Design and validation of a food frequency questionnaire to assess the dietary intake for adults in pastoral settings in Northern Tanzania

Abstract

Objective: Food frequency questionnaires are widely used as a dietary assessment tool in nutritional epidemiol ogy to determine the relationship between diet and diseases. In Tanzania, there are several cultural variations in food intake which makes it necessary to design and validate a culture-specifc food frequency questionnaire (CFFQ). There fore, we designed a 27-items CFFQ and examine its validity in pastoral communities. Validity of CFFQ was assessed by comparing nutrient intake estimated from the CFFQ against the average from two 24-h diet recall (2R24). Spearman’s correlation coefcients, cross classifcation and Bland–Altman’s methods were used to assess the validity of CFFQ. Results: A total of 130 adults aged 18 years and above completed both CFFQ and 2R24. Correlation coefcients between CFFQ and 2R24 ranged from low (r=− 0.07) to moderate (r=0.37). The correlation coefcients were mod erately signifcant for kilocalories (r=0.31, p<0.001), carbohydrate (r=0.33, p<0.001), magnesium (r=0.37, p<0.001), and iron (r=0.34, p<0.001). On average, about 69% of participants were correctly classifed into the same or adjacent quartile of energy and nutrient intake, while 9% were misclassifed by the CFFQ. Bland–Altman’s plot demonstrated that the CFFQ had acceptable agreement with the 2R24.