Vitamin D supplementation and MS: research updates

At Overcoming MS, we are committed to providing the most accurate, evidence-based information. As research evolves, our guidance must keep pace with the latest findings. New studies have given us clearer insights into optimal vitamin D levels and supplementation for people with MS, leading us to refine our recommendations. We’re here to help you understand the latest recommendations and the need for further research.

Vitamin D and MS research

Vitamin D is essential for overall health, supporting bone strength, immune function, and brain health. For people with MS, research suggests even deeper connections—studies have linked low vitamin D levels to increased MS risk, disease activity, and progression.

However, vitamin D research is complex, and different types of studies have strengths and limitations.

• Randomised controlled trials (RCTs) often focus on short-term outcomes, so they may not fully capture the long-term benefits of maintaining healthy vitamin D levels.
• Different studies have used different doses, treatment periods and even units of measurement, often making direct comparison of results difficult.
• Epidemiological studies (studies of MS within populations) show strong links between low vitamin D and worse MS outcomes, but they can’t control for every factor influencing disease progression.
• No single study provides all the answers, experts recommend looking at all types of evidence together—which is exactly what we do when shaping our guidance.

A wide review of recent research has provided more clarity on optimal vitamin D levels and how supplementation affects MS outcomes which has allowed us to refine our recommendations.

Dr Jonathan White, Overcoming MS Medical Advisor:

“There is a rapidly developing body of research into every aspect of multiple sclerosis — prevention, diagnosis, treatments, and the benefits of lifestyle modification. The Overcoming MS Program was founded on the principle of using the best available evidence at any given time, and it is essential that we stay true to that commitment and adapt our recommendations where appropriate.”

A personalised approach for better health

Health is highly individual—and MS is no exception. Today, there is growing recognition that personalised health choices are important, whether in lifestyle, medication, or supplementation.

When it comes to vitamin D, several factors affect how much you might need, including:

• Where you live – sunlight exposure varies by location.
• How much time you spend outdoors – seasonal changes affect vitamin D production.
• Your skin type – different skin tones produce vitamin D at different rates.
• How well your body absorbs and processes vitamin D.

Our updated recommendations

To reflect the new research and growing recognition of personalised medicine, our updated guidance is:

• Take 4,000–10,000 units of vitamin D per day to maintain healthy levels.
• A healthy vitamin D level in blood serum is thought to be between 100–150 nmol/L (40-60ng/ml).
• If possible, get your vitamin D levels tested and consult with your doctor to find the right dose for you.
• If testing isn’t accessible, supplementation within these limits is considered safe.

What this means for you

If you have been following previous Overcoming MS guidance of 5,000-10,000 units per day aiming for blood serum levels of 150-225nmol/l, rest assured—you have already been taking positive steps for your health. Our updated guidance does not mean that past recommendations were unsafe or incorrect; rather, research now allows us to refine the target range for more precision while ensuring long-term safety.

Yasmin Neves, Overcoming MS Facilitator, shares:

“As both a Facilitator and someone following the Program, I feel confident and reassured knowing that the evidence has been reviewed and the advice is being updated. It makes a lot of sense.”

What you can do next

• Check your current vitamin D intake – if you’ve been supplementing at the higher end, you may not need as much.
• Consider getting a vitamin D test if you’ve not had one recently.
• Adjust supplementation if needed – if testing isn’t an option, following the updated recommendation of 4,000–10,000 units per day is still considered safe.

Want to learn more? Dive into our vitamin D pillar page for the latest science and practical tips on maintaining healthy vitamin D levels. 

Curious about vitamin D and safe sun exposure? Find out how to get the right balance here.