The number beside each nutrient — 100%, 50%, sometimes far more — is doing a specific job. Here is what it is measuring, and what it is not.
Most UK supplement panels carry two columns of numbers. The first is the amount of each nutrient per serving, in its proper unit. The second is a percentage. That percentage is one of the more misread figures in nutrition labelling: useful once you know the reference point behind it, and easy to over-read if you do not. This piece explains what the percentage is calculated against, why two different reference systems sit on UK labels, and how to read the figure for what it is.
Two reference systems, used for different things
UK labelling uses two separate benchmarks, and they are not interchangeable.
Reference Intakes (RI) apply to energy and the main macronutrients — fat, saturates, carbohydrate, sugars, protein and salt. The familiar front-of-pack figures, such as an energy reference of 2,000 kcal for an average adult, are RIs. These are the values behind the traffic-light colours on food packaging.
Nutrient Reference Values (NRVs) apply to vitamins and minerals. When a label shows a percentage next to vitamin C, vitamin D, calcium or vitamin K, that percentage is calculated against the NRV, not the RI. Both systems are set out in the same piece of retained legislation (Annex XIII of Regulation (EU) 1169/2011), but in different parts: reference intakes for energy and macronutrients, and NRVs for the micronutrients.
In everyday use the two terms get blurred, and you will see "%RI" printed against vitamins on some labels. Strictly, the figure beside a vitamin or mineral is a percentage of that nutrient's NRV. Knowing which system you are looking at is the first step to reading the number correctly.
What the NRV figures actually are
The NRV is a single reference figure per nutrient, set for an average adult, used to standardise labels so products can be compared on a like-for-like basis. The values were previously labelled as RDAs (Recommended Daily Allowances); the terminology changed under EU labelling law that took effect in 2014, while the figures themselves were carried across.
A few of the NRVs relevant to a bone- and immune-focused formulation, as listed in the legislation:
- Vitamin D — 5 µg
- Vitamin C — 80 mg
- Calcium — 800 mg
- Vitamin K — 75 µg
So a supplement providing 80 mg of vitamin C shows 100% NRV for vitamin C; one providing 40 mg shows 50%. For a food supplement, the percentage is read against the recommended daily dose stated on the pack.
Three things the percentage is not
It is not a personal target. The NRV is a population-level labelling benchmark for an average adult. It is not a calculation of what any individual needs, which varies with diet, circumstances and stage of life. Reference values are deliberately framed as reference points rather than prescriptions.
It is not a maximum. The figure that sets an upper boundary is a different one — the tolerable upper intake level, assessed by the European Food Safety Authority, and reflected in NHS guidance. For vitamin D, for example, NHS guidance states that adults should not take more than 100 micrograms (4,000 IU) a day. That ceiling is unrelated to the 5 µg NRV; they answer different questions.
It is not a measure of quality. A high percentage means a larger amount relative to a reference figure — nothing more. Whether that amount is appropriate for a given person is a question for them and their healthcare professional, not something the percentage itself answers.
Why some figures look very large
This is where the NRV catches people out. Because the labelling NRV for vitamin D is small (5 µg), the percentage rises quickly with dose. A supplement providing 100 µg of vitamin D — that is 4,000 IU — shows 2,000% NRV. The figure is arithmetically correct, but it reflects the size of the reference point, not a suggestion to aim high.
It also illustrates why the NRV should not be read as a recommendation. The NHS recommends that adults consider a daily supplement of 10 micrograms (400 IU) of vitamin D during autumn and winter — itself double the 5 µg labelling NRV — while setting the adult upper limit at 100 micrograms. Three different numbers, three different purposes: the NRV standardises the label, the NHS recommendation reflects dietary guidance, and the upper limit marks the ceiling for adults. Reading any one as a stand-in for the others is the common mistake.
The 15% rule, and why claims appear
There is one more reason the NRV matters: it governs when a nutrient can be named in a claim at all. The legislation defines a "significant amount" of a vitamin or mineral as, broadly, 15% of its NRV — assessed per recommended daily dose in the case of a food supplement. A product has to provide at least that significant amount before it can carry an authorised claim about the nutrient.
This is the link between the percentage column and the claims you read elsewhere on the pack. Because the relevant nutrients meet the threshold, a formula can state, in the wording authorised on the Great Britain Nutrition and Health Claims Register, that vitamin D contributes to the maintenance of normal bones, that vitamin K contributes to the maintenance of normal bones, that calcium is needed for the maintenance of normal bones and teeth, and that vitamin C contributes to the normal function of the immune system. The claim attaches to the named nutrient, and the amount on the label is what entitles the product to make it.
Reading it in practice
Three numbers, in order. The amount per serving, in the correct unit — micrograms (µg) for vitamins D and K, milligrams (mg) for vitamin C and calcium. The percentage, which you now know is read against the NRV for vitamins and minerals. And the serving size — how many capsules or tablets that amount refers to, since a "per serving" figure can mean one capsule or several. A transparent panel gives you all three plainly enough to do the comparison yourself.
Where Nutriluxe sits
The Nutriluxe formulation lists each nutrient with its amount per capsule and the percentage figure shown against it, in the correct units, so the panel can be read exactly as described here. The formula is deliberately short — vitamin D3, vitamin K2 as MK-7, calcium and vitamin C, without unnecessary fillers — and made in the UK in a HFMA GMP-certified facility in small batches. The vitamin D content of 100 µg (4,000 IU) sits at the adult upper limit referenced in NHS guidance above; whether that or any supplement is appropriate for you is a decision for you and your GP or pharmacist. Food and a balanced diet come first; supplementation is one option to consider alongside them.
You can see the full panel and per-serving amounts on the Vitamin D3 + K2 MK-7 product page.
References
- The Provision of Food Information to Consumers — assimilated Regulation (EU) No 1169/2011, Annex XIII (Reference Intakes; Nutrient Reference Values for vitamins and minerals; significant amount). legislation.gov.uk. https://www.legislation.gov.uk/eur/2011/1169/annex/XIII/data.xht
- NHS. Vitamin D. Vitamins and minerals. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
- Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. GOV.UK. https://www.gov.uk/government/publications/great-britain-nutrition-and-health-claims-nhc-register
- European Food Safety Authority. Scientific opinion on the tolerable upper intake level of vitamin D. EFSA Journal 2012;10(7):2813.
This article is for general information and educational purposes only. It does not constitute medical, nutritional, or professional health advice, and should not replace consultation with a qualified healthcare professional. Always speak to your GP, pharmacist, or a registered healthcare practitioner before starting any supplement, particularly if pregnant, breastfeeding, taking medication, or with an existing medical condition. Food supplements are not intended to diagnose, treat, cure, or prevent any disease, and are not a substitute for a varied and balanced diet and a healthy lifestyle. Do not exceed the recommended daily dose. Keep out of reach of young children. Health claims relate to the named nutrients as authorised on the Great Britain Nutrition and Health Claims Register. Information is accurate at the time of publication; guidance may change. Nutriluxe accepts no liability for any action taken on the basis of this content.