Choline in meat, dairy products linked to colon cancer risk in women

Researchers may have discovered a relationship between the risk of colorectal cancer in women and their consumption of choline, which has until now been thought to be an essential nutrient. The link was reported in a study published in the Journal of the National Cancer Institute.Choline is a nutrient found in eggs, meat (especially liver) and dairy products. It plays an important role in the functioning of cells and the distribution of nutrients through the body, including a process called one-carbon metabolism. Prior studies have shown that people with a high dietary intake of other nutrients involved in one-carbon metabolism, such as folate, have a decreased risk for colorectal polyps.Colorectal polyps are often-benign tumors that develop in the colon and can eventually lead to cancer. In the first study to examine the issue, researchers expected to find that consumption of choline, like folate, decreased a person's risk of developing colorectal polyps.To their surprise, researchers found the opposite. In a survey of 39,246 women, researchers used food-frequency questionnaires to estimate the choline contents of participants' diets. All the women had no cancer or polyps when the study began, and had at least one endoscopy between 1984 and 2002. Increased consumption of choline was found to be correlated with a higher risk of colorectal polyps."Clearly, one-carbon metabolism and its role in [cancer development] is more complicated than originally anticipated, and our understanding of the underlying mechanisms is probably incomplete," wrote Regina Ziegler and Unhee Lim, of the National Cancer Institute in Bethesda, Maryland, in an accompanying editorial.While a correlation does not necessarily mean that choline is to blame for the increased colon cancer risk, the authors speculated that it may indeed play a role."Once a tumor is initiated, growth into a detectable [polyp] depends in part on choline availability, because choline is needed to make membranes in all rapidly growing cells," they wrote.Prior studies have linked choline deficiency to fatty liver and muscle damage.