Antioxidants: surprise, surprise.

Science is full of surprises. There's no other way to explain it.

Cancer, heart disease, cataracts and other eye disease...every time you picked up the paper, another killer had reportedly been vanquished by antioxidants.

Over the last few years, sales of vitamin E and betacarotene soared. Even Nutrition Action Healthletter suggested that people consider taking them.

Until April 14, 1994.

That's when researchers from Finland and the National Cancer Institute dropped a double-whammy: Not only did beta-carotene and vitamin E supplements fail to reduce the risk of lung cancer, they might cause harm.

"It was totally unexpected," says Charles Hennekens, the Harvard School of Public Health researcher who co-authored an editorial that accompanied the study in The New England Journal of Medicine.(1)

In the study, researchers randomly divided 29,000 Finnish male smokers into groups that got one of the following every day:

* a dummy pill,

* beta-carotene (20 mg, or 33,333 IU),

* vitamin E (50 mg, or 50 IU), or

* beta-carotene and vitamin E.

After five to eight years, the beta-carotene-takers had an 18 percent higher incidence of lung cancer. There were also hints that beta-carotene might have raised the risk of heart disease. Vitamin E appeared to reduce the risk of prostate cancer but increase the risk of hemorrhagic stroke.

That's the news. Here's the news behind the news.

* This isn't just another study. Earlier studies "observed" lower cancer rates among people who eat fruits and vegetables that are rich in beta-carotene. But observational studies--no matter how many--have a built-in limitation.

"If fruits and vegetables exert a protective effect by a mechanism that does not involve beta-carotene, then high levels of beta-carotene in the diet or in the blood would appear to be protective, but beta-carotene supplements would provide no benefits," wrote Hennekens.

The Finnish trial provides far more powerful evidence, because it was the first to actually give well-nourished people either antioxidants or a placebo and then wait to see who got cancer.

And don't be swayed by supplement-industry claims that the Finnish study doesn't count because it only looked at smokers.

"Many of the observational studies have shown a reduced risk of lung cancer in smokers," says Regina Ziegler, a nutritional epidemiologist at the National Cancer Institute (NCI).

* This isn't the final word. Even a well-designed trial doesn't prove or disprove the benefits of antioxidants.

Certainly, the Finnish trial is inconclusive about vitamin E's purported ability to reduce the risk of heart disease. The men took only 50 mg (IU) a day. Earlier studies suggest that it might take at least 100 mg a day to lower the risk.

We'll have to wait for the results of about a dozen ongoing trials to settle the question. So, until then:

1. Shelve the beta-carotene. For now, hold off on taking more than about 3 mg (5,000 IU) a day. That's what's in most multivitamins. The most cautious approach would be to take none.

How could beta-Carotene supplements be harmful? Foods contain several forms of beta-carotene. Supplements contain only one.

"It's conceivable that large amounts of a single form could interfere with the absorption, transport, or utilization of other forms of beta-carotene, other carotenoids, or other important compounds in fruits and vegetables," speculates NCI's Ziegler.

There's also a tiny chance--less than one percent--that the Finnish results were simply a fluke. But last month, Nutrition Action learned that investigator Robert McLennan called off his trial at the Queensland Institute of Medical Research in Australia after he found that people taking beta-carotene had developed 40 percent more precancerous polyps of the colon. The results are ambiguous, though, and they haven't been published.

2. Reconsider taking vitamin E. The Finnish study hinted that it might increase the risk of hemorrhagic stroke, even at the low dose of 50 mg a day.

While most strokes in the U.S. are due to hemorrhage, it's not a trivial problem. The most cautious approach would be to take none, though 30 mg--the U.S. Recommended Daily Allowance--is likely to be safe. Since earlier studies suggest that 100 mg a day may protect against heart disease, there's certainly no reason to exceed that dose.

3. Don't stop eating fruits and vegetables. There is no--repeat, no--reason to worry about the beta-carotene in foods. People who eat more fruits and vegetables, especially those rich in carotenes, have a lower risk of most cancers.

(1)New England Journal of Medicine 330: 1029, 1080, 1994.