The End of Illness by Agus David B

Author:Agus, David B [Agus, David B]
Language: eng
Format: epub
Publisher: Simon & Schuster, Inc.
Published: 2012-01-17T08:00:00+00:00

• The increased risks for lung cancer that occurred in those who supplemented with beta-carotene began to fall soon after they stopped taking the vitamin and were similar to the placebo group within four years.

• The lower prostate cancer incidence rates in participants taking vitamin E supplements during the trial returned toward normal soon after the trial ended, but remained below the placebo group rates throughout the six-year postintervention period.

The adverse effects from beta-carotene and the beneficial effects from supplementation with vitamin E largely disappeared during the post-trial follow-up period. Really scrutinizing these findings, you’ll notice a symmetry in the times during and after the trial. That is, the time it took for the elevated lung cancer rates and lower prostate cancer rates to happen was similar to the time for these adverse and beneficial effects to disappear. Once the trial ended, no additional beneficial effects on cancer or mortality were observed.

Clearly, the study shot down any upside to taking beta-carotene, and this has been confirmed in other large-scale prevention studies. One of the more famous of these, conducted in the United States, was the Beta-Carotene and Retinol Efficacy Trial (CARET), which compared the effects of beta-carotene plus vitamin A (in the form of retinyl palmitate) to placebo in 18,314 men and women ages forty-five to seventy-four who were either smokers, former smokers, and/or had been exposed to asbestos. A 28 percent higher lung cancer incidence and 17 percent higher overall mortality occurred in the group taking the vitamin supplementation.

As for vitamin E’s potential benefits for preventing prostate cancer, the jury is still out. In 2007, when the National Institutes of Health–AARP Diet and Health Study was published, the results were convincing enough to further give people such as me pause in the use of supplements. This study investigated the association between multivitamin use, which typically contains vitamin E, and risk of prostate cancer in 295,344 men. All of the participants—aged fifty to seventy-one years old—were cancer free at enrollment in 1995 and 1996. During their five years of follow-up, 10,241 of these men were diagnosed with prostate cancer, among which 1,476 were advanced. To these researchers’ surprise, those who admitted to taking lots of vitamins (“excessive use,” defined as more than seven times per week) showed an increased risk of advanced and fatal prostate cancers. Although no association was observed between multivitamin use and the risk of treatable (early-stage) prostate cancer, the risk of fatal prostate cancer among those taking regular multivitamins was double!

Let me temper this result a bit before you jump to too many of your own conclusions. This NIH-AARP study that I just described was observational, and therefore potentially confounded by many other variables, but I will say that the sample studied was large, which reduced random errors, and that overall, the study was well conducted. The results are in accord with the results of systematic reviews and meta-analyses of randomized clinical trials. The findings lend further credence to the possibility of harm associated with increased use of supplements, including increased rates of cancer and death from cardiovascular problems.

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