Preventing disease with antioxidants

Assessment Objectives

The purpose of this assessment has been to systematically review the scientific literature on the relationship between antioxidant intake via food or dietary supplements (tablets) and the incidence of diseases potentially associated with oxidative processes in the body. Approximately 1300 studies were reviewed. The following antioxidants were included: ascorbic acid (vitamin C), tocopherol (vitamin E), beta-carotene, selenium, and ubiquinone (Q10).

The diseases addressed in the review are: cardiovascular disease, diabetes, the most common forms of cancer, eye diseases, neurological diseases, infectious diseases, and rheumatoid arthritis.

An introductory section describes the chemical action of the oxygen in the body and the bodyÎs defense system (where antioxidants are involved), changes in dietary habits over time, the influence of food preparation and storage on antioxidant content, and sales of vitamin and mineral supplements. A section on methodological problems is also included.

The results of the review show that it has not been possible to identify a definite relationship between antioxidants and the rate of disease. Some association was found between the intake of fruit and vegetables and cancer of the gastrointestinal tract. Manufactured antioxidants, ie, tablets or capsules, showed no positive effects and may be harmful in high doses. Vitamin C, however, was found to somewhat ameliorate the course of the common cold.

Assessment Strategy

Systematic literature review.

Data Collection

Systematic review of relevant databases, mainly MEDLINE, and a review of reference lists.

Inclusion Criteria

Inclusion was based on predetermined criteria. The review included: all original studies addressing the relationship between the selected antioxidants and certain human diseases, the relevant literature published from 1989 through 1996, and several publications from 1997. Approximately 1300 studies were reviewed.

Review of Publications

Studies were appraised by three members of the project group. The proposed manuscript of the report was reviewed by the project group, the SBU Board of Directors, the SBU Scientific Advisory Committee, and two external reviewers, Larsson LG, and Sandstrsm BM.