As the General-Anzeiger Bonn reports, the consumer organizations Ökotest and Stiftung Warentest independently examined vitamin D supplements. The conclusion of both tests is similar: Only a handful of products score "good" or "very good," while many supplements fail due to deficiencies such as overdosing or inadequate labeling.
Vitamin D supplements are very popular, especially in the winter months when sunlight is insufficient for adequate endogenous production. However, the tests by Ökotest and Stiftung Warentest show that consumers should look closely when choosing.
According to the General-Anzeiger Bonn, the testers primarily criticize the dosage of many products. Some supplements significantly exceed the maximum amounts recommended by the European Food Safety Authority (EFSA). Long-term overdosing of vitamin D can be harmful to health, for example leading to kidney stones or cardiac arrhythmias. Stiftung Warentest points out in its test that many manufacturers advertise with excessively high dosages that are medically unnecessary.
Ökotest also criticizes that some products contain synthetic additives or that the origin of the vitamin D (e.g., from lichen or wool grease) is not clearly labeled. In the overall assessment, only a few supplements scored "good." According to the General-Anzeiger Bonn, the test winners are products that have a moderate dosage, avoid unnecessary additives, and are transparently labeled.
The test results in detail: In Ökotest, only three out of about 20 tested supplements received the grade "good." Stiftung Warentest rated about a quarter of the tested products as "good." Many supplements failed with "adequate" or "poor." The main points of criticism, besides overdosing, were incorrect or misleading information on the packaging.
Consumers who wish to supplement vitamin D should, according to the test results, pay attention to a dosage of a maximum of 20 micrograms (800 international units) per day, unless a medically diagnosed deficiency exists. Additionally, the testers recommend looking for products that have been awarded a seal by Ökotest or Stiftung Warentest and performed well in the test.
The General-Anzeiger Bonn points out that the tests by Ökotest and Stiftung Warentest are regularly updated. Consumers should therefore check the current results on the organizations' websites before purchasing. The full test reports are available there for a fee.
Background: Vitamin D is a fat-soluble vitamin that the body can produce itself with the help of sunlight. In the winter months or in people who spend little time outdoors, a deficiency can occur. However, such a deficiency should be diagnosed by a doctor before taking dietary supplements.
