Summary Poor nutrition in the first year of a mother's life and undernutrition in utero, infancy, childhood, and adulthood predispose individuals to stroke in later life, but the mechanism of increased stroke risk is unclear. Overnutrition also increases the risk of stroke, probably by accelerating the development of obesity, hypertension, hyperlipidaemia, and diabetes. Reliable evidence suggests that dietary supplementation with antioxidant vitamins, B vitamins, and calcium does not reduce the risk of stroke. Less reliable evidence suggests that stroke can be prevented by diets that are prudent, aligned to the Mediterranean or DASH (Dietary Approaches to Stop Hypertension) diets, low in salt and added sugars, high in potassium, and meet, but do not exceed, energy requirements. Trials in progress are examining the effects of vitamin D and marine omega-3 fatty acid supplementation on incidence of stroke. Future challenges include the need to improve the quality of evidence linking many nutrients, foods, and dietary patterns to the risk of stroke.