March sun: How much vitamin D does my body get from sunshine?

Cloudy and dark winter dampens the mood of many. This is also not surprising, because after all, according to German Society for Nutrition Between 40 to 60 percent of people in this country in the dark months in a Vitamin D deficiency.

Vitamin D is a hormone that 80 to 90 percent is produced by the body through the skin itself, and only 10 to 20 percent is taken in through food.


In order for the body to be able to produce vitamin D, a certain dose of ultraviolet radiation is required, that is, sunlight. These rays penetrate the upper layers of the skin before initiating vitamin D3 production through various intermediate steps.

If the body is getting little or no sunlight, it cannot produce vitamin D. This is also the case in winter or in the months from October to March.

We hope to produce vitamin D

When the sun shines really well for the first time in the spring, people are understandably drawn outside.

Many people raise their faces to the sun in the hope that the body will immediately start producing vitamin D. But are weak rays enough in the first few months of the year to stimulate production?

Unfortunately no. Because the human body can only produce vitamin D from a certain point. It doesn’t matter how warm the winter sun is to you.

The sun is very low even in the middle of the day

Because although the sun is undoubtedly good for you in the winter months and can make you happy, in Germany it is not enough to greatly stimulate endogenous vitamin D production.

We’re just in the wrong latitude for that. From mid-October to late March, the angle of incidence of the sun’s rays is very flat – even in the middle of the day.

The reason for this is simple: the flatter the angle at which the sun’s rays strike the Earth, the longer their path through the ozone layer. However, this means that part of the UV rays are lost and the rays are no longer sufficient for vitamin D production. Then, in April, that angle started to go downhill.

This general rule applies

As a general rule, you can remember: If your shadow is longer than your height, unfortunately, not much vitamin D production occurs.

For your body to produce vitamin D through your skin, the sun must be at least 42 degrees above the horizon.

Skin type affects vitamin D production

But your skin type also plays an important role in vitamin D production.

The more sensitive your skin is to sunlight, the faster it will produce vitamin D, so people with darker skin that are less sensitive need more sunlight, so people with lighter skin, in contrast, need less.

So if you have darker skin, your body only starts producing vitamin D when the sun is most intense.

View the rising sun in spring

By the way, the farther north you are, the more time intervals the angle of incidence of the Sun will be sufficient. Then, even in the summer months, the sun may not be high enough in the morning and evening hours.

If you also want to fill up your vitamin D stores in early spring or late summer, you can using the calculator Determine the height of the sun.

All you have to do is enter your location and choose the time you want to sunbathe. Then the calculator displays the angle and you can see if vitamin D production is possible.

Avoid the midday sun in the summer

In the summer months between the astronomical beginning of spring and fall, the sun is best between 11 am and 3 pm so that the body can produce vitamin D.

In theory, the best time would be around 1 pm. However, in order to keep your skin healthy, you should avoid strong radiation in the afternoon.

Depending on your skin type, 15 to 30 minutes of daylight in summer is enough for your body to produce enough vitamin D3. Even with light cloud cover, your body can deflect rays well.

So don’t underestimate the sun and always wear plenty of sunscreen!


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