Rebuttal to the AHA omega-6 advisory

The American Heart Association (AHA) advisory on the benefits of omega-6 fatty acids is summarized here. Considering all the press about omega-6 and the negative effects of the typical US diet on the omega-3:-6 ratio it was surprising to see.

Ms. Evelyn Tribole (photo), a registered dietitian from Newport Beach, California, emailed her thoughts about the AHA advisory. They’re reprinted below.

What is AHA’s Agenda?
The AHA made sweeping statements that are not supported by the research, while ignoring landmark studies, which don’t support their views.

Here’s one example. Conspicuously absent from AHA’s report were the findings of the famous study, which made the Mediterranean diet a household name — the Lyon Diet Heart study.

This large intervention trial involved two groups of heart patients from France who 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 group eating the Mediterranean diet had a striking 70% reduction in all causes of death, including cancer, compared to the group eating the “heart healthy diet.”

If you interviewed Dr. Michel de Lorgeril, the lead investigator of that famous study, he would likely disagree with AHA’s advisory. Why? Because his study was specifically designed to be low in omega-6 fat in order to mirror the indigenous Mediterranean diet of Crete Islanders who have a low rate of heart disease.

Just last month, Dr. de Legoril chastised researchers for ignoring the omega-6 factor, “…the epidemiologists do not capture one major lipid characteristic of the Mediterranean diet, which is actually low in omega-6” (Notably, the authors of AHA’s advisory were mainly epidemiologists.)

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.

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.

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 17.4grams/day [Wang]. Yet, this genotype had no influence on breast cancer risk if these women ate a lower linoleic acid diet.

Lastly, there is a curious association with Unilever, a large global margarine manufacturer. Three of the 12 scientists declared that they received either advisory or consulting fees from this food conglomerate. Keep in mind that margarines, salad dressings, and spreads are among the highest sources of omega-6 fat in westernized countries.

These are just a few examples of the problems with AHA’s advisory (there are many more). I hope that for the sake of a balanced perspective and journalistic integrity, medical news media — including Medscape — will investigate this issue — rather than blindly accept what the AHA proclaims — as there is a lot more to this story.

Evelyn Tribole, MS, RD

2/15/09 19:10