Carotenoids are chemical responsible for some of the orange, red and yellow colours seen in fruit and vegetables. In plants they are vital compound that aid electron transport in photosynthesis and protect the plant tissues from the singlet oxygen. This antioxidant actions can be useful to humans that consume the carotenoids from plants as evidence suggests that they retain their chemical singlet oxygen radical scavenging ability following consumption. Carotenoids may be one of the reasons that diets high in fruit and vegetables are protective of cardiovascular disease and cancer, and research has shown an association between carotenoid intake and protection from these diseases. Researcher often use purified synthetic β-carotene but this is not the same as eating mixed carotenoids in plants and may explain the lack of efficacy in some clinical trials. However, increases in serum carotenoid levels have been reported upon supplementation with a mixed carotenoid supplement.
For example, researchers1 have analysed the serum carotenoid concentrations of 11 subjects following supplementation with a mixed carotenoid supplement. Measurements at baseline were taken, before subjects followed a low carotenoid diet for 2 weeks. The subjects were then administered a carotenoid supplement containing 8.5mg β-carotene, 3.5mg α-carotene and 0.5mg lycopene for 4 weeks. Following the low carotenoid diet, serum carotenoid levels dropped by around 60%, suggesting that carotenoid intakes had fallen. However, following supplementation with the mixed carotenoid supplement, serum levels of α- and β-carotene increased back to baseline after 1 week, and this increase continued such that by week 4, the values were significantly higher than at baseline. This suggested that the intakes of carotenoids in the supplements were higher than the dietary amounts ingested in the normal diet of the subjects, or that the absorption from the supplements was superior.
As has been seen with other nutrients analysed clinically, there was a large variation in serum levels between the subjects throughout the study. This suggests that individual rates of absorption, metabolism and clearance may vary greatly. Interestingly, those with the lowest α- and β-carotene levels at baseline did not experience large increases in carotenoids with supplementation. The supplements did not increase lycopene levels as much as the other carotenoids and at the end of the study the levels were still below baseline. This may suggest that lycopene was present in the diet in higher amounts than the 5mg present in the supplements. Other studies have reported increases in plasma concentrations of lycopene with supplements of 12mg of lycopene. Importantly, this study used natural sources for the carotenoids in the supplements which included carrot, red bell pepper, spinach and tomato concentrate.
RdB
