Sareh Eghtesad
1 
, Maryam Sharafkhah
1, Azita Hekmatdoost
2, Alireza Ostadrahimi
3, Mojtaba Farjam
4, Alireza Vakilian
5, Yahya Pasdar
6, Motahareh Kheradmand
7, Fariba Shahraki-Sanavi
8, Amir Houshang Mehrparvar
9, Amaneh Shayanrad
1, Zahra Mohammadi
1, Monireh Sadat Seyyedsalehi
10,11, Walter C. Willett
12,13, Reza Malekzadeh
14, Hossein Poustchi
1* 1 Liver and Pancreatobiliary Diseases Research Center, Digestive Diseases Research Institute, Tehran University of Medical Sciences, Tehran, Iran
2 Department of Clinical Nutrition & Dietetics, National Nutrition & Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran
3 Nutrition Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
4 Noncommunicable Diseases Research Center, Fasa University of Medical Sciences, Fasa, Iran
5 Neurology Department, School of Medicine, Non-Communicable Diseases Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran
6 Research Center for Environmental Determinants of Health (RCEDH), Nutritional Sciences Department, Kermanshah University of Medical Sciences, Kermanshah, Iran
7 Health Sciences Research Center, Mazandaran University of Medical Sciences, Sari, Iran
8 Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran
9 Industrial Diseases Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
10 Cancer Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
11 Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
12 Department of Nutrition, Harvard T.H. School of Public Health, Boston, MA, USA
13 Department of Epidemiology, Harvard T.H. School of Public Health, Boston, MA, USA
14 Digestive Diseases Research Center, Digestive Diseases Research Institute, Tehran University of Medical Sciences, Tehran, Iran
Abstract
Background: Food frequency questionnaires (FFQs) are widely used in epidemiologic studies to assess the dietary intake of individuals. In this study, we evaluated the validity and reproducibility of the FFQ used in the Prospective Epidemiological Research Studies in IrAN (PERSIAN) for assessing nutrient intakes.
Methods: Individuals (n=978) from seven PERSIAN cohort centers participated in this study; an initial FFQ was completed for each person upon enrollment (FFQ1), followed by two 24-hour dietary recalls (24HR) each month, for twelve months, and finally, another FFQ at the end of the study (FFQ2). Serum and 24-hour urine (24H-U) samples were also collected each season, and selected biomarkers were measured. To assess validity, correlation coefficients between the 24HRs and the FFQs were obtained. The triad method was used to compare the biomarkers to the FFQs. Correlations between FFQ1 and FFQ2 were evaluated to assess the reproducibility of the questionnaire.
Results: Correlations obtained for energy and macronutrients, in comparing FFQ1 and FFQ2 to the 24HRs were 0.57,0.63 (energy), 0.56,0.62 (protein), 0.51,0.55 (lipids) and 0.42,0.51 (carbohydrates), respectively. Moderate (0.4‒0.6) and high (>0.6) correlations were seen for micronutrients, with only vitamins B6 and B12 being poorly correlated (<0.4). Validity coefficients obtained for urinary protein and sodium, as well as serum folate and selected fatty acids were acceptably above 0.4. Reproducibility correlations ranged from 0.18 (alpha-linoleic acid) to 0.78 (selenium), with 19 of the 30 evaluated nutrients showing high and 2 showing poor correlations.
Conclusion: Overall, the PERSIAN Cohort FFQ is acceptable to rank individuals based on their nutrient intakes.