Vitamin D deficiency or not? Here's the source of the confusion

At a time when health is a hot topic, one vitamin often takes center stage: vitamin D. Some believe everyone should take it, while others see it primarily as something for specific groups. So, what's the truth?

Vitamin D is essential for strong bones and teeth , but also for muscles, the immune system, and even our mood. Yet, it appears that many people—especially in Northern Europe—are deficient.

How does your body make vitamin D?

Vitamin D is produced in the skin when it is exposed to UVB radiation from the sun . Cholesterol plays a role in this process: it is converted into previtamin D3, which is then converted into the active form (calcitriol) by the liver and kidneys.

Important factors for production are:

• Sunlight : in the Netherlands only sufficient between April and September, and only in the middle of the day.
• Season & latitude : From November to March the sun is too weak to produce vitamin D.
• Age & skin color : Older people and people with dark skin produce vitamin D less efficiently.
• Magnesium : necessary for the conversion into the active form.

Food provides only a small amount of vitamin D (maximum 400 IU per serving), compared to the thousands of units you can produce from the sun on a summer day.

Vitamin D deficiency: widespread problem

A vitamin D deficiency can lead to weaker bones, muscle weakness, fatigue, reduced resistance and even mood swings.

Research shows that a third of the global population has a vitamin D deficiency. In Europe, this figure is approximately 40% . The deficiency is particularly severe in winter, among people who spend less time outdoors, and among groups whose skin color or age reduce their vitamin D production.

Risk groups that benefit extra from vitamin D

There are certain groups of people who almost always benefit from supplementation:

• Babies under 1 year old
• Pregnant women
• Elderly (especially in care facilities)
• People with osteoporosis
• People with a gastric bypass
• People with dark skin
• Veiled people

For these groups, there is a high probability that a deficiency will have consequences for bones, muscles and the immune system.

Why Vitamin D Supplementation Is Smart

Although your body can store vitamin D, it's often not enough in the Netherlands. From November to March, there's simply not enough UVB radiation to produce vitamin D. Therefore, it's recommended to take a vitamin D supplement in winter.

Supplementation can also be beneficial during other months if you don't spend much time outdoors or use a lot of sunscreen. Vitamin D supplements are safe in the correct dosage and often have fewer side effects than expected.

Finally

Vitamin D is a crucial building block for your health, but in our climate, many people don't get enough of it. With sufficient sunlight, a healthy lifestyle, and supplementation where necessary, you can prevent a deficiency and optimally support your body.