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Moderate carbohydrate intake optimal for health, longevity

Patients with moderate consumption of carbohydrates had the lowest mortality risk and highest life expectancy compared with high and low consumption, according to data published in The Lancet Public Health.

“Low carbohydrate diets, which restrict carbohydrate in favor of increased protein or fat intake, or both, are a popular weight-loss strategy,” Sara B. Seidelmann, MD, from Brigham and Women’s Hospital, and colleagues wrote. “However, the long-term effect of carbohydrate restriction on mortality is controversial and could depend on whether dietary carbohydrate is replaced by plant-based or animal-based fat and protein.”

To determine the association between carbohydrate intake and all-cause mortality, Seidelmann and colleagues conducted a prospective cohort study of 15,428 adults aged between 45 and 64 years without extreme high or low caloric intake from the Atherosclerosis Risk in Communities (ARIC) study, and a meta-analysis of eight multinational studies (n = 432,179).

Participants completed a dietary questionnaire on the types, quantity and frequency of food and beverages they consumed at baseline and 6 years later. The researchers used data from the questionnaire to calculate the cumulative average of calories that participants derived from carbohydrates, fats and protein. Men reported consuming 600 kcal to 4,200 kcal per day and women reported consuming 500 kcal to 3,600 kcal per day.

Participants in the ARIC study were followed for a median of 25 years, the researchers said.

A total of 6,283 deaths occurred among participants in the ARIC study, and 40,181 deaths occurred across all cohort studies.

Data from the ARIC study showed that patients with low (less than 40% of calories from carbohydrates) and high (more than 70% of calories) intake of carbohydrates had an increased risk of mortality compared with those with moderate intake (50% to 55% of calories).

The average life expectancy for patients aged 50 years and older was an additional 33 years for those who consumed moderate amounts of carbohydrates, 29 years for those who consumed very low amounts of carbohydrates and 32 years for those who consumed high amounts of carbohydrates.

Similarly, the meta-analysis of all cohorts indicated that patients with diets low (HR = 1.2; 95% CI, 1.09-1.32) or high (HR = 1.23; 95% CI, 1.11-1.36) in carbohydrates had a greater mortality risk than those with modest intake.

Participants who replaced carbohydrates with protein and fat from animal sources such as lamb, beef, pork and chicken had a higher risk for mortality than those with moderate carbohydrate intake (HR = 1.18; 95% CI, 1.08-1.29). Conversely, participants who replaced carbohydrates with fat and protein from plant-based sources such as vegetables, nuts, peanut butter and whole-grain breads, had a lower risk of mortality (HR = 0.82; 95% CI, 0.78-0.87).

“Our findings suggest a negative long-term association between life expectancy and both low carbohydrate and when food sources are not taken into account,” Seidelmann and colleagues concluded. “These data also provide further evidence that animal-based low carbohydrate diets should be discouraged. Alternatively, when restricting carbohydrate intake, replacement of carbohydrates with predominantly plant-based fats and proteins could be considered as a long-term approach to promote healthy aging.” – by Alaina Tedesco

Disclosures: Seidelmann reports no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.