By comparison, aspirin, commonly taken by heart patients, provides a 25 to 30 per cent benefit.
The doctors who made the discovery believe this is why Mediterranean people have much less heart disease than northern Europeans.
A team led by Professor Morris Brown, from the Cambridge University Clinical School, studied 2,000 patients with heart problems. Half were given vitamin E in an 18-month trial, while the others took placebo tablets.
The doctors found that the number of heart attacks in the vitamin E group was only a quarter of that in the placebo group, according to research, published in tomorrow's issue of the Lancet.
Professor Brown said: "We're very excited. We didn't expect the effect on heart attacks to be so large. There has been a lot of circumstantial evidence of the benefit of vitamin E, but this is the first time anyone has come up with a clear-cut answer.
"Although it is early days, I will be recommending that patients with angina and those who are at risk of heart disease should be given supplementary vitamin E at a high dose."
Vitamin E is found in vegetable and fish oils. Olives, olive oil, nuts, avocados and oily fish, like tuna and mackerel, all contain large amounts of the vitamin.
The British Medical Journal also carries further evidence for the benefits of alcohol against heart disease, and claims that a range of drinks, not just wine, has a protective effect.
Previous research has suggested that substances found in wine - particularly red wine - known as bioflavenoids, made it more effective than beer or spirits at reducing the risk of death from heart disease.
But American scientists who have reviewed major studies, say that all alcoholic drinks are linked with a lower risk.
Dr Eric Rimm and colleagues from the Harvard School of Public Health, Boston, reviewed a series of previous heart disease studies. Of 10 studies, four found a benefit from moderate wine drinking, four found the same benefit from beer, and four from spirits.
Another paper, written by Danish scientists and also published in tomorrow's British Medical Journal, found that teetotal men with high levels of cholesterol had a five times greater risk of heart attack than those who consumed three or more alcoholic drinks a day.
Dr Hans Ole Hein and a team from Rigshospitalet State University Hospital, Copenhagen, studied 2,826 men aged 53 to 74. They found that the more cholesterol the men had in their blood, the greater was the benefit of alcohol.