Popular low-carbohydrate diets such as the Ketogenic diet, Paleolithic diet and Atkins diet may shorten the life expectancy of your health club members by four years, according to a new study whose senior author called it "the most comprehensive study of carbohydrate intake" ever conducted.
"Dietary Carbohydrate Intake and Mortality: A Prospective Cohort Study and Meta-Analysis," published Aug. 16 in Lancet Public Health, tracked the carbohydrate consumption of 15,428 middle-aged Americans over a 25-year-period. The authors—six of them medical doctors—found that those with moderate, not high or low, carbohydrate intake reported the lowest risk of mortality.
The study states: "[T]here was a U-shaped association between the percentage of energy consumed from carbohydrate and mortality: a percentage of 50 to 55 percent energy from carbohydrate was associated with the lowest risk of mortality. In the meta-analysis of all cohorts, both low carbohydrate consumption (less than 40 percent) and high carbohydrate consumption (as much as 70 percent) conferred greater mortality risk than did moderate intake, which was consistent with a U-shaped association.
The study's low-carbohydrate group reported an average life expectancy of 79 years, while the high-carbohydrate group reported 82 years and the moderate-carbohydrate group reported 83 years.
The authors emphasize that low-carbohydrate diets favoring strict animal protein intake do not aid longevity like more balanced diets that include nuts, vegetables and whole grains.
"Low-carb diets that replace carbohydrates with protein or fat are gaining widespread popularity as a health and weight-loss strategy," lead author Sara Seidelmann told the BBC. "However, our data suggests that animal-based low carbohydrate diets, which are prevalent in North America and Europe, might be associated with shorter overall life span and should be discouraged. Instead, if one chooses to follow a low carbohydrate diet, then exchanging carbohydrates for more plant-based fats and proteins might actually promote healthy aging in the long term."
The study data was derived from the National Heart, Lung, and Blood Institute's Atherosclerosis Risk in Communities Study (ARIC). The results may be limited in that the ARIC was self-reported and only measured diets twice during its 25-year study period.