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Public Health Nutr. 2016 Feb;19(3):437-45. doi: 10.1017/S136898001500138X. Epub 2015 May 11.

Validity of an FFQ assessing the vitamin D intake of young Serbian women living in a region without food fortification: the method of triads model.

Author information

1Centre of Research Excellence in Nutrition and Metabolism,Institute for Medical Research,University of Belgrade,Tadeusa Koscuska 1,11000 Belgrade,Serbia.
2School of Dietetics and Human Nutrition,McGill University,Macdonald Campus,Ste. Anne-de-Bellevue,Québec,Canada.
3Faculty of Chemistry,University of Belgrade,Belgrade,Serbia.



The objective of the present study was to examine the external validity of an FFQ designed to estimate dietary vitamin D intake compared with a plasma biomarker and three repeated 24 h dietary recalls in women of reproductive age in Serbia, where there is no exposure to food fortified with vitamin D. The method of triads was applied.


In a cross-sectional study, 422 women completed the Women and Reproductive Health FFQ (WRH-FFQ) during the winter months. From a representative subgroup (n 44), three 24 h dietary recalls and anthropometric parameters were collected as well as a fasting blood sample for vitamin D biomarker analyses. Correlation coefficients were calculated between each of the dietary methods. Validity coefficients, as a correlation between the measured and estimated 'true' exposure, were calculated using the method of triads. Bland-Altman plots were also constructed.


Three major universities in Serbia.


Healthy young women (n 422) aged 18-35 years.


The WRH-FFQ estimate of vitamin D intake for all participants was 4.0 (sd 3.3) µg/d and 3.1 (sd 2.3) µg/d for the subgroup. Bland-Altman plots for these intakes showed high agreement. Validity coefficients for the FFQ, 24 h recall and biomarker were ρ QI=0.847 (95% CI 0.564, 0.928), ρ RI=0.810 (95% CI 0.537, 0.997) and ρ BI=0.499 (95% CI 0.190, 0.840), while the correlation coefficients were 0.686, 0.422 and 0.404.


The FFQ applied in the present study is a valid tool for assessing dietary vitamin D intake in women living in Serbia, a region without mandatory vitamin D food fortification.


FFQ; Method of triads; Reproductive health; Validation; Vitamin D; Women

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