How to read food labels: traffic light colours, per 100g figures and salt

What do the traffic light colours mean?

Front-of-pack labels show whether a product is high, medium or low in fat, saturates, sugars and salt. Red means a high level of that nutrient, amber means medium and green means low. Guidance suggests choosing products with more green and amber and fewer red. Energy, shown in kilojoules and kilocalories, is not colour-coded.

Should products be compared per 100g or per portion?

The colours are mainly based on the amount in 100g or 100ml of the food. Using the per 100g column makes it easier to compare the nutrient content of similar foods. Portion sizes are chosen by manufacturers and can differ, so per portion figures may not be comparable between products. A serving can be as small as one biscuit, so eating two means doubling the figures.

What are reference intakes?

The percentages on front-of-pack labels are based on guidelines for how much of each nutrient and how much energy an average adult needs in a day. They show how much of that daily amount one portion supplies. Where a label has no colour coding, comparing the percentage of the reference intake in a portion is another way to compare foods.

How is salt shown on a label?

Some labels give sodium rather than salt, and the NHS says multiplying the sodium figure by 2.5 gives the amount of salt. The NHS describes a food as high in salt when it has more than 1.5g of salt per 100g, and low when it has 0.3g or less per 100g. The NHS advises adults to have no more than 6g of salt a day.

Are these labels compulsory?

Government guidance describes front-of-pack nutrition labelling in the UK as voluntary. The nutrition table on the back of the pack is mandatory. Labels therefore differ between products, and the per 100g figures are the common point of comparison.