Does Vitamin E Supplementation Provide a Benefit?
Theoretically, a perfectly balanced diet provides all the vitamins, minerals, and nutrients that a person needs to maintain optimal health. Unfortunately, for most people, eating an ideal diet is difficult, and sometimes impossible. To fulfill nutritional needs, many people choose to supplement their diet with vitamins and other nutrients. In addition to providing balanced nutrition, some supplements are reported to provide extra benefits.
Vitamin E, for example, is believed to have a number of benefits, including preventing cardiovascular disease, protecting against ]]>Alzheimer’s disease]]> , and possibly reducing the risk of cancer. Vitamin E can be found naturally in nuts, vegetable oil, and green leafy vegetables. As a dietary supplement, vitamin E can be purchased in capsule form.
Vitamin E is considered an antioxidant. Antioxidants provide protection against the effects of free radicals, which are by-products of normal metabolism. Free radicals cause damage by disrupting the molecules of cells, which may lead to the development of chronic disorders, such as cardiovascular disease and cancer. It is believed that the ability of vitamin E to inhibit free radicals may slow or prevent the development of those chronic diseases. For example, the damage caused by free radicals causes low-density lipoprotein (LDL, or “bad” cholesterol) to stick to blood vessel walls and block blood flow. The development of these blockages in blood vessels is called ]]>arteriosclerosis]]> . If vitamin E prevents damage to LDL, it theoretically could prevent the blockage from forming.
Unfortunately, clinical studies have not provided conclusive evidence of this benefit. While some observational studies have associated vitamin E supplements with lowered rates of ]]>heart disease]]> , this effect has not been proven in randomized clinical trials. A study published in the March 16, 2005 issue of the Journal of the American Medical Association investigated the effects of long-term therapy with vitamin E on rates of cardiovascular disease and cancer.
About the Study
This study reported the results from a two-year extension of the Heart Outcomes Prevention Evolution (HOPE) study that took place between 1993 and 1999. The researchers used data from both the original HOPE study and the two-year extension (the HOPE-TOO) to determine the long-term effects of vitamin E. The HOPE and HOPE-TOO studies were randomized, double-blind, placebo controlled evaluations of patients aged 55 and older. All participants in the study were diagnosed with either diabetes or cardiovascular disease.
The participants in this study were given either a daily dose of natural vitamin E (400 IU) or a placebo for an average of seven years. To determine whether vitamin E had any preventative effect, the researchers evaluated each patient with regards to incidence of cancer, major cardiovascular events (like heart attack or stroke) or death.
The researchers found that for the HOPE and the HOPE-TOO extension studies, there was no significant difference in the number of participants who experienced cancer, major cardiovascular events or death. An additional finding from the study was that participants who received daily doses of vitamin E had a significantly higher risk of heart failure than those that received placebo.
This lack of significant benefit combined with the additional finding of increased heart failure risk prompted the researchers to suggest that vitamin E should not be used in patients known to have cardiovascular disease or diabetes.
How Does This Affect You?
The theory behind the use of antioxidants like vitamin E to prevent cardiovascular disease, and possibly cancer, seems a sound one. Yet, the HOPE and HOPE-TOO studies did not find any evidence of benefit. Vitamin E supplementation has been promoted as a safe and natural method of preventing heart disease yet there is no convincing evidence that this is the case. In fact, according to this study, the risks of vitamin E supplementation in certain individuals are more apparent than any benefits.
The Center for Responsible Nutrition (CRN), which represents the dietary supplement industry, cautions that the results of this study should be taken in context. Vitamin E, for example, may be effective for a number of conditions, including renal failure and age-related macular degeneration, a condition that can cause blindness. Also, there are currently a number of studies underway to determine whether vitamin E has a preventive effect on specific types of cancers, such as prostate cancer.
However, people with cardiovascular disease, or those at increased risk for it, should probably avoid supplementing with vitamin E. Eating a balanced diet containing plenty of foods rich in anti-oxidants would be a far better choice.
The Office of Dietary Supplements fact sheet on vitamin E
The US Food and Drug Administration’s Tips for Selecting Dietary Supplements
Brown G & Crowley J. Is there any hope for vitamin E. JAMA. 2005. 293(11) 1387-1390.
CRN urges caution in weighing results of new vitamin E study. March 15, 2005. Available at www.crn.org/vitaminEissafe.html. Accessed March 15, 2005.
The HOPE and HOPE-TOO Trial Investigators. Effects of long-term vitamin E supplementation on cardiovascular events and cancer: A randomized controlled trial. JAMA. 2005. 293(11) 1338-1347.
Vitamin E fact sheet. Available at: http://ods.od.nih.gov/factsheets/vitamine.asp . Accessed March 15, 2005.
Last reviewed Mar 16, 2005 by ]]>Richard Glickman-Simon, MD]]>
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