Validity of brief food frequency questionnaire for estimation of dietary intakes of folate, vitamins B6 and B12, and their associations with plasma homocysteine concentrations.

BACKGROUND: Low nutrient intakes of folate, vitamins B(6) and B(12) have been associated with the risk of chronic diseases and neural tube defects. The aim of this study was to develop a brief food frequency questionnaire (FFQ) for the assessment of these nutrient intakes and to assess its validity. METHODS: We developed a brief FFQ designed specifically for estimating intakes of folate and vitamins B(6) and B(12) and covering 21 food items, and used it to carry out dietary surveys of 579 Japanese men and women. The associations of these vitamin intakes with their serum levels and homocysteine concentrations were examined using multiple linear regression analysis after adjusting for sex, age and cardiovascular risk factors. RESULTS: The Spearman correlation coefficients between vitamin intakes and their serum concentrations were 0.10 for folate, 0.08 for vitamin B(6) and 0.22 for B(12). Changes in plasma homocysteine concentrations associated with a one-standard-deviation increment were -0.03 for dietary folate, -0.03 for dietary vitamin B(6) and -0.03 for dietary vitamin B(12), and were -0.06 for serum folate, -0.03 for serum vitamin B(6) and -0.06 for serum vitamin B(12). CONCLUSION: Positive correlations between dietary intakes estimated from our brief FFQ and serum concentrations for folate and vitamin B(12) as well as negative correlations between dietary intakes and plasma homocysteine concentrations suggest the usefulness of this questionnaire.