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Beta Carotene Implicated In Flawed Finnish Study

Despite countless peer-reviewed medical studies documenting the positive preventative effects of beta-carotene and vitamin E in lung cancer research, in 1994 a released trial study of male smokers in Finland sent shock waves through the American public. The report, "The Effect Of Vitamin E and beta-carotene on the Incidence of Lung Cancer and other Cancers in Male Smokers" appeared in the New England Journal of Medicine1. The report sparked banner headlines in newspapers and magazines across the country claiming that beta-carotene is no guard against lung cancer, and the New York Times wrote that not only did the results show no evidence of benefit, but "hinted at actual harm."

By proclaiming that cigarette smokers are not protected by vitamin supplements, these inaccurate and biased media stories may cause many cigarette addicts to abandon the protection antioxidant nutrients confer against a wide range of smoking induced diseases. Before throwing out your supply of beta-carotene, please take a few minutes to look at the study and decide for yourself. As the authors of the study stated, "With regard to lung cancer, which was specified as the primary end point, the trial failed to detect any significant protective effect of either of the two vitamins. In fact, there were significantly more new cases of lung cancer in the group treated with beta-carotene. Although this might be a real finding, it may simply have been due to an extreme play of chance, since the finding is so much at variance with the totality of other evidence suggesting benefit."

The study was conducted by the National Cancer Institute over a six year period. The researchers set out to test the effects of beta-carotene and vitamin E supplements on post middle-aged male smokers in Finland. The subjects were 29,133 male smokers from southwestern Finland, from 50 to 69 years of age. Each participant had smoked over a pack of cigarettes a day for an average of 35.9 years. The smokers were divided into four groups, each receiving a different vitamin regimen: Group 1 took 50 milligrams of vitamin E (alpha tocopherol) per day, group 2 took 20 milligrams of beta-carotene per day, group 3 took both vitamin E and beta-carotene, and the last group took an inactive placebo.

The results of the published study can be summarized as follows:

Of special interest were the results of vitamin E on other cancers: Men receiving the vitamin E had 34% fewer cases of prostrate cancers, and 16% fewer colorectal cancers. Of course this aspect of the report was virtually ignored by the media.

If you wonder how the impressive results of vitamin E got lost in the shuffle, some of the main investigators are pondering the same issue. "I don't think they will be lost on the scientific community and ignored in the long run," said Dr. Demetrius Albanes, a senior NCI investigator and principal researcher in the study. With the media's sensational treatment of the study, it is clear that the press has not even read the full study, which is only about 6 pages long and not difficult to understand. There are several very important and unique defects in the Finnish study that contribute to under-standing why beta-carotene may not have protected the Finnish smokers:

The authors acknowledged the role of selenium, stating "…, a recent large trial in China found a significant reduction in mortality due to cancer among persons whose diets were supplemented daily with the combination of beta-carotene (15 mg.), vitamin E (30 mg), and selenium (50 mcg) for 5 years." Since NCI has known of the anti-cancer benefits of selenium since at least 1980, and they also knew of the extremely low levels of selenium in the Finnish diet, why didn't the researchers include selenium in this very expensive, American taxpayer-funded study? Durk Pearson & Sandy Shaw had previously reported on the effects of selenium in "Life Extension, A Practical Scientific Approach", back in 1983. Pearson & Shaw wrote "Selenium has recently been found to be a powerful inhibitor of cancer formation…The National Cancer Institute is now (1980) recommending that people take about 200 micrograms of selenium every day as a prophylactic against, cancer. They are trying to get the FDA to recommend this in their Recommended Daily Allowances (RDA's)."

"It is plausible that the intervention period was to short to inhibit the development of cancers resulting from a life-time of exposure to cigarette smoke and other carcinogens."

In studying the media headlines, it is clear that the published study does not support the sensational conclusions reported in the press. The authors themselves state "The lack of benefit of beta-carotene is particularly surprising given the substantial and consistent epidemiologic evidence of an association between a higher beta-carotene intake and a lower incidence of lung cancer, including the results of the cohort-based analysis in this study." (The study reported an inverse relationship between dietary intake of beta-carotene at baseline, and the risk of lung cancer during the trial. In other words, the higher the intake of beta-carotene at the beginning of the trial, the lower the incidence of cancer during the trial.)

Other dietary studies are under way, which should help clear up the confusion generated by this study. One study involves 40,000 healthy women who are taking beta-carotene and vitamin E or aspirin and placebos. Another trial has enrolled 18,000 men and women to test beta-carotene in smokers and non-smokers. And a third study involving 22,000 male physicians has already shown that beta-carotene reduces cardiovascular risk, and will be used to determine if the same is true of cancer.

While some may respond to the study by mistakenly cutting back on their intake of beta-carotene supplements, the Alliance for Aging Research, a Washington-based private research institute, stood firmly behind guidelines it issued earlier this year encouraging Americans take 10 to 30 milligrams of beta-carotene daily. "When we put out these recommendations we consulted our scientific board and looked at more than 200 clinical and epidemiologic studies," said Dan Perry, executive director of AAR. "No one can understand this result and why it went in the other direction, and it has been blown way out of proportion."

"We are aware of no other data at this time, however, that suggest harmful effects of beta-carotene, whereas there are data indicating benefit."

The study concluded "Our results raise the possibility that supplementation with beta-carotene may be harmful in smokers. The higher mortality due to ischemic heart disease and lung cancer among the beta carotene recipients requires more detailed analysis, and information from other studies is also needed. We are aware of no other data at this time, however, that suggest harmful effects of beta-carotene, whereas there are data indicating benefit.

Furthermore, there are no known or described mechanisms of toxic effects of beta-carotene, no data from studies in animals suggesting beta-carotene toxicity, and no evidence of serious toxic effects of this substance in humans. In the light of all the data available, an adverse effect of beta-carotene seems unlikely; in spite of its formal statistical significance, therefore, this finding may be due to chance."

  1. N Engl J Med 1994;330:1029-35
  2. Brit Med J 1985; 290:419
  3. Cancer Research 1992; 52: 5705-5712.
  4. Am J Clin Nutr 1990; 52: 500-501
  5. Am J Clin Nutr, 1993;57:787S
  6. J Nat Can Institute 1993;85: 1483-92

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