Measuring Citrus Intake with Urine Tests in a Dietary Study

Greg Howard
19th May, 2024

Measuring Citrus Intake with Urine Tests in a Dietary Study

Image Source: Natural Science News, 2024

Key Findings

  • The study from Harvard T.H. Chan School of Public Health developed a method to correct errors in food frequency questionnaires (FFQs) using food biomarkers and 7-day diet records (7DDRs)
  • Researchers found that urinary proline betaine, a biomarker for citrus intake, was moderately correlated with orange juice intake but weakly correlated with oranges and grapefruits
  • After calibrating FFQ data with biomarkers, the mean intake levels closely matched those from 7DDRs, proving the calibration method's effectiveness
Understanding how dietary intake impacts health is crucial, but accurately measuring what people eat is challenging. Traditional methods, like food frequency questionnaires (FFQs), often suffer from inaccuracies. A recent study from the Harvard T.H. Chan School of Public Health aimed to address this issue by developing calibration equations using food biomarkers and 7-day diet records (7DDRs) to correct measurement errors in FFQs[1]. The study involved 669 men and 749 women from the Women and Men's Lifestyle Validation Study. Researchers used urinary proline betaine, a biomarker for citrus intake, to calibrate FFQ data. They found that urinary proline betaine was moderately correlated with orange juice intake (r: 0.53 for 7DDR and 0.48 for FFQ) but weakly correlated with intakes of oranges and grapefruits. The FFQ data overestimated citrus intake compared to 7DDR. However, after calibration, the mean intake levels from FFQ closely matched those from 7DDR, demonstrating the effectiveness of the calibration approach. This study builds on previous research that highlighted the limitations of self-reported dietary data. For instance, earlier studies showed that uncalibrated energy and protein intakes from FFQs are often underreported and can lead to misleading associations with disease outcomes[2][3]. By using biomarkers to correct these errors, the current study provides a more accurate method for dietary assessment. The new calibration method has significant implications. It can potentially correct systematic measurement errors for other foods and nutrients with established biomarkers in a cost-effective way. This advancement could improve the accuracy of nutritional epidemiology studies, leading to better understanding and prevention of diet-related diseases.

NutritionHealthBiochem

References

Main Study

1) Calibration of citrus intake assessed by food frequency questionnaires using urinary proline betaine in an observational study setting.

Published 16th May, 2024

https://doi.org/10.1016/j.ajcnut.2024.05.011

Related Studies

2) Biomarker-calibrated dietary energy and protein intake associations with diabetes risk among postmenopausal women from the Women's Health Initiative.

https://doi.org/10.3945/ajcn.111.018648

3) Biomarker-calibrated energy and protein consumption and cardiovascular disease risk among postmenopausal women.

https://doi.org/10.1097/EDE.0b013e31820839bc


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