Vitamin D: hype or healer?
Fellow of the American Academy of Dermatology
In looking at the growing number of Google searches for vitamin D over the past several years, it is abundantly clear that vitamin D is very much on our collective mind (Google Trends, 2010). Indeed, there has been a series of highly-publicized debates, articles and missives fueling interest in this previously staid vitamin.
Perhaps kicking off some of this vitamin D mania was the news that Dr. Michael Holick, then a Professor of Dermatology at Boston University, had been fired from his position because of his stance on getting "sensible sun exposure" to ensure adequate vitamin D (Michael Holick Interview, 2006). According to him, this flew in the face of the more stringent recommendations of the American Academy of Dermatology which advocates for total sun protection and vitamin D supplementation rather than reliance on ultraviolet light (AAD Position Statement, 2009). Since then, there have been a number of articles suggesting that many individuals are vitamin D deficient and discussing the proposed benefits of vitamin D, including cancer prevention and protection from autoimmune diseases (Kolata, NY Times 2010). The result has been confusion for both patients and doctors alike, especially when it comes to people with eczema.
What we know
There are a few things we know for certain, and most of the rest is speculation without sufficient evidence. We know for certain that if vitamin D levels are too low, the bones become soft and deformed in a disease called rickets. Some of the guidelines for vitamin D intake were based on preventing this disease alone. We also know that vitamin D plays many other functions in the body beyond the bones, including roles in cardiovascular health, immune system well-being and in cancer prevention.
Daily intake
There is not yet agreement on what is an adequate level of vitamin D in the body, however. The minimum daily intake currently recommended by the U.S. Department of Agriculture is 200 International Units (IU) of vitamin D per day for adults, while most daily multivitamins contain 400 IU of vitamin D.
Sources
Vitamin D can be obtained from foods such as fatty fish, eggs, butter, and fortified foods. It is also produced in the skin when ultraviolet B (UVB) light is present, and Dr. Holick suggests that just a few minutes of sun exposure each day can meet the requirement. Interestingly, a recent study of 93 healthy young adults in Honolulu, Hawaii found that of these active surfers with a remarkable 29 hours of sun exposure per week, 51% had low vitamin D levels (Binkley, 2007). This suggests that even the more conservative levels of vitamin D may not be attainable by sun exposure alone even in Hawaii, let alone in the decidedly less paradise-like climate of Chicago.
Eczema and vitamin D
On the other hand, getting phototherapy with narrow band UVB light has been shown to significantly increase vitamin D levels in those who start with low levels (Cicarma, 2010). And this is where things begin to get interesting for people with eczema. Narrow band UVB phototherapy is a well-known treatment for eczema and is thought to work in several ways, including by local immunosuppression and direct anti-itch effects (Yule, 2005). But increasing vitamin D levels may yield indirect positive effects as well. Supporting this idea is a study by Dr. Sidbury from 2008 which looked at giving vitamin D supplements to children with eczema. In this trial, they found that 80% of the children given vitamin D (1000 IU of ergocalciferol, a slightly less-potent form of vitamin D) improved versus only 17% of the control group (Sidbury, 2008). Interestingly, this was in a group of children with eczema that was reported to worsen during the winter months, suggesting that perhaps a relative deficiency of vitamin D was partly responsible for their flare-ups.
Since then, there have been several other studies in eczema. One recent study found a correlation showing the lower the vitamin D level the worse the eczema in children (Peroni, 2010). Another study confirmed Dr. Sidbury's finding by supplementing eczema patients with 1600 IU of vitamin D each day (along with 600 IU of vitamin E) and found that they improved significantly over placebo (Javanbakht, 2010).
Safety
Vitamin D supplementation appears to be rather safe, thankfully. Very high doses of vitamin D may lead to elevated blood calcium levels with nausea, vomiting, high blood press¬ure and increased risk of kidney stones, but there is evidence that these risks are not relevant until nearly 10,000 IU/day of vitamin D is taken, roughly 10 times the doses in these studies (Hathcock, 2007).
For the risk-averse, topical versions of vitamin D do exist and are used frequently in psoriasis with good success. However, it is well-known that these creams often seem to actually worsen eczema when applied. It is possible that while the vitamin D may be helping, there is simultaneously a direct irritant component which may aggravate the sensitive skin of eczema patients and negate any benefit (Fullerton, 1996). A report from 2005, however, using a different preparation of topical vitamin D ointment showed impressive results for hand and foot eczema, suggesting that there may be future preparations that are non-irritating and may be used successfully (Egawa, 2005).
More studies needed
In closing, it is difficult to say with certainty what the consensus of the scientific community will be. More studies and hence more time will be needed before this can happen. In the meantime, however, we are left with several compelling studies, appealing theories (Searing 2010), and satisfying safety data. I have been recommending that my eczema patients supplement vitamin D, usually 400-1,000 IU daily for children and 2,000 IU daily for adolescents and adults. Like so many uncertain things, we hope for good results as we wait for more concrete answers.
References
1. Google Trends, http://www.google.com/trends?q=Vitamin+D, accessed on 12/2/2010.
2. Michael Holick Interview, Doctor Yourself, 2006. http://www.doctoryourself.com/holick.html, accessed on 12/8/2010.
3. American Academy of Dermatology Position Statement on Vitamin D, 2009, www.aad.org/forms/policies/Uploads/PS/AAD_PS_Vitamin_D.pdf, accessed on 12/8/2010.
4. Gina Kolata, Report Questions Need for 2 Diet Supplements, NY Times, 2010. http://www.nytimes.com/2010/11/30/health/30vitamin.html?_r=2&nl=todayshe... accessed on 12/8/2010.
5. Binkley N, Novotny R, Krueger D, et al. Low vitamin D status despite abundant sun exposure. J Clin Endocrinol Metab. 2007 Jun;92(6):2130-5.
6. Cicarma E, Mørk C, Porojnicu AC, et al. Influence of narrowband UVB phototherapy on vitamin D and folate status. Exp Dermatol. 2010 Aug;19(8):e67-72.
7. Yule S, Dawe RS, Cameron H, et al. Does narrow-band ultraviolet B phototherapy work in atopic dermatitis through a local or a systemic effect? Photodermatol Photoimmunol Photomed. 2005 Dec;21(6):333-5.
8. Sidbury R, Sullivan AF, Thadhani RI, et al. Randomized controlled trial of vitamin D supplementation for winter-related atopic dermatitis in Boston: a pilot study. Br J Dermatol. 2008 Jul;159(1):245-7. Epub 2008 Jul 1.
9. Peroni DG, Piacentini GL, Cametti E, et al. Correlation between serum 25 (OH)-vitamin D levels and severity of atopic dermatitis in children. Br J Dermatol. 2010 Nov 18.
10. Javanbakht MH, Keshavarz SA, Djalali M, et al. Randomized controlled trial using vitamins E and D supplementation in atopic dermatitis. J Dermatolog Treat. 2010 Jul 24.
11. Hathcock JN, Shao A, Vieth R, et al. Risk assessment for vitamin D. Am J Clin Nutr. 2007 Jan;85(1):6-18.
12. Fullerton A, Avnstorp C, Agner T, et al. Patch test study with calcipotriol ointment in different patient groups, including psoriatic patients with and without adverse dermatitis. Acta Derm Venereol. 1996 May;76(3):194-202
13. Egawa K. Topical vitamin D3 derivatives in treating hyperkeratotic palmoplantar eczema: a report of five patients. J Dermatol. 2005 May;32(5):381-6.
14. Searing DA, Leung DY. Vitamin D in atopic dermatitis, asthma and allergic diseases. Immunol Allergy Clin North Am. 2010 Aug;30(3):397-409.
