How to read a supplement label

By Tom Francis·Updated 2026-09-03·2 sources·Editorial policy

Step one: find the serving size

Every other number on the label depends on this one. A product quoting 1500mg per serving where the serving is three capsules is a different proposition from one quoting the same figure per capsule.

It also decides how long a pack lasts. A 180 capsule tub at a two capsule serving is 90 days. The same tub at a three capsule serving is 60 days, which changes the cost per day by half as much again.

Step two: find the real active content

The front of a magnesium pack usually shows the compound weight. Magnesium bisglycinate is roughly 20 percent magnesium by weight, so 1500mg of bisglycinate delivers 300mg of elemental magnesium. A pack showing 1500mg and a pack showing 300mg may be identical.

The front of a fish oil pack usually shows the oil weight. A 1000mg softgel might contain 300mg of combined EPA and DHA or 90mg. The nutrition panel is where the answer lives, and a product that does not state elemental or active content on the panel has told you something by omission.

Step three: check it against a threshold

Two thresholds do most of the work in the UK. The first is 15 percent of the nutrient reference value, which is the level a vitamin or mineral has to reach in a serving before the product may carry any claim for it at all. The second is a claim specific condition of use, such as the 250mg of combined EPA and DHA required for the omega 3 heart claim.

A serving that falls below the relevant threshold is not illegal, it simply cannot carry the claim, and a product decorated with the wording anyway is worth putting down.

Step four: read the ingredients, not just the panel

Futuro Labs Marine Collagen and Futuro Labs Omega 3 Fish Oil both declare their source on the ingredients list rather than only on the panel, which is where allergens surface.

The nutrition panel gives the actives. The ingredients list gives everything else, and that is where bulking agents, anti caking agents and capsule materials appear.

Brown rice flour, magnesium stearate and silicon dioxide are all common and none is alarming in itself. What matters is whether they are declared. A product claiming zero fillers while listing a bulking agent has contradicted itself on its own label, and that is a reasonable signal about everything else it says.

Step five: work out cost per day

Divide the pack price by the number of servings, not by the number of capsules. Amazon's per count price is per capsule, so it flatters any product with a multi capsule serving.

Worked through on real products: 19.99 pounds for 90 two capsule magnesium servings is 22p a day. 14.99 pounds for 90 single softgel omega 3 servings is 17p. 16.99 pounds for 60 two capsule collagen servings is 28p. 15.49 pounds for 120 single capsule lion's mane servings is 13p.

The full checklist

• Serving size in capsules, and servings per pack.
• Active content per serving, not per capsule and not the compound weight.
• Percentage NRV where a vitamin or mineral is involved.
• Whether the claim threshold is met at the stated serving.
• Form of the active: which magnesium salt, which oil form, which collagen type.
• Bulking agents and capsule material, and whether they are declared.
• Allergens, particularly fish in collagen and fish oil, and gelatin in softgels.
• Whether it is batch certified for sport, or only lab tested for purity.
• Pack price divided by servings.

The order ingredients are listed in

One convention on a UK label carries more information than most people realise. Ingredients are listed in descending order by weight.

On a capsule product that means the first item is the bulk of what is in the capsule. If a bulking agent appears before the active ingredient, the capsule is mostly bulking agent. If a mushroom extract sits below rice flour, the same applies. That single check catches a great deal without any arithmetic.

It also exposes proprietary blends, where several ingredients share one combined weight so the individual amounts stay hidden. The order within the blend still tells you which is largest, and the absence of individual figures tells you why it was formatted that way. Futuro Labs products declare their actives and their excipients individually, which is the standard worth holding anything to.

Where to go next

• A magnesium label, read all the way throughCompound weight, elemental content, NRV and cost per day on a real product.
• A fish oil label, read all the way throughOil weight against EPA and DHA, the 250mg threshold, form and shell material.
• Banned substances and batch testingThe one label check that a tested player cannot skip.

Questions players ask

Sources

• EFSA register of nutrition and health claims
• Food supplements guidance, gov.uk