Occurrence of azo food dyes and their effects on cellular inflammatory responses

Objectives: The aim of this study was to examine the occurrence of five azo food dyes-tartrazine, sunset yellow, carmoisine, allura red, and ponceau 4 R-in the food supply chain of Singapore and their effects on the in vitro synthesis of leukotriene B₄ (LTB₄) and F₂-isoprostanes.

Methods: Trained personnel recorded the names of foods and beverages sold in a local supermarket that contained at least one of the five azo dyes. The occurrence of the azo dyes in the local food supply was computed. The synthesis of LTB₄ and F₂-isoprostanes from freshly isolated blood neutrophils were measured using gas chromatography-mass spectrometry.

Results: Of the 1681 processed food items, 194 (11.54%) contained at least one of the five azo dyes. Tartrazine was most prevalent in food and beverage products sold in Singapore, followed by allura red, sunset yellow, ponceau 4 R, and carmoisine. The five azo dyes augmented the in vitro synthesis of LTB₄ and F₂-isoprostanes from blood neutrophils. Tartrazine was significantly more potent in increasing LTB₄ synthesis than the other dyes, which exhibited similar potencies. The five food dyes increased the formation of F₂-isoprostanes from blood neutrophils at all tested concentrations.

Conclusion: The high prevalence of azo dyes in the food supply of Singapore and their ability to elicit proinflammatory responses in vitro suggest a potential health risk to the local population.