Vitamin D

Vitamin D, also known as the "sunshine vitamin", is a nutrient important for our bones and overall health. Sunshine is a source of this vitamin. However, most people don't get enough sunshine to meet their vitamin D needs.

Below we've gathered everything you need to know about vitamin D and how to avoid vitamin D deficiency when the summer is over.

What is vitamin D?

Vitamin D is a so-called fat-soluble vitamin - a nutrient that the body needs to absorb from the food we eat, among other things.

Unlike other vitamins, the body can actually produce vitamin D itself.

But we need a little help: We can only do this when the sun's UVB rays hit the skin. That's why vitamin D is often referred to as the 'sunshine vitamin'.

There are two types of vitamin D:

• D2-vitamin (ergocalciferol)
• D3-vitamin (cholecalciferol).

Both forms are converted in the body to vitamin D (calcitriol), but they have some differences.

What is the difference between vitamin D2 and D3?

Vitamin D3 is formed in the skin with the help of the sun, but can also be supplied through the diet, for example through fatty fish.

D2 is formed in yeast and fungi, also with the help of the sun, so we need to get this vitamin D from our diet, for example when we eat mushrooms.

In other words, it is possible to get both D2 and D3 vitamins through your diet. However, relatively many people don't get enough sun, fatty fish or mushrooms throughout the year or throughout their lives.

That's why vitamin D is one of the nutrients that authorities focus on in their dietary and supplement recommendations for the population.

But why is it so important to get enough vitamin D?

What is vitamin D good for?

Vitamin D has several functions in the body. The most well-known is its role in building and maintaining the skeleton. Vitamin D is necessary for the body's absorption of calcium - the building block of the skeleton.

In addition, vitamin D helps with the absorption of phosphate. Calcium and phosphate are important for the skeleton, metabolism and functions related to nerves and muscles.

Here are the main documented functions that vitamin D contributes to:

• cell division
• normal immune system
• maintenance of the teeth
• maintaining normal muscle function
• maintenance of normal skeleton
• normal calcium levels in the blood

As vitamin D is a necessary nutrient for our health, it can be helpful to know what to do to to get sufficient amounts.

How do you get vitamin D?

From sunlight

The amount of vitamin D our body can produce by exposing our skin to sunlight is limited to the relatively few sunny days we have each year.

Furthermore, the sun needs to be hot enough to ensure that we also take off enough clothes so that the sun's rays actually hit the skin and not just the face and hands.

That's why we rely on getting vitamin D through our food and supplements, especially in the autumn and winter months.

Here's a guide on what to eat to get enough vitamin D:

Foods rich in vitamin D

Unfortunately, vitamin D is not found in many types of food, so it's difficult - but not impossible - to meet the need for this vitamin through food.

The most important foods with vitamin D are fatty fish such as salmon, herring and mackerel, but also roe and fish liver.

This list shows approximately how much vitamin D each of these foods contains per 100 grams:

• Raw cod liver: 100 µg
• Salmon (wild caught): 10-30 µg
• Herring: 10-15 µg
• Canned cod roe: 11 µg
• Smoked mackerel: 6 µg
• Mackerel in tomato: 3 µg

Source: DTU Food Institute

The daily requirement for vitamin D for adults is 10 µg (micrograms). In other words, this means that the daily requirement is covered by a portion of salmon, herring or mackerel for dinner.

Not everyone eats oily fish every day. So it's good to know that there are other ways to meet your vitamin D needs.

Dietary supplements with vitamin D

During the months when we don't get enough sunlight on our skin, and most people need to get the vitamin in the form vitamin D tablets or other supplements.

In addition to cod liver oil, which is perhaps the most well-known vitamin D supplement, vitamin D can be taken in tablet or drop form.

Who needs vitamin D supplements?

If we spent enough time in the sun, we would also get enough vitamin D. But how much sun is enough?

Well, if your face, hands and arms are exposed to the sun in the middle of the day in the summer for 5-10 minutes twice a week, your vitamin D needs are well covered in the summer.

But there are exceptions.

People with dark skin need more sun to produce vitamin D than people with lighter skin.

Using sunscreen is important, but if you use high factor sunscreen, be aware that it reduces the skin's production of vitamin D.

In addition, there are two specific considerations when it comes to when we should get extra vitamin D - the time of year and your age.

When should you take vitamin D?

During the winter months from October through April , there is not enough sunlight to meet our needs by staying in the sun in the northern countries.

Now is the time to take a vitamin D tablet or supplement.

Some people may need a vitamin D supplement all year round.

This applies to e.g:

• Children 0-4 years (D-drops)
• Pregnant and breastfeeding women
• People with a dark skin tone.
• People who don't get outdoors enough or avoid the sun.
• People who wear a covering garment in the summer or use a high sun protection factor.
• People over 70 years of age

Vitamin D recommendations

How much vitamin D you need to supplement with depends on several factors, including your age and skin tone.

There is not yet enough data to make precise recommendations for vitamin D supplementation.

However, the European Food Safety Authority (EFSA) has estimated that 15 μg (micrograms) of vitamin D daily is sufficient for everyone from 1 year and up, and 10 μg for infants.

Source: EFSA (2024)

What are common vitamin D deficiency symptoms?

Vitamin D deficiency is prevalent in regions where sunlight is scarce for much of the year.

Recognizing a vitamin D deficiency isn't always straightforward; however, it can lead to adverse changes in the body.

For instance, prolonged low levels of vitamin D can weaken or damage bone tissue and muscles.

Moreover, there's growing attention to how vitamin D deficiency can compromise the immune system.

Certainly, maintaining adequate levels of vitamin D is crucial for both physical and mental well-being.

If you're uncertain about your vitamin D levels, consider consulting your doctor for testing

Can you get too much vitamin D?

Yes, you can.

Vitamin D is a so-called fat-soluble vitamin. This means that the excess is not peed out, as is the case with water-soluble vitamins.

Therefore, there are also upper limits to how much vitamin D we can tolerate.

Upper safe limit

Here are the upper limits set by EFSA: (2024 numbers)

• Children from 7-11 months: up to 35 µg daily
• Children aged 1-10 years: up to 50 µg daily
• Children from 11 years and older, including pregnant and breastfeeding women: up to 100 µg daily

A higher intake of vitamin D than the upper limits can be harmful over time.

What happens if you get too much vitamin D?

Consuming doses of vitamin D above the recommended upper limit over a long period of time can affect several organs in the body, such as

• Central nervous system
• Digestive system
• The cardiovascular system.

The central nervous system can be affected in such a way that you feel lethargic, have reduced muscle strength and weakened reflexes. You may also feel confused.

The digestive system can cause nausea, vomiting or constipation if affected by an overdose of vitamin D.

The cardiovascular system can be affected, causing blood pressure to rise and heart rhythm to be disturbed.