Wednesday, February 08, 2006

Low-Fat Diets: At the Crossroads

One quote is rather telling in all the hub-bub following the publication of the WHI Dietary Modification Trial data yesterday - the Director of the National Heart, Lung, and Blood Institute (NHLBI), Elizabeth G. Nabel, stays very clear on message - "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."

Basically, even though the findings show no useful reduction in the risk of breast cancer, colon cancer and cardiovascular disease after following a low-fat diet for eight years, we're sticking to those recommendations anyway. Pure hubris.

Another quote from Dr. Nabel shows just how deeply entrenched the theory of restricting fats really is, with the excuse being bandied about for the null findings being that the diet "focused on reduction in total fat and did not differentiate between the so-called good fats and bad fats."

Now we're going to be asked to suspend our disbelief - yet again - and continue with more studies, with more women, asking them to reduce dietary fat even more so we can try again to get the desired results.

"For heart-disease prevention, the data suggests that a greater emphasis on reduction of saturated and trans fats will be needed to have a major difference," Shirley Beresford, PhD, said..."This was a long-term, demanding study for the women in the low-fat group, and they did a marvelous job of trying to adhere to stringent dietary goals,"

Ross L. Prentice, PhD added, "In spite of their efforts, we achieved only 70 percent of the difference in dietary habits between the two groups that we needed to get. If we'd achieved an even higher adherence rate, I believe the study's results would have been more dramatic." And continued with, "While the study didn't give us the results that some people were hoping for, it suggests that we're on the right track. Women can be confident that cutting back on fat and following the recommended Dietary Guidelines for Americans certainly won't hurt when it comes to maintaining a healthy lifestyle and preventing chronic disease...Additional follow-up with these women may yield a stronger, statistically significant conclusion. The low-fat story is partly in, but it is not over yet."

It seems they've already made up their minds and are now looking for excuses to explain why the data showed no significant differences between the women eating less than 30% of calories from fat when compared to the control group eating 38% of their calories from fat.

Among the excuses being put forth:
  • We just need more time is one of the favorites..."There is some evidence that with longer follow-up we might come to some different conclusions," said Shirley Beresford, a Women's Health Initiative investigator and professor of epidemiology at the School of Public Health and Community Medicine at the University of Washington in Seattle.
  • They didn't reduce the right type of fat is another good one...Harvard School of Public Health epidemiology professor Dr. Meir Stampfer was not surprised by the study's results and said a study on the different types of fat may have been more useful. "For heart disease, it is the type of fat and type of grain," he said.
  • They started eating a low-fat diet too late is getting traction too...Dr. David Katz, an ABC News Medical correspondent and Yale School of Public Health professor, said that the dietary changes may have been started too late in life. "The benefits of a healthful diet accrue slowly over time; an eight-year period postmenopause may be an after-the-fact intervention," he said.
  • We didn't know then, in 1993 when the study began, what we know now about fats is also put forth, "Our thinking about dietary fat and heart disease has evolved considerably since this study began in 1993...Participants in the low-fat diet group reduced their intake of saturated fat, but they also reduced their intake of heart healthy fats," wrote Leslie Beck, a Toronto-based dietitian at the Medcan Clinic.
  • Then, of course, is the fantasy that those in the low-fat group weren't eating much fat at the start, "One possible explanation for the findings," said Dr. Henry Black, a preventive cardiologist at Rush University Medical Center in Chicago and one of the study investigators, "is that the women who volunteered for the study were not "eating huge amounts of fat" to begin with, and those in the diet group were able to reduce their fat consumption by only 8 percent when compared with the control group. There were even smaller decreases in consumption of saturated fat and trans fat, and only tiny increases in consumption of fruits, vegetables and grains."
  • Dr. Black added yet another possibility too - that the women in the control group were also eating more healthfully, even though they weren't asked to. Public knowledge about healthy eating was increasing in the period after the study began."

These, with a number of other excuses, are filling article after article written about the study. We're seeing a lot of white wash today to try to cover up the fact the data revealed "null findings" between the intervention group eating less than 30% fat and the control group eating any diet they wanted and consuming an average 38% of fat in their diet. The intervention group did not realize a significant reduction in the incidence of breast cancer, colon cancer or cardiovascular disease compared with the control group.

We're even seeing the data massaged to find something, anything postive...a risky exercise in mental gymnastics called "post doc analysis", where some not involved in the study try to extrapolate a finding from the published data. A number of articles are putting such opinions forth as fact - everything from the supposed trend in the low-fat group having a reduction in risk of breast cancer if you just look hard enough, to the women in the low-fat group reported less incidence of colon polyps (self-reported data is always shaky at best).

The one thing missing in all of this is the acknowledgement that the theory, that launched the low-fat diet as the one for optimal health, may be flawed. Too many people are falling all over themselves to make sure we - the population at large - do not dissent from the message, the recommendations, or think about exploring other options.

But that is exactly what we must do! To simply accept this long-term, randomly controlled, well designed study's "null findings" as an abberation is insane. We have known for decades - yes decades - that reducing fat in the diet is not the "optimal" diet for health and well-being, is not the "best" approach for everyone, and is not the end-all-be-all for population-wide recommendations. Even with a number of prominent scientists and clinicians pointing this out over the decades, little has changed since the theory was put forth and accepted in the 1970's.

We now stand at the crossroads - do we continue on the path of blind faith that low-fat diets work - or - do we set off on the road less traveled and take a long, hard look at the entire body of evidence and explore the possibility we were wrong?

The one thing I agree with from the various perspectives quoted is that these findings do not suggest we have a license to just go eat whatever we want. We have a large body of evidence that supports the fact that we humans require a range of essential nutrients, that our bodies do not function well with processed junk food, and that we should strive for a nutrient-dense diet as often as possible to reduce our risk of health ills in the long-term.

What we don't have, and didn't have thirty years ago, is convincing evidence that a low-fat diet provides for our nutritional requirements and offers protective benefits. If nothing else, we now have long-term data that tells us this approach really does not reduce our risk of disease - it may not do harm as some are suggesting, but isn't the goal to prevent and ward off occurance as long as possible? Low-fat diets failed this important test - they did not reduce the risk of breast cancer, colon cancer or cardiovascular disease!

At the crossroads, where shall we go now?

2 comments:

  1. Thank your for repeating what Diocletian observed thousands of years ago: "One man's meat is another's poison." Different availability of foodstuffs in our ancestor's lands influenced, over many generations, what kinds of foods produce health in different groups of people. D'Adamo's blood-type diet was a first step in recognizing this. The earlier pioneering work of Wolcott, with recent refinements by Kristal and Haig, have provided clinically repeatable success in identifying basic metabolic patterns, regardless of blood type, each with differing macronutrient requirements.

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  2. It's important to keep in mind that the so-called "low-fat diet" group were still eating about three times the level of dietary fat recommended by low-fat diet advocates such as Caldwell Esselstyn Jr. and T. Colin Campbell. Differences in fruit and whole grain consumption between the two groups seem to have been almost negligible.

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