Carbs may explain ethnic variations in cholesterol

NEW YORK (Reuters Health) - Ethnic differences in levels of HDL, the "good" cholesterol, may be due, at least in part, to diet, a new study from Canada suggests.

South Asians ate the most carbohydrate and had the lowest HDL cholesterol levels, while Chinese individuals ate the least carbohydrate and had the highest levels of the beneficial blood fat, Dr. Anwar T. Merchant of the Population Health Research Institute in Hamilton, Ontario and colleagues found.

Previous research has identified ethnic differences in cholesterol and other blood fat levels that couldn't be explained by genes, obesity, lifestyle factors or diet, Merchant and his team note, but these analyses usually looked at dietary fat, not carbohydrate consumption. When calories from carbohydrates replace energy from fat in a person's diet, both LDL and HDL cholesterol levels fall while triacylglycerol levels rise, the researchers explain.

To investigate the role of carbohydrate and HDL levels in a population containing a variety of ethnic groups, Merchant and his colleagues analyzed the diet and blood fats of 619 Canadians of Native American, South Asian, Chinese and European descent. The researchers report their findings in the American Journal of Clinical Nutrition.

As mentioned, South Asians ate the most carbohydrates, followed by Europeans, Native Americans, and Chinese. After adjustment for several factors including age, ethnicity, body mass index and alcohol intake, the association between carbohydrates and lower HDL cholesterol remained, with people consuming the most carbs having an average level of 1.08 mmol/L, compared to 1.21 mmol/L for those who ate the fewest carbohydrates.

Each additional 100 gram per day of carbohydrates was tied to a 0.15 mmol/L drop in HDL cholesterol. Triacylglycerol levels also rose in tandem with carbohydrate intake.

The researchers also found that consuming more sugar-sweetened soft drinks, juices and snacks was tied to a lower HDL level.

"Differences in HDL and triacylglycerols observed in different ethnic groups may be due in part to carbohydrate intake," the researchers write. "Reducing the frequency of intake of sugar-containing soft drinks, juices and snacks may be beneficial."

SOURCE: American Journal of Clinical Nutrition, January 2007.