A slight fall in blood levels of HDL (“good”)
cholesterol in men due to a low-fat, high-
carbohydrate eating plan may not be a problem, researchers reported today at the American Heart Association’s 5
th Annual Conference on
Arteriosclerosis,
Thrombosis and Vascular Biology.
Instead, researchers said that the lower levels of high-density lipoprotein (HDL) cholesterol may be a result of lower levels of low-density lipoprotein (LDL or “bad” cholesterol).
“Even if a low-fat/high-carbohydrate eating plan leads to a slight reduction in the level of HDL in the blood, overall this may not reflect undesirable changes from a cardiovascular risk standpoint,” said Sophie Desroches, M.Sc., R.D., doctoral candidate in Nutrition at the Institute on Nutraceuticals and Functional Foods at Laval University in Quebec City, Canada.
HDL levels normally fall in response to a high carbohydrate, low saturated fat/total fat eating plan even when body weight stays the same or is reduced.
“This created a controversy among scientists, because HDL cholesterol has a beneficial effect on coronary heart disease risk,” Desroches said. “However, body weight is also an important determinant of plasma HDL cholesterol concentrations, and low-fat/high-carbohydrate diets are associated with weight loss.”
To provide information on the effects of eating plans that can help manage weight and cardiovascular risk, the study examined HDL metabolism under realistic conditions in which participants chose how much they ate and weren’t prevented from losing or gaining weight.
Researchers studied 65 men, average age 37.5, who ate according to one of two randomly assigned eating plans for six to seven weeks.
Half the men ate a food low in saturated fat and total fat and high in carbohydrates similar to the plan the American Heart Association and National Cholesterol Education Program (AHA/NCEP) recommend for reducing cholesterol and preventing coronary heart disease. This plan had 58 percent of its calories from carbohydrates, 26 percent from fat (less than 7 percent from saturated fat), and 16 percent from protein.
The other plan was high in mono-unsaturated fatty acids (MUFA) and resembled a Mediterranean-style diet. In the MUFA plan, 40 percent of calories came from fat (with more than half of the fat from olive oil and other MUFAs), 45 percent from carbohydrates and 15 percent from protein.