Plasma (carotenoids, retinol, α-tocopherol) and tissue (carotenoids) levels after supplementation with β-carotene in subjects with precancerous and cancerous lesions of sigmoid colon

Abstract

Objectives: (1) To compare tissue and plasma carotenoids status of healthy subjects and subjects with pre-cancer and cancer lesions; (2) to evaluate the effect of β-carotene supplementation on the concentrations of other carotenoids in tissue (luteine+zeaxanthin, cryptoxanthin, lycopene, α-carotene) and in plasma and also retinol and α-tocopherol levels. Design: Eighteen subjects were divided into three groups on the basis of colonoscopy and histological analytical findings: four healthy subjects (control group A); seven subjects affected by adenomatous polyps (group B with pre-cancer lesions); seven subjects suffering from colonic cancer (group C). Blood and colonic biopsy samples were taken (of colon and rectal mucosa) before and after β-carotene supplementation in all subjects. Groups A and B received a daily dose of β-carotene (30 mg/die) for 43 d. Group C’s supplementation was terminated at the time which was performed, usually within 15 d. The tissue and plasma concentration of carotenoids, retinol and α-tocopherol were determined by high-performance liquid chromatography. Results: The tissue concentrations of each carotenoid were similar in all the intestinal sites examined as regards groups A and B, although there was a high degree of intra individual variability within each group. Only β-carotene made significant increases (P<0.001) after supplementation. The subjects with cancer show tissue levels for each carotenoid lower than those of healthy subjects or subjects with polypous. The plasma levels of α-tocopherol did not change after supplementation while significant increases were noted of retinol, α-carotene (P<0.01) and of β-carotene (P<0.001). Conclusions: The patients with colonic cancer seemed to undergo a significant reduction in their antioxidant reserves with respect to the normal subjects and or polyps. We can confirm that oral B-carotene supplementation induces also an increase in plasma α-carotene in all groups. Sponsorship: This work was supported by the National Research Council of Italy, Special Projects RAISA, Sub project 4, Grant 95.00.206.PF38.