The issue of antioxidant nutrition is complex. Under certain conditions, antioxidants can be pro-oxidants. In its March 29, 2001 e-newsletter, the Competitive Intelligence Adviser (CIA) referred to an assessment by German researchers of the antioxidant properties of a variety of pure carotenes, (all-rac; dl ) alpha-tocopherol, flavonoids and indigoid.(ii)
The pro-oxidant tendencies of certain carotenes such as ß-carotene also were examined. The researchers inferred that this property likely was due to different head and tail chemistries as compared to astaxanthin and zeaxanthin. How relevant such findings are on human nutrition is harder to predict in that the tests generally are performed in vitro (test tube). - Claudia D. O'Donnell, Chief Editor