Dataset Information

The direction of the difference between Canadian and American erythrocyte folate concentrations is dependent on the assay method employed: a comparison of the Canadian Health Measures Survey and National Health and Nutrition Examination Survey.

ABSTRACT: Fortification of select grain products with folic acid and periconceptional supplementation recommendations in Canada and the USA have improved folate status, and have been associated with a reduced risk of neural tube defects. In the present study, we aimed to conduct a comparison of erythrocyte folate concentrations from the 2007-9 Canadian Health Measures Survey (CHMS) and the 2007-8 US National Health and Nutrition Examination Survey (NHANES). Erythrocyte folate concentration was assessed in participants aged 6-79 years (CHMS, n 5248; NHANES, n 7070). To account for different folate assays employed - Immulite 2000 immunoassay (CHMS) and microbiological assay (NHANES) - a conversion equation was generated (n 152 adults) to adjust the CHMS data. t Tests were used to examine country differences. Median Canadian erythrocyte folate concentrations (method-adjusted) were lower than those of Americans (988 and 1100 nmol/l, respectively), but unadjusted median Canadian erythrocyte folate concentrations were higher (1250 nmol/l). The upper 95% CI boundary of the method-adjusted Canadian erythrocyte folate distribution overlapped that of the American erythrocyte folate concentrations, while the lower 95% CI boundary of the method-adjusted Canadian erythrocyte folate data was below the American distribution. In summary, the fact that erythrocyte folate concentrations were either higher or lower in Canadians compared with Americans, depending on whether an adjustment was made to account for assay differences, suggests that caution must be exercised in evaluating erythrocyte folate data from different countries because analytical methods are not readily comparable. Furthermore, we cannot unequivocally conclude that there are true differences in erythrocyte folate concentrations between the Canadian and American populations in the post-fortification era.

SUBMITTER: Colapinto CK

PROVIDER: S-EPMC4806528 | biostudies-other | 2014 Dec

REPOSITORIES: biostudies-other

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The direction of the difference between Canadian and American erythrocyte folate concentrations is dependent on the assay method employed: a comparison of the Canadian Health Measures Survey and National Health and Nutrition Examination Survey.

Colapinto Cynthia K CK Tremblay Mark S MS Aufreiter Susanne S Bushnik Tracey T Pfeiffer Christine M CM O'Connor Deborah L DL

The British journal of nutrition 20141008 11

Fortification of select grain products with folic acid and periconceptional supplementation recommendations in Canada and the USA have improved folate status, and have been associated with a reduced risk of neural tube defects. In the present study, we aimed to conduct a comparison of erythrocyte folate concentrations from the 2007-9 Canadian Health Measures Survey (CHMS) and the 2007-8 US National Health and Nutrition Examination Survey (NHANES). Erythrocyte folate concentration was assessed in ...[more]

PMID: 25296277

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Project description:Serum and erythrocyte (RBC) total folate are indicators of folate status. No nationally representative population data exist for folate forms. We measured the serum folate forms (5-methyltetrahydrofolate (5-methylTHF), unmetabolised folic acid (UMFA), non-methyl folate (sum of tetrahydrofolate (THF), 5-formyltetrahydrofolate (5-formylTHF), 5,10-methenyltetrahydrofolate (5,10-methenylTHF)) and MeFox (5-methylTHF oxidation product)) by HPLC-MS/MS and RBC total folate by microbiologic assay in US population ? 1 year (n approximately 7500) participating in the National Health and Nutrition Examination Survey 2011-2. Data analysis for serum total folate was conducted including and excluding MeFox. Concentrations (geometric mean; detection rate) of 5-methylTHF (37·5 nmol/l; 100 %), UMFA (1·21 nmol/l; 99·9 %), MeFox (1·53 nmol/l; 98·8 %), and THF (1·01 nmol/l; 85·2 %) were mostly detectable. 5-FormylTHF (3·6 %) and 5,10-methenylTHF (4·4 %) were rarely detected. The biggest contributor to serum total folate was 5-methylTHF (86·7 %); UMFA (4·0 %), non-methyl folate (4·7 %) and MeFox (4·5 %) contributed smaller amounts. Age was positively related to MeFox, but showed a U-shaped pattern for other folates. We generally noted sex and race/ethnic biomarker differences and weak (Spearman's r< 0·4) but significant (P< 0·05) correlations with physiological and lifestyle variables. Fasting, kidney function, smoking and alcohol intake showed negative associations. BMI and body surface area showed positive associations with MeFox but negative associations with other folates. All biomarkers showed significantly higher concentrations with recent folic acid-containing dietary supplement use. These first-time population data for serum folate forms generally show similar associations with demographic, physiological and lifestyle variables as serum total folate. Patterns observed for MeFox may suggest altered folate metabolism dependent on biological characteristics.

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Dataset Information

The direction of the difference between Canadian and American erythrocyte folate concentrations is dependent on the assay method employed: a comparison of the Canadian Health Measures Survey and National Health and Nutrition Examination Survey.

Publications

The direction of the difference between Canadian and American erythrocyte folate concentrations is dependent on the assay method employed: a comparison of the Canadian Health Measures Survey and National Health and Nutrition Examination Survey.

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