Could Vitamin D Help Musculoskeletal Pain?

By Bernitta Willoughby, Principal Osteopath at The Waterside Practice, Warboys, Cambridgeshire

A recent case

With much of Cambridgeshire enjoying one of the warmest spells of the year, many of us have been making the most of the sunshine. Whether you've been out walking, spending time in the garden or simply enjoying lunch outdoors, the recent heatwave has certainly encouraged us all to spend a little more time outside. Along with boosting our mood, sunshine provides something else that our bodies rely on: vitamin D.

As osteopaths, we spend every day helping people with musculoskeletal pain. Back pain, neck pain, shoulder pain and painful knees are among the most common reasons patients visit us at The Waterside Practice in Warboys. Every consultation involves looking beyond where the pain is felt and considering the many factors that may be contributing to it.

A recent patient reminded me just how much interest there is in vitamin D. At only 35 years old, she had been experiencing persistent knee pain. After seeing an NHS physiotherapist, she was advised to try taking a vitamin D supplement. Several weeks later she returned feeling much more comfortable and felt the supplement had made a noticeable difference.

As healthcare professionals, we have to be careful not to assume that one person's experience proves cause and effect. Pain often improves for several reasons at once. It may settle naturally, respond to rehabilitation, improve with changes in activity levels or benefit from several interventions happening together. Equally, if someone has been deficient in vitamin D, correcting that deficiency may genuinely improve how their muscles and joints function.

The conversation encouraged me to revisit the latest research. Could vitamin D play a role in musculoskeletal pain, particularly knee pain? The answer is more nuanced than many headlines suggest, but the science is fascinating and increasingly relevant.

What is vitamin D?

Vitamin D is often associated with healthy bones, but its role within the body extends much further than that. It helps regulate calcium and phosphate, allowing us to build and maintain strong bones throughout life. However, researchers have also discovered vitamin D receptors in skeletal muscle and throughout the immune system, meaning it influences muscle function, recovery and immune regulation as well.

When vitamin D levels become too low, symptoms can be surprisingly vague. Rather than experiencing one obvious problem, people may notice general muscle aches, fatigue, weakness or stiffness. Some describe feeling as though their whole body is working harder than it should. In more significant deficiencies, bone pain can also develop.

These symptoms overlap with many of the musculoskeletal complaints we assess in clinic. That does not mean vitamin D deficiency is the cause of everyone's pain, but it does explain why healthcare professionals sometimes consider vitamin D status when patients present with persistent aches or unexplained muscle weakness.

In the UK, vitamin D deficiency is relatively common. Our ability to produce vitamin D depends on ultraviolet B (UVB) rays from sunlight, and during the autumn and winter months the sun simply is not strong enough for our skin to produce adequate amounts. Even during the summer, factors such as working indoors, covering the skin, using high-factor sunscreen or having naturally darker skin can reduce vitamin D production.

Vitamin D and knee pain

Knee pain is one of the most common musculoskeletal problems we see as osteopaths. Whether the pain is related to osteoarthritis, previous injury, overuse, sporting activity or changes in biomechanics, it can have a significant impact on everyday life.

For many years, osteoarthritis was described as simple "wear and tear". Research has since shown that this description is too simplistic. Osteoarthritis involves changes within the cartilage, underlying bone, surrounding muscles and the lining of the joint. Low-grade inflammation also appears to play an important role in how symptoms develop.

Because vitamin D contributes to muscle function and influences aspects of the immune system, researchers began exploring whether correcting vitamin D deficiency could improve knee pain or even slow the progression of osteoarthritis.

It is certainly a logical question. Stronger muscles provide better support for joints, while healthy immune regulation may influence inflammatory processes. If vitamin D supports both of these systems, could ensuring adequate levels reduce pain?

This is where the research becomes particularly interesting.

Looking at the evidence

Over the past two decades, numerous studies have investigated vitamin D supplementation and musculoskeletal pain, particularly knee osteoarthritis.

Some observational studies have found that people with lower vitamin D levels report greater pain, poorer physical function and increased disability. This suggests there is an association between vitamin D deficiency and musculoskeletal symptoms, although an association does not necessarily mean one causes the other.

Several large randomised controlled trials have attempted to answer the question more directly.

One of the best-known studies, published in JAMA by Jin and colleagues in 2016, followed patients with symptomatic knee osteoarthritis over two years. Although vitamin D supplementation successfully increased blood vitamin D levels, it did not significantly reduce knee pain or slow cartilage loss compared with placebo.

Around the same time, the UK-based VIDEO study reached a similar conclusion. Researchers found that vitamin D alone was not an effective treatment for knee osteoarthritis in the study population.

At first glance this might seem disappointing, but the findings deserve careful interpretation.

Many researchers now believe the greatest benefits of supplementation are likely to occur in people who are genuinely deficient in vitamin D rather than those whose levels are already adequate. Correcting a deficiency is very different from taking extra supplements in the hope of treating pain.

Another area attracting considerable attention is inflammation. Vitamin D appears to influence immune cells responsible for regulating inflammatory responses. Recent systematic reviews have suggested supplementation may reduce some inflammatory markers, including tumour necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), although results remain inconsistent and further high-quality research is needed.

Overall, the current evidence suggests that maintaining healthy vitamin D levels is important for normal muscle, bone and immune function. However, vitamin D should not be viewed as a standalone treatment for knee pain or osteoarthritis.

Enjoying the sunshine safely

One positive aspect of the recent warm weather is that our bodies are naturally able to produce vitamin D through sensible exposure to sunlight.

The NHS advises that between late March and the end of September, most people in the UK can make sufficient vitamin D from sunlight on their skin. During the autumn and winter months, however, adults and children over four years of age are advised to consider taking a daily supplement containing 10 micrograms (400 IU) of vitamin D.

Some people may benefit from supplementation throughout the year, particularly those who spend very little time outdoors, cover most of their skin when outside or have darker skin, which naturally produces less vitamin D from the same amount of sunlight.

It is important to remember that making vitamin D does not require prolonged sunbathing or allowing your skin to burn. Sensible time outdoors while protecting your skin appropriately remains the safest approach. Sunburn significantly increases the risk of skin cancer and should always be avoided.

An osteopath's perspective

Having treated musculoskeletal pain for over fifteen years, one thing has become increasingly clear: there is rarely one single explanation for why someone develops pain.

Patients understandably hope there will be one missing piece of the puzzle. Sometimes it is a change in exercise, sometimes it is improving sleep, sometimes it is strengthening weak muscles and occasionally it may involve identifying a nutritional deficiency that has been contributing to recovery.

Vitamin D deserves attention because it plays such an important role in healthy bones, muscles and immune function. If someone is deficient, correcting those levels may improve muscle function and reduce general musculoskeletal aching. However, current research does not support vitamin D as a cure for knee pain or osteoarthritis, and taking large doses is unlikely to benefit someone whose vitamin D levels are already normal.

At The Waterside Practice, we take a whole-person approach to musculoskeletal care. We look at movement, joint function, strength, lifestyle, previous injuries and the many factors that influence recovery. Where appropriate, we may also recommend that patients discuss potential vitamin D deficiency or other health concerns with their GP, particularly if symptoms suggest further investigation would be beneficial.

The recent sunshine is a welcome reminder to spend time outdoors, stay active and enjoy the natural benefits that summer brings. Whilst vitamin D is unlikely to be the complete answer to musculoskeletal pain, maintaining healthy levels is an important part of supporting your overall health and may be one piece of a much bigger picture.

References

Arden, N.K., Cro, S., Sheard, S. et al. (2016). The effect of vitamin D supplementation on knee osteoarthritis: the VIDEO randomised controlled trial. Osteoarthritis and Cartilage, 24(11), 1858–1866.

Jin, X., Jones, G., Cicuttini, F. et al. (2016). Effect of Vitamin D Supplementation on Tibial Cartilage Volume and Knee Pain Among Patients With Symptomatic Knee Osteoarthritis. JAMA, 315(10), 1005–1013.

Saedmocheshi, S. et al. (2024). The effect of vitamin D supplementation on inflammatory cytokines: A systematic review and meta-analysis. Frontiers in Nutrition, 11.

National Institute for Health and Care Excellence (NICE). Vitamin D deficiency in adults: recognition and management.

NHS. Vitamin D. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/

Scientific Advisory Committee on Nutrition (SACN). (2016). Vitamin D and Health.