Can Vitamin D heal your skin?
Vitamin D had a lot of press during the past years due to its role in bone metabolism and immune function, but did you know that Vitamin D could be great for your skin too?
Vitamin D is technically a hormone, small amounts can be taken from diet (vitamin D2 and D3), but the majority is taken from the sun. When UVB rays encounter the cholesterol on the skin, they create vitamin D3 (cholecalciferol), which then is transformed in the liver and becomes calcifediol (this is what we measure in a blood test). This is then further transformed in the kidneys into calcitriol, the active form of vitamin D.
Vitamin D role in the skin is to modulate the production, maturation and death of keratinocytes (=skin cells). Vitamin D also helps to balance the skin immune system, hence particularly important to prevent skin infections. Lastly, it is involved in the production of molecules called glycosylceramides, that are necessary for permeability and integrity of the skin.
Some examples of skin conditions where vitamin D seems to be involved to their pathogenesis are:
This is an inflammatory skin condition with immune system involvement, characterised by a higher turnover and slower death of keratinocytes, forming the classic plaque-like lesions. We are still unsure about the exact causes of psoriasis, however a connection with low vitamin D levels seems to be present. Individuals with psoriasis often present with changes in their vitamin D receptor (VDR) activity, impairing the skin barrier function. This means that the skin becomes less permeable allowing bacteria to enter and water to exit, leaving the skin dry and more prone to infection. Adequate vitamin D seems to decrease inflammation and improve skin integrity.
2-Atopic dermatitis (eczema)
Another inflammatory condition, where we see a malfunctioning skin barrier that led to itchiness and lesions and potentially to infections, is eczema. The exact causes and development of this skin condition are not yet fully understood, however we know that because vitamin D is involved in the inflammatory processes in the body, low levels can increase not only inflammation, but also the likelihood of getting skin infections due to scratching. In eczema, similarly to psoriasis, we have also poor barrier function, and inadequate production of molecules that give strength and structure to the skin (like filaggrins), which also increase skin dryness. Low levels of vitamin D are seen in individuals with eczema.
Acne is characterised by inflammatory lesions and an imbalance of certain bacteria, like Cutibacterium acnes and Staphylococcus epidermis, against the rest of the skin biome. Our immune system recognises this imbalance as foreigner and start to release inflammatory signals to fight it. Vitamin D could, as we already mention, help to mitigate the inflammatory response, and in fact many studies have found a correlation between individuals with low levels of vitamin D and acne prevalence. This does not mean that low vitamin D cause acne, but it could be a contributing factor.
Vitiligo is an autoimmune pigmentation disorder where melanocytes function and their life cycle are impaired. Vitamin D seems to be acting in 2 ways: firstly, is involved in the life cycle of melanocytes by promoting their proliferation and maturation and decreasing their death, and secondly is involved in the immune system by decreasing inflammatory signals (such as tumour necrosis alpha and interferon gamma). Again, low levels of vitamin D have been found in individuals with vitiligo.
The NHS state that for most adults, the requirement for vitamin D is 400IU daily, however is important to remember that those requirements can vary, depending on age, skin colour and medical condition. Certain individuals are more at risk of insufficiency, some risk factors are obesity, smoking, age, or if you suffer from conditions like celiac disease, hyperthyroidism, chronic kidney and liver disease, or if you take certain medications long term like corticosteroids. This does not mean that if, for example, you are obese you are automatically insufficient in vitamin D but means that you should keep an eye on your levels.
Because vitamin D is mostly taken from the sun, during the summer we should get some extra exposure in order to get enough in winter, were there is little or no sun. Unfortunately, many people are still not getting enough of it, and might need to supplement.
If you spend most of your time indoor or if you are concerned about your vitamin D levels, is probably worth checking your levels, and based on the results you could ask your healthcare practitioner about supplementation. Remember that the right dosage and timing are vital to avoid ineffectiveness or toxicity.
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