Objective: This study aimed to compare the similarities and differences among Food Frequency Questionnaire(FFQ), 24-hour dietary recall method, and weighing method in assessing the intakes of foods, energy, and nutrients in pregnant women, and to evaluate the validity of the FFQ.
Methods: From June to September in 2017, a total of 82 pregnant women were recruited across the entire Wuqiang County in Hebei Province. The subjects were surveyed using the FFQ for the most recent week, 24-hour dietary recall for 3 consecutive days, and in-home weighing for 3 consecutive days. The differences in the average daily intakes of food, energy, and nutrients obtained by the FFQ and the other two method were calculated and compared. The correlation and consistency between the FFQ and the other two method were evaluated through the Spearman correlation coefficient and the Bland-Altman plot, respectively.
Results: There was no statistically significant difference between the FFQ and 24-hour dietary recall method in assessing the average daily intakes of soybeans and their products, fruits, dairy products and nuts. The intakes of fruits and dairy products evaluated by the two method were all positively correlated(r=0.34-0.56, P<0.05). There was no statistically significant difference between the FFQ and the weighing method in assessing the average daily intakes of cereals, soybeans and their products, vegetables, fruits, aquatic products, eggs, dairy products and nuts. Among them, the intakes obtained by the two method for cereals, vegetables and nuts were all positively correlated(r=0.53-0.58, P<0.05). There was no statistically significant difference between the FFQ and 24-hour dietary recall method in evaluating average daily intakes of energy, protein, carbohydrates, the ratio of carbohydrates to energy supply, dietary fiber, total vitamin A, thiamine, riboflavin, vitamin C, calcium, phosphorus, potassium, magnesium, iron and zinc. Among them, intakes of energy, protein, fat and carbohydrates were all positively correlated(r=0.41-0.58, P<0.05). There was no statistically significant difference between FFQ and weighing method in evaluating the average daily intakes of energy, fat, the ratio of fat to energy supply, carbohydrates, the ratio of carbohydrates to energy supply, total vitamin A, thiamine, riboflavin, vitamin C, calcium, potassium, sodium and magnesium. Among them, the intakes of energy, protein and carbohydrates obtained by the two method were all positively correlated(r=0.49-0.52, P<0.05). Bland-Altman analysis showed that for most subjects, the intakes of energy, protein, fat and carbohydrates were within the 95% consistency limits between FFQ and 24-hour recall method(91.1%-94.9%)or weighing method(92.9%-100%).
Conclusion: FFQ can relatively accurately evaluate the intakes of food and nutrients among pregnant women.
Keywords: 24-hour dietary recall method; dietary survey; food frequency method; pregnant women; weighing method.