Fructose, also called fruit sugar, was once a minor part of the American diet. A century ago, the average person took in about 15 grams a day (roughly half an ounce), mostly from eating fruits and vegetables. Today, we get more than triple that amount, almost all of it from the refined sugars and high-fructose corn syrup used to make breakfast cereals, pastries, soda and fruit drinks, and other sweet foods. Given the way the body breaks down fructose, that increase may be contributing to liver and heart disease, reports the September 2011 issue of the Harvard Heart Letter.
Liver cells are the only cells in the body that metabolize fructose. Surprisingly, fat is a key byproduct of the breakdown of fructose. Give the liver enough fructose, and tiny fat droplets begin to accumulate in the organ. This buildup is called nonalcoholic fatty liver disease. If it becomes severe enough, it can cause serious liver damage.
Cycling of fructose through the liver also elevates triglycerides in the bloodstream, increases harmful LDL (so-called "bad") cholesterol, promotes the buildup of fat around organs (visceral fat), increases blood pressure, and causes other changes that are harmful to the arteries and heart. Two recent studies have linked higher intake of fructose with higher chances of developing or dying from heart disease.
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