One size does not fit all: Dietary guidelines for choline may be insufficient

"Our study shows that gender, life stage and genetic makeup influence the requirement for choline in humans," said Kerry-Ann da Costa Ph.D., a researcher involved in the work from the Department of Nutrition at the University of North Carolina, Chapel Hill. "We hope that it will focus attention on setting the dietary recommendations at a level that is high enough to meet the needs of those with the greatest requirements for choline."

To make this discovery, da Costa and colleagues analyzed healthy men and women who were fed a baseline diet containing 550 mg choline/day (the adequate intake level set by the Institute of Medicine) for 10 days. Then they were put on a low choline diet (50 mg choline/day) for up to 42 days, and monitored for increased liver fat and changes in liver and muscle function. If they developed clinical symptoms, choline was returned to their diet until these symptoms resolved. Subjects were categorized by symptoms -- liver, muscle or none. DNA isolated from their blood was examined for 200 single nucleotide polymorphisms or SNPs in 10 choline-related genes to see which ones were associated with liver or muscle damage compared to the people with no symptoms. Several SNPs were identified in women that alter their risk when they are on a low choline diet. Other SNPs in the choline transporter gene SLC44A1 and choline kinase beta gene (CHKB) were identified in the people with muscle damage compared to the rest of the study participants. Researchers then looked at these SNPs in European-, Mexican-, Asian- and African-Americans and in individuals of African descent, and found that the distribution was often quite different between the groups.

"Getting the right amount of choline is important, and also important is this study which shows that each person has unique nutritional needs. Today's dietary guidelines are approximations at best, and one size does not fit all," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "As we move toward an age of personalized medicine, studies like this should make it possible for health care professionals to judge how much of each nutrient your particular body needs."