Nutrition

For Carbohydrate Restriction, How Low Is Too Low?

Despite the popularity of low-carbohydrate consumption as a weight loss strategy, these types of diets may actually have a negative impact on mortality risk.

 

According to new findings, a moderate intake of carbohydrates is likely associated with a lower risk of mortality than both low- and high-carbohydrate diets.

YOU MAY ALSO LIKE
Low-Fat vs Low-Carb: Which Is Best For Weight Loss?
Diabetes Patients Benefit From A Very Low-Carb Diet

Researchers arrived at this conclusion following a prospective cohort study of 15,428 American adults aged 45 to 64 years from 4 communities. Median follow-up lasted 25 years.

 

The study included participants who:

 

  • Had completed a dietary questionnaire between 1987 and 1989 upon enrollment in the Atherosclerosis Risk in Communities (ARIC) study.
  • Did not consume an extremely high or low number of calories—defined as less than 600 kcal or 4200 kcal for men and less than 500 kcal or more than 3600 kcal for women.

 

In addition to the prospective cohort study, the researchers performed a meta-analysis of data from the ARIC study, along with data for carbohydrate intake from 7 other multinational prospective studies.

 

Throughout follow-up, 6283 participants from the ARIC study and 40,181 participants across all cohort studies died. Results of the ARIC cohort study revealed a U-shaped association between the percentage of carbohydrates consumed and mortality (mean 48.9%), with the lowest risk of mortality observed for a carbohydrate intake of 50% to 55%.

 

Similar results were seen in the meta-analysis, with a U-shaped association observed for the percentage of carbohydrate intake and mortality. Both low- (less than 40%) and high-carbohydrate consumption (more than 70%) were associated with a higher risk of mortality compared with moderate carbohydrate consumption (pooled hazard ratios [HRs]: 1.20 for low intake, 1.23 for high intake).

 

Notably, these findings varied based on the source of macronutrients. In a further assessment of the effects of substituting animal- or plant-based fats and protein for carbohydrates on mortality risk, the researchers found that exchanging carbohydrates for animal-derived fat or protein sources—including lamb, beef, pork, and chicken—was tied to higher mortality [HR 1.18].

 

Conversely, exchanging carbohydrates for plant-based fat or protein—including vegetables, nuts, peanut butter, and whole-grain breads—was found to be associated with lower mortality.

 

“[This finding suggests] that the source of food notably modifies the association between carbohydrate intake and mortality,” the researchers wrote.

 

These findings were published recently in The Lancet Public Health.

 

—Christina Vogt

 

Reference:

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. https://doi.org/10.1016/S2468-2667(18)30135-X