Broccoli and cauliflower help prevent cancer, right? So you might think, if you relied on much of the nutrition news in the popular press. But the reliability of such information has been questioned -- most recently in an article in the New York Times by veteran science reporter Gina Kolata.
While no one disputes the general healthfulness of a diet replete with fruits and vegetables, low in saturated fats, and in line with caloric needs, apparently the scientific evidence that such a diet (or specific antioxidant-contributing foods) prevent cancer is not particularly robust.
Dr. Barnett Kramer of the office of disease prevention at the National Institutes of Health was quoted in the Times article: "Over time, the messages on diet and cancer have been ratcheted up until they are almost co-equal with the smoking messages...a lot of the public is completely unaware that the strength of the message is not matched by the strength of the evidence."
Certainly, it is true that particular lifestyle choices such as smoking and excessive exposure to sunlight, as well as obesity in postmenopausal women, can increase the risk of various types of cancer. However, the role that diet plays is not clear -- perhaps because the methods used to study the possible relationship between the two are not sensitive enough or because the link, if any, is too weak to detect.
A healthful lifestyle, however, is a bulwark against heart disease -- still the leading cause of death in the United States -- so we should all still be motivated to avoid smoking, be physically active, and consume a balanced diet. But the take-home lesson is that the search for the holy grail of cancer prevention (if one exists) must continue; apparently diet is not likely to be it.
Ruth Kava, Ph.D., R.D., is Director of Nutrition at the American Council on Science & Health (ACSH.org, HealthFactsAndFears.com).
