What influence does nutrition have on my skin?
06.05.2025
Ernährung und HautgesundheitUnsere Haut ist nicht nur unser größtes Or...
On 15.04.2025, Dr. Lea-Sophie Stahl gave a lecture on the topic "Summer is just around the corner - skin and sun protection". Here is an overview of the most important contents of the lecture.
The fascinating functions of the skin
The skin is the largest organ of the human body and fulfills numerous vital functions. It not only serves as a protective shield against heat, cold, pathogens and chemical substances, but is also involved in the absorption of certain substances (resorption), the release of sweat and sebum and the regulation of body temperature (thermoregulation). It also enables the perception of pressure, heat and cold through sensory cells.
UV radiation
UV-C rays are largely intercepted by the atmosphere and do not reach the earth's surface.
Positive effects of UV radiation
Moderate exposure to UV radiation can have positive effects on the body:
Negative effects of UV radiation
However, UV radiation also harbors numerous risks:
Vitamin D - How much sun do we need for sufficient vitamin D production?
For sufficient vitamin D production, it is usually sufficient for adults to briefly expose their face, hands and arms to the sun uncovered two to three times a week. The duration depends on the individual skin type. In Germany, for example, skin types I to III predominate.
For a better understanding, here is a concrete example: a person with skin type II needs around 12 minutes of sun exposure on a sunny day with a UV index of 7 for sufficient vitamin D production. More time in the sun has no additional effect, but increases the risk of skin damage. In the event of a deficiency, vitamin D supplementation can be carried out, but only in consultation with a medical professional.
Skin cancer - "The skin does not forget"
So-called "sun terraces" such as the forehead, ears and back are particularly at risk. UV radiation can lead to irreparable DNA damage as the basal cells are damaged. It is interesting to note that from the age of 85, almost everyone in Europe has at least one actinic keratosis - a possible precursor to skin cancer. Regular skin cancer screening is therefore essential.
Assessment of your own UV protection
Effective UV protection reduces the risk of skin cancer, sunburn and premature skin ageing - but does not offer 1001TP3 protection. Sweating and friction can reduce its effectiveness. In addition to sunscreens, textile sun protection plays a central role, especially for children, athletes or professions with high sun exposure. The 3-H rule applies here: hat, shirt, trousers. Sunglasses are also important to protect the eyes and the particularly sensitive skin around the eyes.
UV protection and water
UV radiation is also an issue in water. Although water provides partial UV protection, around 50 % of UV rays still reach the skin at a depth of one meter. This is why it is essential to apply sunscreen here too. It is also important to consider how well UV protection lasts in water. Two terms are of central importance here. If a product is labeled "water-resistant", >50 % of the sun protection factor is retained after contact with water. If it says "very water-resistant" on the packaging, >80 % is retained after contact with water. This means that you should reapply the cream after every bath and ensure that it is left on for a sufficient period of time before the next bath.
In comparison - chemical and physical UV filters
Chemical filters absorb UV rays (280-400nm), prevent penetration into deeper layers of the skin and inhibit pigmentation and callus formation. Skin and environmental compatibility are important here; products used should not have any hormonal effects, should not contain any microplastic particles and should not penetrate the skin. Pay particular attention to the ingredients in your sun cream with a chemical filter! Since 2021, certain substances such as oxybenzone and octinoxate have been banned in sunscreens as they damage coral reefs and aquatic organisms. The first positive effects of the ban have already been observed.
Physical filters such as mineral pigments (e.g. zinc oxide, titanium dioxide) reflect, absorb and scatter UV rays (100-400 nm). They do not penetrate the skin and are particularly suitable for children. However, they are less effective in the UVA range and are currently undergoing further development.
Self-protection times and application instructions
The self-protection time describes how long a person can stay in the sun without sun protection before sunburn occurs. This time depends on the skin type - for example, this time is around 5-10 minutes for skin type II.
The formula for calculating the self-protection time is as follows:
Self-protection time × sun protection factor = maximum time in the sun
Here is a concrete calculation example for skin type 2: 10 minutes × SPF 30 = 300 minutes
However, it should be noted that the formula is only a rough calculation. Other influencing factors such as sweating or friction from clothing must also be taken into account. It is therefore better to round down than round up.
It all depends on the right amount of sun protection!
Conclusion
Effective UV protection is essential for healthy skin. Chemical filters offer reliable protection, while physical filters are particularly suitable for sensitive skin. In addition to sunscreens, textile sun protection is also crucial. And: direct sun exposure should be reduced as much as possible - because the skin never forgets.
