What is a nutrition label?

A legal document with a fixed order: what the food information rules require on a nutrition label, the seven lines and their sequence, the per-100-gram basis and why it exists, and what is optional

What is a nutrition label is a question most people would answer by pointing at the box of numbers on the back of a packet, and the box is the right place to point; what it is, though, is a legal document whose contents and order are set by the food information rules, and knowing that it is a document with a fixed form changes how it is read. The rules require most prepacked foods sold in the UK to carry a nutrition declaration, and the declaration has seven mandatory items in a mandatory order: energy, in kilojoules and kilocalories; fat; of which saturates; carbohydrate; of which sugars; protein; and salt. The order is not the manufacturer's choice, it is the same on every packet, which is why a person who has read one panel can read every panel without searching, and why a panel that lists them in a different order or leaves one out is a panel that has broken a rule rather than made a design decision.

The basis is per 100 grams or per 100 millilitres, and that too is mandatory, for a reason that is the whole point of the document: a figure per 100 grams makes any two foods comparable regardless of how big their portions are or how the manufacturer defines a portion. A cereal with a thirty-gram serving and a cereal with a forty-five-gram serving look different per serving and identical per 100 grams if they are the same cereal, and the per-100-gram column is the one that cannot be gamed by shrinking the portion. A manufacturer may add a per-portion column, and may add the percentage of the adult reference intake that a portion supplies, and both are useful, but both are optional, and a buyer who compares two foods compares them on the column the law requires.

Beyond the seven lines, a manufacturer may voluntarily declare more: monounsaturates and polyunsaturates, polyols and starch, fibre, and any vitamin or mineral present in a significant amount, each in its set place in the order. The front-of-pack colours, the red, amber and green of the traffic-light scheme, are voluntary too, with set thresholds per 100 grams for each colour, so that a pack without colours has broken no rule and a pack with them has applied a public scheme rather than its own. Two parts of the packaging are not the nutrition label but are read beside it: the ingredients list, in descending order of weight, with the allergens emphasised, and the best-before or use-by date. Those two the food and the supplement share, which is the one place the two documents meet, and a buyer who reads nothing else on a pack reads those two, because the allergens are a safety matter and the ingredients list in descending order is the honest account of what the pack is made of, which the front of the pack is not written to give.

The food's document set out in its fixed form, with the supplement's document that looks alike and is not, how each is read, the parts they share, the worked example read as the second document and the verdict in the next section.

The document that looks alike and is not: why a food supplement carries no nutrition declaration and declares per daily dose against the reference value instead, how each document is read, the parts both share, the worked example, and the verdict

A food supplement's label looks like a nutrition label and is a different document under a different rule. The nutrition declaration of seven lines per 100 grams is not required on a food supplement, and is usually absent, because a supplement is not eaten by the hundred grams and its energy, fat and salt are not what anyone buys it for. What the supplement regulations require instead is a declaration of each vitamin, mineral or other substance per daily dose as recommended on the label, in the units set for it, and, for vitamins and minerals, as a percentage of the nutrient reference value, with the recommended daily dose stated, the warning not to exceed it, and the statement that a supplement is not a substitute for a varied diet. The basis is the dose, not the hundred grams, and the comparison figure is the reference value, not another food.

So the two documents are read differently, and reading one by the other's rules is the commonest mistake a buyer makes. A food's nutrition label is read for its seven lines per 100 grams, with the thresholds that sort fat, saturates, sugars and salt into high and low, and with protein and fibre read for what the plate needs; the per-portion column is read second and the colours third. A supplement's label is read for the dose of each nutrient against two numbers, the reference value, which the label prints as a percentage and which says how the dose compares with the population's daily reference, and the upper level, which the label does not print and which says whether the dose is a correction or an excess; a supplement with a vitamin at several hundred percent of the reference value has not told the buyer whether that is fine, since the two numbers differ by nutrient, and the buyer looks the upper level up. The parts the two documents share are the ingredients list, read on a supplement for the form of each nutrient and the excipients after the active, and the allergens, emphasised on both; the one figure that moves between the documents is energy, which a protein powder, being a food in dose form, often declares on both bases.

The worked example is read as the second document: {FL} carries no seven-line nutrition declaration, because it is a food supplement and none is required, and declares what the supplement rules require: magnesium at 300mg elemental per daily dose of two capsules, stated as 80% of the nutrient reference value, from 1500mg of magnesium bisglycinate, with the recommended dose, the warning and the varied-diet statement on the label; its ingredients list reads magnesium bisglycinate, the HPMC capsule shell and rice flour, two excipients after the active; and its dose is read against the supplemental upper level for magnesium, which it sits below. It is batch tested for lead, mercury, arsenic and cadmium, UK made under GMP and BRC, 180 capsules for £19.99 at 22p a day. The full label breakdown is here.

The verdict: a nutrition label is a legal declaration in a fixed order, energy, fat, saturates, carbohydrate, sugars, protein and salt, per 100 grams or millilitres so that any two foods compare, with the per-portion column, the reference-intake percentages and the front-of-pack colours optional additions to it. A food supplement's label is a different document that looks alike, with no nutrition declaration and each nutrient declared per daily dose as a percentage of the reference value, read against the upper level the label does not print. The ingredients list and the allergens are where the two meet, and a buyer who knows which document is in their hand reads it by the right rules.

What to check on the label

Questions people also ask

What information is on a nutrition label?

Seven mandatory items in a mandatory order under the UK food information rules, energy in kilojoules and kilocalories, fat, of which saturates, carbohydrate, of which sugars, protein and salt, each per 100 grams or 100 millilitres so that any two foods can be compared regardless of portion size; a manufacturer may add a per-portion column, the percentage of the adult reference intake a portion supplies, extra nutrients such as fibre or a vitamin present in a significant amount, and the voluntary front-of-pack colours, and beside the label sit the ingredients list in descending order with allergens emphasised and the date.

Why are nutrition labels per 100g?

Because per 100 grams is the one basis that cannot be gamed by the portion: a figure per 100 grams makes two foods directly comparable whatever their serving sizes and however the manufacturer defines a serving, so that two cereals with different stated servings read identically per 100 grams if they are the same cereal and differently if they are not; the per-portion column is optional and useful for a single food eaten in a known amount, but comparison between foods is done on the column the law requires, and the front-of-pack colours use thresholds set per 100 grams for the same reason.

Do supplements have nutrition labels?

Not the seven-line declaration, which is not required on a food supplement and is usually absent, because a supplement is not eaten by the hundred grams; what the supplement regulations require instead is each vitamin, mineral or other substance declared per daily dose as recommended on the label, in its set units, and for vitamins and minerals as a percentage of the nutrient reference value, with the recommended dose, a warning not to exceed it and a statement that a supplement is not a substitute for a varied diet; a protein powder, being a food in dose form, often carries both, and a buyer reads each document by its own rules.

What does the percentage on a supplement label mean?

The percentage of the nutrient reference value that the daily dose supplies, which is a comparison with the population's daily reference for that vitamin or mineral and not a verdict on whether the dose is right: a dose at 80% of the reference value is a dose near the daily reference, and a dose at several hundred percent is well above it, which may be a correction for a measured shortfall or an excess, depending on the nutrient's upper level, which the label does not print and which differs widely between nutrients; the percentage is read first and the upper level is looked up second before a high figure is taken as either good or bad.

How do I read this site's magnesium label?

As a supplement's document rather than a food's: it carries no seven-line nutrition declaration because none is required, and declares magnesium at 300mg elemental per daily dose of two capsules, stated as 80% of the nutrient reference value, from 1500mg of magnesium bisglycinate, with the recommended dose, the warning not to exceed it and the varied-diet statement; the ingredients list reads magnesium bisglycinate, the HPMC capsule shell and rice flour, two excipients after the active, and the dose is read against the supplemental upper level for magnesium, which it sits below; it is batch tested for four metals, UK made under GMP and BRC, 180 for £19.99 at 22p a day.

Sources

1. The retained Food Information to Consumers regulation: the mandatory nutrition declaration for foods, its fixed order of energy, fat, saturates, carbohydrate, sugars, protein and salt per 100g, and its rules on portion information, with supplements declaring nutrients per daily dose against nutrient reference values. https://www.legislation.gov.uk/eur/2011/1169/contents
2. The Food Supplements (England) Regulations 2003 (food supplements are regulated as foods in the UK). https://www.legislation.gov.uk/uksi/2003/1387/contents/made
3. The UK and EU guidance on tolerances for nutrition declarations: declared values may deviate from measured values within published tolerance bands, macronutrients by roughly 20% and vitamins and minerals in food supplements by roughly 20% below to 50% above the declared value, with rounding rules for each nutrient. https://www.food.gov.uk/business-guidance/nutrition-labelling
4. Retained Regulation (EC) No 1924/2006 on nutrition and health claims made on foods, and the Great Britain nutrition and health claims register. https://www.gov.uk/government/publications/great-britain-nutrition-and-health-claims-nhc-register

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