Nutrient and food group intakes and skeletal muscle index in the Japanese elderly: a cross-sectional analysis of the NHNS 2017

Objective:To examine nutrient and food intakes according to the levels of skeletal muscle mass index (SMI) in the elderly.Design:Cross-sectional study.Setting:Data were derived from the 2017 National Health and Nutrition Survey in Japan. SMI was calculated by dividing appendicular skeletal muscle (or lean) mass (kg) by height squared (m2). We calculated the multivariable-adjusted means of individuals’ dietary intake. Dietary intake of energy, nutrients and food categories was assessed by examining dietary records using a semi-weighed method and compared according to the sex-specific quartiles of SMI.Participants:Men and women aged ≥60 years.Results:Among 797 men and 969 women, individuals with a higher SMI consumed more energy and more nutrients than did those with a lower SMI after adjusting for age, lifestyle and physical activity factors. After further adjusting for energy intake, total dietary fibre, vitamin A, vitamin B6, K, Fe and Cu were positively associated with higher SMI in men (Pfor trend < 0·05). For food categories, men with a higher SMI consumed more vegetables and meats, but the associations were attenuated after adjustment for energy and remained significant for vegetable only (Pfor trend = 0·018).Conclusions:Japanese elderly people with a higher SMI consumed more energy and nutrients and more vegetables than did those with a lower SMI. This finding shows that diet is important in preventing muscle loss among the elderly in an ageing society.