Last updated on 30th March 2010
This blog post is also downloadable as a Word format handout.
The cover picture on January 16th's British Medical Journal is of a blazing sun with the words "Vitamin D deficiency" underneath it. Inside there is a major review by Pearce and Cheetham entitled "Diagnosis and management of vitamin D deficiency". They have looked at all English language articles that they could identify on vitamin D. Their conclusion is "Vitamin D deficiency and insufficiency are common in the UK. Health professionals have been slow to respond to this problem even though the issue has been highlighted in the literature for a number of years ... vitamin D insufficiency now seems unequivocally linked to several ... common and morbid conditions. Local initiatives have been implemented to address this issue, but the high number of patients presenting with symptomatic vitamin D insufficiency highlights the fact that we have some way to go. A change in UK public health policy is long overdue."
They point out that "A recent nationwide survey in the United Kingdom showed that more than 50% of the adult population have insufficient levels of vitamin D and that 16% have severe deficiency during winter and spring. The survey also demonstrated a gradient of prevalence across the UK, with highest rates in Scotland, northern England, and Northern Ireland." The first point in their text box highlighting "Tips for the non-specialist" states "Suspicions regarding a suboptimal vitamin D status in someone at risk are likely to be correct."
The key concern is that such widespread deficiency is not just an issue for our bone health. Again quoting the article "Several observational studies have shown that vitamin D insufficiency, although not enough to cause symptomatic bone and muscle disease, is associated with an increased risk of mortality and of several common diseases including cardiovascular disease, type 2 diabetes, bowel cancer, breast cancer, multiple sclerosis, and type 1 diabetes. An expert consensus is developing that optimal vitamin D status, reflected by optimal calcium handling and best health, is when serum concentrations of 25-OHD are 75 nmol/l (30 µg/l) or more."
Over 90% of humankind's vitamin D supply is derived from ultraviolet B sunlight exposure but, as Pearce & Cheetham point out "Unfortunately, for six months of the year (October to April), all of Scandinavia, much of Western Europe (including 90% of the UK), and 50% of the North American landmass lie above the latitude that permits exposure to the ultraviolet B wavelengths necessary for vitamin D synthesis, leaving millions of people reliant on exogenous sources of vitamin D." These "exogenous sources" include artificially fortified foodstuffs (some breakfast cereals, margarines, and infant formula milk), oily fish, and egg yolks. So there aren't many food sources. Supplementation is a good option for many people.
The article suggests one classify vitamin D status from the easily testable serum level of 25-hydroxyvitamin D concentration as a.) <25 nmol/l, status deficient, manifestation rickets & osteomalacia, treat with high-dose calciferol. b.) 25-50 nmol/l, status insufficient, associated with increased disease risk, treat with vitamin D supplementation. c.) 50-75 nmol/l, status adequate, give lifestyle advice. d.) >75 nmol/l, status optimal, no additional management needed.
For deficiency, Pearce & Cheetham recommend adults be treated with 10,000 IU calciferol daily or 60,000 IU weekly for 8-12 weeks (to convert IU to micrograms, divide by 40). Children need a different dosing regime. For insufficiency - or maintenance therapy after deficiency - they recommend adults continue to take 1,000-2,000 IU calciferol daily or 10,000 IU weekly. Again for infants & children they recommend a different regime depending on age. Clearly these recommendations aim to keep people at optimal vitamin D status with their 25-OHD level >75 nmol/l.
For more detail and access to free full text information, see the blog post I wrote back in the autumn of 2008 "Vitamin D - time to take action".