The sun is important for our well-being and has positive effects on our health. Still, it's important to be aware of the sun's potential effects on the skin. In this blog post we will take a closer look at the effects of the sun on the skin - also in connection with psoriasis.
Positive effects of the sun on the body
Formation of vitamin D - important for bones
When the skin is exposed to the sun, the lucky vitamin D is produced. This is important for muscle and bone functions (1).
Against osteoporosisA vitamin D deficiency increases the risk of developing the painful bone disease osteoporosis. In this disease, bone substance is broken down throughout the entire skeleton, causing the bones to become porous and unstable and, in the worst case, to break (despite little or sometimes no load) (2). The reason for this, as with rickets, is a lack of vitamin D. This is important for the absorption of calcium and phosphate from the intestine, which is necessary for bone formation. If there is a lack of vitamin D, less calcium is available for the bones for mineralization (= the storage of minerals in the bones, for example). Due to the low mineral balance, there is increased bone breakdown and thus bone loss. Therefore, it is important to get enough vitamin D to maintain bone health (4).
Against rickets (children)
Rickets is mainly found in children. For example, children in Northern Europe during the Industrial Revolution often suffered from rickets, also known as “English disease,” due to high levels of air pollution and the resulting lack of sunlight. In this disease, the bone is soft and not sufficiently resilient, so that, among other things, deformations develop in the two bones (2). Rickets is rare these days; according to the AOK, there are 400 cases across Germany every year. The reason for these deformities was a vitamin D deficiency, but as soon as this is corrected, the mineral deficiency is eliminated and misalignments are ideally corrected (3).
Reduces certain disease risks
Vitamin D can help reduce the risk of various types of cancer, such as colon cancer, breast cancer and prostate cancer (1).
Although this sounds promising, it is important to note that well-structured, randomized clinical trials are still needed to understand, for example, the relationship between vitamin D levels and breast cancer risk, breast cancer development, recurrence and chance of survival in the different stages of cancer (5).
In addition, if you suffer from a vitamin D deficiency, you are more susceptible to cardiovascular diseases, multiple sclerosis, rheumatoid arthritis and type 1 diabetes mellitus (2).
Negative effects of the sun on the body
Skin cancer
UV-B rays can damage the DNA of skin cells, causing them to mutate. These mutations can control the cell cycle, causing cell division to occur uncontrollably, which can ultimately lead to skin cancer (6).
Sun, or UV rays, are the biggest environmental risk factor for the development of non-melanoma skin cancer (= non-melanoma skin cancer, occurring in the top layer of skin). Interestingly, it has been found that there is a link between the development of black melanoma and short but intense UV exposure, particularly burns, in childhood.
Suppression of the skin's immune system has been shown to be another mechanism by which the sun's UV radiation triggers and promotes the growth of skin cancer (6).
How do I properly protect myself from the sun?
Long clothing is very effective in protecting yourself from the sun. Above all, it blocks UV-B rays and can thus avoid burning the skin.
Sun protection also helps, of course. Most are a combination of chemical UV-absorbing sunscreens and physical inorganic sunscreens that reflect UV light. This provides broad-spectrum protection for the skin. In addition, the midday sun should be avoided in summer.
How much vitamin D do you need?
With reasonable exposure to the sun (2 to 3 times a week for 5-10 minutes each, on the arms and legs or on the hands, arms and face) and an increased vitamin D intake through food and If you have dietary supplements, you have a good basis for ensuring an adequate supply of vitamin D (2).
Groups that are particularly susceptible to vitamin D deficiency include residents of a nursing home or people with light skin. Here it is advisable to monitor the vitamin D content. If you have a vitamin D deficiency, it can be taken orally. Taking 1,250 μg (50,000 IU) of vitamin D once weekly for 8 weeks has been shown to be effective and safe for treating vitamin D deficiency (8).
Sun and psoriasis
There is also the option of undergoing light therapy to treat psoriasis. UV light has immunosuppressive properties, which means that the immune system's defense reaction is inhibited. This is particularly advantageous for psoriasis, as it is a chronic skin disease that is triggered by an autoimmune reaction in which the body's own tissue is attacked. In this way, skin cells are renewed faster than usual (normally 4 weeks, for those affected by psoriasis approximately every week) and the 'old' ones are carried to the surface of the skin. This process causes the silvery-white plaques to form.
Sun or vitamin D can suppress this immune reaction, but sunbathing should still be enjoyed with caution (depending on skin type, location and other factors). It is important to avoid sunburn as it is not good for skin affected by psoriasis (7).
Sources:
(1) Halliday et al., 2008
(2) Holick, 2004
(3) AOK, 2023
(6) Reichart, 2006
