Harvard Study Links Miser Carbs to 37% Better Healthy Aging Odds
A miser approach to carbohydrates may not be the goal, but a 2025 Harvard and Tufts study found that women who ate more high-quality carbs and fiber at age 40 had better odds of healthy aging after 70. The research followed 47,513 women for more than 30 years and measured whether they reached age 70 without major chronic disease, memory or mobility limits, or poor mental health.
Ardisson Korat and Sun
Andres Ardisson Korat, who co-authored the study, said higher intake of quality carbohydrates and fiber was associated with better healthy-aging odds. Qi Sun also co-authored the research, which was published in 2025 in JAMA Network Open by teams from the Harvard T.H. Chan School of Public Health and the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.
The study linked higher intake of quality carbohydrates and dietary fiber at age 40 with a 6 to 37 percent increase in the chances of healthy aging. It also found that replacing 5 percent of calories from refined carbohydrates with high-quality carbohydrates was associated with about an 8 to 16 percent increase in the chances of healthy aging.
Whole Grains and Legumes
The four carbohydrate families tied to better odds were whole grains, fruits, non-starchy vegetables, and legumes. The study also found that high glycemic index diets and an unfavorable carbohydrate-to-fiber ratio were associated with lower odds of remaining healthy.
That result cuts against the idea that all carbohydrates should be treated the same. Many women reduce pasta or bread after 40 because they think all carbohydrates are bad for weight and health, but this study separated refined carbohydrates from higher-quality sources and fiber.
47,513 Women
Only 7.8 percent of the 47,513 women reached healthy aging in the Nurses’ Health Study. Researchers assessed carbohydrate and fiber intake at age 40, then followed participants for more than 30 years before measuring outcomes after age 70.
The study was observational and involved American nurses who were mostly white and educated, so it does not prove the same result for everyone. Even so, the numbers point in one direction: if a reader wants a practical target from this study, the message is to favor whole grains, fruits, non-starchy vegetables, legumes, and about 25 to 30 grams of fiber per day rather than leaning on refined carbohydrates.
