Researchers Say It's Best to Avoid Extreme Diets, Whether Low-Fat or Low-Carbohydrate
Researchers from the Harvard School of Public Health found no evidence of an association between low-carbohydrate diets and increased cardiovascular risk, even when these diets were high in saturated animal fats.
Low-carb eating even seemed to be protective against heart disease when vegetables were the main sources of fat and protein in the diet.
The study, which appears tomorrow in the New England Journal of Medicine, included almost 83,000 female nurses in the Nurses' Health Study who provided detailed information about their eating patterns once per year for more than 20 years. The nurses were not asked to follow any particular diets.
A clear message from the research was that extreme diets, which severely restrict either fats or carbohydrates, are not the best choices for cardiovascular disease prevention, researcher Thomas L. Halton, ScD, tells WebMD.
Pros and Cons
"Neither a very low-fat diet or a very low-carbohydrate diet proved to be ideal," he says. "There were pros and cons to both of these diets."
Low-fat diets are by definition low in saturated fats, which is good for the heart, Halton says. But they also tend to be higher in refined carbohydrates like sugar and white flour, which spike blood sugar levels.
"Americans tend to pick the wrong carbohydrates," he says. "So the benefits of eating lower amounts of saturated fat and cholesterol are offset to some degree by the poor quality of the carbohydrates they eat."
The most protective diet, in terms of heart disease risk, was a low-carbohydrate that was also low in saturated fats and cholesterol where vegetables were the main sources of fats and protein.
"The vegetable-based low-carbohydrate diet combined the best features of low-fat and low-carbohydrate eating," Halton says.
Following this diet was associated with a 30% reduction in heart disease risk over 20 years.
"The quality of fat and carbohydrate is more important than the quantity," says study researcher Frank Hu, MD, PhD. "A heart-healthy diet should embrace healthy types of fat and carbohydrates."