The transition from independence to disability in older adults is characterized by detectable changes in body composition and physical function. Epidemiologic studies have shown that weight loss, reduced caloric intake and the reduced intake of specific nutrients are associated with such changes. The mechanisms underlying these associations remain unclear, and different hypotheses have been suggested, including the reduction of the antioxidant effects of some nutrients. Changes in muscle mass and quality might play a central role in the pathway linking malnutrition, its biological and molecular consequences, and function. A different approach aims at assessing diets by dietary patterns, which capture intercorrelations of nutrients within a diet, rather than by selective foods or nutrients: epidemiologic evidence suggests that some types of diet, such as the Mediterranean diet, might prevent negative functional outcomes in older adults. However, despite a theoretical and empirical basis, intervention studies using nutritional supplementation have shown inconclusive results in preventing functional impairment and disability. The present work is the result of a review and consensus effort of a European task force on nutrition in the elderly, promoted by the International Association of Gerontology and Geriatrics (IAGG) European Region. After the critical review of different aspects related to the role of nutrition in the transition from independence to disability, we propose future lines for research, including the determination of levels of inadequacy and target doses of supplements, the study of interactions (between nutrients within a diet and with other lifestyle aspects), and the association with functional outcomes.