Validation of a food-frequency questionnaire to assess methyl-group donor intake in preschoolers.

A good assessment of dietary methyl-group donor intake (folate, choline, betaine, methionine) is needed to investigate the effect of methyl-group donor intake on children's health. The aim is to develop and validate a food-frequency questionnaire (FFQ) to estimate the daily intake of methyl-group donors in preschoolers. For the relative validity and reproducibility of the FFQ, a 7-day estimated dietary record (7d EDR) and repeated measurements 6 weeks apart (n = 77) were used respectively. For the validity (n = 75), a moderate ranking ability was obtained (de-attenuated Pearson correlation = 0.43-0.70; weighted ƙ 0.10-0.40), but the FFQ tends to overestimate the real intake. Cross-classification analysis showed that 38% (choline) and 28% (betaine) of the subjects were misclassified. The FFQ shows a moderate to good reproducibility, intra-class correlation coefficients range between 0.67 (betaine) and 0.76 (choline) with a maximal misclassification of 6.5% for betaine (weighted ƙ 0.37-0.69) (n = 77). CONCLUSION: The FFQ is a tool with a moderate validity and reproducibility to estimate the consumption of dietary methyl-group donors in preschoolers. This tool might be used in future research epidemiological studies including preschoolers. WHAT IS KNOWN: • Poor dietary habits during childhood have been associated with chronic disease in adulthood. • Methyl-group donors are important for DNA methylation, which is the underlying mechanism of disease development. WHAT IS NEW: • For the first time, a food-frequency questionnaire that can assess the intake of methione, folate, choline, and betaine has been developed and validated for the use in preschoolers.