Carbs against Cardio
More data that refined carbohydrates, not fats, threaten the heart
BY MELINDA WENNER MOYER
Processed carbohydrates, which many Americans eat today in place of saturated fat, may increase the risk of obesity, diabetes and heart disease more than fat does.
In March 2010 the American Journal of Clinical Nutrition published a meta-analysis—combines data from several studies—compared the reported daily food intake of nearly 350,000 people against their risk of de-veloping cardiovascular disease over a period of five to 23 years. The analysis, overseen by Ronald M. Krauss, director of atherosclerosis research at the Children’s Hospital Oakland Research Institute, found no association between the amount of saturated fat consumed and the risk of heart disease.
Although saturated fat boosts blood levels of “bad” LDL cholesterol, it also increases “good” HDL cholesterol.
Saturated fats are not so bad; they indicate that carbohydrates could be worse.
A 1997 study Krauss co-authored in the Journal of the American Medical Association evaluated 65,000 women and found that the quintile of women who ate the most easily digestible and readily absorbed carbohydrates—that is, those with the highest glycemic index—were 47 percent more likely to acquire type 2 diabetes than those in the quintile with the lowest average glycemic-index score. (The amount of fat the women ate did not affect diabetes risk.) And a 2007 Dutch study of 15,000 women published in the Journal of the American College of Cardiology found that women who were overweight and in the quartile that consumed meals with the highest average glycemic load, a metric that incorporates portion size, were 79 percent more likely to develop coronary vascular disease than overweight women in the lowest quartile.
These trends may be explained in part by the yo-yo effects that high glycemic-index carbohydrates have on blood glucose, which can stimulate fat production and inflammation, increase overall caloric intake and lower insulin sensitivity, says David Ludwig, director of the obesity program at Children’s Hospital Boston.
Right now, Post explains, the agency’s main message to Americans is to limit overall calorie intake, irrespective of the source.
“We’re finding that messages to consumers need to be short and simple and to the point,” he says.
Nobody is advocating that people start gorging themselves on saturated fats, tempting as that may sound. Some monounsaturated and polyunsaturated fats, such as those found in fish and olive oil, can protect against heart disease. What is more, some high-fiber carbohydrates are unquestionably good for the body. But saturated fats may ultimately be neutral compared with processed carbs and sugars such as those found in cereals, breads, pasta and cookies.
“If you reduce saturated fat and replace it with high glycemic-index carbohydrates, you may not only not get benefits—you might actually produce harm,” Ludwig argues. The next time you eat a piece of buttered toast, he says, consider that “butter is actually the more healthful component.”