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Last week, the Food and Drug Administration announced a ban on a food dye called Red No. 3, which has been linked to cancer in animal studies.

The news comes on the heels of a bill that California Gov. Gavin Newsom signed in September that bans six other food dyes from school cafeteria menus, largely over concerns that the dyes could cause behavior problems in kids. Meanwhile, Robert F. Kennedy Jr., President Donald Trump’s pick to run the Department of Health and Human Services, has also singled out dyes, pledging in October to “tell the cereal companies: Take all the dyes out of their food.”

All this can be confusing, even for people who consider themselves reasonably savvy consumers of food and science news (read: me). Do we need to throw out all our Ring Pops? Why is RFK Jr., noted vaccine skeptic and leader of the Trumpian “Make America Healthy Again” movement, on the same side as Newsom, a vocal Trump opponent, and some very mainstream epidemiologists and public health experts? Let’s break it all down.

What does the science say about food dyes?

Synthetic food dyes are liquids or powders added to foods and drinks to make them look cool; nine are currently in use in the US (it’ll be eight when the Red No. 3 ban takes effect in 2027). The dyes show up in everything from Doritos to pickles — RFK Jr. has been especially critical of Froot Loops.

To understand the controversy around these ingredients, it helps to understand the history of........

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