Vitamin D may improve muscle power of overweight people

A supplementation with vitamin D may support gaining muscle power and decreasing waist-to-hip ratio of overweight and obese people who perform resistance training, suggests a new US study.

In the randomized controlled trial, 23 overweight and obese people received either vitamin D (4,000 IU /day) or placebo for 12 weeks in combination in with resistance training (1). The study results showed that within four weeks the participants supplemented with vitamin D had greater muscular power than the placebo group. The elevated vitamin D status was associated with greater losses in terms of waist circumference, but with no additional benefits in lean mass accumulation, muscular strength or glucose tolerance during partici-pation in the 12 week resistance exercise training program.

The researchers commented that the greater decrease inwaist circumference associated with higher vitamin D intake may also represent a potential reduction in risks of type-2 diabetes, metabolic syndrome and cardiovascular disease, as well.

A new review concluded that there is strong evidence to support the important role that vitamin D may play in muscle cells as well as there being an association between increased blood vitamin D concentrations and improved muscle strength/function (2). Decreased outdoor activity, which contributes to increased body mass and decreased sun exposure, combined with inadequate nutrition can lead to low vitamin D status, which negatively affects musculoskeletal strength and function, both directly and indirectly. It has also been reported that people with higher levels of body fat require higher doses of vitamin D because 25(OH)D is sequestered by fat tissue.

1. Carrillo, A. E. et al. Impact of vitamin D supplementation during a resistance training intervention on body composition, muscle function, and glucose tolerance in overweight and obese adults. Clinical Nutrition. Published online September 2012.
    
2. Hazell, T. J. et al. Vitamin D: an overview of its role in skeletal muscle physiology in children and adolescents. Nutrition Reviews. 2012; 70(9):520–533.