Supplements containing as much as 12.5 times the recommended safe upper limit of popular vitamins and minerals sold on online marketplaces, Which? warns
Which? is calling for better regulation and oversight of supplements after the consumer champion found products containing potentially dangerous doses of popular vitamins and minerals for sale on online marketplaces.
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 UK experts based on an assessment of the risk.
Worryingly, the consumer champion 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 that the supplements industry agreed with the government to provide.
Vitamin D
The NHS recommends a daily intake of Vitamin D is 10 micrograms (µg) each day but adults can safely take up to 100µg, including from food sources.
Superdrug Marketplace, TikTok shop, and eBay all listed the Nuke Nutrition 10,000 IU (250µg) vitamin D3 supplements for sale - more than double the safe upper limit. When Which? contacted Nuke Nutrition about this product, they immediately withdrew it from sale while they investigated.
On AliExpress, Which? found two different vitamin D3 supplements in 50,000 IU, or 1,250µg doses - 12.5 times the recommended daily dose.
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.
Even more concerningly, Which? 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.
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
Vitamin A is crucial for vision, supporting the immune system and maintaining healthy skin. 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.
Voluntary guidelines say that a warning should be provided at levels above 800 micrograms advising pregnant women and those trying to conceive not to take the product except on the advice of a doctor or antenatal clinic.
Etsy, TikTok shop, and eBay all sold 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.
Vitamin B6
According to the NHS and EVM, Vitamin B6 helps the body use and store energy and to form haemoglobin, the substance in red blood cells that carries oxygen around the body. It's recommended to consume no more than 10mg.
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 well-known health retailers Solgar and Holland & Barrett. Holland & Barrett withdrew the product from sale after being alerted by Which?.
According to the NHS, a dose of this size taken over time can increase the risk of suffering permanent peripheral neuropathy – damage to the nervous system in extremities like hands and feet that can cause muscle weakness, numbness and damage to co-ordination and balance.
Zinc
Zinc helps with making new cells and enzymes and wound healing but the NHS recommends taking no more than 25mg. If a product has more than 25mg, the voluntary guidance says that it should have a statement that long term usage can lead to anaemia.
Amazon’s most popular zinc supplement was from the brand WeightWorld and contained 50mg – double the 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'.
The 50mg Now Foods zinc supplement, also for sale on eBay and TikTok shop, was even labelled as ‘Amazon’s Choice’. Both Amazon and Superdrug Marketplace offered a 50mg zinc supplement from the brand New Leaf too.
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.
Neither supplement contained the voluntary anaemia warning on the product listings, though New Leaf told us they carried the warning on the packaging itself and would add it to the listing after our investigation.
Some of the supplements found in Which?’s investigation did not have nutrition information detailing how much of the active ingredient is actually in the supplement - making it nearly impossible for consumers to know how much they are taking.
These types of supplements are classed as food under the Food Supplements Regulations 2003 and are regulated by the Food Standards Agency (FSA) and Food Standards Scotland (FSS). Supplements like all foods are subject to a general requirement to be safe. Safe upper levels are only specified within voluntary guidelines based on advice from the UK’s Expert Group on Vitamins and Minerals (EVM) and therefore, these limits are only advisory.
In 2003, the EVM set safe upper levels for different vitamins and minerals - and a voluntary agreement was reached between the food supplement industry and the government on advisory statements to be included on the label and suggested reformulations to reduce levels where there was a risk from taking high doses.
But in the 20 years since these guidelines were established, the popularity of supplements has sky-rocketed and the explosion of online marketplaces means there are no longer just a few reputable brands on the market.
This means brands can sell exceedingly high doses to convince shoppers that their products are the best value for money, while leaving consumers in the dark about what amounts could be harmful.
Better regulation and oversight of the supplements industry is desperately needed to ensure clarity over what levels can legally be sold and to make sure unsafe products are taken off the market. This includes greater oversight of online marketplaces, as well as food supplement manufacturers, to make sure they are taking responsibility for the safety of products offered to consumers.
The government should also ensure there is strong enforcement in place so that any companies breaking the rules - whether manufacturers, retailers or marketplaces - know they will be held to account.
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.”
-ENDS-
Notes to editors
Research
Which? shortlisted vitamins and minerals that could cause harm in excessive doses by using the UK’s Expert Group on Vitamins and Minerals (EVM)’s report on safe upper levels, and the NHS’s guide to vitamins and minerals. Researchers only considered vitamins and minerals where there was enough evidence to set a specific safe upper level in the EVM, or where the NHS used the strongest language (i.e. a warning such as ‘do not take more than X amount of this vitamin’, and not ‘having less than X amount of this vitamin is unlikely to cause any harm’).
Researchers then narrowed this down to the most popular supplements that carry the biggest risk of harm: vitamin A, vitamin B6, vitamin D3, and zinc.
Which? looked at a range of online retailers, primarily online marketplaces, to see if there were any examples of supplements above the safe upper levels. The examples given are not comprehensive.
Rights of replies
Etsy, Now Foods, Pslalae and WeightWorld did not respond to requests for comment.
AliExpress said: “As a global marketplace, AliExpress places great emphasis on product safety. The platform has effective prevention and control strategies in place, and we noticed that this non-compliance product had already been taken down by corresponding monitoring rule early this month before receiving this enquiry.
"We appreciate your attention to this important issue and remain committed to fostering a safe and secure environment on our platform.”
Amazon said: “We require all products offered in our store to comply with applicable laws and regulations, and the products flagged by Which? meet the current government mandated regulatory guidance in relation to upper levels for vitamins and minerals.
“However, we are aware there is continued debate around what the right guidance should be and we look forward to continuing to work with industry experts and government agencies in this area.”
eBay said: “eBay is committed to ensuring that products sold on our marketplace comply with our policies and all applicable laws. The limits published by the NHS and the Food Standards Agency’s Expert Group on Vitamins and Minerals are advisory levels only.
We continue to review our policies in line with evolving guidance from health authorities to help ensure eBay remains a safe and trusted marketplace.”
Holland & Barrett said: “At Holland & Barrett we are committed to providing high-quality, science-backed products, reflecting the latest scientific and regulatory guidance.
“As a responsible retailer, we regularly carry our detailed reviews led by our science and regulatory teams and we took the proactive decision earlier this year to bring our vitamin B6 range in line with the EFSA advisory limit. As a result, newly reformulated products will be available to customers this month. H&B products not in line with the EFSA guidelines are already being withdrawn, with this process due to be complete by end of October 2025.
“Continuous improvement of our portfolio remains central to our mission of supporting the health and wellbeing of our customers, and we will continue to adapt our products in line with the most up to date scientific and regulatory advice.”
Mother Nature said: “We understand the importance of public health guidance and take our responsibility seriously by ensuring our customers are informed about dosage and potential risks. Our product is not marketed for long-term daily use, and we actively encourage customers to consult with their doctor before starting high-dose supplementation especially in cases of pregnancy or pre-existing medical conditions.
“I’m happy to confirm that the cautionary statement has now been added directly to our product labels. All future batches of this supplement will include this information to ensure clarity and transparency for our customers.”
New Leaf said: "Our Zinc supplement provides 50 mg per serving to offer flexibility in dosage, as many customers prefer to take one tablet (25 mg) rather than the full serving. The higher dosage accommodates individuals who choose to consume 40–50 mg daily to help reduce the duration or severity of colds and flu, and to support skin health (acne, eczema, wound healing) as well as athletic performance and recovery, levels comparable to typical ZMA formulations.
“Upper limits are advisory guidance values. In line with compliant labelling, we include the statement: ‘Long-term use may lead to anemia’. Additionally, our formulation contains copper to help mitigate the risk of zinc-induced copper depletion."
Nuke Nutrition said: “We take product safety and regulatory guidance very seriously and are committed to ensuring that all information provided to customers is accurate and responsible. We have taken immediate action by removing the product from sale while we review the matter further with our supplier to determine the best way forward.”
Superdrug said: “Our customers’ health and wellbeing are always our priority. Our marketplace platform sellers must follow the guidance provided and we have therefore removed all the products that have been highlighted by Which?.”
Nestle Health Science, on behalf of Solgar, said: “Vitamin B6 is an essential nutrient that plays a role in numerous functions in the body and can be safely consumed from foods and dietary supplements. The levels of vitamin B6 found within our products are consistent with other B vitamin supplements found on the UK market. Whilst there is no set safe upper levels the UK, the FSA Risk Assessment for Vitamin B6 (pyridoxines) suggests availability of single nutrient supplements without the supervision of a pharmacist with a recommended maximum daily dose of a 100 mg.
“Current industry best practice as per the Health Food Manufacturers’ Association guidance suggests a safe upper level of less or equal to 100mg daily supplementation, as recommended by FSA, DoH and EVM findings.
“Solgar products provide an additional warning on pack for vitamin B6: Long term intakes of this amount of Vitamin B6 may lead to tingling and numbness. And, as with other food supplements, it is prudent for individuals to talk to their healthcare provider about appropriate vitamin B6 intakes to support their health.”
Temu said: “Temu complies with all applicable UK laws and regulations governing the sale of food supplements. We expect all sellers to follow local laws and regulations, and listings found to contravene these are subject to prompt review and removal.”
TikTok shop said: “Supplements containing unauthorised or banned substances are not allowed to be sold on TikTok Shop. We have removed all of the flagged listings from our platform and we consistently align our policies with regulatory and national guidance, including from the NHS. TikTok uses a combination of technology and manual moderation to enforce our policies for TikTok Shop. TikTok has policies and processes to protect customers and promote a trustworthy shopping experience. This includes policies on what can and can't be sold, seller registration and verification requirements, and features like product reviews, reporting tools, and easy returns.”
About Which?
Which? is the UK’s consumer champion, here to make life simpler, fairer and safer for everyone. Our research gets to the heart of consumer issues, our advice is impartial, and our rigorous product tests lead to expert recommendations. We’re the independent consumer voice that influences politicians and lawmakers, investigates, holds businesses to account and makes change happen.
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