Alejandra M Wiedeman1, Roger A Dyer2, Timothy J Green3, Zhaoming Xu4, Susan I Barr5, Sheila M Innis6, David D Kitts7. 1. BC Children's Hospital Research Institute, 950 west 28(th) avenue, Vancouver, BC V5Z 4H4, Canada; Food, Nutrition, and Health Program, University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada. Electronic address: awiedeman@bcchr.ca. 2. BC Children's Hospital Research Institute, 950 west 28(th) avenue, Vancouver, BC V5Z 4H4, Canada. Electronic address: radyer@mail.ubc.ca. 3. BC Children's Hospital Research Institute, 950 west 28(th) avenue, Vancouver, BC V5Z 4H4, Canada; Food, Nutrition, and Health Program, University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada; South Australian Health and Medical Research Institute, Adelaide 5000, South Australia, Australia. Electronic address: tim.green@sahmri.com. 4. Food, Nutrition, and Health Program, University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada. Electronic address: zhaoming.xu@ubc.ca. 5. Food, Nutrition, and Health Program, University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada. Electronic address: susan.barr@ubc.ca. 6. BC Children's Hospital Research Institute, 950 west 28(th) avenue, Vancouver, BC V5Z 4H4, Canada. 7. Food, Nutrition, and Health Program, University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada. Electronic address: david.kitts@ubc.ca.
Abstract
BACKGROUND: Plasma concentrations of choline and its metabolites might serve as biomarkers for the health outcomes of several pathological states such as cardiovascular disease and cancer. However, information about the reliability of biomarkers of choline status is limited. We investigated biological variations in repeated measures of choline and metabolites in healthy adults to assess them as biomarkers. METHODS: Blood samples were collected after an overnight fast at three-time points 12 days apart from 40 adults (mean age, 33 y; male, n = 21). A subset (n = 19; [male, n = 8]) provided one additional sample after a breakfast meal. Plasma free choline, betaine and dimethylglycine were measured using liquid chromatography-tandem mass spectrometry, and plasma phosphatidylcholine, sphingomyelin and lysophosphatidylcholine were measured using high-performance liquid chromatography. RESULTS: The biological variations observed for choline and metabolites were ≤ 13% for adult fasting samples. This corresponded to intra-class correlations (ICC) that ranged from 0.593 to 0.770 for fasting values for choline and metabolites. A similar ICC range was also obtained between fasting and post-prandial states. Although most post-prandial concentrations of choline and metabolites were significantly higher (P < .05) than fasting, all fell within a calculated reference interval. The participants were correctly classified in tertiles for fasting and post-prandial states for choline (68%) and metabolites (range = 32% phosphatidylcholine and 79% for sphingomyelin). CONCLUSIONS: These findings indicate that biological variations of choline and metabolites are low in healthy adults and values from a single blood sample can be used as a biomarker. However, choosing phosphatidylcholine as a biomarker is less reliable.
BACKGROUND: Plasma concentrations of choline and its metabolites might serve as biomarkers for the health outcomes of several pathological states such as cardiovascular disease and cancer. However, information about the reliability of biomarkers of choline status is limited. We investigated biological variations in repeated measures of choline and metabolites in healthy adults to assess them as biomarkers. METHODS: Blood samples were collected after an overnight fast at three-time points 12 days apart from 40 adults (mean age, 33 y; male, n = 21). A subset (n = 19; [male, n = 8]) provided one additional sample after a breakfast meal. Plasma free choline, betaine and dimethylglycine were measured using liquid chromatography-tandem mass spectrometry, and plasma phosphatidylcholine, sphingomyelin and lysophosphatidylcholine were measured using high-performance liquid chromatography. RESULTS: The biological variations observed for choline and metabolites were ≤ 13% for adult fasting samples. This corresponded to intra-class correlations (ICC) that ranged from 0.593 to 0.770 for fasting values for choline and metabolites. A similar ICC range was also obtained between fasting and post-prandial states. Although most post-prandial concentrations of choline and metabolites were significantly higher (P < .05) than fasting, all fell within a calculated reference interval. The participants were correctly classified in tertiles for fasting and post-prandial states for choline (68%) and metabolites (range = 32% phosphatidylcholine and 79% for sphingomyelin). CONCLUSIONS: These findings indicate that biological variations of choline and metabolites are low in healthy adults and values from a single blood sample can be used as a biomarker. However, choosing phosphatidylcholine as a biomarker is less reliable.