Does sunscreen prevent vitamin D production?

The sun's UV rays stimulate the body's own production of vitamin D – a vital vitamin that performs numerous functions in our organism. At the same time, excessive UV exposure can cause significant damage to our skin. Therefore, adequate sun protection is essential, especially in spring and summer.

However, this raises a legitimate question: Does the use of sunscreen restrict or even completely prevent the formation of vitamin D in the body? Here's the answer and a very clear recommendation!

What is vitamin D?

Vitamin D is a collective term for fat-soluble vitamins that belong to the calciferols. The two most important forms are:

• Vitamin D₂ (ergocalciferol), comes from plant sources (e.g., mushrooms exposed to UV light).
• Vitamin D₃ (cholecalciferol), is formed in the skin by sunlight (UVB rays) and is found in animal foods (e.g., fish or egg yolk).

Vitamin D performs numerous tasks in the body, including:

• supports calcium metabolism and is thus crucial for bone health
• plays an important role in muscle building
• strengthens the immune system

How is vitamin D formed?

The majority of vitamin D is produced by the body itself – more precisely in the skin, under the influence of UVB radiation. Diet contributes only a relatively small amount (about 10–20%) to vitamin D supply.

This is how the body's own production works:

1. UVB radiation hits the skin.
2. The provitamin D₃ present in skin cells is converted into previtamin D₃.
3. Through further metabolic processes in the liver and kidneys, active vitamin D is finally formed.

How much vitamin D is produced depends on various factors, such as skin type, age, time of day and year, location and weather conditions, as well as clothing and duration of sun exposure. Excess vitamin D can be stored in muscles and fatty tissue, for example, to draw on in winter.

How high should vitamin D levels be?

Below 30 (nmol/l): deficient
30 to 50 (nmol/l): insufficient
50 (nmol/l) and above: sufficient
Above 125 (nmol/l): too high

What happens in case of vitamin D deficiency?

Vitamin D deficiency can have serious consequences:

• Bone weakness (e.g., osteoporosis)
• Muscle weakness
• Immune system disorders
• Increased risk of cancer and autoimmune diseases

Does sunscreen prevent vitamin D formation?

Sunscreen protects the skin by filtering UV radiation – but it does not completely block the rays. Even with sun protection, UVB rays reach the skin to a lesser extent.

Studies clearly show that people who regularly use sun protection still produce enough vitamin D – especially because even short periods of sun exposure are sufficient to stimulate the body's own production.

How much sun is enough?

The Federal Office for Radiation Protection (BfS) provides a clear recommendation on this:

• For sufficient vitamin D synthesis, it is enough to expose the face, hands and arms to the sun two to three times a week, uncovered and without sun protection.
  
• The time window necessary for sufficient vitamin D formation is approximately half the time it would take to get a sunburn unprotected.
  
• For skin type II with a high UV index (e.g., UV index 7), about 12 minutes of sun exposure are sufficient – without sunscreen.

Important: For longer stays in the sun, UV protection is absolutely necessary, as risks such as sunburn, skin aging or skin cancer outweigh the benefits. Please also note that babies, children and adolescents are particularly sensitive to UV radiation. Infants and babies in their first year of life should generally not be exposed to direct sunlight. Supplementation with vitamin D preparations may be useful in individual cases, but should be clarified and/or accompanied by a doctor.

Conclusion: No sunscreen is no solution!

Sunscreen does not prevent the formation of vitamin D – at least not to an extent that would lead to a deficiency. Even a few minutes of sunlight on unprotected skin are enough to stimulate the body's own production. For example, I go outside in the morning or evening when the UV index is low without sunscreen and thus tank up my vitamin D.