Are you supplementing safely?

Experts generally advise that most people don't need supplements, but many of us are still buying them.

The UK vitamins, minerals and supplement market is huge - in 2023 it was worth £1.5bn, rising by an average of 13.1% annually since 2018, according to a 2024 report by Palladium.

And when we surveyed people about their supplement use, in a March 2025 survey of 2,154 UK adults, the appetite was clear: three-quarters of UK adults take supplements, with two-thirds of these taking them at least once a day. 

Of those, the majority said they take up to three different supplements, with one in six saying they take at least four.

However, our research also revealed confusion, including uncertainty about dosages and a failure to seek professional advice, which experts we spoke to are concerned about.

Live well, eat better, stay healthy – sign up to our free monthly Food & Health newsletter for the latest insights and advice delivered straight to your inbox

Healthy living

Use our expert advice and recommendations to live your best life every day.

Get started

Consumer confusion

Some 38% of people said they were 'sometimes confused' by supplement information, and 14% said they often or always were.

Nichola Ludlam-Raine, registered dietitian and British Dietetic Association (BDA) spokesperson, told us: 'I see first-hand how confusing the supplement space can be for consumers.' She says seeking advice through the correct channels is vital.

'I'd always recommend speaking to a registered dietitian, pharmacist or doctor before starting a new supplement routine, especially if someone is on medication or has a medical condition,' she said.

However, while 37% of those we surveyed who took supplements regularly did ask a GP or other healthcare professional for advice, the majority didn't, including people who didn't seek advice at all (32%) or asked friends or family instead (20%).

'One of our biggest issues is that people self-prescribe based on what they see online or what friends and family suggest,' says Ludlam-Raine. 'Without knowing what they need - or if they need anything at all - they may risk overdosing, or miss the real reason behind a symptom such as fatigue or hair loss.' 

On-pack advice may not cover these scenarios, and that's if you read what's on the label at all. Just 35% of supplement users in our survey said they always read label information, while 44% said they sometimes, rarely or never do.

The supplements you do and don't need - we look at the evidence behind popular supplements to give you the lowdown on who might benefit

Are food supplement regulations up to scratch?

What manufacturers can or can't claim about food supplements is regulated by food law and is the responsibility of the Food Standards Agency (FSA), Food Standards Scotland and the Department for Health and Social Care (DHSC).

The intended purpose of food supplements is to correct nutritional deficiencies, maintain adequate intake of certain nutrients or support physiological functions - if they want to claim that they prevent, treat or cure illness, they have to be classed as a medicine and comply with the associated (more stringent) rules.

However, in reality it's not so straightforward - in fact, even independent research conducted for the FSA in 2018 concluded that the regulatory landscape for food supplements was 'complex', with overlapping areas of responsibility between several bodies and with 'no one department having an overarching lead covering both policy and enforcement'.

Long-planned legislation to cover herbal and botanical ingredients, such as turmeric, ginseng and echinacea - currently lacking approved claims or official safe limits - hasn't materialised. 

One side-effect of this limbo state is that when botanical supplements don't have approved claims, manufacturers will sometimes add in a vitamin or mineral that does, such as vitamin D, B6 or C. They can then make a claim on the pack, such as to 'support immune function'.

If you didn't realise these were added, and are already taking multivitamins, for example, this makes it more likely you could unintentionally overdose on some common vitamins and minerals. Coupled with the rising impact of online influencers on buying habits and our increased focus on health, this is a recipe for risk.

Supplements and social media misinformation

Social media is a formidable channel for selling and promoting products now in a way it wasn't a decade or so ago, and this presents fresh challenges.

Around 15% of young adults (aged 18-34) in our survey said they get information on supplements through social media. And while most people in our survey said they shop for supplements via established high street retailers such as Boots, 25% now head to online marketplaces such as Amazon Marketplace instead.

But social media and online channels can be a wild west of misinformation, and supplements are no exception. A 2024 German study looked at 105 dietary supplements promoted by influencers on Instagram and found that, of these, two-thirds exceeded the recommended maximum daily amounts, but failed to warn of the negative effects of taking too much.

When Australian researchers evaluated TikTok posts for the quality of nutrition content, in a 2025 study, they found inaccurate content, a lack of transparent advertising and failure to point out risks and benefits.

In the UK, the ASA (Advertising Standards Authority) now uses artificial intelligence to hunt down false claims, and in 2024, it banned 28 supplement ads - up from six in 2019. Recently upheld claims include one against Huel, for health claims not backed by specific authorised claims, and Aspire Nutrition, which claimed its supplements could treat symptoms of autism.

Herbal and botanical supplements: what to know before buying We sort fact from fiction

Expert view: consumers need clarity

Sue Davies, Which? Head of Consumer Rights and Food Policy, says: 'The Food Supplements Regulations specify the types and forms of vitamins and minerals that can be used in foods supplements and labelling requirements. They also allow for the setting of safe upper limits, where too much could be harmful.

'However, these have only been set out in guidance, and the regulations mainly cover vitamin and mineral supplements. But supplements can include a much wider range of ingredients, including many herbal and plant extracts that haven't been independently assessed and approved for use.

'There is a requirement in the Food Safety Act that only safe products should be placed on the market, and if a supplement includes a 'novel' ingredient, it would require approval before it could be used. Separate legislation also requires that claims of a health benefit have been independently assessed and approved with specified conditions of use. The DHSC is responsible for this.

'This applies to claims about vitamins and minerals, but an assessment of the claims made by supplements that use herbal or plant-based extracts has been on hold for many years, due to debate about the crossover between their use in herbal medicines as well as foods, where different legislation and levels of substantiation are required.'

Need-to-knows about popular supplements: from Vitamin D to Iron

We explain what you need to know about dosage, safety and side effects for the most commonly taken supplements from our survey.

Vitamin D

Helps with immune function, calcium absorption and healthy bones. 

Current UK government advice is that everyone should consider a 10 microgram (400 IU) vitamin D supplement daily from October to early March. 

Some people may be prescribed higher doses for a short time, or to take it year-round, but 100mcg is the maximum recommended daily dosage. It can build up in your body if you take too much and cause potentially serious health issues. Find out more, including who's more at risk of deficiency and the cheapest places to buy it, in our full guide to vitamin D.

Vitamin C

Used by 25% of people surveyed, vitamin C helps maintain healthy skin, blood vessels, bones and cartilage, protects cells from damage, and aids immune and nervous system function. 

More than 1,000mg a day can cause stomach pain, diarrhoea and flatulence (it resolves when you stop taking it).You should be able to get enough from your diet relatively easily. One orange provides nearly all you need to meet the daily recommended amount, but peppers, broccoli and strawberries are also good sources, according to the NHS.

Iron

Taken by 14% of people in our survey, iron helps to make red blood cells and haemoglobin for oxygen transport, as well as contributing to immune system and brain function. 

Doses over 20mg can cause nausea and stomach upset and taking 25mg or more can also reduce absorption of zinc. Iron taken in very  high doses can even be fatal.

Omega-3

These essential fats, found in nuts and seeds, and oily fish such as salmon, trout and sardines, help with heart, blood vessel and lung health. The British Dietetic Association doesn't recommend that the general population take omega-3 supplements as it says the evidence is inconclusive. If you decide to take one, 450mg daily is equivalent to two portions of fish a week for adults.

Vitamin B complex

These eight B vitamins help with functions including nervous system health and releasing energy from food. B vitamins are water-soluble, so aren't stored in the body, but can still cause side-effects if taken in excess over time. For example, too much vitamin B3 can cause liver damage and excessive vitamin B6 can cause nerve damage.

Magnesium

Approved claims include reducing tiredness and helping with bone health and metabolism. Taking supplement doses of more than 400mg for a short time can cause diarrhoea, although the NHS says there's not enough evidence to say what the effect of taking high doses of magnesium for a long time might be. Find out more in our guide to types of magnesium supplement.

Probiotics and gut health: what you need to know - we look at the evidence for probiotics, cultured yoghurt drinks and other gut health products

Popular supplements to take extra care with

Taking too much of these can cause issues.

Vitamin A

Vitamin A is fat-soluble, meaning it can build up in the body. Too much over time can cause health issues. It's often in fish oil supplements as well as multivitamins, so if you take several supplements you'll need to check that you're not taking more than recommended. Don't exceed 1.5mg per day and avoid supplements containing vitamin A if you are pregnant or trying to conceive.

Vitamin B6 

You shouldn't take more than 10mg of B6 a day in supplement form unless advised to do so by a doctor. Taking too much can cause tingling, numbness and other symptoms. Extremely high doses of 200mg or more a day can lead to loss of feeling in the arms and legs (peripheral neuropathy).

Turmeric

The government's Committee on Toxicity concluded in a 2024 report that substantially exceeding the acceptable daily intake (ADI) of turmeric could be a potential health risk, especially if other medicines are being taken at the same time or for those with altered liver function. So you should exercise caution with supplements, especially ones claiming high doses. 

Using turmeric as a spice in cooking and food, even daily, shouldn't be an issue, as the amounts involved are significantly smaller.

How to supplement safely

Be aware that supplements can be potent. Nichola Ludlam-Raine, registered dietitian and British Dietetic Association (BDA) spokesperson, told us: 'Supplements can absolutely be helpful - but they are not always benign.'  And they can interact with both each other and some foods - or medication you are taking. 

For example, iron and calcium supplements should be taken at least two hours apart, as calcium can reduce iron absorption, and stop biotin at least a few days before blood work, as it can interfere with blood test results. 

So, do your research and don't ignore on-pack advice to speak to a health professional before taking supplements, it's there for good reason.

Buy from a reputable source. Be very wary, too, of unknown brands promising you the world on social media, or buying from online marketplaces where you might not be able to verify a product's provenance. Learning to understand what's on a supplement label can also help (see 'How to read a supplement label' below). Check the dose against NHS guidance to see if it's excessive or not. Companies love to market 'high strength' products as a benefit, but more is not always better.

Don't rely on anecdotal advice. Experts say one of the biggest issues is that people often self-prescribe based on what they see online or what friends and family suggest, without consulting a health professional first. Nichola Ludlam-Raine warns: ‘Without knowing what they actually need or if they even need anything at all, people may risk overdosing (for example, with iron or with fat-soluble vitamins that are stored in the body) or miss the real reason behind a symptom like fatigue or hair loss.'

Speak to a healthcare professional. Speak to a pharmacist, doctor or registered dietitian who can give an evidence-based view on supplementation, including whether you should be avoiding certain ones because of a health condition or medication you've been prescribed. If there's a health issue that necessitates it, a health professional may even be able to prescribe certain vitamins. Or it may be that your symptoms need further exploring so it's better to get advice before splashing out on supplements.

Don't neglect your diet. Although it's not always possible and there are some people who may need to take additional supplements, Professor Kamila Hawthorne, chair of the Royal College of General Practitioners (RCGP), told us: 'The best way of getting all the vitamins we need is through a varied and balanced diet.' Small swaps and aiming to eat a variety of plants, wholegrains and nuts / seeds are all good starts, and it's worth taking stock of your sleep, stress and exercise levels too if trying to improve your general health.

Is the Zoe nutrition app worth it? We asked our expert nutritionist to review it, plus we got real life feedback from hundreds of Which? members who'd used it, to bring you our verdict

How to read a supplement label

Food supplements must be clearly labelled with key information by law, including a list of ingredients and the amount of active ingredients in the product.

Other information should include storage instructions and best-before date, plus they must be labelled as a 'food supplement' and should include the business name and address.

Here are some key bits you'll see on the label and how to make sense of them:

Nutrient Reference Value (NRV)

This is the amount of a nutrient the average healthy person needs to prevent deficiency. It's shown for each active ingredient listed. 

It has replaced (but is identical to) the recommended daily allowance (RDA). Often,  you'll find that the dose in a supplement far exceeds 100% of the NRV. This isn't necessarily an issue as this is a recommended amount rather than a safe upper limit, but arguably it isn't particularly user-friendly if you want to quickly assess if a product is the right dose for you.

Unit measurements

Supplement ingredient quantities are often listed in micrograms (mcg or μg) or milligrams (mg). 1 milligram equals 1000 micrograms. You might also see IU, which stands for 'international units'. This measures the biological activity of a vitamin. Different forms of a vitamin may have different levels of biological activity, despite being the same amount, which is why this is used for a more standardised comparison in some circumstances. You'll likely see it on vitamin D, which can come in different forms such as D2 and D3. 

Recommended dosage

Always check this. Sometimes, to get the full dose, you may need to take two or more tablets or gummies, which also means the product may be much more expensive per dose than anticipated. Equally, for products such as powdered supplements, it's important to carefully follow the recommendations to avoid taking too much.

How to take it

Nutrients are optimally absorbed under different conditions (eg taking fat-soluble nutrients like vitamin D with meals containing fat), so check the label for advice, such as taking them with food, on an empty stomach or with water, to get the best from your vitamins.

Other warnings

Keep supplements out of children's sight and reach. Some, such as gummies, look like tempting sweets. Potential risks include life-threatening iron toxicity from ingesting adult-strength versions, especially if multiple doses are consumed.

Best painkillers: aspirin, ibuprofen or paracetamol? Find out about the different types of painkillers, what works best for different ailments and whether pricey formulations are really worth it

* Survey insights based on a March 2025 nationally representative survey of 2,514 UK adults