Canadians living in northern latitudes may be at increased risk of vitamin D insufficiency and its associated risk of fractures caused by osteoporosis because they are not exposed to enough sunshine -— a source of vitamin D. In a study supervised by David Hanley, Diana Rucker and colleagues investigated the prevalence of vitamin D insufficiency in a group of adults (60 men,128 women) in Calgary aged 27-89 years who were otherwise healthy and not taking vitamin D supplements.
Blood samples were collected every 3 months for a year and tested for several metabolic markers, including vitamin D metabolites,calcium and parathyroid hormone.
Using a recently proposed threshold for vitamin D insufficiency, the authors found that a startling 97%of study participants had vitamin D insufficiency at some point during the year.
Even if a common —- but more conservative —- threshold is used, about one-third of otherwise healthy subjects had vitamin D insufficiency.
As expected, the mean level of vitamin D rose in the spring and summer and declined in the fall, when the subjects were exposed to less frequent and less intense sunlight.
The authors call for more aggressive vitamin D supplementation in the general population, a move supported in a related commentary in the same issue. - By Karen Thomas
(Reference: CMAJ•JAMC CANADIAN MEDICAL ASSOCIATION JOURNAL • JOURNAL DE L’ASSOCIATION MÉDICALE CANADIENNE June 11, 2002, Vol. 166, No. 12 • Le 11 juin 2002, Vol. 166, n o 12 p.1517 Vitamin D insufficiency in a population of healthy western Canadians - D.Rucker et al p.1541 Vitamin D insufficiency: no recommended dietary allowance exists for this nutrient — R.Vieth, D.Fraser.)
[Contact: Dr.David Hanley, Karen Thomas]
11-Jun-2002
