When clinical studies don't produce the expected results

Ever heard of the Women’s Health Initiative (WHI) Dietary Modification Trial? This was supposed to show that if you eat a diet low in fat, high in fiber, with at least 5 servings of fruits and vegetables every day and 6 servings of grain, you'll never, ever, ever die, as opposed to all those gluttons stuffing themselves with Phish Food ice cream and cheesecake and pot roast and lasagna and all those other things that make you a Very Bad Person if you eat them.

Well, guess what: Everything You Know Is Wrong:

News from the Women’s Health Initiative: Reducing Total Fat Intake May Have Small Effect on Risk of Breast Cancer, No Effect on Risk of Colorectal Cancer, Heart Disease, or Stroke

Following an eating pattern lower in total fat did not significantly reduce the incidence of breast cancer, heart disease, or stroke, and did not reduce the risk of colorectal cancer in healthy postmenopausal women, according to the latest clinical trial results from the National Institutes of Health’s Women’s Health Initiative (WHI).

The study was designed to evaluate a low-fat dietary pattern’s effect on the risk of cancer. However, investigators also evaluated the data to review the effect on cardiovascular disease. The results from the largest ever clinical trial of low-fat diet are reported in three papers in the February 8 edition of the Journal of the American Medical Association.

Among the 48,835 women who participated in the trial, there were no significant differences in the rates of colorectal cancer, heart disease, or stroke between the group who followed a low-fat dietary plan and the comparison group who followed their normal dietary patterns. Although the women in the study who reduced their total fat intake had a 9 percent lower risk of breast cancer than did women who made no dietary changes, the difference was not large enough to be statistically significant — meaning it could have been due to chance.

By the end of the first year, the low-fat diet group reduced average total fat intakes to 24 percent of calories from fat, but did not meet the study’s goal of 20 percent. At year six, the low-fat diet group was consuming 29 percent of calories from fat. The comparison group averaged 35 percent of calories from fat at year one and 37 percent at year six. Women in both groups started at 35-38 percent of calories from fat. The low fat diet group also increased their consumption of vegetables, fruits, and grains.

Women were aged 50-79 at trial enrollment in 1993-98 and were followed for an average of 8.1 years. The study diet focused on reducing total fat, and unlike diets used to reduce heart disease risk, did not differentiate between “good fats” found in fish, nuts, and vegetable oils, and “bad” fats like saturated fat and trans fat found in processed foods, meats, and some dairy products. The study design reflected a widely believed but untested theory that reduction of total fat would reduce risks of breast or colorectal cancers. For heart disease, it was anticipated that reduction in total fat would be accompanied by a reduction in saturated fats, which are known to contribute to heart disease risk.

So in other words, the only risk reduction from a reduced fat diet was was a statistically insignificant decrease in breast cancer incidence.

But let's not let these findings stand in the way of telling women what to eat, shall we? The above report goes on to say,

“The results of this study do not change established recommendations on disease prevention. Women should continue to get regular mammograms and screenings for colorectal cancer, and work with their doctors to reduce their risks for heart disease including following a diet low in saturated fat, trans fat and cholesterol,” said National Heart, Lung, and Blood Institute Director Elizabeth G. Nabel, M.D.

Even though the study found no correlation.

Sandy Szwarc has more.

Now, I happen to LIKE fruits and vegetables and lean meats and whole grains and cooking with olive oil and staying away from processed foods full of trans fats which don't taste good anyway. I also like to have a couple of spoonfuls of light Phish Food ice cream every now and then. And occasionally I like to have some barbecued ribs. Or a good steak. Or macaroni and cheese. I also like to have stir-fry chicken and vegetables with brown rice, or roasted tomato and caramelized shallot pie or ratatouille or dover sole stuffed with spinach and feta and a brown-and-wild rice pilaf. You know what I don't like? Fast food. But isn't it funny that in our society in which women are constantly told what they are and are not allowed to eat, a study which seems to debunk all the crap we hear about how we have to deny ourselves everything never gets Sanjay Gupta up there on CNN crowing about the findings?

(Thanks to Kate Harding for finding this.)