Barbara Quinn: Nutrition science is predictably unpredictable

May 2, 2016

You might be a cowgirl if it’s cloudy and cold out when your daughter asks, "Tom needs to check on the cows. Want to help?" and you immediately say, "Yes!"

Maybe it’s the seasonal predictability of this life that I like — riding through spring pastures to see newborn calves wobble close to their protective moms.

Still, there is much in this life that cannot be predicted. In spite of top notch weather forecasters, for example, unexpected changes in the weather can threaten the survival of these precious animals. 

Nutrition science can be unpredictable as well. Even the best research can be threatened with storms of controversy. Case in point: a newly formed non-profit organization called Nutrition Coalition has called on the USDA — which oversees the publication of the Dietary Guidelines for Americans — to re-evaluate the science behind our current nutrition recommendations. 

Their claim: Our current nutrition guidelines are not working and may not be based on the best available science. They especially call into question the recommendation to reduce saturated fat in our diets as a way to curb heart disease. 

What is a healthful diet anyway? According to the extensive panel of experts from top notch universities and research facilities who drafted the Dietary Guidelines for Americans 2015, "the overall body of evidence examined identifies that a healthy dietary pattern is higher in vegetables, fruits, whole grains, low- or non-fat dairy foods, seafood, legumes, and nuts; moderate in alcohol (among adults); lower in red and processed meat; and low in sugar-sweetened foods and drinks and refined grains." 

Yet there is the concern that two of every three American adults are overweight or obese and half of us now have a chronic disease that possibly could have been prevented with a better diet. Does that mean the guidelines have failed or are we failing the guidelines? 

Part of the issue: Our national nutrition recommendations are targeted at healthy people—those with no diabetes, heart disease or cancer. More drastic health conditions may require more drastic diets. Genetic differences between people also come into play. Some people store extra cholesterol in their arteries much more efficiently than others.

So, we return to what should be a predictable answer: How much and what kind of fat should we eat for good health? Here are some facts:

—Replacing excess saturated fat in our diets with unsaturated fats (from vegetable oils, nuts and fish) can lower blood cholesterol levels.

—Saturated fat is an inflammatory type of fat. Heart disease and obesity are now considered inflammatory conditions, according to researchers.

—Scientists have observed that populations of people with lower cholesterol levels have lower rates of heart disease. Lowering cholesterol levels doesn’t always translate to a lower risk for having a heart attack, however.

I doubt, as some have accused, that our current recommendations are based on flimsy science. Nutrition research is fraught with a huge array of unpredictable variables. Differences in our lifestyles and genetics, for instance, may make nutrition recommendations that hold true for every person virtually impossible.

Alas, controversy has been and will continue to be part of our quest for understanding THE optimal diet. Yet I predict that my wise grandfather’s words will continue to hold true: "Too much of anything is not good for you."




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