German consumer organisations have found that most vitamin D supplements sold in the country are dosed well above the levels recommended by the federal risk assessment body. According to ad-hoc-news.de, Stiftung Warentest reported in its 1/2026 issue that the majority of 25 vitamin D products it examined contained excessive amounts, and five were rated "not suitable" because long-term overuse can contribute to kidney damage.
Only two products passed the test. One was "Vitamin D compact" from GSE, which delivers 200 international units (I.U.) per daily dose. The other was the juice "Vital Vitamin D" from Rotkäppchen, at 400 I.U. per daily dose. The Bundesinstitut für Risikobewertung (BfR) advises a maximum of 20 micrograms, or 800 I.U., of vitamin D per day from supplements.
A separate review by Öko-Test reached a similar conclusion. The outlet examined 23 vitamin D products, made up of 14 dietary supplements and nine medicines, and issued a recommendation for just six of them. Two named products failed badly: Doppelherz pure vitamin D3 drops, listed at 2,000 I.U., and Vigantolvit vitamin D3 drops, which the manufacturer states contain 4,000 I.U. Both sit far above the BfR guidance value, ad-hoc-news.de reports.
Why it matters
The findings matter because vitamin D is one of the most widely purchased supplements in Germany, and many buyers assume that a higher dose simply means better protection. The test results suggest the opposite risk: that a large share of the market is formulated at levels public health authorities consider unnecessary or potentially harmful.
The Robert Koch-Institut (RKI) estimates that 44 percent of adults in Germany already have adequate vitamin D status. That figure undercuts the case for routine supplementation among the general population and puts the focus on the specific groups who genuinely need it.
The BfR also states that supplements are generally not needed for healthy children, since baseline supply in Germany is good overall. The EsKiMo-II study found that average intake of vitamin D and iodine from ordinary food falls below reference values, yet experts still caution against giving children colourful vitamin gummies. Fat-soluble vitamins such as A and D are stored in the body, so uncontrolled consumption can lead to overdosing.
Who actually needs supplementation
Risk groups for insufficient supply include people over 65, people with obesity, people with darker skin, and those with chronic kidney, gastrointestinal or parathyroid conditions. People with limited exposure to sunlight also fall into this category.
Specialists quoted in the coverage say it makes sense to measure the calcidiol value, also known as 25-OH-D, in the blood before starting any supplement. That step establishes whether a deficiency exists at all and how large it is, rather than relying on guesswork.
High vitamin D intake can push calcium levels up to dangerous concentrations, producing symptoms that range from fatigue to kidney damage. Products formulated for adults are not appropriate for children, because nutrient reference values are calculated for adults only. Laboratory testing before supplementation remains the safest route, according to the experts cited.
General guidance in the coverage stresses that supplements are only an addition to a balanced diet and cannot replace it. Anyone considering taking them should first seek individual advice from a medical professional. For healthy people eating a complete diet, extra products are in most cases superfluous, with exceptions mainly tied to particular life stages or defined risk groups.
Quality problems extend beyond vitamin D
The same testing round turned up significant variation in the quality of specialist products. Öko-Test examined 19 pregnancy supplements containing folic acid and iodine. Only two earned a "good" rating, while more than half were judged "insufficient."
Overdosing was again the central criticism, with only about a quarter of the products staying within the BfR's maximum quantity recommendations. In 14 of the preparations, vitamin B6 was present at excessive levels, a concern because sustained intake has been linked to nerve damage in the limbs. More than half also exceeded the recommended ceiling of 6 milligrams of iron per day.
Testers additionally criticised excipients they consider problematic, including talc, certain phosphates and carrageenan. These findings widen the picture from vitamin D alone to the broader supplement shelf, where dosage discipline appears inconsistent across product categories.
What to watch
The test results give consumers a concrete benchmark: the BfR ceiling of 20 micrograms, or 800 I.U., per day from supplements, and a short list of products that meet it. Whether manufacturers reformulate in response, and whether retailers adjust what they stock, is the next thing to watch.
