|These are baffling times for health-conscious Americans. It seems that as soon as the implications of the latest diet study sink in, another comes along to contradict it. For example: Eggs are bad, eggs are okay; fiber is good, fiber doesn’t matter; margarine is the better spread, margarine is as bad as butter. These flip-flops are enough to get even the most conscientious eater fed up. And that has detrimental consequences.
In a recent survey of 1,750 adults, the more muddled they were about dietary recommendations, the more likely they were to eat high-fat diets and skimp on fruits and vegetables.
Why the confusion? The ever-evolving “gray” nature of science conflicts with human nature, which craves black-and-white finality. But nutrition science unfolds slowly and its movement is seldom unidirectional. If it seems like the experts are always changing their minds, it’s because they are, explains David Klurfeld, Ph.D., of Wayne State University in Detroit. “Dietary advice is based on what is known today. Tomorrow may contradict today; that’s the nature of science.”
Of Reporters and Researchers. Much of the confusion is compounded because headline writers have different goals than nutrition researchers. Reporters highlight unusual findings to grab your attention. Researchers, on the other hand, view each new study as a stepping stone to the truth, well aware that the latest finding may not stand the test of time. It is the total body of evidence?confirmed and reconfirmed?not the latest headlines, that should influence food choices.
The Making of a Flip-Flop. Uncertain science?especially when mishandled by the media?is often at the core of a seeming flip-flop. For example, last year’s shocking headlines that fiber does not prevent colon cancer misrepresented the research findings as the final word on a diet-disease relationship that is still uncertain. The research in question looked at whether colon polyps?which can turn cancerous?reappeared after eating fiber, but did not even study whether those polyps became cancerous. Perhaps fiber is protective after all or maybe something else in fiber-rich fruits, vegetables or whole grains keeps cancer at bay. For this and other reasons (see chart), you should still aim to eat more high-fiber foods.
Often, what seems like a flip-flop is really just a shift in emphasis for scientists. For example, researchers have known for years that too much fat?especially saturated fat?is not good. It now appears that for some people, a moderate amount of fat?especially if much of it is monounsaturated?may be heart-healthier than a very low-fat diet. Moreover, while saturated fat used to be considered the worst culprit, trans fats are now known to be just as bad. So the fat message didn’t really flip-flop; it became more complex, requiring nutritionists to refine the message.
Advice to Live By. One thing is certain. As scientific knowledge advances, dietary advice will change. To keep today’s advice in perspective, EN recommends the following:
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