New study aims to reduce winter vitamin D deficiency in older people

Published on 05 November 2012

Researchers at Newcastle University are aiming to reduce vitamin D deficiency in people over 70 during the winter months caused by lack of sunlight.

The Arthritis Research UK-funded team are looking at the impact of three different doses of vitamin D supplementation on bone health. They hope supplementation with vitamin D will prevent the 30 per cent reduction in concentration of the vitamin in the blood in the winter and spring months when the population is exposed to little sunlight.

They want to examine whether a constant intake of vitamin D throughout the year will lead to people having stronger bones with an improved bone density. However, key to the research is a better understanding of the interaction of vitamin D with hormones and fat in the body with the aim of better understanding whether vitamin D works to provide protection for bones and ultimately reducing the risk of fractures.

Dr Terry AsprayThe trial is led by Dr Terry Aspray at Newcastle University who said: “Older people in particular may be more susceptible to this decrease in vitamin D, which may result in their spending half the year with lower vitamin D levels, causing deficiency in many cases.

“By giving a supplement throughout the year, we want to examine whether we can decrease this risk, ensuring that older people achieve adequate vitamin D levels across the year and identifying the effect that it has on their bones.”

Vitamin D is important for the maintenance of healthy bones, and deficiency causes rickets in children and osteomalacia in adults. Lower levels of vitamin D in the blood are also a risk factor for osteoporosis, impaired muscle function and an increased risk of falls and fractures.

However, as Dr Aspray explains, our understanding of vitamin D is limited: “Currently we measure the level of vitamin D in the blood, but we do not yet understand how that translates into the mechanisms that influence bone structure and we want to better understand this process.”

As vitamin D is synthesised in the skin on exposure to sunlight, most of our vitamin D requirements can be obtained from this source in the summer months. However, in winter and spring, little vitamin D is synthesised in the skin so it can only be obtained through diet in foods such as oily fish and eggs.

Although there are national and international guidelines on levels of vitamin D supplementation to maintain healthy bones, currently there is no universal consensus on how much should be consumed in our diet.

“We will be asking people in the autumn to join our study – however, they need to not have been taking vitamin D before then”, added Dr Aspray.

The team will recruit 375 people over the age of 70 from GP practices in the Newcastle area, and randomise them into three groups taking different amounts of the supplement equivalent to a daily dose of: 400 international units (iu) the current UK guideline on adequate vitamin D intake in this age group; 800iu; and 1600 iu.

Their bone density will be measured at the beginning and end of the two-year £683,000 study.

For more information call Newcastle University on 0191 2464 570.