What is vitamin D good for?

Vitamin D plays a vital role in the musculoskeletal system as it aids the renewal of bone tissue which helps our bones grow strong. It also helps the body to absorb calcium properly, which is essential for bone health, and without sufficient levels of vit D, our bones can become thin, brittle or misshapen.⁵  

If the body is not able to absorb enough calcium, you could develop either osteomalacia or osteoporosis – two conditions characterised by weak bones that are more likely to fracture.  

Increasing your vitamin D levels could help remineralise bone structures, making them more robust and keeping you stronger for longer. 

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Muscle weakness may be another side effect of low vitamin D levels, especially in the elderly. Recent studies have recognised that vitamin D could play a significant role in muscle function, strength, recovery and even athletic performance.⁶  

Researchers have now located vitamin D receptors (VDR) in muscle cells, the activation of which stimulates enhanced muscle contractions and movement.⁷  

VDRs are found on the fast-twitch muscle fibres, which are built for rapid bursts of energy and movement, therefore are often the first to respond to a fall.⁸  

It is this finding that may explain the decreased fall risk in the elderly, as improved muscle strength and increased sports performance has been linked to adequate vit D levels.⁹ 

Not only is vitamin D instrumental in the development of strong bones and muscles, research also indicates that it plays a key role in keeping your joints healthy.  

They have identified a strong link between vitamin D deficiency and various joint diseases, including rheumatoid arthritis (RA).¹⁰  

It has been suggested that vit D may have some therapeutic applications in the pain management of autoimmune diseases, such as RA, due to the studied anti-inflammatory and immunosuppressive (reduce/weaken the body's natural immune response) properties of the hormone.¹¹ 

Another potential benefit of taking vitamin D is its positive effects on your oral health. Finnish researchers recently discovered that low vitamin D levels are linked to periodontitis or gum disease. Their study found that those with chronic gum disease also had very low levels of vitamin D in their blood.¹² 

A further study in Norway has also found a link between tooth loss and exposure to sunlight – only 11% of those living in the south of the country lost teeth, compared with 65% in the north.¹³  

If only we could get summer holidays on prescription… 

Although vitamin D is best known for its role in keeping our bones healthy, there is some evidence that it may play a much larger role in the body through our immune responses.  

A randomised, controlled study carried out in Japan revealed that vitamin D-deficiency in the winter may be one of the reasons we are more susceptible to certain types of seasonal flu.¹⁴  

Vit D deficiency has also been linked to various autoimmune diseases such as multiple sclerosis, type 1 diabetes, lupus and inflammatory bowel disease.¹⁵ 

Although more research is needed to conclusively determine that vit D has some control of the immune system, the studies that have been published do indicate that vitamin D may have some interesting immunomodulatory properties (able to affect/control how the immune system functions).^16,17 

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Various forms of vitamin D are commonly prescribed to treat psoriasis due to their efficacy and safety.¹⁸  

The anti-inflammatory and immunosuppressant properties of the hormone could explain why vit D oral supplements are successful at keeping the autoimmune disease under control from the inside.¹⁹  

If you are experiencing a flare-up, talk to your GP or a healthcare professional to see what the most suitable solution/treatment is for you, they may suggest a topical oil or ointment (in the form of calcipotriol).²⁰ 

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Scientists have also discovered that there may be a link between vitamin d-deficiency and some forms of acne (both acne vulgaris and nodulocystic acne).  

Multiple studies have revealed that patients suffering from acne often have much lower serum vitamin D levels, than those without. ^21,22,23 

One study even found that the severity of the patient’s acne correlated with the extent of their vit D deficiency, and that taking oral vitamin D supplements led to a significant improvement in their acne inflammation.²⁴ 

That said, most research into this area have been small-scale studies so far, therefore more research is needed to conclusively establish a link between vitamin D and acne.  

Over the years, the link between light exposure and depressive symptoms has been widely investigated, but there is now an increasing specific research focus on the role that vitamin D may play in depression.  

It is apparent that vitamin D interacts with an important part of our neuroendocrine system (the internal system that regulates how our bodies feel, respond and act through hormones) that regulates the production of important neurotransmitters like adrenaline and dopamine.²⁵ 

A Norwegian trial revealed a significant reduction in depressive symptoms in trial subjects that received a high dose of vit D daily for one year, showing a correlation between vitamin D and depression.²⁶  

Another study reported that they found “a significant relationship between depression and vitamin D deficiency”.²⁷ 

While there is a need for further research to be carried out, if meeting our daily vitamin D requirements for the sake of our mental health calls for spending more time outdoors in the sun, eating a balanced and varied diet, or taking supplements, this would be a cost-effective and relatively simple solution for those at risk of depression.²⁸