Low-carb Diets May Negatively Affect Health

A low-carbohydrate diet with protein and fats primarily from meats may increase susceptibility to heart disease or cancer more so than a high-carbohydrate diet, according to a study published last week by researchers at the Harvard School of Public Health.

“The bottom line is that not all low-carbohydrate diets are created equal,” said Frank B. Hu, a professor of nutrition at the School of Public Health and the study’s principal investigator. “The original Atkins diet, which was loaded with animal fats, is certainly not ideal. Versions of low-carbohydrate diets that are high in vegetable protein and fats are significantly healthier.”

All together, the researchers investigated data from over 85,000 women over a period of 26 years and 44,000 men over a period of 20 years, making the study the largest and most comprehensive to be conducted on the topic of low-carbohydrate diets, according to Hu.

The study found that people who ate the most animal-based proteins and lipids were 14 percent more likely to die from heart disease and 28 percent more likely to die from cancer than those who ate a high-carbohydrate diet.

Low-carbohydrate diets have long been touted as wonderful for weight loss and cardiovascular health. However, according to Teresa T. Fung, the study’s lead author and an adjunct associate professor of nutrition at the School of Public Health, when people want to reduce the amount of carbohydrates they eat, they need to decide where to get their energy replacements.

“Proteins and fats come from many sources,” Fung said.

She said that foods like beans, nuts, and vegetable oils should be preferred over meats and animal fat, though she added that a “plant-based diet” does not necessarily mean a vegetarian diet.

People whose diets had the most plant-based protein and lipid substitutions had a death rate 20 percent lower than those who ate the high-carbohydrate diet.

According to Fung, the results were to be expected because previous research has shown that vegetable proteins and fats have been linked to lower risks of cancer and other diseases, whereas red meats and processed meats have been observed to cause increased risks of disease.

The researchers emphasized that their low-carbohydrate diet scores are not meant to mimic any commercial diet regimes.

“The risk estimates do not directly translate to assessment of benefit or risk associated with popular versions of the diet,” the study stated.

—Staff writer Helen X. Yang can be reached at hxyang@fas.harvard.edu.