Vitamin D₃ (cholecalciferol or calciferol) is known as ‘’vitamin from the sun’’. For sure everybody have already heard that it is important for our bones. Simply saying, it regulates calcium uptake in the intestine and proper mineralization of the bones. But is it everything? What is the role of vitamin D3 for our skin? Today I would like to give you a short answer to these questions.

Let’s start with a little bit of boring biochemistry 😉 Although vitamin D can be taken up from food (so called exogenous way), a much more efficient way of its distribution in our organism is its synthesis by skin cells (so called endogenous way). It is synthetized in keratinocytes, which we can find in stratum basale of epidermis. Synthesis of vitamin D requires UV light of approx. 290-315 nm wavelength, which responds to UV-B radiation. Just to remind you, we have four different types of radiation, which can penetrate through our skin. UV-A with 320-400 nm wavelength, UV-B with 280-320 nm wavelength, UV-C with 100-280 nm wavelength and infrared radiation with more then 800 nm wavelength. Vitamin D is produced in keratinocytes from cholesterol. Due to exposure to UV light, cholesterol is converted to pre vitamin D₃ (7-dehydrocholesterol) and transported into the liver, where it has to be double-hydroxylated to its active form. After first hydroxylation (addition of -OH group), it is converted into major circulating form in our organism – 25(OH)D₃ (cholecalciferol or 25-hydroxy vitamin D₃). 25(OH)D₃ is accepted biomarker of vitamin D in our organism. In this form, vitamin D is transported to the kidneys, where it is hydroxylated into active form- 1,25(OH)₂D₃ (1,25-dihydroxy cholecalciferol). Last conversion is strictly regulated by calcium and phosphorus levels in the blood.

Production of vitamin D is dependent on skin pigmentation, age, intensity of the UV radiation (season of the year and latitude) and even our lifestyle. It is important to know that too long exposure to sun light doesn’t lead to production of toxic concentrations of vitamin D₃, as a big part of provitamin D₃ and cholecalciferol in our organism is converted to non-active metabolites like lumisterol (vitamin D₁). Unfortunatelly, in today’s world people suffer from strong vitamin D deficiency. Why? In modern life style we avoid sun light, we go to work with underground or with a car, we park that car in underground parking areas and very ofter we stay the whole day long at our homes. Even if we go out, we put a lot of the sunscreen on our skin, what additionally prevents our organisms from UV radiation, thus blocks biosynthesis of vitamin D. To produce right amount of vitamin D, our body requires exposition of summer sun of 20% of our skin for 30 minutes a day! In modern world we do not achieve even low portion of vitamin D production in the summer period. Consequently, you can imagine, that during colder periods of the year we do not produce that vitamin at all! One can ask, what with vitamin D, which we can find in the food? First of all, that low amount of vitamin D in the food can cover only 10% of totall vitamin D requirement. Secondly, believe me that our modern diet (which actually is full of junk food) do not provide even half of this! Vitamin D₃ we can find in fat fishes and milk products. However, even rich and varied diet is not enough to provide it in a adequate amount. So what to do? The best way to compensate its deficit in our bodies is to supplement it. On the market we can find many different products, which we could introduce into our diet. Depending on the exposition on the sun light, supplementation should very from 500 IU up to 2000 IU per day during summer and winter respectively.

Yes, novadays we should supplement vitamin D almost every day! In the summer, long exposition to the sun can lead to erythema, however it is almost impossible to reach toxic levels of vitamin D₃. Due to autoregulation of its biosynthesis and different photochemical reactions, it will be accumulated and stored in a form of non-active metabolites. Due to some scientist the only way to achieve toxic concentration of vitamin D in the body is wrong supplementation, which can appear after long term application of more than 10000 IU per day, or single administration of 50000 IU.

Why vitamin D is so important for the skin?

– It is known, that vitamin D₃ has a strong impact on immune system. Vitamin D in the skin can lead to decrease of inflammatory cytokines (like interleukin 1, 6, 8,17 and 21) and increase of anti-inflammatory cytokines like interleukin 10. Due to its immunomodulating properties, its deficiency can have a role in occurrence of autoimmune diseases of the skin (psoriasis and lupus– known as well as systemic lupus erythematosus). Psoriasis is a long-lasting disease with raised areas of abnormal skin. A lupus is autoimmune disease as well and leads to attacking by immune system of the body tissues and can appear as a butterfly-shaped erythema on the face. Due to its immunomodulating properties, vitamin D can have influence on reduction of appearance of allergic reactions. As I already wrote, it reduces inflammation and has an impact on cell damage by oxidative stress, what make it important vitamin for all people suffering from neurodermatitis (atopic dermatitis) as well.

– It protects our skin from negative influence of UV radiation, what prevents premature aging and photoaging of the skin.

– It is important for right function of the skin biochemical processes.

– Vitamin D₃ regulates keratinocytes differentiation and proliferation and it has been shown that it can have a very positive influence on acne. Due to the latest publications, supplementation with vitamin D in 2000 IU dosis per day and its topical application led to strong improvement of skin condition in patients, who suffered from acne. It has been shown as well, that there is a very strong correlation between severity of acne and vitamin D deficiency.

I hope I could convince you that vitamin D₃ is not only a vitamin for strong bones. It is extremely important for skin physiology as well and in today’s modern world its supplementation suppose to be implimented in diet of all of us- at least in winter period.

A.