As healthy life expectancy increases, one of the most interesting challenges of recent years is the prevention of sarcopenia, a loss of skeletal muscle mass and physical function, in terms of muscle strength or performance, that occurs with advancing age and has become increasingly common.
Protein and vitamin D are among the most studied nutrients, and several randomised controlled trials seem to suggest a critical role for both in sarcopenia.
In a study of 218 men and women aged 75-96 years with indications of sarcopenia or dynapenia, 40 g/day of milk protein compared with an isocaloric placebo for 12 months did not lead to significant differences in muscle mass or physical performance.
In a group of 62 frail or fragile subjects over 65 years of age, 15 g/day of a milk protein concentrate compared to an isocaloric placebo was given for 24 weeks. In this study, there was an increase in lean mass with supplementation compared to exercise alone, but no effect on strength or physical performance was observed.
In another study, lean red meat was provided to increase dietary protein intake and this was combined with resistance exercise training, and in 100 women treated for 4 months, lean muscle mass and muscle strength improved with supplementation.
Branched-chain amino acids were also studied, and a 2015 systematic review and meta-analysis concluded that leucine increases muscle protein synthesis in older individuals and may be of benefit in addressing age-related muscle mass decline.
It is therefore clear that studies are still needed to determine which amount and sources of dietary protein may offer the greatest benefit. There is some promising data on the role of vitamin D, but it is not yet clear whether the dose, frequency of administration or duration of treatment affects the improvement in muscle mass or function.
It is also possible that obesity may modify the effect of vitamin D on sarcopenia, as a larger effect size has been observed in normal-weight subjects compared to obese subjects.
In 380 sarcopenic individuals aged over 65 years, 20 g/day of whey protein combined with 3 g of leucine and 800 IU of vitamin D compared with an isocaloric placebo for 13 weeks also led to significant improvements in muscle performance, such as significant improvements in appendicular muscle mass compared with the control.
In terms of micronutrients, selenium and magnesium have been evaluated in randomised controlled trials as supplements and through observational studies on diet, highlighting a potential association with physical activity and muscle performance in older individuals.
Omega-3 fatty acids have repeatedly demonstrated efficacy in older individuals in preserving muscle mass and protecting against normal decline, both in randomised controlled trials and in cohort analyses. Although there are no dietary reference intakes for Epa or Dha, this recommendation may need to be revised with respect to older people. However, dosages vary in controlled studies and it is still unclear which are the most effective.
It is also possible that vitamin B12 offers a protective effect against the development of sarcopenia and dinapenia, as many cross-sectional and prospective studies have found significant results linking them. A 2017 study found that compared to elderly patients with vitamin B12 levels >400 pg/mL, patients who had less than 400 pg/mL of this vitamin had lower values of lean mass, total skeletal mass and a lower skeletal muscle mass index compared to control. The study also found a higher prevalence of sarcopenia and dinapenia in the group with values below 400 pg/mL, suggesting a link between vitamin B12 levels and the development of sarcopenia.
The Mediterranean diet is characterised by several healthy eating behaviours, including a high consumption of fruit and vegetables, and in practically all studies it has always shown some association with physical performance, protection against muscle wasting or the development of sarcopenia and frailty. However, there are no randomised controlled trials on this front.
With respect to individual nutrient groups recent data seem to suggest that increased consumption of milk (cheese, low-fat dairy products and milk products) confers some protective effects against sarcopenia and frailty, but further randomised controlled trials are needed to confirm these findings, especially in the elderly.
Bibliography
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Nutrient-rich dairy proteins improve appendicular skeletal muscle mass and physical performance, and attenuate the loss of muscle strength in older men and women subjects: A single-blind randomized clinical trial. Clin. Interv. Aging 2014, 9, 1517.
Low vitamin intake is associated with risk of frailty in older adults. Age Ageing 2018, 47, 872–879.
Whey protein, amino acids, and vitamin D supplementation with physical activity increases fat-free mass and strength, functionality, and quality of life and decreases inflammation in sarcopenic elderly. Am. J. Clin. Nutr. 2016, 103, 830–840.
Magnesium in man: Implications for health and disease. Physiol. Rev. 2015, 95, 1–46.
Sarcopenia as a potential cause of chronic hyponatremia in the elderly. Med. Hypotheses 2019, 127, 46–48.
Dietary omega-3 fatty acid supplementation increases the rate of muscle protein synthesis in older adults: A randomized controlled trial. J. Clin. Nutr. 2011, 93, 402–412.
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