FD&C Blue #2

What is FD&C Blue #2?

FD&C Blue #2 is a synthetic dye used in food, ingested drugs, and sutures in both the US and Europe (1).

It was originally made from indigo extracted from plants (one of the first natural plant dyes discovered) but is now mostly produced synthetically (2).

Other names for FD&C Blue #2:

  • Indigo carmine
  • Indigo blue
  • Indigotine
  • E132 (Europe)

Processed foods that may contain FD&C Blue #2:

  • Baked goods
  • Candy
  • Cereal
  • Drinks
  • Ice cream
  • Pet food

Products that may contain FD&C Blue #2:

  • Breath mints
  • Makeup
  • Medications
  • Mouthwash
  • Shampoo
  • Shave gel
  • Soap
  • Supplements
  • Toothpaste

How is FD&C Blue #2 absorbed and metabolized?

Rat studies suggest that only 3% of FD&C Blue #2 is absorbed in the small intestine. Most of it remains unabsorbed and is excreted in the stool (3).

Very little FD&C Blue #2 is absorbed through intact skin, but absorption is increased significantly when skin is irritated by chemicals like SLS (4).

Is there a maximum amount of FD&C Blue #2 allowed per day?

The FDA has declared an acceptable daily intake level (ADI) of no more than 2.5 mg/kg body weight per day.

Can people have adverse reactions to FD&C Blue #2?

There has been one report of asthma caused by FD&C Blue #2 exposure in the workplace (their job was grinding and mixing food dyes, including Blue #2) (5).

While human studies are lacking, animal studies suggest that FD&C Blue #2 may inhibit mitochondrial function if it is absorbed (6).

Animal studies show that very high doses (over 1,000 mg/kg/day) are not life-threatening in the short or long term, but may cause slight anemia (78).

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