I have recently come across a number of interesting articles highlighting the health benefits of maintaining sufficient/high levels of vitamin D. The headlines grabbing my attention include: UK experts calling for milk to be fortified to halt a rise in rickets; high levels of vitamin D can reduce heart disease and diabetes in the middle aged; and high vitamin D intake in pregnancy may lower the risk of the baby developing MS as an adult.
The main way in which we obtain vitamin D is by synthesizing it in our skin during exposure to sunlight – for this reason it is sometimes referred to as 'the sunshine vitamin'. However, in parts of the northern hemisphere where we have more limited sun exposure (and we are tending to spend more time indoors), food sources of vitamin D become important. Oily fish is a good source and many countries fortify foods. Here in the UK, vitamin D is added to margarines, infant formula and breakfast cereals. In the USA and Canada, milk is also fortified.
I was surprised to read that a recent UK survey of white adults (all 45 years old) found that more than 50% of the participants had insufficient levels of vitamin D, with 16% having severe deficiency during winter and spring1. This is concerning as, in addition to the well-known musculoskeletal effects of vitamin D deficiency, many health problems including cardiovascular disease, type 2 diabetes, several cancers and autoimmune conditions have recently been associated with vitamin D insufficiency2.
Writing in the British Medical Journal in January, medical experts in Newcastle highlighted the rise in the number of British children suffering from rickets3. Several hundred children per year are now treated for rickets in the UK. The combination of high latitude and a trend for more indoor play in children is blamed for the rise in the disease. People with pigmented skin or who cover most of their skin are also at a higher risk. The authors, Professor Simon Pearce and Dr Tim Cheetham, say that given the mounting evidence of the substantial disease burden associated with moderate vitamin D insufficiency, information about appropriate sunlight exposure, the use of vitamin D supplements, and eating oily fish should be made available to the whole UK population. They also suggest a more robust approach to statutory food supplementation with vitamin D (for example, in milk).
[I note that the Department of Health has recently produced a leaflet to raise awareness of the risk of vitamin D deficiency – this can be downloaded here.]
A systematic review just published in Maturitas supports the link between vitamin D levels and cardiometabolic disorders (cardiovascular disease, type 2 diabetes mellitus and metabolic syndrome) in middle aged and elderly people4. Researchers at Warwick Medical School looked at 28 studies including 99,745 participants across a variety of ethnic groups including men and women. The studies revealed a significant association between high levels of vitamin D and a decreased risk of developing cardiovascular disease (33% compared to low levels of vitamin D), type 2 diabetes (55% reduction) and metabolic syndrome (51% reduction).
A study due to be presented at the American Academy of Neurology's 62nd Annual Meeting in April has reportedly found that a high dietary vitamin D intake during pregnancy may help reduce the baby's chances of developing multiple sclerosis (MS) as an adult. This is one of a number of studies suggesting that vitamin D may have an effect on MS, but it appears that this effect may begin in the womb.
Delving in to our Nutrition and Food Sciences Database, reveals numerous records on the link between vitamin D and health/disease – asthma, allergies, stroke risk, Alzheimer's, arthritis, non-specific musculoskeletal pain – too many studies to go into detail here, but see the references for a selection.
So, plenty more reasons to look forward to some sunshine!
1. Hypovitaminosis D in British adults at age 45 y: nationwide cohort study of dietary and lifestyle predictors. Hyppönen, E.; Power, C. American Journal of Clinical Nutrition 2007 Vol. 85 No. 3 pp. 860-868
2. Vitamin D: a D-Lightful health perspective. Holick, M. F. Nutrition Reviews 2008 pp. S182-S194
3. Diagnosis and management of vitamin D deficiency. Pearce, H. S.; Cheetham, T. D. BMJ 2010 Vol. 340 pp.142-147
4. Levels of vitamin D and cardiometabolic disorders: Systematic review and meta-analysis. Parker, J.; Hashmi, O.; Dutton, D.; Mavrodaris, A.; Stranges, S., Kandala, N.; Clarke, A.; Franco, O. H. Maturitas 2010 Vol. 65 No. 3 pp. 225-236
From Nutrition and Food Sciences Database/CAB Direct:
Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease Holick, M. F. American Journal of Clinical Nutrition 2004 pp. 1678S-1688S
Vitamin D: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Holick, M. F. American Journal of Clinical Nutrition 2004 Vol. 79 No. 3 pp. 362-371
Association of vitamin D deficiency with cognitive impairment in older women: cross-sectional study. Annweiler, C.; Schott, A. M.; Allali, G.; Bridenbaugh, S. A.; Kressig, R. W.; Allain, P.; Herrmann, F. R.; Beauchet, O. Neurology 2010 Vol. 74 No. 1 pp. 27-32
Epidemiology of disease risks in relation to vitamin D insufficiency Grant, W. B. Progress in Biophysics & Molecular Biology 2006 pp. 65-79
Myalgias or non-specific muscle pain in Arab or Indo-Pakistani patients may indicate vitamin D deficiency. Badsha, H.; Daher, M.; Kong KokOoi Clinical Rheumatology 2009 Vol. 28 No. 8 pp. 971-973
Vitamin D fortification as public health policy: significant improvement in vitamin D status in young Finnish men. Laaksi, I. T.; Ruohola, J. P. S.; Ylikomi, T. J.; Auvinen, A.; Haataja, R. I.; Pihlajamäki, H. K.; Tuohimaa, P. J. European Journal of Clinical Nutrition 2006 Vol. 60 No. 8 pp. 1035-1038
Vitamin D deficiency during pregnancy may impair maternal and fetal outcomes. Lapillonne, A. Medical Hypotheses 2010 Vol. 74 No. 1 pp. 71-75
Prevalence of severe hypovitaminosis D in patients with persistent, nonspecific musculoskeletal pain. Plotnikoff, G. A.; Quigley, J. M. Mayo Clinic Proceedings 2003 Vol. 78 No. 12 pp. 1463-1470