Both high and low carbohydrate diets are associated with increased mortality, as is a low carbohydrate diet that favors animal-derived protein and fat sources, according to findings published in Lancet Public Health.
Low carbohydrate diets have become a popular weight loss strategy, but the long-term effect of restricting carbohydrates on mortality is controversial and may be dependent on whether carbohydrates are being replaced by plant-based or animal-based fat and protein. In this study, the investigators evaluated the association between carbohydrate intake and mortality in 15,428 adults (age 45-64 years) who participated in the Atherosclerosis Risk in Communities study (between 1987 and 1989). None of the participants reported an extreme caloric intake (<600 kcal or >4200 kcal per day for men and <500 kcal or >3600 kcal per day for women). The primary outcome of the study was all-cause mortality.
At a median follow-up of 25 years, and following multivariable adjustment, there was a “U-shaped” association between the percentage of energy consumed from carbohydrate intake (mean 48·9%, SD 9·4) and mortality. A percentage of 50% to 55% energy from carbohydrate was associated with the lowest risk for mortality, whereas low carbohydrate consumption (<40%) and high carbohydrate consumption (>70%) were linked with a higher mortality risk vs moderate intake. These findings did vary according to the source of macronutrients, as mortality increased when carbohydrates were replaced with animal-derived fat or protein (hazard ratio 1.18; 95% CI, 1.08-1.29) and declined when replaced with plant-based products (hazard ratio 0.82; 95% CI, 0.78-0.87).
“Our findings suggest a negative long-term association between life expectancy and both low carbohydrate and high carbohydrate diets when food sources are not taken into account,” wrote the authors.
Seidelmann SB, Claggett B, Cheng S, et al. Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis [published online August 16, 2018]. Lancet Public Health. doi: 10.1016/S2468-2667(18)30135-X