Synthetic Food Dyes and Colorectal Cancer: Is There a Link?

Medscape Staff

December 10, 2021

What are the health effects of the dyes used to make food more colorful? A pharmaceutical researcher examines the evidence in time for the holidays.

What to know:

  • The standard American diet ― 60% of which is made of ultraprocessed foods like sweets, soft drinks, and processed meats ― is associated with an increased risk of colorectal cancer.

  • There is some evidence that the artificial dyes used in these foods, from candy canes and cookies to salmon and ham, may be contributing to that risk, according to Lorne J. Hofseth, PhD, the director of the Center for Colon Cancer Research at the University of South Carolina.

  • Currently, nine synthetic dyes are approved for use in food by the US Food and Drug Administration. Fewer are approved in the EU, and none are classified as carcinogens.

  • However, evidence suggests that gut bacteria can break down the dyes into molecules that can cause cancer. Studies have also shown that synthetic dyes can stimulate inflammation, which when extended over long periods can damage otherwise healthy cells.

  • Unpublished research by Hofseth and his colleagues suggests that approved dyes like Red 40 and Yellow 5 can cause DNA damage in colon cancer cells in vitro with increased dosages and length of exposure, though the results have yet to be replicated in animal and human models.

This is a summary of the article, "Colorful Sweets May Look Tasty, but Some Researchers Question Whether Synthetic Dyes May Pose Health Risks to Your Colon and Rectum," published The Conversation on December 10. The full article can be found on

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