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19.12.2015

Daily dose of vitamin D keeps over 50s' muscles in shape

People in their 50s who don't do any exercise or physical work lose a little bit of muscle and with it strength as the years pass. Taking a moderate dose of vitamin D3 as a supplement can stop this process, write Brazilian researchers at Sao Paulo State University in Osteoporosis International.

Vitamin D and muscles
Muscles have vitamin D receptors. When a vitamin D molecule attaches itself to that receptor the muscle cells start to make more protein and at the same time inhibit the breakdown of protein. [Endocrinology. 2011 Aug;152(8):2976-86.] [Biomed Res. 2015;36(2):71-80.] Experiments done with old people have shown that vitamin D supplementation increases the manufacture of fast muscle fibres. [J Clin Endocrinol Metab. 2013 Dec;98(12):E1927-35.]

Huge numbers of people have less than optimal levels of vitamin D in their body and really should take a supplement containing this vitamin. Because vitamin D is important for muscles the researchers wanted to know whether vitamin D3 supplementation might slow down or inhibit age-related muscle breakdown.

Study
The researchers gave a group of 70 women aged between 50 and 65 a daily 1000 units of vitamin D3 for a period of nine months. They gave an equal-sized control group a placebo with no active ingredients. The women were healthy but did not do any sports.

The researchers measured the women's fat and lean body mass before the experiment started and at the end. They also measured the women's muscle strength using the hand-grip test and the chair rising test. The hand-grip test involves clenching a spring as tightly as possible; the chair rising test involves standing up from sitting in a chair as frequently as possible.

Results
The women's fat mass hardly changed at all during the experiment. The lean body mass of the women in the control group seemed to decrease a little, while it seemed to increase a little in the vitamin D group. [Muscles are part of the lean body mass.]

The women in the control group lost a little strength during the experiment. The strength of the women who had taken vitamin D increased a little.

Conclusion
"Vitamin D supplementation alone in postmenopausal women was an expressive protective factor against the occurrence of sarcopenia, permitting an important increase in muscle strength and control of the progressive loss of lean mass", the researchers concluded.

The study was financed by the Brazilian government.

Source:
Osteoporos Int. 2015 Oct;26(10):2413-21.

More:
More vitamin D, more muscle mass 07.04.2015
Animal study: 1000 IU vitamin D3 inhibits muscle breakdown in athletes 29.11.2013
Vitamin D3 boosts anabolic effect of leucine 19.09.2013

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