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Vitamin D supplement increases muscle strength

The over seventies develop more muscle strength if they take extra vitamin D, write Austrian gerontologists in Osteoporosis International.

The researchers did an experiment with two hundred and forty elderly people who still lived unassisted. Half of the group were given one gram of calcium each day; the other half got eight hundred units of vitamin cholecaliferol (vitamin D) as well as the calcium. The intake was divided over two meals and the experiment lasted twenty months.

The researchers measured the muscle strength in the subjects' legs at the start and end of the period. The results showed that the people who had taken vitamin D had become stronger than the ones who only took calcium. The researchers got their subjects to stand up from a sitting position and to walk to a point a few metres away the timed-up-and-go-test. The vitamin D users were able to this faster than the calcium users.

Vitamin D supplement increases muscle strength

The researchers also measured how sure the old peoples' movements were: the length of the 'body sway'. This decreased in the vitamin D group, indicating that their muscle coordination had improved.

The researchers recorded the number of falls the subjects made during the experiment. The elderly fall more often as their muscle power and coordination decreases. The researchers noticed that, certainly after the experiment had been running for a while, the vitamin D users were less likely to fall than the subjects who only took calcium. The lines on the graph below show the chance of the elderly falling. The steeper the downward slope, the greater the likelihood of a fall.

Vitamin D supplement increases muscle strength

CT = calcium treatment, CVT = calcium plus vitamin D treatment.

The researchers selected their test subjects on the basis of their vitamin D levels. Only elderly people with less than thirty nanograms of 25-hydroxy vitamin D per millilitre were invited to join the experiment. That makes it look as though the researchers studied a small select group of elderly who were undernourished or not healthy, but this is not the case. The majority of those who responded to the request for subjects had low vitamin D levels.

Moreover: "It should be noted that our study subjects, who were recruited by newspaper advertisements or mailing lists out of the general population were probably healthier than their age-related counterparts", the researchers write.

Previous studies have also shown that vitamin D helps the elderly to increase their muscle bulk. And the longevity characteristics of vitamin D are becoming clearer: a high level of vitamin D slows down the molecular process of aging.

Osteoporos Int. 2009 Feb;20(2):315-22.