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September 4, 2006

The Lowdown on Low-Fat Diets
By Meghan A.T.B. Reese
For The Record
Vol. 18 No. 18 P. 34

According to many news reports, a comprehensive study has shown that ordering that triple bacon cheeseburger won’t adversely affect your health. Don’t buy it, say leading dietitians.

In February, the results of the largest study ever to examine the effect of low-fat diets on the risk reduction of chronic diseases were released. The National Institutes of Health’s eight-year, $415 million Women’s Health Initiative (WHI) study involved nearly 49,000 women aged 50 to 79 who were placed on a low-fat diet. The results showed that the cutback in dietary fat had almost no effect on the incidence of breast and colon cancer, heart attacks, and strokes among the women studied. The findings were jarring to the researchers but could be detrimental to consumers who aren’t being presented with the entire story and, in essence, are hearing what they want: “Low-fat diets won’t help me, so pass the chips.”

Extra, Extra
The study’s findings were not as disappointing as the sensationalistic media flurry bemoaning them. For days, sprawling headlines denounced the study and low-fat diets. The Boston Globe: “Study Finds No Major Benefit of a Low-Fat Diet.” The Los Angeles Times: “Eating Lean Doesn’t Cut Risk.” On February 8, The New York Times decried, “Low-Fat Diet Does Not Cut Health Risks, Study Finds.” Many news organizations were touting the WHI study as a big (low-) fat failure.

Mara Vitolins, DrPh, RD, an associate professor of public health sciences at Wake Forest University Baptist Medical Center in Winston-Salem, N.C., says, “The headlines were so frustrating. I was really disappointed. It took my breath away because I was like, ‘What study is that?’”

But it was not only the headlines doing the damage. According to the lead of a Washington Post article titled “Low-Fat Diet’s Benefits Rejected,” “Low-fat diets do not protect women against heart attacks, strokes, breast cancer or colon cancer, a major study has found, contradicting what had once been promoted as one of the cornerstones of a healthy lifestyle.” The Post article, also published on February 8, boasted some weighty quotes: “‘Based on our findings, we cannot recommend that most women should follow a low-fat diet,’ said Jacques Rossouw, MD, of the National Heart, Lung and Blood Institute, which funded the $415 million study.”

While the study’s findings may be pertinent information for public awareness, the way the results are being reported may be hurting more than helping. “It does a disservice. It’s what is going to catch the reader’s attention, but in the end, it is harmful if the only words that a reader sees are ‘low-fat diet’ and ‘not proven,’” says Anastasia Snelling, PhD, RD, an associate professor at American University in the department of health and fitness. “People may gravitate away from the recommendation of eating low fat, which is still a healthier alternative to eating bacon and sausage every day. And certainly the study comes out to say that, but you won’t keep most readers’ attention long enough to get to that paragraph.”

In the case of the Post story, information hinting at the benefits of a low-fat diet couldn’t be found until the fifth paragraph. Vitolins says she wanted to run out and shout, “Please don’t abandon your low-fat diets!” because “people were coming in and saying, ‘Well, I heard low-fat diets don’t work.’ People will filter out and hear what they want to hear, and for people who wanted to abandon eating low fat, well, that was just perfect.”

Population Problems
In the aftermath of the media blitz, healthcare professionals need to help consumers sort between fact and what was published to sell papers, with much of the print encouraging the public to apply the study results to their own life. But Vitolins says, “Applying group results to one person isn’t fair.” She says doing so is an injustice because this study was population-specific in terms of age, gender, and diet. Thus, the results aren’t universal or a one-size-fits-all solution and should not be adapted as such.

One hole in the headlines is the exclusion of the study sample: postmenopausal women. There is a high likelihood that the damage had already been done in the postmenopausal group. “Starting at 50 to 79 does seem a little late. ‘Chronic’ means it could have started many years ago. Heart disease starts in your teens. When does cancer progression begin? We don’t know, but breast cancer doesn’t start at 50,” Snelling says. “But in these longitudinal studies, you have to pick a point where you start to look at it, and they chose postmenopausal women. I don’t fault them for that.”

Vitolins echoes Snelling’s thoughts that postmenopause may be a little late to expect extraordinary results. “You have to think, ‘Gee, at 50, maybe I shouldn’t expect the same effects [as] at 30.’ You can’t assume that at menopause you can change your diet and get huge effects.” However, Vitolins notes that it’s paramount to tell clients it’s always better late than never. “We need to eat healthy across our life span, but it’s never too late to change, no matter the age, to dump the bad fats, and the faster you can implement those changes, the better off you are.”

Another flaw in not mentioning the sample in the headlines dispelling low-fat diets is that men and women are different in many ways, including dietary needs and recommendations. The previously mentioned Washington Post article states, “Although the study involved only women, the findings probably apply to men as well.” But Vitolins’ response to men looking at this study as an easy out is, “Are you kidding? You’re going to apply a study of postmenopausal women to your life? I think the applications do not apply one bit to men—we have different hormone levels, we have children, [and] all those things make a difference.”

Aside from the study being focused on older women, the sample studied was by no means consuming a healthy or even moderately balanced diet. This is yet another reason Vitolins doesn’t advocate applying the study results to the general population. “This study was particular to a group and a group that was eating a high-risk diet. They were selected because they had high-fat diets,” she says. “The findings clearly don’t speak against following the MyPyramid guide or recommended guidelines because we really took a group of women who were eating, on average, 39% of their calories from fat a day at the beginning of the study, and that’s high and probably a marker of a poor diet throughout life.”

Additionally, necessary considerations for filtering the results are timeline and advancements made since the study began in 1992. “People need to put themselves into the mind frame that at the time we were developing the hypotheses and testing, people didn’t have cell phones, [and] most people didn’t have access to e-mail and computers. You can imagine if technology made those kinds of advances, so has science,” Vitolins says.

One of those advances is the recognition of different types of fat and their spectrum of effects on the body. “But you don’t change your hypotheses in the middle of a trial and go, ‘Oh, now we’re going to worry about types of fat,’ so we had to stay with what we had originally hypothesized and that was lowering fat in one’s diet was going to lower risk for breast cancer and cardiovascular disease. At the time, we didn’t know about trans fat,” Vitolins says.

More recently, trans fat has come under fire as public consumption enemy No. 1. Web sites such as www.bantransfats.com are advocating the elimination of it from supermarket shelves and making examples of those still using the harmful, artery-clogging fats, such as some fast-food chains.

In addition to honing in on trans fats, since the study began the distinction between “good fats” and “bad fats,” while not quite black and white, is less grey. “What we know 15 years later is that not all fats are created equal,” Snelling says. “In that 15 years, the harmful effects of trans fats [have] been recognized and now are labeled. We recognize the very positive effect of monounsaturated fat. We’ve learned a lot in 15 years from when this study was designed, but consumers don’t look at nutrition in a longitudinal manner. They look at what’s [on] the supermarket shelves and what’s on their kitchen table today; they don’t look at 13 years and how different it is.”

Back to the Drawing Board
Since the WHI study was examining total fat, the participants were advised not to lose weight. “We were not testing weight loss. We were testing fat, so they couldn’t lose weight,” Vitolins says. “We also did not encourage them to exercise more than they typically did. Researchers hoped to bring fat consumption from an average of 38% down to 20%. But there [have been questions about] whether women involved in the study were able to attain the 20% fat intake consistently throughout the study.

“That’s one of the tricky pieces to measuring diet intervention. It’s very difficult to quantify what 20% fat looks like,” Snelling says. “Pharmaceutical research is much easier to do than clinical research. You take a placebo, I’ll take the pill, but there’s no guessing how much we take. With diet research—like with behavioral research—it’s much harder to quantify over a much larger period of time.” But Snelling says the upside is that we are starting to recognize diet as a potential piece to any of these chronic diseases.

Vitolins says it is important to remind clients that the women who followed the diet the best benefited the most. “This is proof positive that this can work if you adhere to it,” she says.

In retrospect, Snelling says it’s easier to design an improved study. “Hindsight is 20/20. We all could perhaps design a better study now, but you have to start somewhere. And there have only been a handful, maybe two handfuls, of good diet nutrition studies looking at some chronic disease.”

Certainly, this was a large-scale study that cost an enormous amount of money, but Snelling says it retains its investment and value because it makes people think how to design better studies and how to use this information. “I don’t think at all it was a waste, but what we have to do is learn from how to control and how to define low-fat diets,” she says. “It’s about total health, which we don’t define as just eating a healthy diet. It may be fiber, it may be fat, it may be physical activity, it may be soy. It’s all these and that’s what is very difficult about trying to find the one magic bullet with diet. Most would agree there are many components to a healthy diet, and fat is only one aspect.”

Vitolins has her own suggestions for tweaking and hopefully improving the study. “I would add three arms off the diet arm. I would have had diet only; diet and exercise; [and] diet, exercise, and weight loss and had groups large enough to test that. I think that would have shown more risk reduction.”

Move Along
The only option now is to move forward. Snelling and Vitolins’ recommendations don’t stray far from suggestions long upheld and dispensed by academics and nutritionists alike. Snelling believes the study has much more of a researcher’s interest in mind than it does public consumption and accordingly should not shift dietitians’ recommendations.

“The consumer should go back to the American Cancer Society’s [ACS] guidelines that state a plant-based diet, one that’s low in fat coupled with physical activity that maintains a healthy body weight, is still the solid recommendation that, over time, has been shown to reduce risk for certain types of cancers,” she says. “I think it’s [the study] a good contribution to research literature on the evolution of cancer and diet, but for the general public, the recommendations should not change from the ACS guidelines.”

Once upon a time, patients and consumers got their health information from doctors. But in the age of constant news bombardment, Snelling says, “medical studies have become part of consumer literature, but sometimes the consumer literature—in the sense of headline news—does not do it service because they are sending the wrong message to the public.”

The bottom line, according to Vitolins: “Certainly eating low fat, although it did not have the result investigators wanted, is still important for a whole range of chronic disease reduction, as well as attaining a healthier lifestyle.”

— Meghan A.T.B. Reese is an editorial assistant at For The Record.

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