Diet and Cancer Risk
Like stress, there is a great deal written and not much actually proven about the contribution of diet to cancer risk or to cancer prognosis/progression. A study presented last week at AACR (American Association for Cancer Research) reinforced this reality:
April 22, 2009 (Denver, Colorado) — Numerous studies on diet and cancer were presented here at the American Association for Cancer Research (AACR) 100th Annual Meeting, but several of the findings that were highlighted in AACR press releases — and thus are likely to be picked up by the lay media — run counter to the accumulated body of evidence, and some of the comments based on these studies are untrue or premature. So said Walter Willet, MD, DrPH, from the department of nutrition at Harvard School of Public Health, in Boston, Massachusetts, in an exclusive interview with Medscape Oncology.
"No conclusions should be made on the basis of a single study," he said.
Dr. Willett presented an overview entitled "Diet, Nutrition, and Cancer: The Search for Truth," in which he reviewed many of the associations that have been suggested by epidemiologic studies. These include consumption of red meat, meat cooked at a high temperature, a high-fat diet, and alcohol all increasing the risk, and fruit and vegetables decreasing the risk. However, much of the evidence for these links is rather weak, he said; the most robust evidence supports a link between obesity and an increased risk for cancer.
"The estimate that diet contributes to around 30% to 35% of cancers is still reasonable," Dr. Willet said, "but much of this is related to being overweight and inactive."
"At this point in time, being overweight is second only to smoking as a clear and avoidable cause of cancer," he said. "People should stay as lean as they can, recognizing that it is more difficult for some than for others."
What we are looking at are little slices of life.
Beyond this clear message about obesity, there are only hints from the rest of the data. One of the main limitations of all of the studies so far is that they have looked at a specific time of life — for example, women after menopause — and they have had fairly short follow-ups, often less than 10 years. "So what we are looking at are little slices of life," Dr. Willet said, whereas the effect of diet is lifelong, and might be particularly important in the years before adulthood (e.g., during adolescence).
If you would like to read more about this study, here is the link:http://www.medscape.com/viewarticle/701722
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