By Perry Holman, Executive Director, Vitamin D Society
Canada has one of the highest rates of multiple sclerosis in the world. What can we do to reduce the incidence of multiple sclerosis? Its simple, get out in the sun especially in the summer.
A new study1, led by University of British Columbia neurology professor Dr. Helen Tremlett, examined data from the Nurses Health Study, a large cohort of 120,000 nurses established in 1976 and found that sun exposure reduces the incidence of multiple sclerosis (MS).
The study reported:
- Living in high (vs low) UV-B areas before MS onset was associated with a 45% lower MS risk across all age groups combined
- For those 5 to 15 years of age, high summer outdoor exposure in areas of high ambient UV-B was associated with a statistically significant 55% lower risk of MS
The study concluded: Living in high ambient UV-B areas during childhood and the years leading up to MS onset was associated with a lower MS risk. High summer sun exposure in high ambient UV-B areas was also associated with a reduced risk.
This new study adds to what we know from existing research:
A study of twins, funded by the Multiple Sclerosis Society of Canada, found that the risk of MS was 60% lower for the twin who spent more time suntanning.10
There is compelling evidence that suggests that higher levels of sun exposure are associated with decreased risk and disease activity in MS, probably through both vitamin D and non-vitamin D pathways.5 Occupational studies have found that outdoor work in an area of high sunlight could reduce the risk of MS mortality by 76%.6 Higher sun exposure during childhood and early adolescence is associated with a 69% reduced risk of MS.7 A study from Sweden reported that subjects with low UVR exposure had a 2X increased risk of MS.8 Frequent sunscreen use between birth and the age of 6 was associated with a 44% increased risk of MS in Norway.9
Studies have indicated that UVR is likely suppressing MS independent of vitamin D production and that vitamin D supplementation alone may not replace the ability of sunlight to reduce MS susceptibility.3
People who have spent more time in the sun and those with higher vitamin D levels may be less likely to develop multiple sclerosis (MS).2 Epidemiological studies have demonstrated that MS incidence typically follows a latitudinal gradient in both hemispheres.3 In Australia, Tasmania has a 6 times higher rate of MS than in Queensland.4
But remember, don’t burn! Never overexpose. Know your skin and skin type. Skin type 1’s should avoid sun exposure.
References:
1. Tremlett H, Zhu F, Ascherio A, Munger KL. Sun exposure over the life course and associations with multiple sclerosis. Neurology 2018;0:e1-e9. Doi:10.1212/WNL.0000000000005257
2. Lucas RM et al. Sun exposure and vitamin D are independent risk factors for CNS demyelination. Neurology. 2011 Feb 8;76(6):540-8.
3. Becklund BR, Severson KS, Vang SV, DeLuca HF. UV radiation suppresses experimental autoimmune encephalomyelitis independent of vitamin D production. Proc Natl Acad Sci U S A. Apr 6, 2010; 107(14): 6418–6423.
4. Hollingworth S, Walker K, Page A, Eadie M. Pharmacoepidemiology and the Australian regional prevalence of multiple sclerosis. Mult Scler. 2013 Nov;19(13):1712-6.
5. Lucas RM, Byrne SN, Correale J, Ilscner S, and Hart PH. Ultraviolet radiation, vitamin D and multiple sclerosis. Neurodegener Dis Manag. 2015 Oct;5(5):413-24. doi: 10.2217/nmt.15.33. Epub 2015 Oct 19.
6. Freedman DM, Dosemeci M, Alavanja MCR. Mortality from multiple sclerosis and exposure to residential and occupational solar radiation: a case-control study based on death certificates. Occup Environ Med. 2000 Jun;57(6):418-21.
7. Van der Mei IAF, Ponsonby AL, Dwyer T, Blizzard L, Simmons R, Taylor BV, Butzkueven, Kilpatrick T. Past exposure to sun, skin phenotype, and risk of multiple sclerosis: case-control study. BMJ. 2003 Aug 9;327(7410):316.
8. Baarnhielm M, Hedstrom AK, Kockum I, Sundqvist E, Gustafsson SA, Hillert J, Olsson T, Alfredsson L. Sunlight is associated with decreased multiple sclerosis risk: no interaction with human leukocyte antigen-DRB1*15. Eur J Neurol. 2012 Jul;19(7):955-62.
9. Bjornevik K et al. Sun exposure and multiple sclerosis risk in Norway and Italy: The EnvlMS study. Multiple Sclerosis Journal Jan 10, 2014
10. Islam T, Gauderman WJ, Cozen W, Mack TM. Childhood sun exposure influences risk of multiple sclerosis in monozygotic twins. Neurology. 2007 Jul 24;69(4):381-8.
