The Role of Diet and Nutritional Intake in Preventing Muscle Mass and Function Decline Related to Sarcopenia: A Review of Available Evidence in Adults and the Elderly

Background: Sarcopenia, characterized by the loss of muscle mass and function, is a major public health concern in the aging population. Considering the role of nutrition in preventing this condition and the existing knowledge gaps regarding the preventive potential of diet in adulthood, this narrative review aimed to evaluate the available evidence on the impact of diet and nutritional intake on preventing the decline of muscle mass and function related to sarcopenia in adults and the elderly. Methods: A systematic search was conducted in Scopus, PubMed/MEDLINE, and Web of Science databases for articles published from January 2010 to December 2025. Inclusion criteria were human studies with a prospective design (cohort) or randomized controlled trials on adults (aged 18 years and older) that examined the association between dietary intakes, dietary patterns, or nutritional supplements with indicators of muscle mass, muscle strength, or physical performance. Results: The available evidence, particularly from prospective studies, indicates a positive association between higher diet quality in midlife (such as the Mediterranean diet and the MIND pattern) and better preservation of muscle mass and function in later years of life. Higher consumption of fruits and vegetables was associated with better physical performance, while evidence regarding dairy and meat is conflicting, and harmful effects may be limited to processed meats. Regarding protein, there is strong evidence for the benefits of protein supplementation only in combination with resistance training, not alone. Evidence on vitamin D and other micronutrients (such as antioxidants and minerals) is limited and in some cases conflicting. Conclusion: Although evidence supports the protective role of high-quality diets in preventing sarcopenia, this field faces limitations such as heterogeneity in outcome measurement tools, a lack of longitudinal studies with repeated dietary assessments, and variability in study designs. Conducting intervention trials with whole diets and prospective studies with more homogeneous designs is essential to identify key dietary components and develop precise preventive strategies.