Dietary low- and high-quality carbohydrate intake and cognitive decline: A prospective cohort study in older adults.

Background & Aims: The association of dietary intake of carbohydrate (CHO), especially high- and low-quality CHO, with the decline of cognitive function remains uncertain. We aimed to investigate the prospective association of dietary total, low- and high-quality CHO intake with cognitive decline, and further examine the effect of isocaloric substitution with protein or fat, in the elderly population.

Methods: A total of 3106 Chinese participants aged ≥55 years from China Health and Nutrition Survey (CHNS) were included in this study. Dietary nutrient intake information was collected by 24-h dietary recalls on 3 consecutive days. The cognitive decline was defined as the 5-year decline rates in global or composite cognitive scores based on a subset of items from the Telephone Interview for Cognitive Status-modified (TICS-m).

Results: The median follow-up duration was 5.9 years. There was a significantly positive association of dietary low-quality CHO (per 10 percentage energy [%E] increment, β, 0.06; 95%CI, 0.01-0.11) and a no significant association of dietary high-quality CHO (per 10%E increment, β, 0.04; 95%CI, -0.07-0.14) with the 5-year decline rate in the composite cognitive scores. Similar results were found for the global cognitive scores. In model simulations, substituting dietary low-quality CHO with isocaloric animal protein or fat, instead of isocaloric plant protein or fat, was significantly and inversely associated with cognitive decline (All P values < 0.05).

Conclusions: The dietary intake of low-quality CHO, rather than high-quality CHO, was significantly associated with a faster cognitive decline in the elderly. In model simulations, isocaloric substitution of dietary low-quality CHO with animal protein or fat, rather than plant protein or fat, was inversely associated with cognitive decline.