When “natural” isn’t regulated: how to read a supplement label

Walk into any health shop and the shelves look clinical: capsules, milligrams, confident claims. But in the UK most supplements are not medicines. They are sold as food, under food law, and they do not go through the testing a medicine does before it reaches the shelf.

That one fact explains most of what is, and is not, on the label. Once you know the rules, a supplement pot becomes much easier to read. This piece explains what the law requires, what it forbids, and what nobody had to prove.

Sold as food, not medicine

In England, vitamin, mineral and similar products sold in pill, capsule or liquid form fall under the Food Supplements (England) Regulations 2003, with matching rules in Wales and Northern Ireland. To sell them, a business registers as a food business with its local authority. Government guidance for sellers mentions registration, not any approval of the product itself before it goes on sale.

The same guidance is clear about what a food supplement is not. It says such products cannot exert a pharmacological, immunological or metabolic action, and are not intended to treat or prevent diseases. Products that do those things are medicines, and medicines are licensed by the Medicines and Healthcare products Regulatory Agency (MHRA), which looks at evidence of quality, safety and effectiveness. Enforcement of food supplements falls mainly to local authorities.

A supplement label is a set of legal requirements, not a promise. Read it for what it has to say, and for what it is not allowed to say.

What every label must show

The 2003 regulations set out a short list of things a food supplement label must carry. If any of them are missing, that is a reason to be cautious about the whole product.

• The words “food supplement” as the name it is sold under.
• The category of each nutrient or other substance that characterises the product, such as a vitamin, a mineral or a plant extract.
• The amount of each of those vitamins, minerals or other substances in the product.
• The portion recommended for daily consumption.
• A warning not to exceed the stated recommended daily dose.
• A statement that food supplements should not be used as a substitute for a varied diet.
• A statement that the product should be stored out of the reach of young children.

The law also stops sellers implying that a balanced and varied diet cannot provide enough nutrients in general. If the marketing suggests that ordinary food is no longer enough for anyone, it is pushing against the rules. The NHS view is that most people should get all the nutrients they need from a varied and balanced diet, although some people need extra.

What a label is not allowed to claim

Food law forbids any food, including a supplement, from claiming to prevent, treat or cure a human disease, or from referring to such properties. This applies to advertising and presentation, not just the small print on the pot. A supplement that says it cures arthritis, fights cancer or treats depression is either breaking the law or is being sold as something it is not.

Health claims are tightly controlled too. In Great Britain, only claims listed as authorised in the government’s nutrition and health claims register can be used. Those authorised claims tend to be narrow and specific, for example linking a named vitamin to a named normal body function. Vague phrases such as “supports wellbeing” or “boosts vitality” are only allowed when they sit alongside a specific authorised claim.

So the useful question is not whether a claim sounds scientific. It is whether the claim is specific, whether it matches the ingredient, and whether the product contains enough of that ingredient for it to apply.

Herbal products: look for the THR mark

Herbal products sit in a grey area. Some are sold as food supplements. Others are registered as traditional herbal medicines under an MHRA scheme known as Traditional Herbal Registration (THR). A registered product carries a THR certification mark and a registration number on the pack.

A THR is only granted for minor conditions that do not need medical supervision, such as a cold. To get one, a company has to provide evidence on safety and on the quality of its ingredients, and show the remedy has been used for at least 30 years, including at least 15 years in the EU or EEA. That is a meaningful check on quality and safety. It is not proof that the remedy works: the claim rests on traditional use, not on clinical trials.

The NHS advises checking that any herbal medicine has a THR mark and an MHRA product code, and warns against buying unlicensed herbal medicines online because they may not be safe.

Interactions, pregnancy and doses

“Natural” products can change how prescribed medicines work. The NHS says people taking statins, antidepressants, diabetes medicines, blood thinners or hormonal contraceptives should not use herbal medicines without speaking to a pharmacist first. St John’s wort, the best known example, should not be taken with some contraceptive injections. People with kidney or liver problems need particular caution, and the NHS does not recommend herbal medicines for children or during pregnancy and breastfeeding.

More is not better with vitamins either. The NHS advises adults not to take more than 100 micrograms (4,000 IU) of vitamin D a day, because too much over a long period can cause calcium to build up and damage bones, kidneys and the heart. The everyday amount it suggests most people consider in autumn and winter is 10 micrograms. In pregnancy, the NHS recommends 400 micrograms of folic acid a day from before conception to 12 weeks, and warns against cod liver oil or supplements containing vitamin A (retinol), which can harm a baby’s development. Multivitamins often contain vitamin A, so the label matters.

Products sold online and from abroad

The riskiest products are often the ones that look least like ordinary supplements. In 2015 the MHRA said it had found hundreds of products since 2005 that claimed to be herbal but were adulterated with pharmaceutical ingredients. Many slimming pills marketed as natural contained sibutramine, a drug withdrawn in 2010 because of an increased risk of heart attack and stroke.

The problem has not gone away. In February 2026 the MHRA said nearly 20 million illegally traded erectile dysfunction pills had been seized over five years, warning that such products may contain no active ingredient, the wrong dose, hidden drugs or toxic ingredients. If a product promises dramatic weight loss, muscle gain or sexual performance, treat that as a warning sign rather than a selling point.

A quick checklist before you buy

• Check it says “food supplement”, lists the amount of each active ingredient and gives a daily dose with a warning not to exceed it.
• If a label gives one total for a “blend” without the amount of each ingredient, ask why, and be wary.
• Treat any claim to prevent, treat or cure a disease as a red flag.
• Read health claims for what they actually say. Narrow and specific is normal. Sweeping and vague is marketing.
• For herbal remedies, look for the THR mark and registration number.
• Avoid buying from social media, messaging apps or unknown websites.
• Check the total across everything you take, since the same vitamin can appear in several products.

This article is for general information and is not medical, legal or financial advice. Laws differ between countries. Read our editorial standards.