Vitamin D has received a lot of attention both in research and in the media recently, and I recently wrote about the importance of this vitamin for expectant mothers and their children. It is becoming clear that adequate levels of vitamin D are critical at all stages of life. A new study published in the European Journal of Clinical Nutrition suggests that low levels of Vitamin D can increase the risk of death in frail, older adults (1).
The study, which analysed data on 4300 adults over the age of 60, found that inadequate Vitamin D levels increased risk of death from all causes by 30 percent.
‘Frailty’ is defined as a decrease in physical function, marked by symptoms such as slow walking, muscle weakness, low physical activity and unintentional weight loss.
The study found that those who had lower vitamin D levels were more likely to be frail. It also found that frail adults with low levels of vitamin D also had triple the risk of death over people who were not frail and who had higher levels of vitamin D.
The effect of Vitamin D on muscles and bones has indeed been known for some time. When Vitamin D receptors are activated within the cell, this stimulates new protein synthesis which affects muscle growth (2). In fact a prospective study found that Vitamin D supplementation increased the number of fast-twitch muscle fibres and improved muscle function in elderly women with osteoporosis (3). This is particularly interesting as it suggests that the protective effect of Vitamin D on fracture risk is not solely a result of its effect on bone mineral density. It may also be a result of improved muscle strength leading to better physical function and lower numbers of falls.
The study does not prove whether Vitamin D plays a causative role. In other words, it is not clear whether Vitamin D deficiency contributed to frailty, or whether frail adults were more likely to develop the vitamin deficiency because of health problems.
“If you have both, it may not really matter which came first because you are worse off and at greater risk of dying than other older people who are frail and who don’t have low vitamin D,” says study leader Ellen Smit. “This is an important finding because we already know there is a biological basis for this. Vitamin D impacts muscle function and bones, so it makes sense that it plays a big role in frailty.”
The researchers suggest that older adults should be screened for Vitamin D levels, and that they should spend more active time in the sun. A carefully managed diet can also help to boost levels. For example, oily fish such as salmon or mackerel can provide 350iu per serving, so try to include this a couple of times each week. Eggs can help too, with a single egg supplying 20iu of Vitamin D. For elderly people who spend little time outdoors it may be wise to supplement Vitamin D in order to ensure adequate levels, especially during the winter months. Sunlight is of course the best source, and just 20 minutes outdoors between the hours of 10am and 2pm will provide around 400iu of the vitamin.
Written by Nadia Mason, BSc MBANT NTCC CNHC
1. E Smit, C J Crespo, Y Michael, F A Ramirez-Marrero, G R Brodowicz, S Bartlett, R E Andersen (2012) The effect of vitamin D and frailty on mortality among non-institutionalized US older adults. European Journal of Clinical Nutrition
2. Boland R. (1986) Role of vitamin D in skeletal muscle function. Endocr Rev 7:434-48.
3. Sorensen OH, Lund B, Saltin B, et al. (1979) Myopathy in bone loss of ageing: Improvement by treatment with 1 alpha-hydroxycholecalciferol and calcium. Clin Sci (Lond) 56:157-61.