Fish Tied to Lower Colon Cancer Risk: Study
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By Aparna Narayanan
NEW YORK (Reuters Health) May 11 – People who eat plenty of fish may have a lower risk of colon and rectal cancers, a new meta-analysis suggests.
“People who rarely eat fish may experience health benefits in a variety of areas — heart disease, reproductive and now colon cancer — by increasing their fish consumption somewhat,” said Dr. Michael Gochfeld, a professor of environmental and occupational medicine at University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School.
“If you eat fish very frequently, it’s not clear whether your benefit continues to go up (by eating even more),” he told Reuters Health.
The new study focused specifically on fresh fish, but the authors were unable to pinpoint what types of fish people ate or the manner in which fish was prepared in the prior studies.
“Cooking temperatures might affect the risk of colorectal cancer,” Dr. Jie Liang of Xijing Hospital of Digestive Diseases in Xi’an, China, who worked on the study, wrote in an email to Reuters Health.
Dr. Liang cited recent evidence that suggests eating lots of meat and fish barbecued or grilled over high heat may actually be tied to an increased cancer risk.
For the new report, Dr. Liang’s group pooled data from 41 studies from the U.S., Norway, Japan, Finland and elsewhere, published between 1990 and 2011, that measured fish consumption and tracked cancer diagnoses.
Overall, regularly eating fish was tied to a 12% lower risk of developing or dying of colon or rectal cancer, after adjustment for age, alcohol and red meat intake, family history of cancer and other risk factors.
The protective effect tied to fish consumption was stronger for rectal cancer than colon cancer.
People who ate the highest amounts of fish had a 21% lower risk of rectal cancer than those who ate the least. That compared to just a 4% lower risk of colon cancer, which was not statistically significant.
The study, published April 18th in the American Journal of Medicine, was partially funded by the National Natural Science Foundation of China.
Dr. Liang’s team did not investigate why eating fish may have a positive effect on colorectal cancer risk. The study also can’t prove that it’s the fish, itself, that was responsible for a lower cancer risk in some participants.
“It doesn’t tell us whether the benefit you get from fish has to do with specific nutrients in the fish, or with the fact that people who tend to eat fish tend to adopt other healthful lifestyles, such as avoiding red meat or processed meats,” said Dr. Gochfeld, who was not involved in the research.
If fish indeed is behind the lower colorectal cancer risk, the added benefit could be coming from the omega-3 essential fatty acids found in certain fish such as salmon and sardines, Dr. Gochfeld said.
But even if the high omega-3 levels in fatty fish have a protective effect, it’s unclear whether or not the same benefit extends to supplements such as fish-oil capsules, he said.
Am J Med 2012.