How to Choose a Supplement: A Straight-Talking Guide for UK Buyers

July 20, 2026|Barry Lees

Walk into any health shop, or scroll any supplement website, and you will be met with the same thing: big claims, impressive-sounding blends, and very little you can actually verify.

I run a small supplement business. I am not going to pretend that puts me above the problem — it means I look at labels every week and I know exactly how easy it is to make a product sound better than it is. So this guide is the one I would want if I were buying rather than selling.

First: do you actually need one?

A supplement is exactly what the name says — something that supplements a diet. The legal wording on every UK label says it plainly: food supplements are not a substitute for a varied and balanced diet and a healthy lifestyle. That is not a disclaimer someone added to cover themselves. It is the actual regulatory position.

Some people have genuine gaps. The NHS recommends that everyone in the UK considers a vitamin D supplement in autumn and winter, because we do not get enough sunlight. Vegans need a reliable B12 source. Anyone pregnant or trying to conceive is advised to take folic acid. Those are specific, evidence-based situations.

Outside of those, be honest with yourself about what you are hoping for. A supplement will not out-run a bad diet, poor sleep or no exercise. If a product implies otherwise, that tells you something about the seller.

Ignore the front of the bottle

The front is marketing. The back is information. That is where you should be looking.

What you want to find on the back:

The full ingredients list, in descending order by weight
The amount of each active ingredient, in mg or µg
The %NRV for vitamins and minerals
Allergen information, usually in bold within the ingredients
Directions and any warnings

If a product will not tell you how much of something is in it, that is your answer.

→ Full breakdown: how to read a supplement label, line by line

Watch out for the proprietary blend

You will often see something like: "Super Herbal Blend 1,200mg: turmeric, ginger, black pepper, ashwagandha, green tea."

One number, five ingredients. That tells you nothing. The blend could be 1,190mg of the cheapest ingredient and 10mg spread across the rest — and there is no way for you to know.

Blends are not automatically dishonest, and some formulators use them for genuine commercial reasons. But if you cannot see individual quantities, you cannot compare products or judge value. Treat it as a gap in the information, not a feature.

Understand %NRV — it matters more than you think

NRV stands for Nutrient Reference Value. It is the EU and UK benchmark for how much of a vitamin or mineral an average adult needs daily, and it is what the percentage on the label refers to.

Here is the part almost nobody mentions: a product can only make a health claim about a nutrient if it contains at least 15% of the NRV per serving. Below that threshold, the nutrient is legally considered present in an insignificant amount.

This is genuinely useful when you are comparing. If a product lists an impressive nutrient but the NRV is 5%, it is there for the label, not for you. I have found this on my own products, and it has meant rewriting descriptions.

Equally, very high percentages are not automatically better. Some nutrients are water-soluble and simply excreted. Others — vitamin A, vitamin B6, iron, selenium — have upper limits worth respecting.

→ More detail: what %NRV actually means

Certifications: which ones mean something

This is where a lot of noise lives. Some badges represent real, audited standards. Others are essentially decorative.

Worth looking for:

GMP (Good Manufacturing Practice) — covers facility hygiene, staff training and process control. A baseline you should expect.
ISO 22000 — a food safety management standard, independently audited by bodies such as Lloyd's Register or BSI.
HACCP — a preventive system that monitors critical control points during production rather than only testing the finished product.
Informed Sport / Informed Manufacturer — third-party testing for banned substances. Particularly relevant if you compete in sport.
Soil Association organic — a certified organic standard with a traceable licence number.

Less meaningful: vague phrases like "lab tested", "pharmaceutical grade" or "clinically proven" with nothing to verify. If a claim has no certifying body and no number attached, it is a marketing line.

→ Full guide: what supplement certifications actually mean

Health claims: what a company is actually allowed to say

In the UK, health claims on food supplements are tightly controlled. There is a register of authorised claims, and a company can only use the approved wording, only where the product contains enough of the nutrient in question.

That is why compliant labels read a little stiffly — "vitamin C contributes to the normal function of the immune system" rather than "boosts immunity". The stilted version is the legal one.

So when you see a supplement promising to cure, treat, relieve or fix a named condition, you are not looking at a bolder company. You are looking at one either unaware of the rules or ignoring them. In either case, it is reasonable to wonder what else they are relaxed about.

Botanicals are a particular grey area. Ingredients like ashwagandha, turmeric and milk thistle do not have authorised claims, so a compliant seller can name them and describe them but cannot tell you what they do. If someone is making confident claims about a herb, they are almost certainly outside the rules.

→ In depth: what's legal and what's marketing

Check the allergens, even if you think you are fine

Supplements contain ingredients people do not expect. Glucosamine is often derived from shellfish. Collagen is animal-sourced — usually bovine or fish, never vegan, whatever the packaging implies. Greens powders frequently contain barley and wheat grass, which means gluten.

UK labels must declare the 14 major allergens in bold within the ingredients list, plus any "manufactured in a facility that also handles" warning. Read both. The facility line matters if your reaction is severe.

A few practical red flags

No quantities for active ingredients
Claims to treat or cure a named medical condition
Before-and-after photos or dramatic testimonials
Urgency tactics — countdown timers, "only 3 left"
No physical address or contact details on the site
No allergen information anywhere on the product page
Prices that seem impossible — quality raw material costs what it costs

Where the product is made

UK and EU manufacturing carries real regulatory obligations: registration with local authorities, adherence to the Food Supplements (England) Regulations 2003 and the Food Safety Act 1990, and inspection by Trading Standards.

That does not make every UK-made product good, or every imported product bad. But it does mean there is an accountable party and a legal framework. With a product shipped direct from an unregulated market, there is often neither.

The honest summary

Most of what makes a supplement worth buying is boring: adequate doses, transparent labelling, a manufacturer that can be audited, and claims that stay within the law. None of it photographs well.

If a company is willing to tell you exactly what is in a product, how much, where it was made and what it legally cannot claim — you are probably in reasonable hands. If they lead with transformation and leave you hunting for the ingredients panel, keep walking.