Journal of the American College of Nutrition, Vol. 18, No. 5, 424-425 (1999)
Published by the American College of Nutrition
Introductory Editorial
Sudhir K. Dutta, MD
Division of Gastroenterology, Sinai Hospital of Baltimore, University of Maryland School of Medicine, Baltimore, Maryland
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INTRODUCTION
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The role of antioxidants in the treatment and prevention of a variety of chronic progressive disorders in humans has been increasingly recognized in the last decade [1–4]. It has been postulated that the generation of free radicals, among them reactive oxygen molecules, as the result of metabolic processes, is associated with cellular and metabolic injury. Several lines of evidence and numerous publications in the medical literature have suggested that oxidative damage is a common underlying mechanism in the progression of a large number of disorders such as atherosclerosis, carcinogenesis, arthritis, cataracts and macular degeneration [1,3–5].
The process of aging and its associated disorders has also been linked to progressive oxidative damage. These seminal observations have sparked a great deal of interest in the use of antioxidants, that is, compounds which can prevent oxidative damage. Vitamin C (ascorbic acid), vitamin E (tocopherols), vitamin A (retinoids) and their precursor compounds, carotenoids, have been well recognized and accepted as important antioxidant substances. A large number of other compounds, such as selenium, zinc and flavonoids, are also considered antioxidants and serve as free radical scavengers. It is noteworthy that, to date, we have not identified all the compounds which may function as antioxidants. Furthermore, even among the well-recognized antioxidants such as vitamin C and vitamin E, there is a tremendous dearth of information about the clinical and metabolic effects on oxidative processes of different doses and durations of individual and combinations of antioxidants. Although hundreds of articles have been published on antioxidants, there are few well-controlled, prospective clinical trials of antioxidants in well-defined patient populations. A large portion of the literature in this field is retrospective and epidemiological in nature, involving significantly different sample sizes [6]. Furthermore, findings in the literature are based on the administration of one or more antioxidants, with doses and durations that are often arbitrarily selected. Finally, those antioxidants which have recommended dietary allowances are in general given at doses substantially higher than their recommendations. Interventional studies are sorely needed which administer antioxidants to well-defined patient populations in order to determine optimal doses and durations.
Due to considerable public interest in antioxidants and lack of available guidelines about the doses and durations of their supplementation, former ACN president, Dr. George Brewer, asked me to assemble a panel of experts who would not only review the established biological functions of the antioxidants, but also provide a concise and critical review of the available literature about the clinical application of these compounds in preventing and/or reducing the progression of various clinical disorders. As a result, I contacted experts who are considered authorities in their respective fields to consider writing clinically relevant reviews for the nutritional community at large. After careful examination of the literature, we decided to review four well-established antioxidants: 1) carotenoids, 2) ascorbic acid, 3) 
-tocopherol and 4) selenium. A well-defined format was developed and agreed upon, with primary focus on high-quality, pertinent clinical information in relation to heart disease and cancer prevention. Each author was asked to provide a concise review of available information on a specific nutrient in the following areas:
- Biochemistry and physiology—250 words
- Availability in different food products—250 words
- Cellular and molecular studies on the potential prevention action in heart disease and carcinogenesis—500 words
- Relevant animal data in the same field—1000 words
- Important clinical studies—1000 words
- A summary of the available information base which supported the preventive role of the nutrient in heart disease and cancer—500 words
- A list of 30 to 60 references for each nutrient
- An abstract or summary statement for lay people—300 words
The first article in this series is published in the current issue of the Journal. This particular review on carotenoids and their role as antioxidant agents has been prepared by Dr. Robert Russell and his colleague at HNRC on Aging of USDA Boston. Dr. Russell has worked in and followed this field very closely for a long period of time. His group is intimately familiar with the strengths and limitations of the clinical and scientific information in this area. This report is a very concise, focused and well-balanced review of clinically relevant information on carotenoids as antioxidants. I hope that readers of this journal will find this article most exciting, thought-provoking and clinically relevant.
Received March 1, 1999.
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INTRODUCTION
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