Orlando, Fla. ? Getting plenty of vitamin E by eating foods like nuts and olive oil appears to cut in half people’s risk of bladder cancer, the fourth-leading cancer killer among men, a new study suggests.

The research, released at a cancer conference Sunday, is the latest blip in the ups and downs of perceptions about this nutrient’s powers to ward off disease. Experts once had high hopes that vitamin E would prove to be an important safeguard against heart attacks. But that idea eventually faded as repeated studies failed to show any protective effect.

Whether vitamin E does anything to stop cancer is still far from proven, but some think the vitamin may be helpful, perhaps by warding off the damaging effects of oxygen. The strongest evidence of this so far has been against prostate cancer, and a large federally sponsored experiment is under way to help prove this.

The new study offers a strong hint that dietary vitamin E also may protect against bladder cancer, which kills about 12,500 Americans annually and is four times more common in men than women.

The study was based on questionnaires of the eating habits of about 1,000 Houston residents. Those whose vitamin E intake was in the top 25 percent had just half as much bladder cancer as those in the lowest quarter. The actual difference in the amount of vitamin-rich food the two extremes ate was small, however, the equivalent of a daily serving of spinach or a handful of almonds.

The research was presented by John Radcliffe, a nutrition researcher from Texas Woman’s University, at a meeting of the American Association for Cancer Research in Orlando.

The reduction was roughly the same, regardless of whether people got their vitamin E from food alone or in combination with vitamin pills.

The team looked at the two most common forms of vitamin E, called alpha- and gamma-tocopherol, and found that only the alpha variety was linked with lower bladder cancer risk. Good sources of this include almonds, spinach, mustard greens, peppers, sunflower seeds and a variety of oils, including olive, cottonseed and canola.

Experts say it is too soon to make any firm recommendations about vitamin E intake for cancer prevention beyond the usual advice to eat plenty of vegetables and other plant-based foods.