Nutrients and nutrition in older adults: several open questions and some answers

Nutrition is the set of integrated processes by which cells, tissues, organs and the whole body acquire the energy and nutrients for physiological structure and function, which is achieved at body level through dietary supply, and transformation of substrates and cofactors necessary for metabolism. An appropriate nutrition starting early in the life course has a significant impact on health as it could determine the future resilience of the individual to stresses and susceptibility to disease. Not only the quantity, but also the quality of the diet is important to ensure healthy growth and the appropriate proportions of lean and fat mass. Furthermore, nutrition is not simply a matter of diet, but should also take into account physical activity level, stressors and underlying conditions (physical, behavioral, social), which modulate nutrient availability and handling. There is a clear evidence of the important role of nutrition in primary and secondary prevention for several diseases. With respect to primary prevention, this role is related both to specific dietary patterns, such as the Mediterranean diet, but also to single micronutrients, such as poli-unsaturated fatty acids (PUFAs). Besides Mediterranean diet, other nutritional patterns, such as some of spices used in in Asian cultures that have beneficial effects on human health and are commonly used in the Ayurveda, the Indian traditional medicine. One of these spices, curcumin, has also been studied in the occidental traditional medicine for its anti-inflammatory, anti-oxidant and anti-cancer properties, and new compounds derived from curcumin have been studied for the treatment of cancer and other diseases. On the other hand, also micronutrients usually introduced with the diet, such as vitamin D, or nutritional status per-se, have an important role in secondary prevention. Furthermore, nutrition can have a role in the context of other diseases, such as anemia in influencing biomarkers concentration in heart failure. While the role of nutrition seems to be well established, some questions remain open, especially in older adults, that are a population usually less studied respect to younger adults. In fact, if we consider the "classical" associations, such as sodium intake and cardiovascular diseases, most of the studies did not include older adults, a population in which the coexistence of multiple diseases, polytherapy, frailty, high prevalence and risk of disability, might influence these associations. Therefore, an association evident in young adults might lack or being more evident in older adults, thus changing dietetic indications in this specific population. The aim of this thesis was to study the role of nutrition in influencing clinical outcomes in older adults, paying particular attention to: - The role of micronutrients in primary prevention; with respect to this, we studied the association between sodium and PUFA intake and mortality in older adults. - The role of micronutrients and nutritional status in influencing outcomes; with respect to this, we studied the association between vitamin D and nutritional status in functional improvement in older adults admitted to rehabilitation settings and the association between nutritional status and functional status and outcomes in older adults affected by chronic heart failure. - The role of nutrition and nutrients in the context of other diseases; with respect to this, we studied the role of curcumin in lung diseases and melanoma and the role of anemia in influencing concentration of natriuretic peptides in older adults.