not only don’t raise blood cholesterol, they have several beneficial impacts on cardiovascular disease risk markers. For example, a meta-analysis of 17 low-carb diet trials covering 1,140 obese patients published in the journal Obesity Reviews found that low-carb diets neither increased nor decreased LDL cholesterol. However, they did find that low-carb diets were associated with significant decreases is body weight as well as improvements in several CV risk factors, including decreases in triglycerides, fasting glucose, blood pressure, body mass index, abdominal circumference, plasma insulin and c-reactive protein, as well as an increase in HDL cholesterol. (7) Above the author complains that the studies were of short duration yet this cohort ranged from 3 to 36 months and “The authors stated that further research was needed on the long-term effects of low carbohydrate diets, perhaps including the follow-up of existing cohorts.” And just because LDL levels did not change significantly does mot mean it was a good thing if baseline was high to begin with. Not a real good study! Not conclusive by any stretch of the imagination.
If you’re wondering whether saturated fat may contribute to heart disease in some way that isn’t related to cholesterol, a large meta-analysis of prospective studies involving close to 350,000 participants found no association between saturated fat and heart disease. (8) “Clinical trials that replaced saturated fat with polyunsaturated fat have generally shown a reduction in CVD events, although several studies showed no effects. An independent association of saturated fat intake with CVD risk has not been consistently shown in prospective epidemiologic studies, although some have provided evidence of an increased risk in young individuals and in women. Replacement of saturated fat by polyunsaturated or monounsaturated fat lowers both LDL and HDL cholesterol. However, replacement with a higher carbohydrate intake, particularly refined carbohydrate, can exacerbate the atherogenic dyslipidemia associated with insulin resistance and obesity that includes increased triglycerides, small LDL particles, and reduced HDL cholesterol. In summary, although substitution of dietary polyunsaturated fat for saturated fat has been shown to lower CVD risk, there are few epidemiologic or clinical trial data to support a benefit of replacing saturated fat with carbohydrate.” Read carefully what the authors say. Bold accents are mine. Why would Chris Kresser state that this study found no association? It did. The main argument this study points to is that you need to look at what you replace saturated fats with. Refined carbs AKA processed and junk foodstuff, are not what your supposed to substitute saturated fat with! A Japanese prospective study that followed 58,000 men for an average of 14 years found no association between saturated fat intake and heart disease, and an inverse association between saturated fat and stroke (i.e. those who ate more saturated fat had a lower risk of stroke). (9) This is the conclusion from that study in 2010
“SFA intake was inversely associated with mortality from total stroke, including intraparenchymal hemorrhage and ischemic stroke subtypes, in this Japanese cohort.” This one is from some of the same authors on another study published in 2013 “Conclusions In this Japanese population, SFAs intake was inversely associated with deep intraparenchymal haemorrhage and lacunar infarction and positively associated with myocardial infarction.”
So if your Japanese and consume low saturated fat you may suffer from a stroke but if you increase saturated fat intake you can get a myocardial infarction! I don’t know about you but this does not seem to be conclusive of anything. What do you think? If you read the study you will see the folly that drawing a concrete conclusion from any of these studies are. “Therefore, recommendation to increase SFA intake cannot made in current Japan, since both SFA intake and coronary heart disease incidence rate are increasing among urban Japanese men.[38,39]“
Thought you might enjoy that sentence as well from the article. Conclusive? Yes it is conclusively pointing to the fact that it is not conclusive.
That said, just as not everyone responds to dietary cholesterol in the same manner, there’s some variation in how individuals respond to dietary saturated fat. If we took ten people, fed them a diet high in saturated fat, and measured their cholesterol levels, we’d see a range of responses that averages out to no net increase or decrease. (If dietary saturated fat does increase your total or LDL cholesterol, the more important question is whether that’s a problem. I’ll address that in the next article in this series.)
Another strike against the diet-heart hypothesis is that many of its original proponents haven’t believed it for at least two decades. In a letter to the New England Journal of Medicine in 1991, Ancel Keys, the founder of the diet-heart hypothesis said (10):
Dietary cholesterol has an important effect on the cholesterol level in the blood of chickens and rabbits, but many controlled experiments have shown that dietary cholesterol has a limited effect in humans. Adding cholesterol to a cholesterol-free diet raises the blood level in humans, but when added to an unrestricted diet, it has a minimal effect. Why would this be indicative that there is dissension among the research or the hypothesis? It is not a statement on saturated fat but dietary cholesterol intake. Basic Human Physiology states the same.
In a 2004 editorial in the Journal of American College of Cardiology, Sylvan Lee Weinberg, former president of the American College of Cardiology and outspoken proponent of the diet-heart hypothesis, said (11):
The low-fat, high-carbohydrate diet… may well have played an unintended role in the current epidemics of obesity, lipid abnormalities, type 2 diabetes, and metabolic syndromes. This diet can no longer be defended by appeal to the authority of prestigious medical organizations. This is an article and an opinion by Dr. Weinberg.
“There followed what became perhaps one of America’s most extensive public relations campaigns: convincing the profession as well as the public that avoiding dietary fat was a key element in the prevention and treatment of atherosclerotic CAD. The NIH, NCEP, AHA, USDA, and a host of medical organizations were joined by the food industry in publicizing and promoting this concept. One had only to walk through any supermarket to find a plethora of cookies, cakes, ice cream, and nearly every imaginable food product prominently marked “low-fat.” The message, perhaps unintended, was unmistakable: eat all the low-fat foods you want; they are safe. Yet many of these low-fat foods were high in carbohydrates (Carb) and prepared with saturated and trans-fatty acids (6).”
Are you following this? This is not what a low fat diet is supposed to be. This is simply substituting one evil with another! That seems to be the message ignored by everyone that claims the diet heart hypothessis is flawed. This was never the intent of the diet! You cannot eat refined processed junk foodstuff that is “low fat”, yet full of saturated fat and trans fats, and expect to prevent anything. It is ludicrous!
We’ve now established that eating cholesterol and saturated fat does not increase cholesterol levels in the blood for most people. In the next article, I’ll debunk the myth that high cholesterol in the blood is the cause of heart disease. How can Chris Kresser say this? We cannot blindly follow what anyone says without investigating the basis of the claim! Your health and that of your loved ones is way to valuable to simply rely on hyperbole. Not one of his citations backs any of his assertions. A low carb diet or a stereotypical Paleo diet will be better than a low fat diet that substitutes saturated fat with processed and junk foodstuff. But that what was never the intent. The message was eat real food, mostly plant based and reduce or eliminate processed and junk foodstuff while reducing saturated fat intake. Your thoughts?