How to Read Nutrition Labels in the UK: Your Complete Guide

November 24, 2025 •

3 min read

According to NHS guidance, food labels are an essential tool for understanding the nutritional content of what you eat, helping you to make healthier choices. This complete guide will teach you how to read nutrition labels in the UK, equipping you with the knowledge to make informed decisions about your diet and health.

Quick Summary

Decipher UK food packaging by learning to understand the traffic light system, interpret nutritional information tables, and find allergen information to make healthier choices for you and your family.

Key Points

Traffic Light System: Quickly assess a food's fat, saturated fat, sugar, and salt levels using the red (high), amber (medium), and green (low) colours on the front of the pack.
Check 'Per 100g': For accurate comparison between similar products, ignore varying portion sizes and focus on the standardized nutritional values given 'per 100g' or 'per 100ml'.
Reference Intakes (RIs): Understand that the % RI figures show how much a portion contributes to an average adult's recommended daily limit, providing context for your overall diet.
Ingredients List Order: Remember that ingredients are listed by weight, so the first few items make up the bulk of the product. Be mindful of sugar's many aliases.
Allergen Emphasis: Look for bolded or otherwise emphasised allergens within the ingredients list, as this is a legal requirement in the UK, especially under Natasha's Law for PPDS foods.
Dates and Claims: Differentiate between 'Use by' (safety) and 'Best before' (quality). Be sceptical of marketing claims like 'low-fat' and always check the nutritional panel for the full truth.

Understanding the UK Traffic Light System

Many pre-packaged food products in the UK feature a colour-coded 'traffic light' system on the front of the pack. This voluntary labelling scheme offers a quick, at-a-glance guide to a product's fat, saturated fat, sugar, and salt content. Choosing products with more green and amber lights and fewer red ones is a simple way to opt for healthier options.

Green: Low. The product is low in this nutrient. The more green lights, the healthier the choice.
Amber: Medium. The product contains a medium amount of this nutrient. Having these foods most of the time is generally fine.
Red: High. The product is high in this nutrient. These foods should be consumed less often and in smaller quantities.

The traffic light criteria is based on the amount of a nutrient per 100g of the product. The exact values that define high, medium, and low differ slightly depending on the nutrient.

Deciphering the Nutritional Information Panel

Behind the pack, you'll find the mandatory nutritional information panel, a table that provides detailed values for energy (calories), fat, saturated fat, carbohydrates, sugars, protein, and salt. This is where the real detail lies, allowing for direct, comparable analysis between products.

Per 100g or 100ml: This is the standard measurement unit used for comparison. To compare two similar items, always look at the 'per 100g' column to ensure a fair assessment, as serving sizes can vary between brands.
Per portion: Many labels also provide values 'per portion'. Be aware that the manufacturer's suggested portion size may differ from your own.
Reference Intake (RI): This is a guideline for the daily amount of nutrients and energy needed for a healthy diet, based on an average adult woman. The label often shows the percentage of the RI that a portion contributes, providing context for how a food fits into your overall diet. RIs are a guide, not a strict target, as individual needs vary.

The All-Important Ingredients List

The ingredients list provides the ultimate transparency into a product's composition. In the UK, ingredients must be listed in descending order of weight, meaning the primary components appear first. If you see sugar, fat, or salt near the top of the list, it indicates a high proportion of that ingredient. It’s also crucial to remember that sugar has many different names (e.g., maltose, sucrose, cane syrup), and recognising these can help you spot hidden sugars.

Key Regulations: Allergens and Date Marks

Allergen Information: UK food law requires the 14 major allergens to be clearly highlighted in the ingredients list using a contrasting font, style, or colour, typically bolding. This is critical for individuals with allergies. For prepacked foods for direct sale (PPDS) like sandwiches made in-store, Natasha's Law now mandates a full ingredients list with allergens emphasised. Precautionary statements like 'May contain…' are used where cross-contamination is a risk.
Date Marks: A 'Use by' date relates to food safety and is for highly perishable items; eating food after this date can be unsafe. A 'Best before' date refers to food quality; while it may not taste as good after this date, it is generally still safe to eat if stored correctly.

Decoding Common Food Claims

Marketers use various claims to position products as healthier, but these can be misleading. For example, a 'low-fat' product might be high in sugar to compensate for flavour, or a 'natural' product could still be highly processed. Always check the nutrition panel and ingredients list to get the full picture, rather than relying on claims alone.

Comparison Table: High vs. Low Criteria per 100g


Nutrient	High (Red)	Low (Green)
Fat	More than 17.5g	3g or less
Saturated Fat	More than 5g	1.5g or less
Sugars	More than 22.5g	5g or less
Salt	More than 1.5g	0.3g or less

Conclusion: Empowering Your Healthy Choices

Mastering how to read UK nutrition labels is a simple yet powerful skill that puts you in control of your diet. By understanding the front-of-pack traffic lights, the detailed back-of-pack panel, and the ingredients list, you can move beyond marketing claims and make choices that genuinely benefit your health. Always compare products using the per 100g column for accuracy and never overlook the allergen information. With this knowledge, you are well-equipped to navigate the supermarket aisles with confidence.

For more detailed guidance and the latest information on food labelling regulations, it is always recommended to consult official sources like the UK's Food Standards Agency (FSA) website.

Frequently Asked Questions

A red traffic light indicates that the food is high in a particular nutrient, such as fat, saturated fat, sugars, or salt. These are foods that should be consumed less often and in smaller quantities.

To make a fair comparison, you should always use the 'per 100g' or 'per 100ml' column on the nutritional information panel, as this standardises the values regardless of different portion sizes suggested by manufacturers.

Reference Intakes are a guide to the approximate daily amounts of nutrients and energy an average adult needs for a healthy diet. They provide context for how a single food product contributes to your overall daily intake but are not individual targets.

UK law requires that any of the 14 major allergens used as ingredients must be emphasised within the ingredients list, typically in bold text. For 'prepacked for direct sale' foods, a full list is now mandatory.

A 'use by' date relates to food safety and must be followed, especially for perishable goods. A 'best before' date relates to food quality; the food may still be safe to eat after this date, but its taste or texture might have declined.

Food regulations in the UK mandate that ingredients are listed in descending order of weight. This provides transparency by showing you the main components of the product first, indicating its overall composition.

No. While legally defined, these claims can sometimes be misleading. A 'low-fat' product might be high in sugar, and a 'sugar-free' item could use other additives. Always check the full nutritional table and ingredients list.