Sunlight and Vitamin D: How to optimally absorb Vitamin D?

We know how important it is to protect ourselves from the sun to prevent premature skin aging and skin cancer, but UVB rays are the best source of vitamin D for the human body. How can you safely expose yourself to the sun to absorb as much vitamin D as possible?

How does our body produce vitamin D?

When your skin is exposed to the sun, it naturally produces vitamin D. The sun’s ultraviolet B (UVB) rays interact with a protein—7-dehydrocholesterol—that’s present in our skin cells. This interaction produces previtamin D3, which the liver and kidneys then convert into vitamin D.

What is our daily need for vitamin D?

The daily dose of vitamin D that is generally recommended from adolescence onwards is 15 µg per day (i.e. 600 IU). Food provides only about 10% of the vitamin D we need. The sun is the most important source (90%).

Which skin types absorb vitamin D from the sun best?

Pale skin produces vitamin D faster than darker skin when exposed to UVB rays. Darker skin contains a higher amount of melanin pigments. These act as a natural filter and prevent ultraviolet rays from penetrating the epidermis. The process of converting 7-dehydrocholesterol into pre-vitamin D3 is therefore less effective. With less melanin to absorb UVB rays, people with pale skin produce vitamin D more efficiently.

The skin of older people is also less efficient at producing vitamin D. With age, the concentration of 7-dehydrocholesterol in the skin decreases, which reduces the production of vitamin D3 under the influence of UVB rays.

Also read: What role does vitamin D play in the development of colon cancer?

At what time of day should I get some sun to get the most vitamin D?

The recommended time is when UVB rays are most intense: between 10am and 3pm.

How long should you be exposed to the sun to absorb the most vitamin D?

According to ANSES, you can ensure your body gets enough vitamin D every day by exposing yourself to the sun for 15 to 20 minutes in the late morning or afternoon. For people with dark skin or on cloudy days, 30 to 40 minutes are needed.

Which part of the body should be exposed to the sun to better absorb vitamin D?

Exposure of the back causes the body to produce more vitamin D than exposure of the hands and face. However, exposing one-third of your body surface to the sun is sufficient to absorb the necessary amount of vitamin D.

Do you absorb the same amount of vitamin D from sunscreen?

Some experts believe that sunscreens limit the body’s ability to produce vitamin D.

High SPF sunscreens are designed to filter out most of the sun’s UVB rays, as UVB damage is the leading cause of sunburn and can lead to skin cancer. However, clinical studies have never shown that daily sunscreen use leads to vitamin D deficiency. In fact, most studies show that people who wear sunscreen daily can maintain their vitamin D levels.

One explanation for this could be that no matter how much sunscreen you use or how high the SPF is, some UV rays still penetrate the skin.

An SPF 15 sunscreen filters out 93% of UVB rays, SPF 30 blocks out 97%, and SPF 50 filters out 98%. This means that between 2% and 7% of the sun’s UVB rays reach your skin, even with sunscreens with a high SPF.

Can you absorb vitamin D behind glass?

No, the body cannot produce vitamin D when exposed to sunlight through a window, because the glass blocks the sun’s UVB rays. However, the glass does allow UVA rays (which are responsible for skin aging) to pass through.

How to absorb vitamin D in winter, summer and on cloudy days?

• From late March to late September, most people can produce all the vitamin D they need thanks to the sun’s rays coming into contact with their skin.
• In the fall and winter, the sun is lower and shines less often. The UVB rays are no longer strong enough to produce vitamin D. You have to get it from your diet. However, it is difficult to get enough vitamin D from food alone. Taking oral supplements is therefore often recommended during these seasons.