Carbohydrates don’t just fuel the body—they may also influence how the brain ages. A large long-term study found that diets high in fast-acting carbs that rapidly raise blood sugar were linked to a higher risk of dementia. People who ate more low-glycemic foods like fruit, legumes, and whole grains had a noticeably lower risk of Alzheimer’s. The quality of carbs, not just the amount, appears to matter for brain health.