Harvard Health Blog
A sugar-laden diet may raise your risk of dying of heart disease, even if you aren't overweight. So says a major study published online in the Journal of the American Medical Association-Internal Medicine.
Added sugars make up at least 10 percent of the calories the average American eats in a day. But about one in 10 people get a whopping one-quarter or more of their calories from added sugar.
Over the course of the 15-year study, participants who took in 25 percent or more of their daily calories as sugar were more than twice as likely to die from heart disease as those whose diets included less than 10 percent added sugar. Overall, the odds of dying from heart disease rose in tandem with the percentage of sugar in the diet--and that was true regardless of a person's age, sex, physical activity level, and body-mass index (a measure of weight).
Sugar-sweetened beverages, such as sodas, energy drinks, and sports drinks, are by far the biggest sources of added sugar in the average American's diet. They account for more than one-third of the added sugar we consume as a nation. Other important sources include cookies, cakes, pastries, and similar treats; fruit drinks; ice cream, frozen yogurt and the like; candy; and ready-to-eat cereals.
Nutritionists frown on added sugar for two reasons. One is its well-known links to weight gain and cavities. The other is that sugar delivers "empty calories" -- calories unaccompanied by fiber, vitamins, minerals, and other nutrients. Too much added sugar can crowd healthier foods from a person's diet.
Could it be possible that sugar isn't the true bad guy boosting heart disease risk, but that it's the lack of heart-healthy foods like fruits and veggies? Apparently not. In this study, the researchers measured the participants' Healthy Eating Index. This shows how well their diets match up to federal dietary guidelines.
"Regardless of their Healthy Eating Index scores, people who ate more sugar still had higher cardiovascular mortality," says Dr. Teresa Fung, adjunct professor of nutrition at the Harvard School of Public Health.
Exactly how excess sugar might harm the heart isn't clear. Earlier research has shown that drinking sugar-sweetened beverages can raise blood pressure. A high-sugar diet may also stimulate the liver to dump more harmful fats into the bloodstream. Both factors are known to boost heart disease risk.
Federal guidelines offer specific limits for the amount of salt and fat we eat. But there's no similar upper limit for added sugar. The Institute of Medicine recommends that added sugars make up less than 25 percent of total calories. But that advice dates back to 2002, before the data about sugar's potentially dangerous health effects were available, says Dr. Fung.
Fung supports the American Heart Associationâs recommendation that women consume less than 100 calories of added sugar per day (about 6 teaspoons) and men consume less than 150 per day (about 9 teaspoons).
To put that in perspective, a 12-ounce can of regular soda contains about 9 teaspoons of sugar, so quaffing even one a day would put all women and most men over the daily limit.
"If you're going to have something sweet, have a fruit-based dessert," says Dr. Fung. "That way, at least you're getting something good out of it." Of course, plain fruit with no added sugar is ideal. If you're trying to curb a soda habit, Dr. Fung suggests substituting a little fruit juice mixed with seltzer water.
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