Vegetable concentrates interact with canthaxanthin to affect carotenoid bioavailability and superoxide dismutase activity but not immune response in rats

We examined tomato paste and dried spinach powder as dietary sources of lycopene and lutein and determined their interactions with canthaxanthin (CX) in water-soluble beadlets. Mature male rats, 10/group, were fed a basal diet containing 16% fat and 2 g per kg CX from beadlets (+CX) or placebo beadlets (-CX) for 8 weeks. Tomato paste or spinach powder was added to each of these diets at 0, 5 (low tomato, low spinach) and 15% (w/w) (high tomato, high spinach). The low and high levels of tomato paste and spinach powder contained 0.03 and 0.09 g lycopene and 0.02 and 0.06 g lutein per kg of diet, respectively. CX was detected in liver and plasma. High tomato decreased liver CX concentrations 5-fold and plasma CX 2-fold; low tomato had no effect. Liver lycopene concentrations increased as the concentration of tomato paste increased in the diet. However, feeding CX dramatically decreased liver lycopene concentrations. Feeding high tomato and no CX lowered liver superoxide dismutase activity. Neither dietary carotenoids nor CX treatment altered mitogenic response of splenic mononuclear cells to concanavalin (Con A) or lipopolysaccharide (LPS). These data from rats illustrate how a carotenoid-rich food may influence the bioavailability of a carotenoid supplement. Likewise, supplementation with a single purified carotenoid may antagonize the bioavailability of carotenoids in food matrices.