The Nutritional Pickle: The Dangers Of The Nutritional Pickle

The nutritional pickle so many Americans are now in is largely a result of “an oversimplification of dietary recommendations that created a fat phobia,” Dr. Frank B. Hu of the Harvard T. H. Chan School of Public Health told me.

Starting in the 1970s, when accumulating evidence from animal and human studies showed that a diet high in saturated fats and cholesterol was an important risk factor for cardiovascular disease, dietary guidelines urged people to eat less fat.

Although health advice focused on saturated fats from high-fat animal foods, many people generalized the advice to mean all fats, choosing in their stead a panoply of reduced-fat and fat-free foods rich in carbohydrates, from crackers to sweetened yogurts. They especially increased their consumption of two kinds of

Starchy foods with highly processed grains that have been stripped of dietary fiber act more like sugar in the body. They are rapidly digested and absorbed, raising blood levels of glucose and prompting the secretion of insulin to process it. When consumed in excess of the body’s need for immediate and stored energy, refined carbs and sugars can result in insulin resistance and contribute to fatty liver disease.

Alas, potatoes, the nation’s most popular vegetable, act like sugars and refined carbohydrates. They have what is called a high glycemic index, the ability to raise blood glucose rapidly. Potatoes, Dr. Hu explained, are made of long chains of glucose easily digested by enzymes in the mouth and stomach, and the fat in French fries slows the process only slightly.

The concept of a glycemic index, proposed in 1981 by David Jenkins and his colleagues in The American Journal of Clinical Nutrition, has since been validated repeatedly and is now accepted as a good way to distinguish between the kinds of carbohydrates that are health-promoting or at least neutral and those that have negative health