MONDAY, April 12, 2010 (Health.com) — Women who eat more white bread, white rice, pizza, and other carbohydrate-rich foods that cause blood sugar to spike are more than twice as likely to develop heart disease than women who eat less of those foods, a new study suggests.
Men who eat lots of those carbohydrates—which have what’s known as a high glycemic index (GI)—do not have the same increased risk, however, perhaps because their bodies process the carbs differently, the researchers found.
Only carbohydrates with a high glycemic index appear to hurt the heart. Carbs with a low glycemic index—such as fruit and pasta—were not associated with an increased risk of heart disease, which suggests that the increased risk is caused “not by a diet high in carbohydrates, but by a diet rich in rapidly absorbed carbohydrates,” says the lead author of the study, Sabina Sieri, PhD, of the Fondazione IRCCS Istituto Nazionale dei Tumori, a national institute for cancer research in Milan, Italy.
The glycemic index ranks on a scale from 1 to 100 how quickly (or slowly) carbohydrates affect your blood-sugar levels. (White bread scores 100.) Foods that rank below 55 are considered to have a low glycemic index and produce only small fluctuations in blood glucose and insulin levels; foods that rank above 70 are said to have a high glycemic index and tend to cause unhealthy spikes in blood sugar.
In the study, published this week in the Archives of Internal Medicine, Sieri and her colleagues analyzed data from a large, ongoing study of nutrition and cancer risk. The researchers surveyed roughly 48,000 Italian adults about their diets in detail, noting the amount and types of carbohydrates they consumed on a regular basis. (People with diabetes, who have abnormal levels of blood sugar and insulin, were excluded.) Not surprisingly—the study was conducted in Italy, after all—bread, pasta, and pizza were common sources of carbs.
During the eight-year follow-up period, 463 people in the study—65% of them men—experienced heart problems (including heart attacks), had angioplasty or bypass surgery, or died of heart-disease-related causes.
The women who reported eating the most carbohydrates had twice the risk of developing heart disease as their counterparts who consumed the fewest carbs.
When the researchers broke the carbs into high and low glycemic index categories, the increased risk was even more apparent: Women who ate the most high glycemic foods had about 2.25 times the risk of developing heart disease than women who consumed the fewest. (To isolate the effect of the carbs on heart health, the researchers took body weight, physical activity, saturated fat intake, smoking, and a range of other health factors into account.)
Next page: For men, a different story