PhD Oral Defense: Preserving Muscle Mass, Strength and Performance in Free-living Older Adults: A Focus on Dietary Protein Quantity, Distribution and Dairy Products

PhD Oral Defense of Samaneh Farsijani, School of Dietetics and Human Nutrition

Older people form the fastest growing proportion of the world’s population. Loss of muscle mass and strength, known as sarcopenia, and impaired physical function are well-recognized aspects of aging.

Sarcopenia is considered an important predictor of frailty, disability, institutionalization and mortality, imposing a heavy burden on the healthcare system. Among many possible etiologic factors, an unbalanced diet and specifically inadequate protein intake, is thought to contribute to sarcopenia in senior adults. It remains to be determined whether mealtime distribution of protein intake, independent of protein quantity, affects muscle mass and physical performance in older adults in the long-term. Despite the potential contribution of dietary factors to healthy aging, the role of dairy products on body composition and physical performance in free-living older adults has been scarcely studied in longitudinal studies.

The global objectives of this thesis are: (1) to examine the extent to which total protein intake and mealtime protein distribution are associated with lean mass (LM) and appendicular LM (aLM) and their 2-y changes; (2) to examine the cross-sectional and longitudinal relationship between mealtime distribution of protein intake and physical performance; and (3) to investigate the association between total dairy intake and changes in body composition and physical performance over 3 years, using the NuAge database (Quebec Longitudinal Study on Nutrition as a Determinant of Successful Aging) in community-dwelling men and women (aged 67-84 y).

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