Question

Following on from the question in the Summer issue of ME Essential about the risk of developing osteoporosis in ME and the use of vitamin D supplements, I was concerned to see a newspaper report about someone who had been recommended to take a vitamin D supplement by a nutritionist which had caused serious side-effects and resulted in hospital admission.

So should people with ME/CFS be taking vitamin D supplements? Or any vitamin supplement? And is it safe to do so?

Answer

There was an important warning about the dangers of overdosing on vitamin D in the British Medical Journal back in July. This is where the press reports came from. The person involved had been taking very high doses of vitamin D and this caused nausea and vomiting, abdominal pain, leg cramps and weight loss.

Although there have been some small studies reporting minor abnormalities in vitamin status in ME/CFS, there is no firm evidence that vitamin deficiencies are present in people with ME/CFS, or that vitamin supplements are a safe and effective form of treatment for ME/CFS

However, there are two important exceptions. Firstly, if someone with ME/CFS is taking a diet that may be restrictive in vitamin content it would be sensible to take a good multivitamin supplement. Secondly, we know from both patient evidence and research into vitamin D status in people with ME/CFS that there are some people, especially those at the severe end of the spectrum, who are deficient in vitamin D. This is not surprising because vitamin D is produced in the body through the action of sunlight on the skin and lack of exposure to the sun is a well recognised factor in producing vitamin D deficiency.

So people with ME/CFS who are housebound, or largely housebound, and do not go outdoors should check with their doctor about their vitamin D status – as any significant deficiency will need to be treated. And, as the NHS now advises, everyone should consider taking a daily vitamin D supplement throughout the year.  The daily requirement is 10 micrograms or 400iu (international units). Inexpensive over the counter supplements containing this dose can be purchased from pharmacies.

See also: Treatment: Vitamin D

More information

• The ME Association has detailed information about Vitamin D and Deficiency available to download from the website shop.
• British Medical Journal Case Report: Vitamin D supplement ‘overdosing’ is possible and harmful, warn doctors | July 2022
• NHS guidance: Vitamins and Minerals – Vitamin D | August 202o