Tests, which included products sold in well-known British health stores, as well as online platforms such as Amazon, eBay, TikTok Shop, and AliExpress, showed that many supplements contained more than double the maximum safe level recommended by UK health officials, with some exceeding these levels by as much as 12 times.
Sue Davies, head of food policy at Which?, said it was "alarming that supplements containing potentially dangerous doses are so readily available online," adding that taking more than the recommended dose of some vitamins and minerals can lead to serious side effects such as liver damage, bone weakness, and kidney failure.
According to the UK National Health Service (NHS), adults are advised to take 10 micrograms of vitamin D per day, and can safely tolerate up to 100 micrograms.
But an investigation revealed that the Nuke Nutrition Vitamin D3 supplement, offered on sites such as Superdrug Marketplace, TikTok Shop, and eBay, contained 250 micrograms — more than double the safe limit.
After notifying the producing company, the product was withdrawn from the market.
The organization also detected other vitamin D supplements on the AliExpress platform containing 1,250 micrograms, 12 times the recommended dose.
The NHS warns that excessive vitamin D intake can lead to hypercalcemia, a buildup of calcium in the body, which weakens bones and damages the kidneys and heart, especially since the vitamin is fat-soluble and remains in the body for a long time.
Violations were not limited to vitamin D. Which? found that supplements intended for children, such as Pslalae's "Height Booster" available on the Temu platform, contained doses far higher than the maximum safe limit for children of 50 micrograms.
The organization also revealed that Etsy, TikTok Shop, and eBay are selling Mother Nature Supplements vitamin A supplements containing 7,500 micrograms of the vitamin—five times the recommended daily allowance—despite only a simple warning for pregnant and breastfeeding women.
As for vitamin B6, one of its supplements sold by Holland & Barrett was found to contain ten times the safe daily limit.
According to the NHS, long-term use of such doses can lead to permanent peripheral neuropathy, causing weakness and numbness in the hands and feet. The company announced the immediate withdrawal of the product after being notified of the results.
Regarding minerals, the investigation revealed that one of the most popular zinc supplements on Amazon, from WeightWorld, contains 50 mg—double the maximum safe intake of 25 mg, which can lead to copper deficiency and anemia with prolonged consumption.
The organization noted that some products do not clearly detail the amount of active ingredients, making it difficult for consumers to accurately know what they are consuming.
Etsy, Now Foods, Pslalae, and WeightWorld did not respond to requests for comment, while AliExpress confirmed that it removed the violating products, stressing its "commitment to a safe shopping environment."
Amazon said it "follows government regulations regarding maximum levels of vitamins and minerals," while eBay explained that it "continuously reviews its policies to ensure compliance with health guidelines."
Holland & Barrett confirmed that it has already begun reformulating its vitamin B6 products to comply with the maximum recommended level by the European Food Safety Authority (EFSA), noting that the new products will be available before the end of October 2025.
