Synthetic Dyes

Petroleum-derived colourings added to foods, medicines, and cosmetics to make them look brighter. They have evocative names in the US system — Red 40, Yellow 5 — and chemical or trade names elsewhere. They aren't necessary nutritionally; they're there to make products look more appealing, especially to kids.

Pure marketing. Brightly-coloured cereal, sweets, and drinks sell better than dull-coloured ones, especially to children. They're cheap, stable, and produce more intense colours than natural sources.

FD&C Red 3 (now banned in US food), Red 40 (Allura Red AC), Yellow 5 (tartrazine), Yellow 6 (Sunset Yellow), Blue 1 (Brilliant Blue), Blue 2 (Indigo Carmine), Green 3. In Europe, you might see E102 (Yellow 5), E110 (Yellow 6), E124 (Ponceau 4R), E122 (Carmoisine), E104 (Quinoline Yellow), E129 (Allura Red). 'Artificial colours' or 'colour' on ingredient lists.

Brightly-coloured kids' foods are the main place: breakfast cereals, fruit-flavoured drinks, sweets, gummies, sports drinks, frozen desserts, baking sprinkles. Also in some children's medicines and toothpastes.

Almost entirely through food and drink. Cosmetic dyes contribute a much smaller amount via skin contact.

No strong evidence of pregnancy-specific harm at typical exposures. Reducing intake during pregnancy is a low-cost precaution but not high-priority.

No documented fertility concerns at typical exposure.

This is the main concern group. The 2007 'Southampton study' linked a mix of six synthetic dyes (plus sodium benzoate) to increased hyperactivity in some children — this is what triggered the EU warning label requirement. Not all kids react. The kids who do, do meaningfully. If you have a child who's struggling with attention or seems to react after sweets and brightly-coloured snacks, a dye-free trial is worth running.

No specific concerns.

Red 3: FDA banned it in food in 2025 based on animal studies showing thyroid cancer at high doses. Other dyes: behavioural effects in some children are real (Southampton study, EU response, subsequent meta-analyses), though disputed in size. California's OEHHA released a 2021 report concluding synthetic food dyes can cause adverse neurobehavioural effects in children. The cancer concern is largely confined to Red 3.

Low to moderate for adults at typical exposure. Worth taking seriously for kids — not because every child reacts, but because the kids who react can react significantly, and it's easy to test.

Foods coloured with fruit and vegetable extracts (beet juice, turmeric, paprika, annatto, carrot). Many mainstream cereal and snack brands have already removed synthetic dyes from their EU formulations but still use them in North America — same brand, different formula. Worth checking when shopping internationally.

Very easy with label reading. Most dye-free alternatives exist in every category.

Look at the snacks and drinks your kids consume most often. If you see Red 40, Yellow 5, Yellow 6, or Blue 1 prominently, swap to a dye-free version of the same category for two weeks. Often unmissable difference in some kids; nothing in others.

For most adults: low priority. For families with kids — especially kids with attention or behaviour challenges — one of the easier 'experiments' to run. Cheap, reversible, immediate feedback.

FDA on food colour additives, California OEHHA report on synthetic food dyes and neurobehavioural effects, EFSA opinions on individual dyes. See References below.