Largest vitamin E trial shows reduced risk of cardiovascular death in women
could lower the risk of heart attacks and stroke in older women as
well as cardiovascular deaths, writes Dominique Patton.
Results from the largest ever trial on vitamin E supplementation - almost 40,000 American women participated - appear to confirm previous research showing that the vitamin does not prevent heart disease or cancer.
But those women taking the high dose natural alpha-tocopherol supplements did have a significantly lower risk of death and also a much lower risk of heart attack and stroke if they were over the age of 65, according to the major trial out today.
Researchers on the study, published in the 6 July issue of the Journal of the American Medical Association (vol 294, no1), say these findings should be investigated further.
Industry will also welcome the lack of adverse effects reported during the 10-year study, the longest trial period for vitamin E supplements to date.
The Harvard Medical School team writes that there were no differences between reported adverse effects among women taking vitamin E or placebo, apart from a small increase in the risk of epistaxis (nosebleeds).
This finding contrasts with a recent meta-analysis that reviewed studies of people already ill with cancer, heart disease or other serious medical conditions who appeared to be at a much higher risk of death when taking vitamin E supplements.
However the authors of the Women's Health Study, a randomized, double-blind, placebo-controlled trial that also looked at the effects of low-dose aspirin, noted that many previous trials on vitamin E "have been conducted primarily among participants with cardiovascular risk factors and/or CVD or at high risk of cancer".
Many were also limited to five years. Their trial was designed to investigate a potential benefit from vitamin E over a longer time period and in healthy people.
Dr Andrew Shao, vice president of regulatory and scientific affairs at the US trade association Council for Responsible Nutrition (CRN), welcomed the data from a healthy population, noting that previous studies of vitamin E had examined unhealthy populations and then incorrectly used the results to reach conclusions about the safety of vitamin E in healthy individuals.
"The WHS should help dispel some of the dubious myths surrounding vitamin E. We hope these results will inspire other researchers to continue to study vitamin E and its potentially beneficial effects," he said.
However Rita Redberg, writing in an editorial in the same journal, noted that most of the women in this trial were at very low risk of heart disease, and this could therefore have eliminated any benefit from the vitamin in overall prevention of heart disease.
Nevertheless the new findings could be important if they are confirmed in further work. Cardiovascular disease is the leading cause of death among women in all European countries, and in men in all of Europe apart from France. It causes nearly half (49 per cent) of all deaths in Europe, or 4.35 million each year, according to the European Heart Network.
The study found a 24 per cent reduction in cardiovascular deaths among the nearly 20,000 women who took vitamin E supplements compared with the nearly 20,000 women taking placebo.
For women 65 and over, taking vitamin E supplements had an even greater positive effect, reducing cardiovascular death by 49 per cent compared to placebo and heart attack by 34 per cent.
While the authors said it was possible that the decreased cardiovascular deaths, not observed in other studies, could be "due to chance," they acknowledged that this finding "should be explored further".
They also noted that few previous trials of vitamin E have reported findings by age.
Professor Maret Traber, a principal investigator at the Linus Pauling Institute at Oregon State University and a leading expert on vitamin E, said: "Vitamin E has clear value in helping to reduce the risk of heart and other serious degenerative diseases. This is especially important for people who smoke, have high blood pressure, or who don't eat properly, habits which can leave them with inadequate levels of this essential vitamin."
Results from a long-term study investigating the benefits of vitamin E in men - the Physician's Health Study - are not due until 2008 but they will offer further data to clarify today's results.
The Women's Health study also showed that 100mg of aspirin on alternate days reduced the risk of stroke overall in the women studied and the risk of both stroke and heart attack in those aged 65 and older.
