Health

Carbs may raise risk of cancer

A new study raises concerns about high-carb diets beyond how they affect weight. Breast cancer was more than twice as common in women in Mexico who ate a lot of carbohydrates as it was in those who limited carbs to roughly half of all calories they consumed, the research found.

The typical American diet is half carbohydrates, and the study was launched in 1995, when people were urged to eat carbs and avoid fats. Now, many are following low-carb diets, which generate argument about how they affect cholesterol and heart disease.

"The findings do raise concern about the possible adverse effects of eating lots of carbohydrates," said Dr. Walter Willett, chief of nutrition at the Harvard School of Public Health.

He did the study with doctors in Cuernavaca, Mexico. It was funded by the U.S. Centers for Disease Control and Prevention, the Ministry of Health of Mexico, and the American Institute for Cancer Research. Results were published Friday in the journal Cancer Epidemiology, Biomarkers & Prevention.

Fats, fiber and specific foods have long been studied for their effects on cancers, but few firm links have emerged. Being overweight raises risk, but the new study took that into account.

Scientists think carbs may increase cancer risk by rapidly raising sugar in the blood, which prompts a surge of insulin to be secreted. This causes cells to divide and leads to higher levels of estrogen in the blood, both of which can encourage cancer.

Researchers enrolled 475 women newly diagnosed with breast cancer and a comparison group of 1,391 healthy women in Mexico City who were matched for age, weight, childbirth trends and other factors that affect the odds of getting the disease.

Those who got 62 percent or more of their calories from carbs were 2.22 times more likely to have breast cancer than those whose carb intake was 52 percent or less.

How applicable the results are to American women is debatable.

In Mexico, the main carbs are corn-derived. Corn isn't fortified with folate and other nutrients as are many grains, cereals and other sources of carbohydrates in the United States, and those nutrients might help prevent cancer, noted Sandra Schlicker of the American Society for Clinical Nutrition.

"This study alone isn't enough for people to make changes in their diet, but it's a cautionary sign," Willett said.

The Institute of Medicine recommends that carbohydrates constitute 45 percent to 65 percent of calories, and that no more than 20 percent come from added sugars.

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