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Vitamin D necessary for your immune system during dark days

Vitamin D is becoming more and more familiar in a family. This super vitamin plays a major role in various processes throughout the body and has a very important influence on the immune system due to the shorter days.

Especially now that vitamin D shortages are lurking, it is important to keep an eye on your vitamin D level. The days are getting shorter during autumn and winter and the country is in a new lockdown, because of the current COVID-19 (or Corona) situation. As a result, we stay indoors in large numbers and are exposed to much less sunlight.

In addition, autumn and winter are often known as the seasons of colds, where viruses and bacteria are ubiquitous. Enough reasons to pay extra attention to your immune system and vitamin D status!

vitamine d

What is vitamin D?

When it comes to vitamin D, the sun is often thought of immediately, and rightly so! It is not for nothing called the ‘sun vitamin’. After all, sunshine ensures that vitamin D is produced in the skin.

It is therefore a necessary vitamin that plays a role in various processes all over the body. This important substance plays a role in different processes all over the body. It is good for the bones, teeth, muscles, the immune system and the absorption of calcium. A deficiency will soon lead to reduced resistance.

When do you have a higher risk of shortage?
  • During the autumn and winter months, the sun not only shines less often but also less strongly.
  • When you come out around noon (11-15h) less than a quarter of an hour or cover your hands, arms and head when you come out in the sun.
  • When using a strong protective sunscreen. Sun cream is a good and necessary protection for the skin but also stops UV rays which are necessary for the production of vitamin D in the body.
  • Persons with dark skin produce less vitamin D.
  • Elderly: With aging, the skin’s capacity for production decreases.
  • Children too: During the growth spurt, the body needs extra to build up bones.
  • Vegans and vegetarians consume little vitamin D-containing food.
  • Pregnant women: vitamin D is important during pregnancy for the baby’s bone development.
Is too much vitamin D possible?

Vitamin D is produced by the body itself under the influence of the sun. In the summer months, it is enough to walk outside with bare arms and head for a quarter of an hour in the afternoon for your daily dose. However, during autumn and winter the sun doesn’t shine strongly enough, on top of that we spend a lot more time indoors and usually only are warmly dressed when going outside. This can quickly lead to a shortage.

In addition, vitamin D from food makes only a limited contribution to the daily requirement and is mainly found in fatty fish (mackerel, salmon, herring), eggs, whole dairy products, fortified margarines. Moreover, fruit and vegetables are not a rich source. To get your daily requirement out of food alone, you would have to eat large quantities of fatty fish and offal every day, which is not good for a balanced diet.

The combination of the above factors and the amount of time we spend indoors means that the chance of too much vitamin D is very small. On the contrary, many people have a shortage.

A large-scale Flemish study of 4460 test subjects shows that only 11% have enough vitamin D in their blood (>75 nmol/l), 29% have not enough (50-75 nmol/l) and no less than 60% have a shortage (<50 nmol/). Since 2003, Child and Family therefore recommend that children, from birth up to and including the age of 6 years, should be given an extra 400 IU or 10 μg of vitamin D every day (independent of the milk supply). And this all year round.

How do you know if you have a shortage?

You can’t really feel a shortage, but it does have consequences. The vitamin is, among other things, important for the immune system and bone building. For example, a shortage can lead to a greater risk of bone fractures and osteoporosis. Moreover, during the winter months many bacteria and viruses are lurking and at the same time, the production of this vitamin in the body is lower due to the limited sunlight.  You can always have your status of deficiency checked by your doctor.

A vitamin D supplement can be a good supplement in case of shortages.

What are the qualities of a good vitamin D supplement?
  • Choose the body’s own form of vitamin D namely cholecalciferol or vitamin D3 and no ergocalciferol or vitamin D2 that is less beneficial to the body.
  • Go for a supplement in oil form, it is very absorbent.
  • It is also always convenient to choose a supplement in drop form, so you can easily adjust the dosage for young and old and use the same product for the whole family.
  • 1 dose per day is more effective than 1 high dose per week or month: Research into the effect of equivalent doses of vitamin D3 (15 μg or 600IE/day; 105 μg or 4200 IU/week; 450 μg or 18000 IU/month) on vitamin D status in 338 rest home residents showed that a daily intake was more effective than a weekly one, while a monthly high dose had the least effect2.

1) Faché WA, the Grand Guy. 4460 serum 25-hydroxyvitamin D levels representative for Flanders Ghent region. CRI lab Ghent., 2) Chel V, Wijnhoven HAH, Smit JH et al. Osteoporos Int 2008; 19:663-71.

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