Vitamin D supplements: what dose?
The use of moderate dose vitamin D supplements remains controversial. In this newsletter I provide a rationale, based on bone health, for keeping yourself vitamin D replete.
Although low levels of vitamin D are associated with a higher risk of getting MS this is an association and does not necessarily mean that by correcting low vitamin D levels in at-risk individuals you will prevent them from developing MS. This is why we need to do well-designed prevention studies to test this hypothesis. The latter is not for want of trying, but the MS community has not been able to get its shit together to set up these trials.
What about vitamin D supplements to treat MS? There is evidence that low vitamin D levels correlate with increased MS disease activity. However, this is again an association and not necessarily causation. In other words, MS disease activity may be responsible for lower vitamin D levels. T-cells and other immune cells consume vitamin D levels when they proliferate. This explains why almost all inflammatory conditions and infections are associated with low vitamin D levels. Supplementing vitamin D may have little or no impact on the underlying condition.
There have, however, been several add-on vitamin D trials to see if vitamin D can treat MS, i.e. vitamin D is being used as disease-modifying therapy. Although some trials have been weakly positive overall I am not convinced by the data that vitamin D supplementation modifies the disease course in MS.
Another reason for taking vitamin D is for bone health. As you are aware pwMS are at risk of osteopaenia, osteoporosis falls and fractures. Vitamin D deficiency and insufficiency are risk factors for poor bone health. Therefore for bone health reasons, it is a good idea to keep yourself vitamin D replete.
What dose of vitamin D?
This is probably the most controversial issue in the field. What I can say is that the current RDA (recommended daily allowance) is based on very old studies on rickets prevention, which were done in the first half of the twentieth century. It was found that a teaspoon of cod liver oil prevented rickets and that equated to about 400 IU or 10 micrograms of vitamin D3 per day and in older women (>70 years) the RDA is 800 IU per day. Please note that in some countries the RDA is 600 IU per day.
Many vitamin D experts disagree with these recommendations as they are based on the role of vitamin D in bone health and ignore vitamin D’s role in inflammation. Studies have shown that moderate vitamin D supplementation, of up to 10,400 IU/day is safe in pwMS and has favourable effects on the immune system. The immunological changes on moderate dose vitamin D are congruent with the effects we would want to see if MS was an ‘autoimmune disease’; e.g. moderate doses of vitamin D reduce a population of T-cells in the blood that is where putative autoreactive T cells may reside.
Why do I say moderate dose vitamin D supplementation rather than high-dose? This is because 10,400IU per day is physiological vitamin D supplementation. If you expose your upper body ~20-30 minutes in mid-summer your skin will produce this sort of dose of vitamin D; therefore 10,400 IU is not high-dose. Please note the darker your skin the longer you will need to expose yourself to produce an equal amount of vitamin D in your skin.
What is also clear it is not only skin colour and sun exposure that determines your vitamin D levels, but diet, use of sunblock and how you metabolise vitamin D. Therefore, in an ideal world every person should have a personalised dose of vitamin D, which is not practical. In the past, I have advised my patients to ensure they are vitamin D replete; with the aim of having a plasma level of 25OH-vD3 of greater than 100 nmol/L and less than 250 nmol/L. To achieve this target you have to have vitamin D levels measured, which is difficult because the NHS has all but stopped vitamin D level monitoring. This is why most vitamin D experts now recommending one level of supplementation that is safe for the general population.
This makes sense. In the past, I adopted the Vitamin D Council’s recommendations. However, the Vitamin D Council has been disbanded so I have had to adjust my recommendations to be in line with what the European Food Safety Agency and other authorities are recommending as safe levels of supplementation. Please note that although the Vitamin D Councils website has been taken down their recommendations are still present on their Twitter and Facebook sites.
My current recommendations
For adults, this is 4,000 IU of vitamin D3 per day, for children 2-10 years of age 2,000 IU per day and for children less than 2 years of age 600 IU per day. In pregnancy, the dose should be doubled to 8,000 IU per day because of the higher requirements during pregnancy. Please note that these recommendations are not international; public health officials still stick with the RDA based on bone health.
In an ideal world, you would supplement vitamin D to a target, i.e. you would start on the recommended dose of 4,000 IU/day and have your blood levels checked about 12 weeks later. If levels are still low and you have been adherent to the supplements you would then increase the dose to 8,000 IU/day. If your blood levels were too high on 4,000 IU/day you would reduce the dose to between 1,000-2,000 IU/day.
I never tell my patients that vitamin D supplements will improve or help their MS; I say it may do this but the real reason for being vitamin D replete is to improve, or maintain, your bone health.
Please note I do not recommend calcium supplementation in parallel with vitamin D supplementation. As far as I am concerned there is no reason for pwMS to take calcium supplements unless they have thin bones (osteopenia or osteoporosis). If you are taking moderate or high-dose vitamin D and calcium supplements together you will need to have your calcium levels monitored (please discuss this with your HCP).
With regard to the target of plasma vitamin D levels, I have adopted the evolutionary medicine approach espoused by Reinhold Veith a Canadian vitamin D expert. This theory is based on what your vitamin D levels would be if you worked outdoors with skin exposed (lifeguards & farm labourers) and what vitamin D levels are in hunter-gatherer societies. This approach gets around using a reference population and the likelihood that modern societies are vitamin D deficient and hence you can’t use a general population to establish a normal range of plasma vitamin D levels.
I am raising funds from subscriptions to administer the MS-Selfie Newsletter and microsite. The subscriptions, for case studies only, will be used to hire an administrator to proofread, curate and transfer the contents of the Newsletter onto the companion MS-Selfie microsite. If you find these Newsletters helpful and can afford to subscribe I would urge you to do so; it will help me and the MS community.
The case study from the 6th of September is about a patient on dimethyl fumarate who has inactive secondary progressive MS and wants to switch to siponimod. In this case study, I discuss the issues around MS disease definitions and the problem of the current siponimod label.
General Disclaimer: Please note that the opinions expressed here are those of Professor Giovannoni and do not necessarily reflect the positions of Barts and The London School of Medicine and Dentistry nor Barts Health NHS Trust. The advice is intended as general advice and should not be interpreted as being personal clinical advice. If you have problems please tell your own healthcare professional who will be able to help you.