Junkfood Science Exclusive: The big one — results of the biggest clinical trial of healthy eating ever

Everybody knows what it means to eat healthy. We’ve heard about healthy foods and the importance of eating right our entire lives: “To be healthy and prevent heart disease, cancers and other chronic diseases of aging — and to maintain a slim, “healthy” weight — we should eat a low-fat and high-fiber diet with lots of fresh fruits and vegetables and whole grains.” This advice comes from respected doctors and health officials and we hear it everywhere, so it is unfathomable that these dietary beliefs have never actually been clinically tested...until recently.

While there have been decades of observational population studies and well-designed small trials that have disproven many of the popular beliefs of healthy eating, debates have continued. Observational studies finding correlations between certain foods or diets and health benefits often turn out to be unsupported in clinical trials because foods and diets are frequently markers for the real things influencing health, such as genetics and social-economic status. Only well-designed clinical intervention trials can credibly demonstrate causation, correlations never can.

So, to settle the issue once and for all, one of the largest, longest and most expensive randomized, controlled, primary dietary intervention clinical trial in the history of our country was launched in 1993. This was to be THE study to end all studies and proponents believed it would finally prove the benefits of not just low-fat diets, but what has come to epitomize the government's very definition of “healthy eating.” According to the National Institutes of Health, it was "one of the largest studies of its kind ever undertaken in the United States and is considered a model for future studies of women’s health.” It was a major undertaking, costing $415 million and conducted at 40 medical centers across the country. It was a well-designed and carefully conducted study and researchers were confident this would prove the rightness of eating “right.”

A lot was riding on this.

It was named the Women’s Health Initiative (WHI) Dietary Modification Trial. A total of 48,835 postmenopausal women (the age most associated with risks for developing heart disease and cancers) were randomly assigned (with each group well matched) to either their regular unrestricted diet or to a “healthy” diet that was low-fat (20% fat) and high fiber, with at least five servings of fruits and vegetables, and six servings of grains a day. The “healthy” eaters endured an “intense behavioral modification program by specially trained and certified professionals” to keep them on their diets. While they backslide a little, they did surprisingly well in sticking to the diet — as good as dietary prescripts will ever get and money can buy — at a cost of $8,498 spent per person!

The women in the healthy eating intervention group cut their total fat intakes down to 24% of their calories and 8% saturated fat the first year — well below the control group eating about 38% total fat and nearly 40% more saturated fats. By the end of the study, the “healthy eaters” were still averaging 29% fat, compared to 37% in the control group. The “healthy” dieters also ate about 25% more fruits and vegetables, grains and fiber than the typical American diet of the control group.

The researchers stated in their trial design that the dietary changes the participants made — while predictably not 100% compliant — were significant enough they were certain this study would find significant benefits, and confidently projected a 14% decrease in breast cancer, for example.

The women were closely followed for more than eight years and the incidences of clinically confirmed breast cancer, colon cancer, heart disease, heart attacks and strokes were carefully monitored.

So what did this nearly decade-long clinical trial show?

Most of the study results were published at the beginning of last year, in a series of articles in the Journal of the American Medical Association. If healthy eating showed health benefits, the results would have been shouted far and wide. Since they weren’t (the spins don't count), you’re probably beginning to guess that it failed to support long-held beliefs about “healthy” eating. And you would be right.

After more than eight years, there were no difference in the incidences of breast cancer, colon cancer, heart attacks or strokes among those who ate “healthy” and those who ate whatever they pleased.

Cardiovascular disease (the biggest cause of death as we age)

Healthy eating proved to have no effect on cardiovascular disease. The researchers concluded: “a dietary intervention that reduced total fat intake and increased intakes of vegetables, fruits, and grains did not significantly reduce the risk of CHD, stroke, or CVD in postmenopausal women.” (And among the women who had heart disease at the beginning of the study, the low-fat diet slightly increased their risks for heart disease.) Not surprisingly, as recently reviewed, the body of evidence reviewed by the American Heart Association in looking for support for its “heart healthy” diets for the primary prevention of heart disease, found no support.

Breast cancer

Healthy eating proved to have no effect on breast cancer incidences. The researchers concluded: “We found no evidence that lower intake of total fat or specific major types of fat was associated with a decreased risk of breast cancer.” (For those who might be quick to suggest that a “healthy” and low-fat diet might have proven effective if begun earlier, the results showed that the women who’d been eating the lowest fat diets before the study began had slightly higher risks for breast cancer than women who’d been eating the most fat; while the women who had managed to most reduce their dietary fat fared the worst, with the highest risks for breast cancer.)

Colorectal cancer

Healthy eating proved to have no effect on colon or rectal cancers. The researchers concluded: “a low-fat dietary pattern intervention did not reduce the risk of colorectal cancer in postmenopausal women during 8.1 years of follow-up.”

Body Weight

Not only that, but the women following a “healthy” diet for eight years didn’t end up thinner. They lost a bit at the beginning, but had regained it back years before the end of the trial, despite continued restrained eating and eating fewer calories (361 kcal/day less than they had been at the start of the study). During the last years of the trial and at the end, the researchers found an insignificant difference in weight changes between the intervention and control group of a mere 0.7 kg. They concluded: "A low-fat eating pattern does not result in weight gain in postmenopausal women."

More significantly, those in the control group who were not “watching what they ate” and were eating whatever they wanted didn’t gain weight, even though through the end of the trial they were eating more calories and fat than the dieters. Imagine how women who’ve spent their lives denying themselves foods they love must feel. [Years of restrictive eating versus eating whatever you choose equals about a one pound difference in the end!]

The swiftness in which all of the “healthy eating” and “low-fat” diet interests rushed to issue press releases to spin the results of the WHI study was reminiscent of the same desperate reactions after the CDC Flegal et.al. study debunked the government’s “obesity” death statistics. But none of the spins or claims held up to the data, and the results of this huge study, despite the hundreds of millions of dollars of taxpayer money spent on it, were quietly buried. (This author sent out countless queries last year trying to find a publication, including a national size acceptance publication, that would print this and it was rejected. "We can't tell people that!")

To admit, “We were wrong, never mind!” would crumble the entire house of cards.

And the myth of “healthy” eating goes on as if nothing ever happened.

Beliefs that people need to be told to eat healthy and can't be trusted to eat right are equally entrenched, despite no scientific evidence in support for such dietary messages. In fact, as we've already learned, the U.S. Preventive Services Task Force found in 1996 and 2003 that dietary counseling for healthy eating of adults or children lacked evidence.

The take-home message is that the soundest science for decades supports eating normally, enjoying everything and not worrying so much. When we enjoy a variety of foods from all of the food groups — as most everyone naturally does when they’re not trying to control their eating — and trust our bodies, we’ll get the nutrients we need to prevent deficiencies. And that is the only thing that nutritional science can credibly support. The rest is dietary religion.

Health is not evidence of moral character and pristine diets. Don’t let anyone try to scare you, threaten you, or get you to believe that if you don’t eat “right” (whatever their definition) you’ll get fat, cancer, heart disease or die sooner. There is simply no good evidence.

In Part Two, we’ll look at the latest results of the WHI just released!

© 2007 Sandy Szwarc