Welcome to the Vitamin D category at VitAdvice. Since 1999, we have been your trusted online pharmacy and specialist in high-quality supplements. Vitamin D is one of the most important nutrients for a vital life—especially in a country like the Netherlands, where sunshine is not always guaranteed. Whether you want to strengthen your immune system, keep your bones flexible, or simply support your energy levels, you will always find a suitable option in our assortment.

From drops for the very youngest to powerful capsules for seniors and specific combinations with vitamin K2, we are happy to help you make the right choice. Thanks to our years of experience, we select only brands that excel in purity and effectiveness. Moreover, with us you not only choose your health, but also the environment, thanks to our sustainable, plastic-free packaging.

Why is Vitamin D indispensable?

Vitamin D is often called the “sun vitamin” because your body produces it when your skin is exposed to sunlight. In reality, it functions in your body as a pro-hormone and is involved in numerous crucial bodily processes.

• Strong bones and teeth: Vitamin D is essential for the absorption of calcium and phosphate from your diet. Without sufficient vitamin D, your body cannot properly utilize these building blocks, which in the long term can lead to brittle bones or dental problems.
• Immune system: It plays a key role in activating your immune defenses. Adequate levels contribute to normal immunity, helping you stay better protected against external influences.
• Muscle function and cell division: The vitamin contributes to normal muscle function (important for reducing fall risk in older adults) and plays a role in the process of cell renewal.
• Mood: While much research is ongoing, many people experience that a healthy vitamin D level contributes to more energy and a better mood, especially during the dark winter months.

When do you need extra Vitamin D?

In the Netherlands, sunlight strength between October and April is often too weak to produce sufficient vitamin D. A handy way to check this is the “Shadow Rule”: if your shadow is longer than you are tall, the sun is too low and you produce virtually no vitamin D. This means that many people rely on their reserves or supplementation during autumn and winter.

In addition, there are specific groups for whom extra intake is recommended year-round to prevent deficiencies:

• Babies and children (0–4 years): For healthy bone development.
• Women aged 50 and over: Due to hormonal changes and the maintenance of bone density.
• Older adults (70+): Because aging skin produces vitamin D less efficiently, even when the sun is shining.
• People with darker skin tones: More pigment (melanin) acts as a natural sunscreen, slowing vitamin D production.
• People who spend little time outdoors or wear covering clothing: If the skin is not directly exposed to sunlight, no vitamin D is produced.
• Pregnant women: To support both the mother and the baby’s development.

Which form is best: Vitamin D3 or D2?

When browsing our assortment, you will encounter terms such as Cholecalciferol (D3) and Ergocalciferol (D2). The distinction between them is important for effectiveness.

Vitamin D3 (Cholecalciferol) is the form your body produces naturally and that is found in animal products (such as fatty fish). Research shows that D3 is significantly superior to D2. It is absorbed up to 85% better and is used and stored much more effectively by the body. For this reason, at VitAdvice you will find almost exclusively D3-based supplements.

Vitamin D2 (Ergocalciferol) is the plant-based form. It is utilized less efficiently by the body. For vegans, D2 used to be the only option, but today there are excellent vegan D3 supplements available, derived from lichen or algae (such as those from the brand Garden of Life). This means vegans no longer have to compromise on quality.

The importance of an oil base

Vitamin D is a fat-soluble vitamin. This means it requires fat to be absorbed through the intestinal wall into the bloodstream. Supplements in which vitamin D is already dissolved in a high-quality oil (such as olive oil, coconut/MCT oil, or sunflower oil) are preferred over dry tablets. Especially oil-based softgels and drops ensure optimal bioavailability.

Dosage: What suits you?

Determining the right dosage is highly individual. There is a difference between the minimum amount needed to prevent deficiency and a dosage aimed at optimal health. Below we explain the most common dosages.

Please note: 10 micrograms (mcg/μg) equals 400 International Units (IU).

1. Basic needs and prevention (10 mcg / 400 IU to 20 mcg / 800 IU)

These are the guidelines often used to prevent deficiencies:

• 10 mcg (400 IU): The standard recommendation for children up to 4 years old, pregnant women, and adults with darker skin or limited sun exposure. Women between 50 and 69 years often fall into this group as well.
• 20 mcg (800 IU): Specifically advised for everyone aged 70 and over to help prevent osteoporosis and muscle weakness.

2. Optimal health (25 mcg / 1000 IU to 50 mcg / 2000 IU)

Many experts and recent insights suggest that slightly higher levels are needed to fully benefit from all health advantages, such as a strong immune response.

• 25 mcg (1000 IU): An excellent maintenance dose for most adults, especially during the winter months.
• 50 mcg (2000 IU): Often chosen by people aiming to optimize blood levels (for example to 75–100 nmol/L) or by people who are overweight. Because vitamin D is stored in fat tissue, individuals with a higher BMI often need more to reach the same blood levels.

3. Therapeutic dosages (75 mcg / 3000 IU and higher)

Dosages such as 75 mcg or even 100 mcg (4000 IU) are usually used to quickly replenish a diagnosed deficiency. Although the safe upper limit for adults is 100 mcg per day, we always advise consulting a doctor or therapist before using these higher dosages.

The power of synergy: Vitamin D3, K2 and Magnesium

In our assortment, you will increasingly see combination products. Vitamin D does not work alone in your body; it needs “partners.”

Vitamin K2: This is the perfect partner for vitamin D3. While vitamin D ensures calcium absorption, vitamin K2 (especially in the MK-7 form) ensures that this calcium is directed to the right places: the bones, not the blood vessels or kidneys. Especially at higher vitamin D dosages, adding K2 is wise to help prevent arterial calcification and maximize bone strength.

Magnesium: Often the missing link. Magnesium is required to convert vitamin D into its active form in the body. If you have a magnesium deficiency, your vitamin D supplement may work less effectively. It can therefore be beneficial to use magnesium alongside vitamin D.

Our brands: Quality and reliability

At VitAdvice, the groundwork has already been done for you. We select brands based on strict criteria: purity, origin, absence of unnecessary additives, and independent testing. Here is a selection of our favorites:

• Vitals: Known for uncompromising quality and high dosages (such as 3000 IU) in a high-quality olive oil base. Ideal for replenishing deficiencies.
• Pharma Nord: Offers pharmaceutical-grade quality with their well-known Bio-D-Pearls. The small pearls are very easy to swallow and provide excellent absorption.
• Orthica: A reliable Dutch brand, highly popular for their vitamin D drops for babies and children. Easy to dose and neutral in taste.
• NOW Foods: Offers excellent value for money. Their softgels are often free from allergens such as gluten, soy, and dairy.
• Garden of Life: The go-to choice for vegans. They use vitamin D3 derived from sustainably harvested lichen and often combine it with pure, unprocessed whole foods.

Forms of intake: What suits you?

• Drops: Ideal for babies, young children, and people who have difficulty swallowing. You can adjust the dosage very precisely (for example, 2 drops instead of 1 when extra is needed).
• Softgels/Capsules: The most popular form. They often contain oil for direct absorption and are tasteless.
• Tablets: Often compact and practical, but be sure to take them with a fatty meal for proper absorption.
• Sprays: A convenient alternative for those who prefer not to swallow; the vitamin is absorbed through the oral mucosa.

Safety, Medication and Advice

Vitamin D is safe, but “more” is not always “better.” Excess is rare and typically occurs only with long-term use of extremely high doses (well above 4000 IU per day). Symptoms of excess may include nausea or thirst due to elevated calcium levels. Therefore, adhere to the recommended dosages.

Medication: Are you taking medication? Then be vigilant. Some medications, such as prednisone (corticosteroids), certain anti-epileptics, or weight-loss medications, can inhibit vitamin D absorption or accelerate its breakdown. In these cases, higher intake may be required—always in consultation with your doctor. Conversely, diuretics combined with vitamin D can sometimes raise calcium levels too much.

Unsure about your vitamin D status? A blood test via your GP is the only way to be certain if you have a deficiency. With symptoms such as persistent fatigue, muscle pain, or bone pain, this is strongly recommended.

Frequently Asked Questions (FAQ)

Is 50 mcg (2000 IU) of vitamin D too much?

No, for many adults this is a safe dosage to achieve optimal blood levels, especially in winter. It remains well below the safe upper limit of 100 mcg per day.

What is the difference between IU and mcg?

These are different units for the same substance. 1 mcg (microgram) = 40 IU (International Units). So 25 mcg is the same as 1000 IU.

Is vitamin D reimbursed?

Generally, supplements are not covered by basic health insurance. Only in specific medical cases and with a prescription is this sometimes an exception.

How quickly will I notice an effect?

Vitamin D levels rise slowly. It can take several weeks to months to correct a deficiency and notice physical improvements in energy or muscle strength. Consistency is key.

When is the best time to take the supplement?

Because vitamin D is fat-soluble, it is best taken with a meal that contains some fat, such as dinner or a breakfast with dairy or butter. This maximizes absorption.

Choose quality with VitAdvice

Choosing the right supplement is an investment in your well-being. Whether you opt for a daily maintenance dose, a specific solution for seniors, or a synergistic formula with K2, at VitAdvice you will find the expertise and quality you can rely on.

Discover our extensive range below, easily filter according to your preferences, and order your ideal vitamin D supplement today. Still have questions after reading? Our expert customer service team is ready to provide you with personal advice.