Key Points

Question  Is dietary carbohydrate intake in midlife prospectively associated with healthy aging considering chronic diseases, physical and cognitive function, and mental health?

Findings  In this cohort study of 47 513 women, intakes of total and high-quality carbohydrates; carbohydrates from whole grains, fruits, vegetables, and legumes; and total dietary fiber in midlife were associated with increased odds of healthy aging and several domains of positive health status in older adulthood. Conversely, refined carbohydrate intake was associated with lower odds of healthy aging.

Meaning  These findings suggest that intakes of dietary fiber, high-quality, and refined carbohydrates may be important determinants of overall health status in older adulthood.

Abstract

Importance  Dietary carbohydrate quality is inversely associated with risks of chronic disease and all-cause mortality. However, limited evidence exists regarding the role of carbohydrate quality and dietary carbohydrate types in promoting healthy aging.

Objective  To evaluate the long-term role of dietary carbohydrate intake and carbohydrate quality in healthy aging.

Design, Setting, and Participants  This prospective cohort study used data from the Nurses’ Health Study (NHS) from January 1984 to December 2016 and included participants aged younger than 60 years in 1984. Data were analyzed from January 2023 to February 2025.

Exposure  Intakes of total carbohydrates; refined carbohydrates; high-quality carbohydrates from whole grains, fruits, vegetables, and legumes; dietary fiber; and the dietary glycemic index (GI) and glycemic load (GL).

Main Outcomes and Measures  Nutrient intakes were derived from 1984 and 1986 food frequency questionnaires. The primary outcome was healthy aging, defined as the absence of major chronic diseases, lack of cognitive and physical function impairments, and having good mental health, according to 2014 or 2016 NHS questionnaire data. Multivariate logistic regression was used to calculate associations of each carbohydrate variable with healthy aging.

Results  Among 47 513 participants (mean [SD] baseline age, 48.5 [6.2] years), 3706 (7.8%) met our healthy aging definition. Every 10%-calorie increment in intakes of total carbohydrates (odds ratio [OR], 1.17; 95% CI, 1.10-1.25) and high-quality carbohydrates (OR, 1.31; 95% CI, 1.22-1.41) was positively associated with healthy aging. Refined carbohydrates were associated with lower odds of healthy aging (OR, 0.87; 95% CI, 0.80-0.95). Intakes of carbohydrates from fruits, vegetables, and whole grains were positively associated with odds of healthy aging (ORs ranging from 1.11; 95% CI, 1.07-1.15 to 1.37; 95% CI, 1.20-1.57 per 5% energy increment). Additionally, intakes of total dietary fiber and fiber from fruits, vegetables, and cereals were associated with higher odds of healthy aging (ORs ranging from 1.07; 95% CI, 1.03-1.11 to 1.17; 95% CI, 1.13-1.22 per 1-SD increment). GL was positively associated with healthy aging, which was attenuated by dietary fiber adjustment. A higher GI (OR, 0.76; 95% CI, 0.67-0.87) and carbohydrate-to-fiber ratio (OR, 0.71; 95% CI, 0.62-0.81) were inversely associated with healthy aging when comparing extreme quintiles. There were positive associations for isocaloric replacements of refined carbohydrates, animal protein, total fat, or trans fats with high-quality carbohydrates (ORs ranging from 1.08; 95% CI, 1.01-1.16 to 1.16; 95% CI, 1.11-1.21).

Conclusions and Relevance  In this cohort study of women, intakes of high-quality carbohydrates and dietary fiber were associated with positive health status in older adulthood, suggesting that dietary carbohydrate quality may be an important determinant of healthy aging.

Introduction

The population of older adults in the US is expected to double in the next 4 decades. Importantly, this group bears a disproportionately large burden of chronic diseases and declining physical and cognitive function.1-4 Diet is an important determinant of chronic diseases,5,6 premature death,7 physical frailty,8 and healthy aging.9 Dietary carbohydrate accounts for approximately 50% of energy intake in the US diet.10 However, most of it consists of refined carbohydrates (42% of total calories), while only 8% consists of high-quality carbohydrates from whole grains, legumes, fruits, and vegetables.10 The association of total carbohydrate intake with all-cause mortality risk follows a U-shaped curve with the lowest risk for 50% to 55% of total calories.11 In contrast, intakes of high-quality carbohydrate sources are consistently associated with reduced risk of chronic disease incidence and mortality.12-14 However, limited evidence exists regarding the role of dietary carbohydrate in the development of healthy aging.15

Similarly, the associations of carbohydrate quality indices with healthy aging have not been elucidated. A high carbohydrate-to-fiber ratio has been associated with higher risks of all-cause and cardiovascular disease mortality; however, it has not been evaluated in the context of healthy aging.16-18 The glycemic index (GI) and glycemic load (GL) reflect the glycemic effects of carbohydrate intake.19,20 GI is a relative measure of the incremental blood glucose response per gram of carbohydrate,21 and the GL considers the glucose response to both the quantity of carbohydrate intake and its GI.22 The association of GI and GL with various health outcomes has been extensively evaluated20; however, their role in healthy aging remains inconclusive.15 This study aims to comprehensively evaluate the association of dietary carbohydrate quantity and quality assessed in midlife with the likelihood of healthy aging, defined as longevity with no major chronic diseases, good mental health, and no impairments in either cognitive or physical function, in the Nurses’ Health Study (NHS).23 We hypothesized that high-quality carbohydrate intake would be positively associated with healthy aging.

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