The antioxidant religion takes another hit

Women who took beta carotene or vitamin C or E or a combination of the supplements had a similar risk of cancer as women who did not take the supplements, according to data from a randomized controlled trial in the December 30 online issue of the Journal of the National Cancer Institute. Epidemiological studies have suggested that people whose diets are high in fruits and vegetables, and thus antioxidants, may have a lower risk of cancer. Results from randomized trials that address the issue, however, have been inconsistent and have rarely supported that observation.

In the current study, Jennifer Lin, Ph.D., of the Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues tested the impact of antioxidant supplements on cancer incidence in a randomized controlled trial. A total of 7,627 women who were at high risk of cardiovascular disease were randomly assigned to take vitamin C, vitamin E, or beta-carotene.

With an average of 9.4 years of follow-up time, there was no statistically significant benefit from antioxidant use compared with placebo in terms of disease risk or mortality due to cancer. Overall, 624 women developed cancer and 176 died from cancer during the follow-up time. Compared with placebo, the relative risk of a new cancer diagnosis was 1.11 for women who took vitamin C, 0.93 for women who took vitamin E, and 1.00 for women who took beta carotene. None of these relative risks was statistically significantly different from 1.

"Supplementation with vitamin C, vitamin E, or beta carotene offers no overall benefits in the primary prevention of total cancer incidence or cancer mortality," the authors conclude. "In our trial, neither duration of treatment nor combination of the three antioxidant supplements had effects on overall fatal or nonfatal cancer events. Thus, our results are in agreement with a recent review of randomized trials indicating that total mortality was not affected by duration of supplementation and single or combined antioxidant regimens."

In an accompanying editorial, Demetrius Albanes, M.D., of the National Cancer Institute, reviewed data from previous randomized controlled trials that examined supplement use and cancer incidence. He noted that while the trial data reported by Lin are negative with respect to lowering cancer risk, there is valuable information uncovered that should not be overlooked. There was a trend for a reduction in colon cancer with vitamin E supplementation, which has been observed in other studies. Additionally, beta carotene use was associated with a modest excess of lung cancer, which is consistent with previous reports.

"Null trials or those with unexpected outcomes should not, however, be viewed as failures; they have and will continue to shed light on the causes of cancer and help us discover the means for its prevention," the editorialist concludes.

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Too much thinking 'can make you fat'

Wacky though it sounds, I think they have a point below. Students getting frequent attacks of the "munchies" while studying are pretty well-known

Researchers found the stress of thinking caused overeating with heavy thinkers seeking out more calories. The research team, supervised by Dr Angelo Tremblay, measured the spontaneous food intake of 14 students after each of three tasks. The first was relaxing in a sitting position, the second reading and summarizing a text, and finally completing a series of memory, attention, and vigilance tests on the computer. After 45 minutes at each activity, participants were invited to eat as much as they wanted from a buffet.

The researchers had already discovered that each session of intellectual work requires only three calories more than the rest period. However, despite the low energy cost of mental work, the students spontaneously consumed 203 more calories after summarizing a text and 253 more calories after the computer tests. This represents a 23.6 per cent and 29.4 per cent increase, respectively, compared with the rest period.

Blood samples taken before, during, and after each session revealed that intellectual work causes much bigger fluctuations in glucose and insulin levels than rest periods. Jean-Philippe Chaput, the study's main author, said: "These fluctuations may be caused by the stress of intellectual work, or also reflect a biological adaptation during glucose combustion." The body could be reacting to these fluctuations by spurring food intake in order to restore its glucose balance, the only fuel used by the brain.

Mr Chaput added: "Caloric overcompensation following intellectual work, combined with the fact we are less physically active when doing intellectual tasks, could contribute to the obesity epidemic currently observed in industrialised countries. "This is a factor that should not be ignored, considering that more and more people hold jobs of an intellectual nature." The results of the study, carried out at Universite Laval in Quebec, Canada, are published in the journal Psychosomatic Medicine.

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