In Search of a Righteous Diet

Eating healthy can easily morph into a quest for a righteous diet that goes well beyond evidence-based nutrition. You can find quite a spectrum in the significance that people attach to the concept of a healthy diet.

In the extreme, a quest for a righteous diet can take to the form of what some have defined as an eating disorder — orthorexia nervosa.  People who develop this condition may start with a genuine desire to eat healthfully that progresses into an obsessive pursuit of a rigidly pure diet. Eventually, this diet may become so restricted that nutrition and health begin to suffer. Some believe that orthorexia should be recognized as a distinct eating disorder. Others treat it as a variant of obsessive compulsive disorder.

Even evidence-based guidelines are sometimes influenced by conventional wisdom that hasn’t stood up to rigorous experimental testing. As an example, low-fat dairy has been a key recommendation of nutrition guidelines for some time. Much of the impetus for recommending that people stick with low-fat dairy has been data linking the high saturated fat content of regular dairy products to cardiovascular disease.

Now comes a series of studies that seemingly link low-fat dairy consumption to weight gain. This observation has been made in both adults and children. A meta-analysis of 16 observational studies in the European Journal of Nutrition found the results favored a conclusion contrary to conventional wisdom — high-fat dairy products do not contribute to cardiovascular risk and may actually reduce the risk of obesity.

Of course, this finding is far from conclusive, but it serves to illustrate how a supposition — like the health benefits of low-fat dairy — can be become an article of faith without the backing of solid experimental evidence. And with any article of faith, doubts can emerge to overturn cherished assumptions.

The superiority of a plant-based diet is another article of faith for many people. Growing numbers of folks have legitimate philosophical reasons for preferring a vegetarian or vegan diet.

But evidence-based guidelines for nutrition and health must remain separate from philosophical preferences. Individual choices will inevitably be guided by personal philosophies. To make good personal choices, though, people need reliable facts — based on unbiased nutrition science — to weigh through the lens of their own values.

Click here to read more about the link between dairy fat and obesity, here to read the study from the European Journal of Nutrition, here to read more about the challenges of evidence-based nutrition guidelines, and here to read more about orthorexia.

Staff of Life, photograph © kendiala / flickr

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