MedicalResearch.com Interview with:
Annlia Paganini Hill PhD
Project Scientist Biostatistician and Epidemiologist
Department of Neurology, School of Medicine
University of California, Irvine, Irvine, California
Medical Research: What is the background for this study? What are the main findings?
Response: Free radicals are formed when one exercises and when the body converts food to energy. Environmental sources (e.g. smoke, air pollution, sunlight) also expose the body to free radicals. Free radicals can cause “oxidative stress” and damage cells. Oxidative stress is thought to play a role in a variety of diseases: cancer, cardiovascular disease, diabetes, Alzheimer’s disease, Parkinson’s disease, cataracts, and age-related macular degeneration.
Antioxidants are man-made or natural substances that may prevent or delay some types of cell damage. Antioxidants are found in many foods and are also available as dietary supplements. Vegetables and fruits are rich sources of antioxidants. There is good scientific evidence that eating a diet with lots of vegetables and fruits is healthful and lowers risks of certain diseases. However, it is unclear whether this is because of the antioxidants, something else in these foods, other foods in people’s diet, or other lifestyle choices.
While antioxidants have been shown to counteract oxidative stress in cells and animal studies, whether consuming large amounts of antioxidant supplements benefits human health is debated. Given the continued use of vitamin supplements by a large proportion of the population and the presumed safety of antioxidant supplementation, we assessed the relationship between antioxidant vitamin intake and all-cause mortality in older adults.
We examined these associations using data from the Leisure World Cohort Study, a study of nearly 14,000 residents of a California retirement community. In the early 1980s, participants (median age, 74 years) reported details on use of vitamin supplements and dietary intake of foods containing vitamins A and C. During followup (1981-2013), over 93% of participants had died (median age at death, 88 years).
Medical Research: What are the main findings?
Response: Previously, we had found that a number of factors were associated with lower risk of death in our cohort — not smoking, physical activity, moderate alcohol consumption, caffeine intake, ideal body mass index (neither too fat nor too thin), and no history of high blood pressure, angina, heart attack, stroke, diabetes, rheumatoid arthritis, or cancer .
Neither dietary nor supplemental intake of vitamins A, C or E were significantly associated with reduced mortality in this study once these other lifestyle behaviors and disease conditions were taken into account.
In Leisure World Cohort and in the general population, health-promoting habits often cluster; e.g. those who take vitamin supplements often exercise, do not smoke, and are not obese. Thus, these factors explain the observed association between longevity and vitamin supplements in our and previous studies.
Medical Research: What should clinicians and patients take away from your report?
Response: Antioxidant supplements should not be used to replace a nutritionally adequate diet. A healthful diet characterized by high amounts of fruits and vegetables, whole grains, and fish should be recommended to avoid nutritional deficiencies and to prevent chronic disease.
Additionally, other studies have shown that high-dose antioxidant supplements may even be harmful (increased risks of prostate cancer, hemorrhagic stroke, and lung cancer in smokers). And because antioxidant supplement may interact with other medications, use of supplements should be discussed with a health care provider.
Antioxidant Vitamin Intake and Mortality: The Leisure World Cohort Study.
Paganini-Hill A, Kawas CH, Corrada MM.
Am J Epidemiol. 2014 Dec 29. pii: kwu294. [Epub ahead of print]