As a volunteer for TEACH, I often find my hands stained with the food coloring used for an experiment. After a few days of scrubbing my hands, I find myself concerned with the potential health dangers of a food additive that stains my hands for so long. Besides the fact that foods with added food coloring are generally unhealthy to begin with, some scientists have also proposed that they are genotoxic. Genotoxic chemicals can cause mutations in the DNA sequence, which can lead to cancer.
It is important to distinguish between natural food coloring, which is generally considered to be safer, and artificial food coloring, which is more controversial. Each can potentially carry its own risks. Though the most dangerous colors are not allowed to be used in the United States, many of the ones that are used may be genotoxic.
Two researchers from the University of California reviewed the research on nine food dyes that are approved by the FDA and used in the United States. The authors of the study noted that the dye Yellow 5 was clearly genotoxic, as proven by microbiological and rodent studies. The other dyes also caused serious safety problems, including cancer and hypersensitivity reactions (Kobylewski and Jacobson, 2012).
Some research seems to suggest that a by-product of caramel may be also be carcinogenic. The process for forming caramel coloring, which is added to many soft drinks, can also form 4-Methlimidazole, a known carcinogen (Norozadeh et al., 2015). In a study performed at Cukurova University, mice were exposed to 4-methylimidazole and their bone marrow cells were examined for chromosomal aberrations and for unusual rates of cells undergoing mitosis at one time (mitotic index). Significantly more chromosomal aberrations were found in the mice and decreases in their mitotic index were observed. This research indicates that this compound found in caramel coloring is genotoxic (Norozadeh et al., 2015).
Research was also done to compare the effects of various concentrations of different dyes. Amaranth, patent blue, carminic acid, indigotine, and erythrosine colors were tested on Drosophila melangaster. This study utilized the Somatic Mutation and Recombination Test (SMART) (Sarikaya et al., 2012). In this test, an experimental group of Drosophila melangostar larvae are exposed to a foreign compound while the control group is exposed to distilled water. The compound is mutagenic if single mosaic spots are noted on the wing blade of adult fruit flies (Graf et al., 1984). Carminic acid and indigotine both consistently had negative results, indicating that they were not genotoxic. Erythrosine was inconclusive and further studies are required to determine if it is genotoxic. The 25 mg/mL concentration of patent blue showed positive results, indicating that it was mutagenic. Additionally, the 12.5 mg/mL, 25 mg/mL, and 50 mg/mL concentrations of amaranth all showed positive results, indicating that they spurred mutations (Sarikaya et al., 2012).
Research performed in French universities seems to suggest that food coloring may not be genotoxic. One particular study examined the effect of amaranth, sunset yellow, and tartazine colors in mice. Genotoxicity was measured through the micronucleus gut assay (Poul et al., 2009). In this test, cells in the duodenum and colon were examined to see if there was micronucleus formation after a foreign compound was introduced (Coffing et al., 2011). No genotoxic affects were detected by the micronucleus gut assay (Poul et al., 2009).
A study done through the National Institute of Health Sciences in Japan noted that Allura Red AC, a synthetic food dye, is not genotoxic. Researchers exposed live mice to the food dye and used comet assays, micronucleus tests, and transgenic mutation assays to detect genotoxicity. Mice were exposed to one of three concentrations of Allura Red AC, or were used as positive or negative controls. The results for this study show that there does not seem to be any genotoxicity stemming from the ingestion of Allura Red AC (Honma., 2015).
In sum, scientists are not in agreement about the genotoxicity of food coloring. It is clear that different types of food coloring carry different risks. The research implies that natural food coloring generally contains less toxicity risk than artificial food coloring, though specific colors may still pose problems. However, even within artificial dyes, contrasting results make it difficult to evaluate the risks. Further research must be done to come to clearer conclusions. In general, the FDA does not allow the most blatantly genotoxic colors to be used in the United States. As with everything, food coloring should only be ingested in moderation. Keep calm and snack on.
Bibliography:
Coffing, S., Engel, M., Dickinson, D., Thiffeault C., Spellman R., Shutsky T., Schuler M., 2011, The rat gut micronucleus assay: a good choice for alternative in vivo genetic toxicology testing strategies., Environ Mol Gen 54:269-279.
Graf, U., Würgler, F., Katz A., Frei H., Juon H., Hall C., Kale P., 1984, Somatic mutation and recombination test in Drosophila melanogaster., Environ Mutagen 6:153-188.
Honma, M.., 2015, Evaluation of the in vivo genotoxicity of Allura Red AC (Food Red No. 40), Food and Chemical Toxicology 84:270-275.
Kobylewski, S., Jacobson, M., 2012, Toxicology of food dyes, Int J Occup Environ Health 18: 220-246.
Norizadeh, M., Topaktas, M., Yilmaz, M., 2015, Assessment of chromosomal aberration in the bone marrow cells of Swiss Albino mice treated by 4-methylimidazole, Drug Chem Toxicol 4:1-5.
Poul, M., Jarry, G., Elhkim, M., Poul, J., 2009, Lack of genotoxic effect of food dyes amaranth, sunset yellow and tartrazine and their metabolites in the gut micronucleus assay in mice, Food and Chemical Toxicology 47: 443-448.
Sarıkaya, R., Selvi, M., Erkoç, F., 2012, Evaluation of potential genotoxicity of five food dyes using the somatic mutation and recombination test, Chemosphere 88: 974-979.