Jessica Berman Washington -- A comprehensive study unveiled this week shows people regularly eating red meat, such as beef, are at a higher risk of developing colon cancer than those with a more balanced diet.  

A long-term study published in the Journal of the American Medical Association tracked the eating habits of 150,000 people between 1982 and 1992.

From the time the data were collected until the study's conclusion a decade later, researchers found that those who consumed the most red meat had a 30 to 40 percent greater risk of colon and rectal cancer than those whose diets were rich in fish and chicken. 

Study co-author Margie McCullough of the American Cancer Society notes the research confirms the results of many other smaller studies.

"What's different about this study is that we were able to look at diet over two time periods spread apart by 10 years,” she said.  “So, we could look at consistency of diet over the long term in relation to colon and rectal cancer."

In the same issue of the Journal, researchers report a diet rich in fruit and vegetables does not appear to protect women against breast cancer.  The results seem to contradict other scientific evidence, as well as a commonly held belief, that fruits and vegetables are protective against cancer.

Despite the latest findings, Ms. McCullough says women shouldn't stop eating vegetables.

"Although the association wasn't strong with breast cancer, there are plenty of reasons to eat a lot of fruit and vegetables in the diet for reducing the risk of cardiovascular disease and some other cancers,” she added.  “And there are obviously important for good nutrition.  So, there are plenty reasons to eat a diet high in fruits and vegetables.  But for strongly reducing the risk of breast cancer, strongly reducing the risk of breast cancer doesn't seem to be one of them."

But she says there is evidence to show obesity may be a factor in breast cancer risk.  Eating fruits and vegetables, she says, helps women to keep their weight down.