Nutritional intervention effect on muscle 'less than expected': Review
The review found exercise to have the biggest impact on muscle mass and muscle function in healthy subjects aged 60 years and older.
However, nutritional interventions, which included a selection of proteins, essential amino acids, creatine, β-hydroxy-β-methylbuthyrate (HMB), vitamin D, and multi-nutrients, exhibited large variations in results.
“Based on the included studies, mainly performed on well-nourished subjects, the interactive effect of dietary supplementation on muscle function appears limited,” the study concluded.
The study pointed out that most of the studies included in the review looked at healthy older subjects.
According to one of the study authors, it was likely that populations with nutritional or physical deficiencies would benefit more from nutritional interventions than well-nourished populations.
A total of 37 randomised control trials (RCTs) were identified and included in the review carried out at the University of Southampton in the UK.
Studies were varied in terms of procedures for physical exercise and dietary supplementation.
In 79% of the studies (27/34 RCTs), muscle mass improved with exercise but an additional effect of nutrition was only found in 8 RCTs (23.5%).
Muscle strength increased in 82.8% of the studies (29/35 RCTs) after exercise intervention and dietary supplementation’s additional benefits were found in a small number of studies (8/35 RCTs, 22.8%).
Lastly, most of the studies showed an increase of physical performance following exercise intervention (26/28 RCTs, 92.8%) but interaction with nutrition supplementation was only found in 14.3% of these studies (4/28 RCTs).
"Previous trials have shown that physical activity and primarily resistance training interventions have a positive impact on muscle strength and physical performance,” said Dr René Rizzoli, emeritus professor of Medicine at University Hospitals of Geneva.
”Other studies have suggested that certain dietary supplements play a role in muscle mass or function. However, more needs to be learned about the synergistic effects of these two interventions."
Creatine and HMB
The study noted that the majority (75%) of studies used creatine as a dietary supplement, which showed a higher effect on muscle mass once exercise intervention was included.
Because of muted response in muscle protein synthesis in older adults and reduced post-meal inhibition of muscle protein breakdown, previous studies recommended increasing protein intake to 1.2 g/kg body weight/day in older adults and even more in frail older adults or elderly with acute or chronic disease
“The combination of creatine supplementation and resistance training seems to act synergistically,” the study said.
“Based on these recommendations, we hypothesized a beneficial effect of protein supplementation in muscle function in older people.”
The review also pointed out the number of studies that showed subjects combining exercise and HMB supplementation has lesser decline of lean body mass compared to subjects undergoing exercises only.
However, they found HMB supplementation did not increase muscle mass but merely prevented its decline.
The study authors highlighted the need for more well-designed studies that evaluated the effect of combining exercise with diet particularly in frail and sarcopenic populations, as well as those suffering from nutritional deficiency or at risk of malnutrition.
In addition, future studies should include rigorous documentation of the subjects' baseline exercise levels and nutritional status prior to the implementation of intervention regimens.
Source: Osteoporosis International
Published online ahead of print: DOI: 10.1007/s00198-017-3980-9
“Nutrition and physical activity in the prevention and treatment of sarcopenia: systematic review.”
Authors: Denison HJ, Cooper C, Sayer AA, Robinson SM