Diet studies blow to colon cancer

WASHINGTON - People who eat more fruit and vegetables than others do not seem to have a lower risk of colon cancer, say researchers.

But they stressed that a diet rich in vegetables and fruit has been clearly found to protect against other, more common ailments, such as heart disease and diabetes, and urged people to eat more of them.

Karin Michels of Harvard University in Boston, who led the study, said she feared the study might encourage people to eat more junk food.

"Even though we couldn't find an association with colorectal cancer, fruits and vegetables definitely protect for other important diseases such as cardiovascular disease, stroke, diabetes and potentially other cancers. These are some of the best foods we can eat - there is no doubt about it."

Colon cancer is the biggest cancer killer in the United States after lung cancer, and affects 130,000 new people every year, killing 56,000.

Dr Michels and colleagues used two long-term studies - the 88,000-member Nurses Health Study, which follows various health issues, and the 47,000-man Health Professionals' Follow-Up Study.

The participants answered pages of questions about what they ate, and then were watched for 16 years to see who developed colon cancer. The results are reported in the Journal of the National Cancer Institute.

Andrew Flood and Arthur Schatzkin of the National Cancer Institute noted that the participants ate an average American diet for the most part.

"Only 2 per cent of the nurses cohort consumes more than 4.5 servings of vegetables per day; in the health professionals cohort only 3 per cent consumed more than 3.5 servings per day," they wrote in a commentary.

The minimum recommended intake is five servings of fruits and vegetables a day. Mr Flood and Mr Schatzkin said that perhaps if people ate more fruits and vegetables, they would lower their risk of colon cancer. Other studies have suggested that vegetarians, for instance, have a lower risk of cancer.

Dr Michels said that because the people studied were health professionals, they probably had a better than average diet. But they were certainly not all health food fanatics.

"We certainly have people among them who eat a meat diet, who eat a diet high in fats, and who also as a consequence are overweight," she said.

"We had a surprisingly large number of obese people.

"I am not trying to say we have all these slim, trim, fit nurses in this study. They reflect the American population but they are a touch above the others in terms of diet."

Dr Michels, whose group also reported recently that fibre intake did not seem to protect against colon cancer, said she feared sending out the wrong message.

"I am in a dilemma. I would rather have found something else. But I have to report it. I actually was surprised by my findings," she said.

"I also was very concerned about the fibre findings because they got misreported and misinterpreted," she added.

"This is not an excuse not to eat fruits and vegetables."

Other factors might account for the findings. "We know that red-meat consumption increases the risk of colorectal cancer," she said. "Obesity, smoking, exercise, all have an effect."

It may also be that the study did not go back far enough. "We did cover 16 years but maybe we didn't cover enough. I think that adolescent diet may be important. Maybe it is important what we ate 30 years ago. I don't have the foggiest idea."

- REUTERS