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Vitamin D supplements are available in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D3 is the type that most experts agree should be used in clinical practice. Humans synthesise vitamin D3 in response to sunlight and therefore it is the most natural form to supplement. Vitamin D3 is more bioavailable and significantly more effective at increasing blood levels of Vitamin D than Vitamin D2 (Lehmann U, 2013). A review published in The American Journal of Clinical Nutrition stated: that vitamin D2 should no longer be regarded as a nutrient appropriate for supplementation or fortification of foods (Houghton LA, 2006).
Vitamin D in the Diet
Despite contributing minimally to our vitamin D levels, we should not forget to mention dietary sources. Unfortunately, there are few good quality, natural sources of vitamin D. Oily fish – such as wild salmon, sardines and mackerel and eggs provide vitamin D but otherwise, most other food sources come in the form of highly processed fortified foods such as margarine and breakfast cereals which I do not recommend.
Safe Sun Exposure
There’s no doubt that most of us could benefit from spending a little less time indoors and a little more time outside. Making a conscious effort to tear ourselves away from a screen and get out for a short daily walk could improve our health and well-being in many ways. NICE, in their 2011 report stated that: "Exposure to the sun has a number of benefits. For example, it increases people's sense of wellbeing, allows them to synthesise vitamin D and provides opportunities for physical activity" (Lowdon J, 2011)
As with many things in life, the key to safe, Vitamin D-promoting sun exposure is moderation. The NHS website advises the following: ‘Short daily periods of sun exposure without sunscreen during the summer months (April to October) are enough for most people to make enough vitamin D. Evidence suggests that the most effective time of day for vitamin D production is between 11 am and 3 pm.
A short period of time in the sun means just a few minutes – evidence suggests that about 10 to 15 minutes is enough for most lighter-skinned people – and is less than the time it takes you to start going red or burn' That said, we often (quite rightly) advocate the daily use of sunscreen as part of a skincare regime and in doing so could be inadvertently reducing our client or patient’s ability to synthesise vitamin D from the sun. Therefore recommending a daily vitamin D3 supplement, especially during the winter months, is something you might wish to consider.
In summary, when advising your clients or patients on vitamin D, consider the following:
References
Bordelon P, Ghetu MV, Langan RC. (2009) Recognition and management of vitamin D deficiency. Am Fam Physician. 80(8):841-6.
Christakos S, Hewison M, Gardner DG, et al (2013) Vitamin D: beyond bone. Ann N Y Acad Sci. 1287:45-58.
DeLuca HF (2004) Overview of general physiologic features and functions of vitamin D. Am J Clin Nutr. 80(6 Suppl):1689S-96S.
Feldman D, Pike JW, Adams JS. (2011) Vitamin D, Third Edition Elsevier Academic Press
Haines ST, Park SK. (2012) Vitamin D supplementation: what's known, what to do, and what's needed. Pharmacotherapy. 32(4):354-82
Holick MF (2006) Resurrection of vitamin D deficiency and rickets J Clin Invest. 116(8): 2062–2072
Houghton LA and Vieth R (2006) The case against ergocalciferol (vitamin D2) as a vitamin supplement American Society for Clinical Nutrition. 84 (4) 694-697
Lehmann U, Hirche F, Stangl GI, et al (2013) Bioavailability of vitamin D(2) and D(3) in healthy volunteers, a randomized placebo-controlled trial. J Clin Endocrinol Metab. 98(11):4339-45.
Loomis WF. (1967) Skin-pigment regulation of vitamin-D biosynthesis in man. Science. 157(3788):501-6.
Lowdon J. (2011) Rickets: concerns over the worldwide increase. J Fam Health Care. 21(2):25-9
Kennel KA, Drake MT, Hurley DL (2010) Vitamin D Deficiency in Adults: When to Test and How to Treat Mayo Clin Proc. 85(8): 752–758
Matsumoto K, Azuma Y, Kiyoki M, et al (1991) Involvement of endogenously produced 1,25-dihydroxyvitamin D-3 in the growth and differentiation of human keratinocytes. Biochim Biophys Acta. 1092(3):311-8.
Norval M, Wulf HC. (2009) Does chronic sunscreen use reduce vitamin D production to insufficient levels? Br J Dermatol. 161(4):732-6.
Reichrath J, Nürnberg B. (2008) Solar UV-radiation, vitamin D and skin cancer surveillance in organ transplant recipients (OTRs). Adv Exp Med Biol. 624:203-14.