N05062: 15 month longitudinal study of dietary and sunlight influences on vitamin D status in a well-characterized population of postmenopausal women at 57ºN
Friday 16 June 2006
This research project aims to establish dietary vitamin D requirements for the UK. (Joint project with N05064).
Background
There is currently no dietary recommendation for vitamin D intakes for adults in the general population, although it is recognised that the elderly and those who cover up are at risk of deficiency.
It is also apparent that there are regional differences with northerly locations having less exposure to sunlight of the appropriate wavelength than the south of England required for cutaneous vitamin D synthesis.
This study will address the vitamin D status in women over 15 months.
Research Approach
A total of 360 women will be recruited and their 25-hydroxy vitamin D (25(OH)D) levels will be measured at 3 month intervals, over a period of 15 months. The 25(OH)D test measures the amount of 25-hydroxy vitamin D in the blood and is an accurate measure of the amount of vitamin D in the body.
All the participants will complete food diaries, sunlight exposure diaries, have skin colour, muscle strength and bone resorption assessed at 3 month intervals and wear dosimeters for 1 week every 3 months. A subgroup will use accelerometers as an estimate of physical activity for 1 week every 3 months.
All participants will have bone mineral density scans in autumn and spring. It will then be established if dietary factors and the previous summer�s sunlight exposure, maintain 25(OH)D levels of those living on the northerly latitudes of the UK. Additionally, dietary vitamin D requirements (if any) will be determined.