[Vitamins and therapy of malignancies]

Area of Science:

• Biochemistry
• Oncology
• Nutritional Science

Background:

• Bone marrow transplantation conditioning involves chemotherapy and irradiation, leading to toxic effects.
• These toxicities may stem from oxidative stress and antioxidant depletion.
• Key antioxidants include vitamin E (alpha-tocopherol), carotenoids (beta-carotene, lycopene), retinol, and ascorbic acid.

Purpose of the Study:

• To examine antioxidant levels in patients undergoing conditioning therapy for bone marrow transplantation.
• To investigate the impact of conditioning therapy on plasma concentrations of various antioxidants.
• To evaluate the efficacy of high-dose antioxidant supplementation in mitigating antioxidant loss and toxicity.

Main Methods:

• Plasma levels of alpha-tocopherol, gamma-tocopherol, beta-carotene, lycopene, retinol, and ascorbic acid were measured in 22 patients.
• Patients received standard conditioning therapy (chemotherapy and/or total body irradiation).
• Intervention studies compared antioxidant status and toxicity in supplemented versus unsupplemented groups.

Main Results:

• Plasma concentrations of alpha-tocopherol and beta-carotene significantly decreased post-conditioning therapy (20% and 50% loss, respectively).
• Increased plasma lipid peroxide concentrations correlated with the loss of lipid-soluble antioxidants.
• Intravenous administration of retinol and ascorbic acid maintained their plasma levels.

Conclusions:

• Conditioning therapy for bone marrow transplantation leads to significant depletion of key antioxidants.
• Oxidative stress, indicated by increased lipid peroxides, likely contributes to antioxidant loss.
• High-dose oral supplementation with alpha-tocopherol, ascorbic acid, and beta-carotene warrants further investigation for reducing toxicity.