A low-carbohydrate diet that derives fats and proteins from vegetable sources rather than meats is probably healthier, new research finds.
Comparing the two types of diets over two decades, researchers found that the low-carb, vegetable-based plan resulted in reduced rates of death from cardiovascular disease and cancer, and a lower rate of all-cause death overall.
"You can have the initial Atkins-type of low-carb diet, which is loaded with sausages, bacon, steaks, and you can have healthy versions of the low-carb diet with more vegetable- or plant-based protein and fat," said Dr Frank B. Hu, senior author of a study in the Annals of Internal Medicine.
"We looked at these two versions of low-carb diets and found that the impact of the two are drastically different," Hu said.
Ratio of food important
"Those who follow the animal-based low-carb diet have an increased risk of total mortality, and cancer mortality in particular," said Hu, a professor of nutrition at the Harvard School of Public Health in Boston.
"It's the ratio that's important," said Karen Congro, director of the Wellness for Life Programme at the Brooklyn Hospital Centre in New York City. "This tells you that meat is the issue. Red meat is out."
Although several smaller, short-term studies have shown that the Atkins-type low-carb diets lead to weight loss, "there has been a lot of concern that a low-carb diet, which typically [incorporates] animal fat and animal protein, may increase the risk of chronic diseases," Hu said. These include type 2 diabetes and coronary heart disease.
Two studies are reported here, one that followed 85,168 women from 1980 through 2006 and one that followed 44,548 men from 1986 through 2006.
Men and women on the animal-based low-carb diet had a 23% increased risk of death, a 14% increased risk of dying from heart disease and a 28% increased risk of dying from cancer, the study authors found.
Those on an "Eco-Atkins" diet, the ones who incorporated vegetable-derived fats and proteins, had a 20% lower death rate and a 23% lower risk of dying from heart disease, the findings indicated.
Plant-based low-carb diets get their fats mostly from vegetable oils, nuts and peanut butter. Proteins can come from legumes, nuts and whole grains instead of bacon and sausage, Hu said.
Avocados are also a healthy source of fat, and soy and tofu are good sources for protein, Congro said.
People eat too many carbs
Overall, the participants in the studies had a relatively low-carb intake compared to the carb-crazy population as a whole.
"People are just over-carbing," she added. "Cereal bowls look like bowls for a casserole. People eat granola bars all day. They get into carbs without even realising it. Because heart disease is so prevalent, anything we can do to lower the risk, the mortality" is important.
"This study is one of the first to actually differentiate types of low-carb diets in relation to long-term health impact," Congro added.
An accompanying editorial pointed out that the design of the study may not have taken into account other variables, such as smoking and education levels, indicating the need for a large-scale clinical trial.