Vitamin D: function, daily requirement, and proper supplementation
The sun is back, and that's not just good for your mood — it's also the season when your body can produce its own vitamin D again. Yet, a large part of the Dutch population has a low vitamin D status, even in summer. May is a good time to consider your vitamin D status: your summer supply determines how you get through winter. In this article, you can read what vitamin D does in your body, who needs extra, how much vitamin D you need, and which form and dosage are right for you.
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What does vitamin D do in your body?
Vitamin D is technically not a vitamin, but a prohormone. Your body produces it itself when your skin comes into contact with UVB radiation from sunlight. It is then converted in the liver and kidneys into the active form calcitriol, which plays a role in almost every cell in your body — from bone and tooth health to your immune system and muscle function.
The European food authority EFSA has recognised several health claims for vitamin D: vitamin D contributes to the maintenance of normal bones, normal muscle function, normal teeth, normal functioning of the immune system, normal absorption of calcium and phosphorus, and plays a role in cell division.
Source:
EU Register on nutrition and health claims(Regulation (EU) 432/2012 — officially authorised health claims).
Two things stand out: vitamin D is precisely in the links related to your bones (both directly and through calcium absorption), and it acts on your immune system and muscles.
Whether your needs are higher depends on factors such as age, lifestyle, and diet (see below). Do you want certainty about your status? A blood test through your doctor can provide clarity on this.
Who is at risk and how much vitamin D do you need?
While everyone in the Netherlands is susceptible to a vitamin D deficiency in the winter months, some groups are at extra risk—even in summer:
People with dark skin
The more pigment the skin contains, the less UVB radiation is converted into vitamin D. Someone with dark skin needs up to 5 times more sun exposure to produce the same amount of D as someone with light skin.
Seniors (60+)
As you age, your skin's ability to produce vitamin D decreases. For a 70-year-old, production is about 25% of that of a 20-year-old with the same sun exposure. In addition, seniors often spend less time outdoors.
People who spend little time outdoors
Those who work indoors a lot, spend long working days behind a screen, or go outside covered for religious or practical reasons, miss the UVB exposure needed for natural production.
Pregnantwomen, babies, and young children
Pregnant women, babies, and young children have an increased need. For these groups, specific supplementation is often maintained, regardless of the season.
People who are overweight
Vitamin D is fat-soluble and is stored in fatty tissue. In overweight individuals, a larger portion can become "hidden" in fat cells, leading to lower blood levels with the same intake.
How much vitamin D do you need?
A common daily amount for most adults is 10 micrograms (400 IU) of vitamin D per day, and 20 micrograms (800 IU) for seniors aged 70 and above, women during pregnancy, and people with dark skin who spend little time outdoors.
However, these are lower limits to prevent a severe deficiency—not the dosages at which optimal blood levels are achieved. In orthomolecular practice, higher dosages are often used: 25 to 75 micrograms per day (1000 to 3000 IU), depending on baseline levels, age, season, and body weight.
For those who truly want to know their vitamin D status, a blood test (25-OH-vitamin D) is the most reliable indicator. Based on the results, an appropriate dosage can be determined—possibly in consultation with a doctor or orthomolecular therapist.
Frequently Asked Questions about Vitamin D
How much sun do I need in the summer to make enough vitamin D?
How much sun do I need in the summer to make enough vitamin D?
For light skin, 15-30 minutes of uncovered skin exposure (face, arms) per day between 11:00 AM and 3:00 PM during the Dutch summer is sufficient for self-production. For darker skin, this duration is considerably longer. Sunscreen (factor 15+) almost completely blocks production. In winter (October to March), the sun's intensity in the Netherlands is too low for effective production – supplementation is advisable for most people then.
Can I take too much vitamin D?
Can I take too much vitamin D?
Vitamin D is fat-soluble and can indeed cause an excess at high doses. The EFSA applies a safe upper limit of 100 micrograms (4000 IU) per day for long-term use. At doses up to 3000 IU per day, an excess is highly unlikely. Anyone wishing to experiment with higher doses should do so in consultation with a physician and based on a blood test.
When is the best time to take vitamin D?
When is the best time to take vitamin D?
With a fat-containing meal — for example, breakfast with yogurt, lunch with avocado, or dinner with olive oil. The time of day is less important than the presence of fat. Many people choose the morning because a daily routine helps them not to forget.
Do I need vitamin D in the summer too?
Do I need vitamin D in the summer too?
For most people in the Netherlands: yes, or at least a lower dose. Research shows that even in the summer, a large proportion of the Dutch population has suboptimal blood levels. Those who spend a lot of time outdoors and use little sun protection will have less need for supplementation in the summer months, but for risk groups, year-round supplementation remains advisable.
Can I combine vitamin D with other supplements?
Can I combine vitamin D with other supplements?
Yes. In practice, Vitamin D combines well with Vitamin K2 (for optimal calcium distribution to the bones), magnesium (needed to activate Vitamin D), and calcium. A complete multivitamin often already contains a basic dose of D — in which case, pay attention to the total daily intake.
Which form of vitamin D do you choose?
D2 or D3 — and how to find them in the Plenthera range
Vitamin D comes in two main forms: D2 (ergocalciferol, from yeast or mushrooms) and D3 (cholecalciferol, from animal sources or from lichen for the plant-based variant). Research shows that D3 increases blood levels more effectively and stably than D2. D3 is therefore the preferred form for most people.
Softgels (oil capsules)
Vitamin D is fat-soluble — it is best absorbed when taken with a fat-containing meal. Softgels contain D3 already dissolved in oil, which facilitates absorption. Practical and stable.
Drops
Liquid drops are useful for those who cannot or do not want to swallow capsules (young children, the elderly, people with swallowing difficulties). Here too, the D3 is in an oil base for optimal absorption.
Combinations with K2
Vitamin D ensures that calcium from your food is absorbed. Vitamin K2 then helps to direct that calcium to the right place — to your bones instead of to your blood vessels. That's why many people choose a combination product with D3 + K2.
In the Plenthera assortment
Vitals Vitamin D3 3000 IU softgels contain 75 micrograms of vitamin D3 (cholecalciferol) per softgel — enough to bring blood levels to a healthy level given an average baseline. One softgel per day, taken with a fat-containing meal. For those who don't want to swallow capsules: Vitals D3 Drops 20 ml offers the same D3 in liquid form — convenient for the whole family. Lovers of a combination product with K2 will also find Arthur Andrew KD Ultra (vegan, full-spectrum K2 with vegan D3) in the assortment.
Vitamin D is one of the few nutrients for which it is difficult to achieve optimal levels without supplementation or intensive sun exposure — especially in a country like the Netherlands, where the winter sun provides insufficient UVB for half a year. May is a good month to build up your reserves for the winter.
Disclaimer:This article is for informational purposes only and does not replace medical advice. A dietary supplement is not a substitute for a varied and balanced diet and a healthy lifestyle. In case of doubt or medication use: consult a doctor or pharmacist. Do not exceed the recommended daily dosage. Keep out of reach of young children.
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