Effects of non-toxic doses of various food additives on the structure of mammalian retina: Investigation by mid-infrared spectroscopy

Potential health effects of food additives have captured the interest of both public and scientific community because of the controversy regarding their side effects, and in particular their possible role in vision impairment. In this study we analyzed the effects of ingestion of non-toxic doses of tartrazine, carmoisine, sodium benzoate and their mixture on rat’s retinae using mid-infrared spectroscopy after 45 days and 90 days of ingestion. The resulted infrared spectra were statistically evaluated to clarify the relationship between the ingestion periods of the food additives and their effects on retinal structure. The obtained spectra after ingestion of food additives either separately or their mixture were different than the control spectra. Regarding the lipid moiety of retinal membranes, there are changes in lateral packing of the fatty acyl chains while; lipid chain length and branching were different in food additives groups than the control ones. Several modifications in proteins secondary structure were accompanying food additives ingestion, more specifically the detection of β-turns. The effect was obvious in the mixture group where, retinal proteins structure is dominant by β-sheet. Multivariate analysis indicates that there is a reverse relationship between the biological effects of tartrazine, carmoisine and the food additives mixture and the ingestion periods. Paradoxically, this is in contrast to the effects of sodium benzoate. The present study indicates that there is a positive, confirmed relationship between the ingestion of food additives and the changes in both lipids and proteins of the retina, this will affect its function and consequently, vision.