Low and High Carbohydrate Diets Associated With Increased Mortality

Lunch with friends
Lunch with friends
Investigators examined the long-term associated between mortality risk and carbohydrate intake.

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.

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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