Inability of red beet betalain pigments to initiate or promote hepatocarcinogenesis

A short-term bioassay was used to determine the ability of red-beet betalain pigments to initiate or promote hepatocarcinogenesis in rat liver. Female Sprague-Dawley rats were partially hepatectomized and separated into nine groups (6-11 animals/group). Four of the groups were treated with betacyanin pigment preparations (betacyanin solution after fermentation, 50 mg/kg; pure betanin, 50 mg/kg; degraded betanin, 50 mg/kg; a betacyanin diet containing 2000 ppm/kg) to evaluate their ability to initiate hepatocarcinogenesis. N-Nitrosodiethylamine (NDEA: 10 mg/kg) was used for the positive control. Another group, previously initiated with NDEA, received daily a betacyanin solution (100 ppm; 3.5 mg/rat/day) to determine the pigment's ability to promote NDEA hepatocarcinogenesis in comparison with positive and negative controls treated respectively with and without a promoting agent (0.5% phenobarbital in the diet). Animals were killed after month 6 (promotion test) or 8 (initiation test). Liver sections were stained with haematoxylin and eosin and for gamma-glutamyl transpeptidase (GGT) activity. The number of enzyme-altered foci and the percentage of liver volume so affected, were determined for each group, by scoring for GGT. Comparison of the results obtained for the experimental groups with those for positive and negative control groups indicated that the betacyanin pigments tested in this assay did not initiate or promote hepatocarcinogenesis in rat liver. These findings provide further evidence that betalain colourants may be viable alternatives for synthetic dyes currently used as food additives.