Cancer clarifications

A new study out of the UK tries to make sense of decades of often-confusing research about the risks and benefits of specific foods.

A review of the evidence, published September 12, 2002, in the British medical journal The Lancet, concludes that studies over the years have confirmed little. Does broccoli really ward off cancer? The evidence isn't in yet, says Timothy Key, PhD, and his fellow scientists at the cancer unit of the University of Oxford. Previous studies had suggested that dietary components such as red meat, broccoli, garlic, fiber, folic acid, vitamin C and soy can either encourage or prevent certain cancers—but the links haven't been proven, says Key.

However, the study does find that some general indications are conclusive:

* Dietary choices account for about 30 percent of all cancers in Western countries, making food second only to tobacco as a potentially preventable cause of cancer.
* Obesity increases the risk of cancers in the breast, esophagus, colon, rectum, endometrium and kidney.
* Alcohol causes cancers of the oral cavity, pharynx, larynx, esophagus and liver, and it causes a small increase in the risk of breast cancer.
* Adequate intakes of fruits and vegetables probably lower the risk for several types of cancer, especially cancers of the gastrointestinal tract.
* The idea that a high intake of calcium and vitamin D might reduce the chances of colorectal cancer looks promising.
* Micronutrients—vitamins and minerals — might reduce the risk of some cancers.
* Beta-carotene and vitamin E, previously suggested as possible anti-cancer nutrients, showed no effect on lung cancer rates.
* High dietary fiber is linked in many studies with a reduction in colorectal cancer, but the evidence is inconsistent in larger studies.
* Preserved meats such as cured ham, bacon and sausages could increase cancer risk, but the proof for a link between cancer and fresh red meat isn't clear.

“The public is confused by stories that broccoli cures whatever ails you,” says Key. “We wanted to get away from that and report what we know is really important.

“The prudent advice is to maintain a healthy weight, restrict alcohol consumption and select a conventionally balanced diet ensuring an adequate intake of fruits, vegetables and cereals.”

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