Relative validity of a 2-day 24-hour dietary recall compared with a 2-day weighed dietary record among adults in South China.

AIM: To determine the relative validity of a 2-day 24-hour dietary recall (HR) designed to assess energy and nutrient intake among Chinese adults compared with a 2-day weighed dietary record (WD).

METHODS: Data were obtained from an ongoing population-based, prospective cohort study of adults aged 18-65 years in South China. A total of 41 adults completing a HR and a WD within 14 days were included in the present analysis. Estimations of individual mean differences, Spearman's correlation coefficients, cross-classifications and Bland-Altman plots were used to assess the agreement between the intakes of energy and 18 nutrients obtained from the HR and the WD.

RESULTS: With the exception of total fat, saturated fatty acids, thiamine, potassium and magnesium, the energy and nutrient intakes between the HR and WD showed no significant differences. All dietary intakes that were evaluated by the HR were correlated significantly with the dietary intake from the WD (de-attenuated correlation coefficients ranged from 0.10 to 0.87). The proportion of participants classified into quartiles correctly ranged from 61% for tocopherol intake to 90% for energy intake. The weighted k values ranking the participants ranged from 0.11 for tocopherol intake to 0.41 for the intakes of energy and calcium. The Bland-Altman plots showed moderate/good agreement among all the dietary intakes that were estimated from the HR and WD, except for total fat.

CONCLUSIONS: This study suggests that an HR could be a valid tool for estimating the energy and nutrient intakes among adults in South China at the group level.