What are the health benefits of Vitamin D?

Vitamin D is needed to absorb calcium from food into the body, which is important for the growth and maintenance of strong bones and teeth. In addition, vitamin D plays a role in the proper functioning of the muscles and the immune system. Read all about “sunshine vitamin” D and its importance for your health in this blog.

Sun vitamin

The UV radiation in sunlight stimulates our body to produce vitamin D. Our own production with the help of the sun is our most important source of vitamin D (provides >80% of your vitamin D), more important than diet.

In the Netherlands, 25 micrograms (1000 IU) of vitamin D is produced after just a few minutes in the middle of the day in the summer with cloudless skies and clear air.

However, many people use sunscreen during that period, which greatly hinders production. Applying a cream with protection factor 8 reduces vitamin D3 production by 97.5%. Protection factor 15 even inhibits vitamin D production by 99%.

In winter, at the same latitude, it is under no circumstances possible to maintain an adequate vitamin D status solely with the help of sunlight. Then you are dependent on nutrition and supplementation.

Vitamin D in food

Vitamin D is a fat-soluble vitamin and can be found in foods such as oily fish, such as herring, salmon and mackerel. Meat and eggs also contain vitamin D, but clearly less than oily fish. Food provides less than 20% of your vitamin D needs.

In the Netherlands, vitamin D is also added to low-fat margarine, margarine and baking and frying products (but not to oil). Butter naturally contains vitamin D, but much less than what is added to margarines and low-fat margarines.

Vitamin D is also added to artificial infant formula in accordance with the applicable EU directive (1 to 2.5 micrograms 40 to 100 IU/100 kcal).

Two forms of vitamin D

Vitamin D occurs in the diet in 2 forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).

Both forms are formed under the influence of ultraviolet radiation (UV radiation). This radiation is part of sunlight.

Vitamin D2 is formed in certain mushrooms and molds and vitamin D3 in the skin of humans and animals. Therefore, vitamin D3 occurs naturally in foods of animal origin.

Both vitamin D2 and vitamin D3 are used in supplements and fortified foods. Both forms are active, so they do their work in our body. Vitamin D3 does have a stronger effect than vitamin D2.

Absorption and activation of vitamin D

Vitamin D is best absorbed in the intestine if fat or oil is also present. The average absorption of vitamin D from food is estimated at 80%. The body can store vitamin D in fatty tissue and organs, such as the liver.

In the liver, vitamin D is converted into 25-hydroxyvitamin D. This form is not active in the body, but the level in the blood is suitable for determining whether the amount of vitamin D in the body is sufficient. In the kidneys, 25-hydroxyvitamin D is then converted into 1,25-dihydroxyvitamin D.

This is the active form of vitamin D.

What is vitamin D good for?

Vitamin D has several functions in the body:

It ensures that calcium and phosphorus from food are properly absorbed and absorbed into the bones and teeth during growth. It is necessary to limit bone decalcification as much as possible, and thus reduce the risk of osteoporosis later in life.

It plays an important role in maintaining proper muscle function.

It is important for the proper functioning of the immune system.

But it has not yet been sufficiently demonstrated that a vitamin D supplement reduces the risk of infections, such as the common cold.

EFSA health claims

The following claims have been approved by the European Food Safety Authority (EFSA) and may be used:

Relevant for adults:

• Vitamin D contributes to the normal functioning of the immune system and ensures good resistance
• Vitamin D is involved in the cell division process and contributes to the production of cells and tissues
• Vitamin D contributes to the normal absorption of calcium and phosphorus in the blood
• Vitamin D increases the absorption of calcium in the bones and is good for maintaining strong bones
• Vitamin D is important for building and maintaining strong teeth
• Vitamin D is good for the muscles and is important for maintaining normal muscle function

Furthermore, vitamin D helps people over 60 to reduce the risks of falls due to postural instability and muscle weakness. Falling is a risk factor for bone fractures in men and women aged 60 and over. This claim only applies to a minimum of 600 IU per dose and a daily intake of at least 800 IU from all sources.

Relevant for children:

• Vitamin D contributes to the normal functioning of the immune system and ensures good resistance
• Vitamin D is necessary for normal growth and development of the bones of children

Consequences of a vitamin D deficiency

A child with a serious deficiency of vitamin D and calcium will have increasingly weak bones. This also affects growth. These children are smaller, have weaker muscles, crooked shins, a protruding forehead and lumps along the ribs. We call this Rickets or English disease.

Deficiency of vitamin D and calcium can also cause osteoporosis, especially in postmenopausal women. This is called osteoporosis. With osteoporosis, these more brittle bones have a greater chance of breaking. This can cause vertebrae to collapse at an older age.

In adults, a kind of softening of the bones may occur with bone and muscle pain in the thighs and hips, difficulty getting up from a chair, staggering walking and bones breaking easily. This is called osteomalacia.

Vitamin D deficiency is not associated with complaints such as fatigue, dizziness and not feeling well.

Vitamin D and osteoporosis

Bone decalcification (osteoporosis) causes the bones to become more brittle. They are more likely to break and the vertebrae of the spine collapse. You do not notice that you have osteoporosis. Your doctor can use a bone density test to see how strong the bones are.

Osteoporosis occurs because the bones do not absorb enough calcium (calcium). There should be a constant balance between bone production and breakdown. In bone loss (osteoporosis), the breakdown is stronger than the production.

Bone decalcification can occur under various circumstances. The most important are the following:

• Older age. From around the age of 45, bone production is less than bone breakdown. This is the case for both men and women, but men generally have stronger bones than women, making them less likely to suffer from osteoporosis.
• Menopause in women. The body then produces less estrogen. Estrogens are female sex hormones that also ensure a balance between the production and breakdown of bone tissue. The less estrogen, the weaker the bones.
• Removal of the ovaries in women, as the ovaries produce estrogens, which help build bone.
• Use of many adrenal cortex hormones (corticosteroids), such as prednisone, for a longer period of time or certain medications used for breast cancer and prostate cancer. These have osteoporosis as a side effect.
• Too little exercise. Exercise stimulates bone building.
• Too little outdoor exposure and sun exposure. If you don't spend much time outdoors, you run the risk of not getting enough vitamin D. Vitamin D ensures that the bones absorb calcium.

Consequences of too much vitamin D

Excessive vitamin D intake can only occur as a result of using too many supplements for a long time.

Long-term use of high doses above the acceptable upper limit can cause too much calcium to enter the blood, especially if you also use calcium or if you have reduced kidney or thyroid function.

Do you get gastrointestinal complaints, such as nausea, vomiting, diarrhea or constipation, persistent headache, dizziness, dry mouth, muscle weakness, muscle pain, bone pain, fatigue, unsteady gait, itching or palpitations? These symptoms may indicate too much calcium. Then consult your doctor.

This does not occur with a normal diet and following the advice for intake. Long-term exposure to sunlight also poses no risk of excess vitamin D. The skin then regulates its production.

In practice, an overdose in healthy people rarely occurs.

What is your vitamin D status?

The Health Council recommends vitamin D supplementation for large groups in the population, regardless of the vitamin D level. Determination of the vitamin D content is therefore only rarely done.

The GP can request the vitamin D level:

• if your doctor has doubts about whether you get enough sunlight
• if you have osteoporosis or an increased risk of falling but you still consume enough calcium (1200 mg per day)
• if you have complaints of osteomalacia (diffuse bone and muscle pain in the thighs and hips, difficulty getting up, staggering walking).

Your vitamin D status is expressed in nmol/L.

The reference intake of vitamin D in the Netherlands is based on maintaining 30 nmol/L for people under 70 years of age and 50 nmol/L for people over 70 years of age. Many people do not achieve this: city dwellers in the Northern Hemisphere have an average of 20 nmol/L.

But what is a good blood value? For this, it is best to look at the blood values ​​of hunter-gatherers.

Hunter-gatherers around the equator have a vitamin D3 blood level of around 115 nmol/L. That is about six times higher than the average blood value in city residents.

Orthomolecularly, at least a blood value of 80 nmol/L is recommended. This is a nice target value.

Nutritional advice from the Nutrition Center

Young children, the elderly, people with a tanned skin color, people who rarely spend time outside and pregnant women are advised to take extra vitamin D.

A daily recommended amount of 10 micrograms (400 IU) of vitamin D applies to everyone. Only people over 70 should consume 20 (800 IU) micrograms per day.

The tolerable upper limit of vitamin D intake for adults and children aged 11 to 17 years is 100 micrograms (4000 IU) per day. For children aged 1 to 10 years, the limit is 50 micrograms (2000 IU) per day and for children up to 1 year old, the upper limit is 25 micrograms (1000 IU).

Would you like to check how much vitamin D you consume? This is possible with our online food diary 'the Eetmeter' on My Nutrition Center.

Fortified foods for young children

In the Netherlands, vitamin D may be added to foods, with a maximum fortification level of 4.5 micrograms (180 IE)/100 kilocalories to avoid excessive intake.

There are mainly fortified dairy products on the market for young children, such as desserts, cottage cheese, yoghurt, porridge and toddler milk. But when you, as a parent, give extra vitamin D in the form of drops, capsules or tablets, you already know that your child is getting enough vitamin D.

Moreover, you know exactly how much your child is consuming. It is therefore not necessary to give products with extra vitamin D.

Vitamin D supplements for certain groups

Some groups need more vitamin D than they can get from sunlight and diet.

For example, it has been shown that a vitamin D supplement reduces the risk of rickets for young children and the risk of falls and fractures for the elderly. For pregnant women it reduces the risk of having a child with a low birth weight.

People with tanned or dark skin or with make-up with sun protection factor produce less vitamin D in the sun. And even if the skin does not often come into the sun, for example because someone does not go out much or wears a veil, vitamin D is not produced.

Extra vitamin D is recommended for these groups.
The Health Council says that pregnant women do not have an increased need for vitamin D. However, she advises all pregnant women to use 10 micrograms (400 IU) of vitamin D per day, just to be on the safe side. You can decide for yourself whether you choose this.

Buy vitamin D supplements

You can buy vitamin D supplements in the form of drops, capsules or tablets at the pharmacy or drugstore. Cheaper house brands are just as good as the more expensive A-brands.

The label usually states vitamin D3 (cholecalciferol), and sometimes D2 (ergocalciferol). Preferably choose a supplement with vitamin D3, the more active form of vitamin D. The microgram amount is stated on the label. Micrograms are usually written with the abbreviation µg or mcg.

The translation between microgram and IE (International Units, also called IU, International Units) is: number of micrograms x 40 = number of IU.

click here for vitamin D3 products offered by WHC.

Interaction with other supplements

Vitamin D3 and vitamin K2 both play a role in the absorption of minerals and calcium in the bones and are good for maintaining strong bones.

Do you take calcium tablets? Then take them together with vitamin D3 and K2 to ensure that the calcium gets to the right place.

Frequently Asked Questions

Question: What is vitamin D good for?

Answer: It contributes to the normal functioning of the immune system and ensures good resistance. It contributes to the normal absorption of calcium and phosphorus in the blood and is good for maintaining strong bones and teeth. It is good for the muscles and is important for maintaining normal muscle function.

Question: How much vitamin D should I have in my blood?

Answer: The Health Council recommends a reference intake of vitamin D in the Netherlands based on maintaining 30 nmol/L for people under 70 years of age and 50 nmol/L for people over 70 years of age. Many city dwellers are below this level. People who spend a lot of time outside have above 100 nmol/L in the summer period.

Question: How much Vitamin D should I take?

Answer: Everyone has a daily recommended amount of 10 micrograms (400 IU) of vitamin D. Only people over 70 should consume 20 (800 IU) micrograms per day.

Question: What is the maximum amount of vitamin D I can take?

Answer: The tolerable upper limit of vitamin D intake for adults and children aged 11 to 17 years is 100 micrograms (4000 IU) per day. For children aged 1 to 10 years, the limit is 50 micrograms (2000 IU) per day and for children up to 1 year old, the upper limit is 25 micrograms (1000 IU).

Question: What should I do if I have osteoporosis during menopause?

Answer: Always take calcium tablets in combination with a good Vitamin D3 and K2 supplement to ensure that the calcium is properly absorbed into the blood and bones and ends up.

Sources

Nutrition Center

Inspection Board Claims Database

Wikipedia

Dutch Society of General Practitioners

Thuisarts.nl