Calibration of Dietary Data: “Folate and Nutrients Involved in the 1-Carbon Cycle in the Pretreatment of Patients for Colorectal Adenocarcinoma in a Referral Center for Oncology in Southeastern Brazil”

Objective: Calibrate the FFQ and evaluate its performance in relation to the consumption of energy, carbohydrate, protein, fat, alcohol, folate, vitamin B2, vitamin B6, vitamin B12, methionine, choline and betaine in the study population “Folate and nutrients involved in the 1-carbon cycle in the pretreatment of patients for colorectal adenocarcinoma in a referral center for oncology in southeastern Brazil.Materials and methods: For calibration, we used three 24-hour dietary recalls (R24s; n=270) and the second FFQ (n=90) collected in a previous study. The R24 data were used as a reference method and subjected to linear regression, with β1 values used as a calibration factor for the FFQ data collected.Results: Comparing the R24 data to observed FFQ data and observed FFQ data to calibrated FFQ data; the means were significantly different for all nutrients. When comparing calibrated FFQ data to R24 values, the means were statistically similar for carbohydrates, vitamin B2, vitamin B6, natural folate, synthetic folate, DFE diet and betaine.Conclusion: The calibration coefficients were low, however the reference method used may not have been the best way to eliminate measurement errors found in the FFQ.