Choosing vitamin D starts with reading a dose. On Amazon, boxes at the same price range from 1,000 to more than 5,000 IU a day, and the strongest is not the best: past a certain point you exceed the safety limit set in Europe. Here is how to read a label, what the science really establishes, and the product we pick from five best-selling vitamin D3 supplements.
Prices, ratings and compositions were recorded on 31 October 2026 on Amazon.fr and may have changed since. Compositions are those stated by the manufacturers: Picksly has neither tested nor analysed these products. This article does not replace advice from a doctor or pharmacist, and it does not apply to children or infants.
Our pick in brief
For an adult looking for an everyday vitamin D, we pick the Igennus Vitamin D3 2000 IU: a dose below the safety limit, €12.99 for a year, and by far the most reviews of the five (12,090). The full ranking, with other formats, is in our vitamin D Top.
IU and µg: reading the dose on the label
Vitamin D is expressed in two units: 1 µg = 40 IU. So 2,000 IU is 50 µg, and 4,000 IU is 100 µg.
That last figure is the one that matters. In 2023 the European Food Safety Authority confirmed an upper limit of 100 µg a day for adults, from all sources combined, food included. It adds that the people most likely to exceed it are precisely regular users of high-dose supplements.
| Dose per day | In µg | Against the 100 µg limit |
|---|---|---|
| 1,000 IU | 25 µg | Well below |
| 2,000 IU | 50 µg | Half |
| 4,000 IU | 100 µg | Right at the limit, no margin for food |
| 5,000 IU | 125 µg | Above |
Also watch out for products dosed "per week" or "per month", and for drops, where the dose depends on the number of drops. A product showing 20,000 IU per tablet is not taken like a daily tablet.
What vitamin D does, and what it does not
On the label of a supplement sold in Europe, only certain claims are authorised: vitamin D contributes to the normal function of the immune system and to the maintenance of normal bones and muscle function. That does not mean it prevents a disease.
The best example comes from the VITAL trial, one of the largest on the subject: about 26,000 American adults aged 50 and over, taking 2,000 IU of D3 or a placebo for about five years on average. The result, published in the New England Journal of Medicine in 2022: no fewer fractures than with the placebo. These participants were not selected for a deficiency or osteoporosis, which limits what the result says about people at risk.
In other words, a supplement can help correct an insufficient intake, especially in winter, but taking more does not bring more. Only a blood test tells you where you stand. If you are on treatment or have kidney disease, talk to your doctor first. To place vitamin D among the other supplements studied, see our guide to what really has evidence for ageing better.
Tablet, oil or drops?
Vitamin D is fat-soluble: take it with a meal containing some fat, whatever the form. Some manufacturers praise olive oil, others the dry tablet, each claiming better absorption than the other. We have nothing to settle this, and it should not decide your purchase.
Form matters mostly for convenience: small tablets are taken once a day without thinking; drops let you adjust the dose, provided you count them.
Should you add vitamin K2?
Many products combine D3 and K2 (MK-7 form). The idea is appealing, and our health pages present it, but it is not a must: a D3-only product often costs almost half as much. And there is one important precaution: vitamin K interacts with warfarin-type anticoagulants. If you take one, do not add it without talking to your doctor.
Five vitamin D3 products compared
| Product | Daily dose | Stated format | Price | Rating and reviews |
|---|---|---|---|---|
| Igennus D3 | 2,000 IU | 365 tablets | €12.99 | 4.5/5 (12,090) |
| Vitavea D3 | 2,000 IU | 365 tablets | €12.90 | 4.5/5 (1,127) |
| WeightWorld D3 + K2 | 2,000 IU + 200 µg K2 | 365 micro-tablets | €22.99 | 4.6/5 (8,292) |
| AAVALABS D3 olive oil | 4,000 IU | 365 capsules | €22.99 | 4.7/5 (635) |
| HN D3 + K2 | 5,000 IU + K2 | 365 capsules | €23.40 | 4.5/5 (1,170) |
- Igennus is our pick: 2,000 IU, a short formula without magnesium stearate according to the manufacturer, and the track record of more than 12,000 reviews. It is derived from lanolin, so vegetarian but not vegan.
- Vitavea ties on dose and price. Made in France, in the Vendée, according to the brand: the alternative if origin matters to you. It contains sorbitol and magnesium salts of fatty acids, with far fewer reviews.
- WeightWorld is the right choice if you want K2: same D3 dose, at nearly twice the price. Amazon shows a unit price of €0.13, which does not match the 365 tablets stated: check the quantity before buying.
- AAVALABS has the best rating, but 4,000 IU alone reach the safety limit, with no margin for food. Keep it for a prescription or a blood test that justifies it.
- HN provides 5,000 IU, or 125 µg: above the European limit of 100 µg if taken daily. We do not recommend it for daily use without medical advice.
An Amazon rating measures buyer satisfaction, not efficacy or purity: here it helps separate products of the same dose, not judge their quality.
Which vitamin D for your profile?
- Budget: the useful dose at the lowest price. The Incite Nutrition 2000 IU showed €7.99 for 400 tablets on the day of the survey, with more than 35,000 reviews.
- Smart: Igennus, the best balance of dose, price and track record.
- Premium: no need for a stronger dose. Pay instead for what matters to you: plant origin with NOVOMA 2000 IU, or K2 with WeightWorld.
Frequently asked questions
How much vitamin D should I take per day?
It depends on your situation and your blood level: only a health professional can say for you. The safety reference is not to exceed 100 µg (4,000 IU) a day for an adult, from all sources combined.
Can these products be given to a child?
No, these supplements are for adults. The French food safety agency Anses has reported serious overdoses in infants linked to supplements and recommends favouring medicines, on medical advice.
D3 or D2?
The five products compared here contain D3 (cholecalciferol), the most common form in supplements. "Plant-based" D3 versions, from lichen for example, generally cost more.
Where do the prices and ranking come from?
From Amazon.fr listings reread on 31 October 2026. Picksly has not tested these products. Picksly may earn a commission on purchases made through its links, at no extra cost to you (how Picksly is funded); this does not change our criteria, dose first.
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