What is the American Heart Association’s Agenda? —It Sure Ain’t Science or Public Health
Old School Cholesterol Dogma versus Science
On January 27, 2009 the American Heart Association (AHA) issued an advisory touting the benefits of eating plenty of omega-6 fats. Here's the problem--AHA made sweeping statements that are not supported by the research, while ignoring landmark studies, which don’t support their views [Harris]. While the cholesterol myth has finally been put to rest as the cause underlying heart disease (it's inflammation and beyond), it would seem that heart healthy eating would need some refinement.
Yet, the American Heart Association's key rationale for promoting omega-6 polyunsaturated fats, is because of their ability to lower blood cholesterol, when eaten in the place of saturated fats. (Keep in mind that one out of every two people with heart disease has a normal blood cholesterol level.) Furthermore, the AHA asserts that if Americans were to lower their current omega-6 fat, their heart health would suffer.
Omega-6 fat intake has sky-rocketed in the last century, so it would seem that we should see a dramatic lowering of heart disease in the USA, yes? No. The incidence of cardiovascular disease has increased in parallel with the increase in linoleic acid intakes in many countries [Ghosh]. Linoleic acid is the most commonly eaten omega-6 fatty acid. Notably, people who have died from heart disease have higher blood levels of the omega-6 fat, arachidonic acid, as shown below [Okuyama].
Do Countries with Low Omega-6 Fat Diets Have Higher Rates of Heart Disease?
Given the American Heart Associationn's
rationale, we should see elevated heart disease in countries that
eat diets low in omega-6 polyunsaturated fats. Nope, again. Think
Mediterranean diet. Cultures that eat Mediterranean diets have much
lower rates of heart disease.
Enter the Lyon Diet Heart study, a large intervention trial in which two groups of heart patients from France, were fed either a Mediterranean diet (low in omega-6 polyunsaturated fat) or a diet advocated by the American Heart Association, with indiscriminate use of polyunsaturated fats. The people eating the Mediterranean diet had a striking 70% reduction in all causes of death, including cancer, compared to the folks eating the "heart healthy diet".
While scientists have
yet to agree, as to what officially defines the Mediterranean diet,
most would agree that it is higher in monounsaturated fats and lower in polyunsaturated fats, which is synonymous with omega-6 fats. The
dominate cooking oil used in these cultures is olive oil.
Olive Oil 101
The type of fat in Olive oil is mainly monounsaturated fatty acids. Nearly 75% of olive contains oleic acid, the monounsaturated fatty acid which is an omega-9 fat. Notably, olive is also low in both saturated fats and polyunsaturated fats. Here's the breakdown of olive compared to soybean oil. (Soybean oil is one of the top three sources of omega-6 fat in the American diet):
One of the most disturbing aspect of AHA's advisory is the complete disregard for studies published within the last five years, which demonstrate potential cardiac harm from eating the current status quo levels of omega-6 fats.
- Severity of Atherosclerosis Associated with Dietary Omega-6 Fats. A study published in the New England Journal of Medicine evaluated the arteries of seemingly healthy people with a LOX genotype [Dwyer]. The scientists found an increase in the thickness of the carotid-artery intima–media, (which reflects atherosclerosis). Morever, increased dietary arachidonic acid significantly enhanced the apparent atherogenic effect of this genotype. Both dietary omega-6 fats, linoleic acid and arachidonic acid, were significantly associated with increased severity of atherosclerosis. The researchers concluded, “The observed diet–gene interactions further suggest that dietary n–6 polyunsaturated fatty acids promote, whereas marine n–3 fatty acids inhibit, leukotrienes-mediated inflammation that leads to atherosclerosis in this subpopulation.”
- Tufts Scientists Say, "High Dietary PUFA n-6 May Not Result in Atherosclerosis Protection." The 2006 Framingham study by Tufts University scientists [Lai] investigated the effect of dietary omega-6 fats in people with a high risk of heart disease, because they have genetic mutation effecting lipoprotein( APOA5). Their findings showed that omega-6 fats, specifically, promoted the risk of atherosclerosis. The researchers concluded that for people with this genetic profile, "high dietary PUFA n-6 may not result in atherosclerosis protection." Notably, the subjects were eating a typical American diet, high in omega-6 fats.
- Dietary Linoleic Acid (Omega-6 Fat) Increases Toxicity of LDL Cholesterol.A study on nearly 400 men in Finland [Louheranta] showed that as the amount of dietary linoleic acid (omega-6) increased, so did the oxidation of LDL which makes it more hazardous for heart health.
- Canadian Study: Heart Benefits Are Not Achieved on Diets Rich in Omega-6 Fats “Our results also clearly raise the possibility that any positive effects of ALA [the omega-3 fatty acid found in plants, such as flax] are only realized when the diet is also low in linoleic acid , such as those found in intervention trials incorporating a Mediterranean diet high in monounsaturated fatty acids.” [Ghosh]. This animal study was designed to represent the differing and broad range of omega-6 and omega-3 fats in the human diet; and the impact on the heart. Their findings show that diets low in omega-6 fat, with high plant-based omega-3 fats, decreases the level of the potent omega-6 fat, arachidonic acid in the cell membranes of the heart. “An effect that is evident only when the diet also contains low levels of the omega-6 linoleic acid”. Furthermore, diets high in omega-6 fat influenced the enzymes in the heart responsible for increasing both inflammation and the availability of arachidonic acid.
Science Silo Mentality
You really can't be an expert of every field, especially in matters relating to diet and health. While I would not expect a heart scientist to be an expert on breast cancer, I would certainly hope that if heart experts are claiming that there is no harm from eating the current high levels of omega-6 fat, that they would use an inter-disciplinary approach to confirm their thinking. Sadly, that's not what happened.
Instead, we have a science silo mentality (a phrase coined by Bill Lands, PhD). In this situation, scientists work in their area of expertise, reaping their data, but without any of the necessary cross-talk with scientists in other fields.
Large studies from the USA, France and Sweden indicate a compelling link between high intakes of omega-6 fat and the development of breast cancer [Tribole.] For example, in a case-control study on nearly 1700 women, researchers demonstrated that women with a genotype influencing the LOX enzyme, had a two-fold increase in breast cancer risk if they ate high levels of the omega-6 fat, linoleic acid, and amount of 17.4g/day [Wang]. Yet, this genotype had no influence on breast cancer risk, if these women ate a lower linoleic acid diet. (For more details see,
The Omega-3 Fat Deficiency Gap
Another key factor, not taken into consideration is the gaping omega-3 fatty acid deficency in the American diet. The typical American eats only 85 of the 650 milligrams of the recommended omega-3 fatty acids (DHA + EPA). This is significant, because in the body, the omega-3 and omega-6 fats compete for the same enzymes to make their potent compounds. It's like a biological game of the "musical chairs", where there will always be a shortage--and in the case of fatty acids, the dominant fats "win" the enzyme.
No One is Suggesting the Elimination of Omega-6 Fat
In 1999, there was enough scientific evidence to prompt scientists to recommend an upper limit for omega-6 fats, to no more than 6.7 grams per day [Simopoulos]. This ceiling is based on eating a maximum of 3% fat calories from omega-6 fat on a 2000 calorie diet. (Note, this is a similar level to the the Lyon Diet Heart study.) Now, ten years later, the American Heart Association is urging people to continue to eat more than double that amount.
No scientist is urging for the elimination of omega-6 fats. Linoleic acid is the chief omega-6 fatty acid consumed by Americans and westernized countries, and it is essential but in small quantities. This is similar to the nutrient sodium, it's essential in small amounts, but in excess it's not good for your health.
When the dietary omega-3 and omega-6 fats are in balance, it's truly a beautiful synergy in the body. But in excess, the omega-6 fatty acids are like overzealous fire-fighters, chopping down your door because of a chronic false fire alarm. Yes, we need fire departments and fire fighters, but if they destroy the very buildings they are trying to protect, it's a problem--akin to chronic inflammation in the body, which lies at the root of many diseases.
To advocate for the status quo, when there is evidence of harm is unconscionable--especially when lowering omega-6 fats to a more balanced level is clearly NOT harmful to health.
Links to Sources
American Heart Asssociation News Release. Omega-6 fatty acids: Make them a part of heart-healthy eating DALLAS, Jan. 27, 2009.
de Lorgeril M et al. Mediterranean Diet, Traditional Risk Factors, and the Rate of Cardiovascular Complications After Myocardial Infarction : Final Report of the Lyon Diet Heart Study Circulation1999;99:779-785 (Free full text)
Dwyer, James H., Allayee, Hooman, Dwyer, Kathleen M., Fan, Jing, Wu, Huiyun, Mar, Rebecca, Lusis, Aldons J., Mehrabian, Margarete.Arachidonate 5-Lipoxygenase Promoter Genotype, Dietary Arachidonic Acid, and Atherosclerosis. N Engl J Med 2004 350: 29-37.
Ghosh S, Novak EM, and Innis, SM. Cardiac proinflammatory pathways are altered with different dietary n-6 linoleic to n-3
-linolenic acid ratios in normal, fat-fed pigs. Am J Physiol Heart Circ Physiol (2007)293: H2919-H2927, Free Full Text.Harris WS et al. Omega-6 Fatty Acids and Risk for Cardiovascular Disease. A Science Advisory From the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation published January 26, 2009,. Free Full Text. doi:10.1161/CIRCULATIONAHA.108.191627.
Hibbeln, Joseph R, Nieminen, Levi RG, Blasbalg, Tanya L, Riggs, Jessica A, Lands, William EM. Healthy intakes of n-3 and n-6 fatty acids: estimations considering worldwide diversity.Am J Clin Nutr 2006 83: S1483-1493. Free Full Text.
Lai CQ et al.Dietary Intake of n-6 Fatty Acids Modulates Effect of Apolipoprotein A5 Gene on Plasma Fasting Triglycerides,Remnant Lipoprotein Concentrations, and Lipoprotein Particle Size: The Framingham Heart Study.Circulation (2006)113: 2062-2070. Free Full Text.
Lands WE.Dietary fat and health: the evidence and the politics of prevention: careful useOkuyama. H. Prevention of Coronary Heart Disease From the Cholesterol Hypothesis to omega-6/omega- 3 Balance. World Review of Nutrition and Dietetics (2007)Vol. 96:1-158.
of dietary fats can improve life and prevent disease. Ann N Y Acad Sci. 2005 Dec;1055:179-92.
Leaf A.Dietary Prevention of Coronary Heart Disease:The Lyon Diet Heart Study.Circulation 1999;99:733-735. Free Full Text.Circulation 1999;99:733-735. Free Full Text.Circulation 1999;99:733-735. Free Full Text.
Louheranta, AM, Porkkala-Sarataho, EK, Nyyssonen, MK, Salonen, RM, Salonen, JT. Linoleic acid intake and susceptibility of very-low-density and low
density lipoproteins to oxidation in men. Am J Clin Nutr 1996 63: 698-703.
Ramsden CE, Hibbeln JR, Lands WE. Letter to the Editor re: Linoleic acid and coronary heart disease.Prostaglandins Leukot Essent Fatty Acids. 2009 Jan 13.PMID: 19147338
Simopoulos AP.The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular diseaseTribole, E..What happened to do no harm? The issue of dietary omega-6 fatty acids.Prostaglandins Leukot Essent Fatty Acids. 2009 Jan 13. [Epub ahead of print] . PMID: 19147337
and other chronic diseases.Exp Biol Med (Maywood). 2008 Jun;233(6):674-88.Free Full Text.
Simopoulos, AP, Leaf A, and Salem N. Workshop on the Essentiality of and Recommended Dietary Intakes for Omega-6 and Omega-3 Fatty Acids.
J Am Coll Nutr 1999 18: 487-489. (free full text)
Wang J et al. 5-Lipoxygenase and 5-Lipoxygenase-Activating Protein Gene Polymorphisms, Dietary Linoleic Acid, and Risk for Breast Cancer. Cancer Epidemiol Biomarkers Prev October 1, 2008(17): 2748-2754
Categories: Arachidonic Acid,commentary,Mediterranean Diet,Omega-6 Fat,APOA5 Gene,Biomarkers,Cardiovascular,Full Text Studies-FREE
I feel that you misread the advisory.
The AHA does not advocate the unlimited consumption of omega-6 fats. It advocates a range of intakes of w-6 that are advisable to consume (5-10%) in place of saturated fat. The conclusion clearly states that higher intakes may be beneficial-- but we don't yet have great data to support higher levels. So it's a safe conclusion, but based on the most robust and rigorous evidence available for now. This is a reasonable recommendation, which is what I'm looking for in dietary advice.
The overall suggestion for w3-w6 PUFA balance is best met by raising intake of w3, not decreasing intake of w6.
I'm interested in what would you replace the w6 with, since you seem to advocate a reduction in intake?
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Hi Russ,
Thank you for taking the time to share your views.
The issue of an optimal level of dietary omega-6 fats is far from settled. But there are a plethora of studies, published in the last decade, which merit a serious discussion on the public health issue of dietary omega-6 fats. The American Heart Association pre-empted and minimized the issue, by going straight to the media with their press release advisory, (which described in lay terms, their paper published in Circulation.)
Perhaps another way of looking at the AHA advisory, is simply, that it does not make sense in the context of the Mediterranean pattern of eating, (for which there have been many studies documenting benefit at both an epidemiology level and at the level of intervention diet trials.) I do know there are scientists currently working on a letter to the editor with their many concerns with AHA's n-6 advisory, but I imagine it will be some time before we will read it in the Circulation journal, because of the time involved in the publishing-peer-review process itself.
Diet-disease relationships are quite complex. I would advocate for a Mediterranean-type diet. It is a time-tested diet pattern that addresses the omega-6/omega-3 PUFA's quite nicely. This would mean replacing the omega-6 fats with monounsaturated fat, specifically, omega-9, oleic acid, the chief fatty acid in olive oil.
Take care,
Evelyn
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Thanks for this reply Evelyn to this absurd message from AHA. I hope Circulation publish letter submitted by Dr Barry Sears. I personally advocate a modified mediterranean diet like Zone Diet. Hugs from mediterranean Spain.
http://www.drsears.com/tabid/399/itemid/13303/Consume-more-omega6-fatty-acids-They-have-to-be.aspx
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Great article. You're clearly much better informed than the authors of the AHA advisory. I saw you referenced the Okuyama/Lands book. I have that sitting on my bookshelf right now, what a great book. I had to get it from across the state on interlibrary loan.
Anyway, what I wanted to say is that these people don't allow themselves to be informed by the underlying biology. Once you're at 4% n-6, piling more on top doesn't further increase inflammatory eicosanoids if n-3 is kept constant because you're near maximal tissue percentage of n-6 HUFAs. At that point, all you can do is add n-3. That's why the diet trials where they replaced sat fats with n-6 didn't increase CHD (except the earliest ones, Rose et al and the anti-coronary club trial), because n-6 was already above 4%. The Lyon trial reduced n-6 to about 3.6%, increased ALA and you know what the result was.
These guys at the AHA are just trying to cover their own butts. They don't want to admit that their advice has perpetuated a staggering amount of chronic disease. They try to throw up a smokescreen but anyone who's intimately familiar with the evidence knows that we currently have the means to make heart attacks a thing of the past.
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Thanks, Stephan. To add further insult to this dis-service of "science", the editorial policy of the American Heart Association's journal, Circulation, is that they do NOT publish letters to the editor regarding scientific statements. I found out first hand, when I submitted my letter, (as did other scientists).
Here's the behind the scenes story. Since Circulation's editorial guidelines allow only 5 cited references per letter, a group of scientists divided up the flaws in AHA's paper to cover more "territory". (I was thrilled and honored to be invited by these scientists, to help divide and conquer).
We got the same canned response from their Director of Scientific Publishing:
Here's a link to my unpublished letter http://www.box.net/shared/s1qioje9sg.
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Ah, what a shame they didn't publish your letter. Their policy doesn't surprise me. It's a consensus-driven journal from what I've seen.
I managed to get a letter accepted to the journal Obesity recently pointing out that the "high-fat diet" used in a rat study to produce fatty liver and metabolic disturbances was actually a high-linoleic, high-sugar diet. High-fat diets only cause fatty liver in rats if they are high-LA. Butter and coconut oil don't do it. But of course they don't mention that in the text body. It's being held up because the study authors are dragging about their rebuttal. The paper was published in October, my letter was accepted in early Feb, and it still hasn't been published.
The AHA is going to perpetuate this stuff to the bitter end. Things are not going to change from the top down. Bill lands has been screaming about this to the academic community for decades, and getting ignored for the most part. Weak advisories like the one above get treated like gold, while one of the pioneering researchers in the PUFA and eicosanoid field is practically invisible to the public.
Change will come from the bottom up, as informed public opinion changes due to the efforts of people like you. As public opinion changes, the media will reflect it, and NIH funding priorities will change. It's unfortunate but true that they fund what's in vogue to a certain degree. And it's certainly true in the nutrition-health field that the same result gets interpreted in drastically different ways depending on what's in vogue.
I'm going to review some of Bill Lands' papers and the Lyon diet-heart study on my blog in the next few weeks if you're interested.
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I am hopeful that the transparency of the internet combined with easier access to studies, will help disseminate the data quicker. It's the main reason I started this omega-6-research news site--to let the data speak for itself (with an occasional commentary from me).
I got intrigued about the omega-6 fat health issue while writing my Ultimate Omega-3 book. I was amazed at the depth of the omega-6 data indicating a problem (from mechanisms to intervention studies), yet, the omega-6 issue was not even on the public health radar in 2007. As for Bill Lands--he is a champion-scientist indeed--(there were so many seminal studies by him that I wrote a mini-feature of his work in my book!)
It seems that the "heart healthy" food companies are also keeping the fire lit on the omega-6-fats-are-heart-healthy mantra. There is a curious association with AHA and Unilever, (a large global margarine manufacturer). Three of the 12 AHA scientists declared that they received either advisory or consulting fees from this food conglomerate, (which sells margarines, salad dressings and spread), which as you know, are among the highest sources of omega-6 fat in westernized countries.
Lastly, here's some info for your upcoming reviews (the first of which, is a recent paper by Lyon Diet Heart study investigators):
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Ah, Unilever. That doesn't surprise me at all. Have you heard of the MARGARIN study? They tried to replicate the Lyon trial on a high omega-6 background. I'm corresponding with a journalist who says that Unilever pressured the investigators into keeping omega-6 high. They wanted to demonstrate that adding omega-3 margarine onto a high omega-6 background improves markers of heart disease progression, but failed. It reduced CRP but that's it. The study wasn't powered to detect differences in mortality.
You'd think someone would try to replicate the omega-6 intake of the Lyon trial. There's a lot to be gained if it works. It won't happen if the study is funded by Unilever though. They should breed the LA out of their oils like we did to high-oleic sunflower oil, then their financial interests would be well aligned with public health.
Thanks for the links.
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