Nutrition in Older Adults: A Primary Care Perspective on Malnutrition, Sarcopenia, Frailty and Gut Microbiota

Nutrition is an important component of healthy ageing and the primary care of older adults. This review synthesises clinically relevant evidence on malnutrition, dehydration, sarcopenia, frailty, micronutrient deficiency, and gut microbiota, based on a structured search of PubMed and the Cochrane Library. Nutritional vulnerability in older adults emerges through overlapping physiological, psychological, social, functional, and medication-related pathways. Social isolation, loneliness, and the loss of shared meals may contribute to poorer diet quality, reduced nutritional intake, and lower adherence to hydration and meal planning. Malnutrition and dehydration are associated with higher mortality, hospitalization, falls, functional decline, and institutionalization. Preventing and treating sarcopenia requires adequate protein intake, appropriate distribution across meals, and resistance exercise, while frailty is influenced by energy-protein balance, diet quality, and micronutrient status. Mediterranean-style dietary patterns rich in fibre and polyphenols may support healthier gut microbiota composition and attenuate chronic low-grade inflammation. In primary care, systematic screening, medication review, individualized dietary counseling, food-first strategies, oral nutritional support when indicated, hydration planning, and function-focused follow-up are central to geriatric nutritional care. Assessment of social support and selective use of 3–7-day dietary and fluid diaries may further support the management of older adults at nutritional risk.