What do experts say about vitamin D?

80% of Belgians are vitamin D deficient. Experts and doctors remind us of the importance of having enough vitamin D in our blood. Read the opinions of several experts here.

The importance of vitamin D is confirmed and encouraged by a lot of doctors and experts. ‘It’s very simple: taking vitamin D improves resistance and lowers the chances of catching a corona infection,’ says Professor Harry wichers ( 1).

Despite vitamin D being very important, the majority of Belgians are deficient. Chantal Mathieu, Endocrinologist at KU Leuven confirms, “If we look at the vitamin D levels in the blood of people where they measure it, we see that 80% or more are deficient” (2).

"If we look at vitamin D levels in the blood of people where people measure it, we find that 80% or more are deficient."

Chantal Mathieu
Prof. Endocrinologist


Why so many people are deficient can be clearly explained. In Belgium, it is more difficult to make vitamin D through sunlight. This is because we have fewer days of sunshine than countries closer to the equator. Doctor De Smet of AZ Delta points this out to us: “We live in a country where many people lack vitamin D anyway. This is because there is not too much sunshine in Belgium. This is important for the production of vitamin D” (3).

The sun is also too low in winter for optimal vitamin D production. Belgians spend a lot of time indoors and should spend more time outdoors. “In Belgium, the sun is too low from October to March. Therefore, the UV rays do not have the right wavelength to make vitamin D in our skin.”, says Chantal Mathieu, Endocrinologist at KU Leuven (4).

Sunlight provides 80% of the daily vitamin D needed and 20% we should get from food. However, very few foods contain much vitamin D. As a result, even with food, it is difficult to meet the daily allowance. So says Aline Légipont, chief pharmacist at Newpharma: “So it is very difficult, if not impossible, to achieve the recommended concentrations just by diet alone. Let’s also not forget that many people are vegetarian or vegan and so they need to be extra careful about shortages.” (5).

The implications according to experts

Having a vitamin D deficiency has negative consequences on your health. Vitamin D ensures proper functioning of the immune system and development of bones and teeth. In addition, it allows your body to ward off diseases and infections, and it can reduce the risk of cancer.

“It’s very simple: taking vitamin D improves resistance and lowers the chances of catching a corona infection,” Professor Harry Wichers of Wageningen University can attest (1). Endocrinologist Chantal Mathieu also reminds us of its importance: “We have found that vitamin D plays a central role in the immune system” (4).

Aline Légipont, chief pharmacist at NewPharma, explains the consequences of deficiency: ” A vitamin D deficiency can also lead to cardiovascular disease (hypertension) and an increased risk of cancer in people with a history of cancer” (5).

Experts advocate that people should be more conscious of their bodies and that preventing vitamin D deficiency is very important. “Vitamin D deficiency is a risk factor in many infections (including tuberculosis) and bone disease. Eat plenty of variety and take a supplement if a deficiency is detected,” said Steven Callens, Infectiologist (6).

Vitamin D stimulates bone development. Among these is a lack of vitamin D, a risk for osteoporosis. ” According to the International Osteoporosis Foundation’s latest report, the disease affects 22 million women and 5.5 million men, resulting in 43,000 deaths,” writes the International Osteoporosis Foundation. Experts expect it to increase by 25% by 2025 and suggest it will cost Europe 37 billion euros a year. “They remind us of the precautions. Adequate exercise and a sufficient supply of vitamin D are important for bone health at any age, but these factors become absolutely critical in older age.” (7)(8)(9).


  1. Vitamin info (2020.) Experts: vitamin D against corona.
  2. Julie Chamberlin, Eos Science (2019). Should 8 in 10 Flemings take vitamin D supplements? https://www.eoswetenschap.eu/gezondheid/moet-8-op-10-vlamingen-vitamine-d-supplementen-slikken
  3. Florence De Pauw (2020.) Research AZ Delta: “Eating more oily fish may help prevent getting seriously ill from corona.” https://www.vrt.be/vrtnws/nl/2020/11/09/onderzoek-az-delta-meer-vette-vis-eten-kan-helpen-voorkomen-d/
  4. Wim De Maeseneer (2018.) “Everyone should take extra vitamin D in winter.” https://www.vrt.be/vrtnws/nl/2018/02/23/_iedereen-zou-in-de-winter-extra-vitamine-d-moeten-nemen/
  5. Sweater English (2019.) Do we or do we not need a vitamin D supplement during the dark winter months? https://www.knack.be/nieuws/gezondheid/hebben-we-nu-wel-of-niet-een-vitamine-d-supplement-nodig-tijdens-de-donkere-wintermaanden/article-normal-1541381.html
  6. Stefan Simons (2021.) Prof explains: Is vitamin D really a panacea for corona? https://www.redactie24.be/coronavirus/prof-geeft-uitleg-vitamine-d-echt-een-wondermiddel-tegen-corona-120190
  7. Nicolas Rousseau (2021.) Osteoporosis costs Europe 37 billion euros a year. https://www.foodinaction.com/nl/osteoporose-kost-europa-37-miljard-euro-per-jaar/
  8. Nicolas Rousseau (2021.) Osteoporosis affects 22 million European women over the age of 50. https://www.foodinaction.com/nl/osteoporose-europese-vrouwen-boven-50-jaar/
  9. Bess Dawson-Hughes et al, Bone care for the postmenopausal woman, International Osteoporosis Foundation, 2013.

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