Surreal illustration of coffee beans transforming into urine droplets, symbolizing the measurement of caffeine biomarkers in urine.

Caffeine Check: How Accurate Are Your Intake Estimates?

"New research compares a 24-hour caffeine recall tool with urinary biomarkers to assess caffeine intake among young adults, revealing insights into consumption patterns and validation methods."


Caffeine is a widely consumed stimulant, and its presence is increasingly noted in various products marketed towards young adults. With this rise in consumption, accurately measuring caffeine intake becomes crucial, yet existing tools often fall short, especially among younger populations.

To bridge this gap, researchers developed the 24-Hour Caffeine Intake Recall (CIR-24), modeled after the Automated Self-Administered 24-Hour Dietary Assessment Tool. This tool uses a brand-specific database of caffeine-containing foods, beverages, and supplements to estimate caffeine consumption over the previous 24 hours.

A new study has evaluated the accuracy of the CIR-24 by comparing it with caffeine concentration biomarkers in urine and a caffeinated beverage intake frequency screener (CBQ). The research offers insights into the effectiveness of different assessment methods for gauging caffeine consumption in young adults.

Decoding the Study: Comparing Recall with Reality

Surreal illustration of coffee beans transforming into urine droplets, symbolizing the measurement of caffeine biomarkers in urine.

The study involved 79 young adults aged 18 to 29, who provided 24-hour urine samples and completed both the CIR-24 and CBQ. Researchers then quantified caffeine and eight caffeine metabolites from the urine samples using advanced techniques like high-performance liquid chromatography-polarity switching electrospray ionization-tandem quadrupole mass spectrometry with stable isotope-labeled internal standards.

Statistical analyses were performed to determine the correlation between the self-report tools and caffeine biomarkers. Pearson correlations and weighted κ coefficients were calculated to assess the linear associations and quartile ranking concordance.

  • The CIR-24 showed a significant positive association with all caffeine biomarkers (rp=0.28 to 0.52, κ=0.39 to 0.59).
  • The CBQ was also significantly positively associated with most biomarkers (rp=0.21 to 0.40, k=0.32 to 0.45), though slightly less consistently.
  • Notably, the CIR-24 yielded a higher mean intake of caffeine compared to the CBQ. There was strong linear correlation between the CIR-24 and CBQ (rp=0.60, P<0.001), but only moderate agreement in absolute caffeine consumed (t=2.83, P=0.006); quartile ranking concordance was 0.44 (P<0.001).
  • Across all biomarkers, the CIR-24 performed better than the CBQ in both linear correlation and quartile ranking.
These findings suggest that while both tools can capture caffeine intake reasonably well, the CIR-24 demonstrates stronger agreement with urinary biomarkers, making it a promising tool for evaluating caffeine intake among young adults.

Key Takeaways and Future Directions

The study confirms that both the CIR-24 and CBQ perform reasonably well in capturing caffeine intake when compared with urinary biomarkers. However, the CIR-24 showed stronger agreement, suggesting it is a more accurate tool for assessing daily caffeine consumption.

For those looking to monitor their caffeine intake, especially young adults, the CIR-24 appears to be a reliable method. It accounts for a broader range of caffeine sources, including foods and supplements, which are often missed by other tools.

Future research could focus on automating the data coding process of the CIR-24 to enhance its usability. Additionally, examining the tool's sensitivity to changes in caffeine consumption over extended periods would further validate its effectiveness.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1016/j.jand.2018.07.016, Alternate LINK

Title: Evaluation Of A 24-Hour Caffeine Intake Assessment Compared With Urinary Biomarkers Of Caffeine Intake Among Young Adults In Canada

Subject: Nutrition and Dietetics

Journal: Journal of the Academy of Nutrition and Dietetics

Publisher: Elsevier BV

Authors: Lana Vanderlee, Jessica L. Reid, Christine M. White, Rachel B. Acton, Sharon I. Kirkpatrick, Ching-I. Pao, Michael E. Rybak, David Hammond

Published: 2018-12-01

Everything You Need To Know

1

What is the CIR-24, and how does it work to estimate caffeine intake?

The CIR-24, or 24-Hour Caffeine Intake Recall, is designed to estimate caffeine consumption over the previous 24 hours. It is modeled after the Automated Self-Administered 24-Hour Dietary Assessment Tool and uses a brand-specific database of caffeine-containing foods, beverages, and supplements. This level of detail helps in providing a more accurate estimate compared to methods that might rely on broader categories or general recall.

2

How was the accuracy of caffeine intake estimates evaluated in this study?

The accuracy of caffeine intake estimates was assessed by comparing two self-report tools, the CIR-24 and the Caffeinated Beverage intake frequency Questionnaire (CBQ), against caffeine concentration biomarkers found in urine. Researchers used advanced techniques such as high-performance liquid chromatography-polarity switching electrospray ionization-tandem quadrupole mass spectrometry with stable isotope-labeled internal standards to quantify caffeine and eight caffeine metabolites from the urine samples. Statistical analyses, including Pearson correlations and weighted κ coefficients, were performed to determine the correlation between the self-report tools and caffeine biomarkers.

3

Did the 24-Hour Caffeine Intake Recall (CIR-24) tool show a positive association with caffeine levels in the body?

Yes, the CIR-24 showed a significant positive association with all caffeine biomarkers (rp=0.28 to 0.52, κ=0.39 to 0.59). The CBQ was also significantly positively associated with most biomarkers (rp=0.21 to 0.40, k=0.32 to 0.45), though slightly less consistently. Across all biomarkers, the CIR-24 performed better than the CBQ in both linear correlation and quartile ranking.

4

Between the CIR-24 and the Caffeinated Beverage intake frequency Questionnaire (CBQ), which tool was more accurate, and why?

While both the CIR-24 and the CBQ performed reasonably well in capturing caffeine intake, the CIR-24 demonstrated stronger agreement with urinary biomarkers. This suggests the CIR-24 is a more accurate tool for assessing daily caffeine consumption among young adults. The stronger performance of the CIR-24 could be attributed to its detailed, brand-specific database which enables better estimation of caffeine content in consumed products.

5

What specific urinary biomarkers were analyzed, and how were they used to validate caffeine intake?

The urinary biomarkers included caffeine and eight caffeine metabolites, which were quantified using high-performance liquid chromatography-polarity switching electrospray ionization-tandem quadrupole mass spectrometry with stable isotope-labeled internal standards. By measuring these substances in urine, researchers were able to obtain an objective measure of caffeine intake against which the self-reported estimates from the CIR-24 and CBQ tools were compared. This method provides a more reliable measure than self-reporting alone, which can be subject to recall bias or inaccuracies in estimating portion sizes and caffeine content.

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