Contributed by Lisa Olen| 15 March, 2005 22:46 GMT
'Other research has not found an increase in heart failure in patients taking vitamin E. As the HOPE-TOO authors state, further studies need to be undertaken on the effects of vitamin E and heart disease. Until that occurs, these results can only be interpreted as questionable, chance findings that need to be confirmed.'
Taking vitamin E supplements was linked to an increased risk of heart failure in patients over age 55 who had a history of heart disease, stroke or diabetes, plus at least one other cardiovascular risk factor, a new study has found. The results are perplexing to the study's authors and other scientists, who note that they contradict earlier research.
Vitamin E is an antioxidant that offers a variety of potential health benefits, including reducing the risk of Alzheimer's, cancer and heart disease, according to a wealth of research conducted over the past 50 years.
However, unexpected findings on vitamin E and heart health emerged in the new study, published this week in the Journal of the American Medical Association (JAMA). The results "cannot be confirmed at this time by other trials" and "could be due to chance," say the authors.
Results Interpreted as 'Questionable'
In contrast to the latest findings, the Cambridge Heart Antioxidants Study (CHAOS), which was published in The Lancet in 1996, concluded there was a decrease in deaths from heart failure in participants taking vitamin E supplements who had coronary artery disease.
The Vitamin E Consumption and the Risk of Coronary Disease in Women study, conducted by Harvard, evaluated more than 80,000 nurses and found a 41% reduction in the risk of heart disease in nurses who took vitamin E for two years. That research was published in the New England Journal of Medicine in 1993.
"Other research has not found an increase in heart failure in patients taking vitamin E. As the HOPE-TOO authors state, further studies need to be undertaken on the effects of vitamin E and heart disease. Until that occurs, these results can only be interpreted as questionable, chance findings that need to be confirmed," cautions Dr. Ishwarlal Jialal, M.D., Ph.D., Robert E. Stowell Endowed Chair in Experimental Pathology, Director of the Laboratory for Atherosclerosis and Metabolic Research and Professor of Internal Medicine and Pathology at UC Davis School of Medicine.
Latest Study Contradicts Earlier Findings
"Previously, vitamin E has been shown in some randomized clinical trials to reduce cardiovascular events [and] viral infections in the elderly, and prevent institutionalization in patients with Alzheimer's disease," adds Dr. Jialal.
"We did not identify any previous articles of an adverse effect of vitamin E on heart failure, and none of the previous large randomized trials of vitamin E published information about heart failure," the HOPE-TOO researchers acknowledge.
Interestingly, in a previous study, the same HOPE-TOO investigators found in the sub-group of diabetic patients that "there were no significant differences between the study groups in the rates of all secondary outcomes, which included heart failure and hospitalization for heart failure." Their work was published in Diabetes Care in 2002.
Vitamin E, a fat-soluble vitamin, acts as an antioxidant to protect cells in the body against the effects of free radicals, which are potentially damaging by-products of cell metabolism.
The scientific community should conduct long-term, large scale trials in well-defined populations to continue to understand the benefit of vitamin E, as well as any potential adverse effects, Dr. Jialal concludes. |
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