Sunlight & Vitamin D

What is Vitamin D? 

The term ‘vitamin D’ generally refers to two very similar molecules. Vitamin D3, also known as cholecalciferol, is created by skin cells in response to ultraviolet B light. Vitamin D2, or ergocalciferol, occurs naturally in some mushrooms and yeast. Neither version has any biological activity in the body. Both must be modified to first generate 25-hydroxyvitamin D (25D). 25D is the main form of vitamin D circulating in the blood.

Vitamin D & MS

For many years, vitamin D has been known to have important effects throughout the body.

In the early 1800s, vitamin D, in the form of cod liver oil and the exposure of skin to sunlight were found to be effective treatments for rickets, a severe bone-deforming disease which is seen mostly in children.

Recent studies have linked low vitamin D levels to disease, raising concerns that widespread vitamin D deficiency is contributing to a number of serious illnesses.  In the past it has been postulated that there is a link between MS and exposure to sunlight and ultraviolet radiation due to the geographical frequency of MS. The prevelence of MS is greater in populations located further away from the equater, nearer to the colder areas of the world.

In recent years there has been increasing evidence that vitamin D may infl uence MS susceptibility and may also be of use for treating MS itself. ƒ Past exposure to sunlight, particularly during childhood, has been linked to the risk of developing MS.

A study of 79 pairs of identical twins, where only one of the twins had MS, concluded that past exposure to sunlight, particularly during childhood, is linked to the risk of developing MS. By looking at nine different activities, which implied exposure to sunlight, they concluded that the twin who developed MS had significantly lower exposure to the sun during childhood.

In another study, when a group of people with MS were compared to another group without MS, the risk of MS was found to be lower in those who in their childhood had been exposed to sunlight during their holidays and weekends, a finding that was confirmed by skin changes indicating cumulative sun exposure.

Sources of Vitamin D


The major natural source of vitamin D is exposure of the skin to ultraviolet B wavelengths in sunlight. However, there are risks of skin cancer associated with extended exposure to sunlight.


Only a relatively small number of foods contain substantial amounts of vitamin D. Oily fish, including salmon, mackerel and trout contain the highest amounts of vitamin D3. Smaller amounts are found in eggs. Cod liver oil is a rich source of vitamin D3.

Vitamin D2 occurs naturally in some mushrooms (for example shiitake and chanterelle) and yeast. The amount in most vegetables is negligible. Some foods such as breakfast cereals and margarine have vitamin D added during manufacture.


There are two types of vitamin D supplements: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). For a number of reasons, it is generally considered that vitamin D3 is the most effective form for supplements . The best approach for supplementing in people with lower levels of vitamin D has not been established and varies depending on the individual. Short courses of high doses can be used to adjust levels. Prolonged supplementation with very high doses can lead to loss of calcium from the skeleton causing problems such as weakening of bones, high blood pressure and kidney problems. For this reason, high doses of vitamin D are often combined with calcium supplements.

Levels of vitamin D in people with MS

Some studies have looked at vitamin D levels in people who already have MS.

A study of samples from 267 people found that higher levels of vitamin D were associated with a lower relapse rate. Low levels were associated with higher disability scores. People with progressive forms of MS had lower levels than those with relapsing remitting MS.

Another study of 132 people found signifi cantly lower levels of vitamin D in people experiencing a relapse than in people who were in remission.ˆ

A study in Tasmania found a high prevalence of vitamin D deficiency in both people with MS and in a matched group without MS; however people with MS with higher disability (EDSS - a disability scale - greater than 3) were more likely to have insufficient levels of vitamin D, perhaps as a result of lower sun exposure.

Vitamin D as a treatment in MS

Despite the accumulating evidence which suggests its importance in MS, there have so far been only a limited number of studies on treatment with vitamin D:

  • In a small study, a two year course of treatment with vitamin D (5000 IU/d in the form of cod liver oil) in ten people with MS found a 60% reduction in the predicted number of relapses.Š
  • In another small uncontrolled study, 15 people with MS who received 100 IU/d for 48 weeks experienced a 50% reduction in relapses.11
  • High doses of vitamin D3 (cholecalciferol, 14,000 IU/d) over a period of 6-12 months increased blood levels of vitamin D to nearly 400 nmol/l and did not lead to hypercalcaemia (excessively high levels of calcium in the blood) or other signifi cant side effects. 12 After 12 months, a 41% reduction in the number of relapses and a signifi cant improvement in EDSS was reported for the 25 people receiving vitamin D3 compared to the 24 who were untreated.13
  • 39 people were treated\ with 1000 IU/d vitamin D3 for six months compared to 22 untreated controls. There was a significant increase in certain cytokines, mediators of the immune response.14

Further studies into the role of vitamin D in MS

Research to date has provided circumstantial evidence to support a role for vitamin D in the risk of developing MS as well as for treating MS. Studies are currently underway or in the planning stages to look more closely at the prevalence of vitamin D deficiency in people with MS, to establish the safety of high doses (up to 40,000 IU/day) of vitamin D in MS and to assess the effects of supplementation on the immune system and on the skeleton.

Further studies are needed to evaluate the role of vitamin D during pregnancy and early years for reducing the risk of children developing MS later in life.


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(3). Myhr K. Vitamin D treatment in multiple sclerosis. Journal of Neurological Sciences 2009;286:104-108.

(4). Islam T et al. Childhood sun exposure influences risk of multiple sclerosis in monozygotic twins. Neurology 2007;69:381-388.

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(10). Goldberg P et al. Multiple sclerosis: decreased relapse rate through dietary supplementation with calcium, magnesium and vitamin D. Medical Hypotheses 1986;21:193-200.

(11). Wingerchuck DM et al. A pilot study of oral calcitriol (1,25-dihydroxyvitamin D3) for relapsing-remitting multiple sclerosis. Journal of Neurology Neurosurgery and Psychiatry 2005;76:1294-1296.

(12). Kimball SM et al. Safety of vitamin D3 in adults with multiple sclerosis. American Journal of Clinical Nutrition 2007;86:645-651.

(13). Burton JM et al. A phase I/II dose-escalation trial of oral vitamin D3 with calcium supplementation in patients with multiple sclerosis. Multiple Sclerosis 2008;14(Suppl 1);S34.

(14). Mahon BD et al. Cytokine profi le in patients with multiple sclerosis following vitamin D supplementation. Journal of Neuroimmunology 2003;134:128-132