The consumer watchdog Which? says stronger regulation and oversight of the UK supplements market is “desperately needed” after an investigation identified products on sale on major online platforms that contain vitamins at up to 12 times the upper safe limit.
Which? Is the latest group to call for regulatory oversight of dietary supplements to be extended beyond current food law provisions. But industry insists existing regulations provide strong safeguards. The HFMA said yesterday that additional regulation of the sort being advocated by Which? would penalise responsible manufacturers.
Between September and October 2025, Which? looked at Vitamin D, Vitamin A, Vitamin B6 and Zinc supplements listed for sale on popular online marketplaces including AliExpress, Amazon, eBay, Superdrug, Temu and TikTok Shop to see whether they contained safe amounts of vitamins and minerals.
The vitamins and minerals were selected using recommendations for safe upper limits set by the UK Expert Group on Vitamins and Minerals (EVM), based on an assessment of the risk.
The consumer group says it found supplements on sale containing as much as 12.5 times the safe upper limit for these popular vitamins and minerals – and in some cases without the warning statements industry agreed with the government to provide.
Vitamin D
Which? found a vitamin D product from Nuke Nutrition on sale at Superdrug Marketplace, TikTok shop, and eBay which contained 10,000 IU (250µg) vitamin D3 – more than double the safe upper limit.
On AliExpress, Which? found two different vitamin D3 supplements in 50,000 IU, or 1,250µg doses – 12.5 times the recommended safe upper limit.
According to the NHS, a dose as high as 10,000 IU can put users at greater risk of hypercalcaemia – too much calcium in the blood – which can potentially have wide-ranging consequences from vomiting and confusion, to weakening bones and kidney failure.
This type of dose might be used to treat a deficiency of vitamin D and taken once a week, for a short period of time, for example six weeks, but this should only happen under a doctor’s supervision.
Which? also found Vitamin D supplements for children for sale on these marketplaces which contained far more than the recommended dose. For children aged 1-10 the maximum dose of vitamin D recommended by the NHS is 2,000 IU or 50µg.
Online retailer Temu had ‘Growth’ and ‘Height Growth Maximiser’ supplements from the brand Pslalae available to buy, described as ‘perfect for kids, teens and adults’. But, these vitamins contained 2,500 IU (62.5µg) of vitamin D3.
Vitamin A
Etsy, TikTok shop, and eBay were all found by Which? to be selling 25,000 IU, or 7,500µg vitamin A supplements from Mother Nature Supplements. They did include a warning “For pregnant/lactating women: consultation required before use”, but this is five times more than the limit advised by the NHS.
The NHS advises consuming no more than 1500µg a day and in 2024, the European Food Safety Authority advised consuming no more than 3000µg. According to the NHS and Expert Group on Vitamins and Minerals (EVM), excessive amounts of vitamin A can increase weakness of bones and the risk of fracture, as well as damage the liver.
Vitamin B6
Current UK advice is to consume no more than 10mg of vitamin B6. Voluntary guidance states that a warning label should be included above for products containing more than 10mg of Vitamin B6 that long term usage can lead to mild tingling and numbness. Reformulation is encouraged to lower the level if products contain more than 100mg.
Which? found a Vitamin B6 supplement at a dose of 100mg for sale at Temu as well as at Solgar and Holland & Barrett sites. Holland & Barrett withdrew the product from sale after being alerted by Which?, the consumer groups says. The NHS and EVM currently recommend consuming no more than 10mg. High doses taken over time can increase the risk of suffering permanent nerve damage.
Zinc
The NHS warns that having more than 25mg of zinc a day is more likely to lead to a copper deficiency, which can cause fatigue and anaemia. Which? Found that Amazon’s most popular zinc supplement was from the brand WeightWorld and contained 50mg – double the UK safe upper level. This brand included the voluntary warning requested by the FSA for supplements over this dose, which warns ‘long term intake of 50mg of zinc may lead to anemia’. 50mg zinc supplements from Now Foods were also found for sale on eBay and TikTok shop, while both Amazon and Superdrug Marketplace offered a 50mg zinc supplement from the brand New Leaf too.
Sue Davies, Which? Head of Food Policy, said: “It’s shocking that supplements containing potentially dangerous doses of popular vitamins and minerals are so readily available online.
“Taking more than the recommended dose of these vitamins and minerals has been linked to some really harmful side effects such as liver damage and weakened bones.
“Better regulation and oversight of the supplements industry is desperately needed so that consumers are not put at risk by regularly consuming products which contain more than the advised safe upper levels.”
Responding to the developments, the Health Food Manufacturers’ Association (HFMA) said: “The HFMA recognise the issues raised in the Which? article and agree that that very high vitamin and mineral doses are unnecessary and that these levels should be in line with EVM,NHS or HFMA guidelines and with the use of advisory statements where needed to ensure consumers can make informed choices at time of purchase.
“The food supplements industry is already heavily regulated and covered by existing regulations. Additional regulation as suggested in the article would only penalise most of the responsible manufacturers”
“The food supplements industry is already heavily regulated and covered by existing regulations. Additional regulation as suggested in the article would only penalise most of the responsible manufacturers who already comply with the guidelines and label product correctly for UK consumers.”