NEW YORK (Reuters Health) - A high intake of trans fats could increase colon cancer risk, according to new research published in the American Journal of Epidemiology.
People who ate the most trans fatty acids were more likely to have pre-cancerous growths or polyps in their colons than those who consumed the least, Dr. Lisa C. Vinikoor of the University of North Carolina in Chapel Hill and colleagues found. "These results provide further support for recommendations to limit consumption of trans-fatty acids," they conclude.
Trans fats are formed by processing vegetable oils to increase their shelf-life, and are found in many baked goods, crackers, snacks and other packaged foods. Eating them increases levels of "bad" LDL-cholesterol, and hence heart disease risk. US food producers are now required to list the amount of trans fat contained in their products, and health authorities recommend people avoid eating trans fats entirely.
While there has been little research on whether trans fats boost colorectal cancer risk, there are many possible ways that they could do so, for example by changing the normal balance of fatty or bile acids in the colon, Vinikoor and her colleagues say.
To investigate a possible link, they looked at 622 people who had colonoscopies at University of North Carolina Hospitals in 2001 and 2002. Study participants were interviewed about their diet, physical activity and other health issues within 12 weeks of having the screening test.
People in the top fourth based on trans-fatty acid consumption, most of whom took in 6.54 grams daily, were 86 percent more likely to have colon polyps than those in the bottom quartile for trans fat intake, for whom median intake was 3.63 g, the researchers found. There appeared to be a threshold effect, with no increased risk seen for people in the bottom three quarters of fatty acid consumption.
Among the 38.5 percent of study participants found to have colon polyps, average trans fatty acid intake was 4.97 g, while most consumed 4.12 g. Average intakes for people who were free of the colon growths was 4.42 g, while the median was 3.61 g.
These results suggest that consumption of high amounts of trans-fatty acid may increase the risk of colorectal polyps, the researchers write, adding that the findings also back current recommendations to limit trans fat intake.
SOURCE: American Journal of Epidemiology, August 1, 2008.