Caffeine-Related Disorders Clinical Trial
Official title:
Evaluation of a 24-hour Caffeine Intake Assessment Compared to Urinary Biomarkers of Caffeine Intake and a Brief Caffeinated Beverage Questionnaire
A 24-hour Caffeine Intake Recall (CIR-24) was developed to estimate caffeine consumption in
the previous 24 hours, modeled after the Automated Self-Administered 24-hour Dietary
Assessment Tool (ASA24), using a brand-specific database of caffeine-containing foods,
beverages and supplements. The objective of this study was to evaluate the accuracy of the
CIR-24 compared to caffeine concentration biomarkers in urine and a caffeinated beverage
intake frequency screener (CBQ) among a young adult population.
79 young adults ages 18 to 29 years provided 24-hour urine samples and completed the CIR-24
and CBQ. Excretion rates for caffeine and eight caffeine metabolites were quantified from
urine samples using high performance liquid chromatography-polarity switching electrospray
ionization-tandem quadrupole mass spectrometry with stable isotope labeled internal
standards.
The objective of this study was to evaluate the accuracy of the CIR-24 compared to caffeine
concentration biomarkers in urine and a caffeinated beverage intake frequency screener (CBQ)
among a young adult population.
A 24-hour Caffeine Intake Recall (CIR-24) was developed to estimate caffeine consumption in
the previous 24 hours. The online, self-administered CIR-24 was developed to measure dietary
intake of caffeine from food, beverages, and supplements. The tool was based on the Automated
Self-Administered 24-hour Dietary Assessment Tool (ASA24), a web-based, self-administered
tool for collecting dietary recalls and records. ASA24 uses a multiple-pass method adapted
from the Automated Multiple-Pass Method (AMPM) used in NHANES in the US and the Canadian
Community Health Survey in Canada. The same general question structure was used in this
custom online survey, but the items queried were limited to foods, beverages and supplements
that may contain caffeine. The tool was created for the Canadian context by listing only
Canadian products, changing container sizes to reflect the Canadian marketplace, and
including a French version. The food, beverage, and supplement categories and sub-categories
can be found in Supplemental Table 1. Specific items listed were based on ASA24 and the
Canadian Nutrient File, with additional items identified through the USDA National Nutrient
Databases and internet searches. Respondents were asked about the consumption of items from
each of four main categories (beverages, foods, energy products with added caffeine, and
supplements) in the prior day. Based on each food or beverage reported, the participant
receives tailored probes based on their responses, to identify the specific items that may
have contained caffeine (e.g., if carbonated beverage consumption was reported, the
participant is asked to specify the type of carbonated beverage and brand consumed). Amounts
of each item consumed were ascertained based on the particular category: food amounts were
estimated by the number of items/pieces consumed, or by a volume amount (depending on the
item); beverage amounts were estimated using images of container types and sizes (adapted
from the ASA24) (or volume for powders, liquids, and concentrates); and supplements were
estimated by unit (or volume for powders and liquids). The CIR-24 tool is available at
http://davidhammond.ca/wp-content/uploads/2015/11/2014-CED-Technical-Report.pdf.A database
was compiled of the caffeine content of all food and beverage items in the Canadian Nutrient
File listed as containing caffeine (with some additional items from the USDA National
Nutrient Database for Standard Reference), plus energy drinks, shots, and products (sourced
from the nutrition information on products purchased in previous studies, as well as internet
searches), and supplements listed as containing caffeine in Health Canada's Licensed Natural
Health Products Database
(http://www.hc-sc.gc.ca/dhp-mps/prodnatur/applications/licen-prod/lnhpd-bdpsnh-eng.php) or
identified through an online pharmacy (www.well.ca). More precise and brand-specific values
were added for popular products such as coffee, using information provided by manufacturers
(e.g., Starbucks, Tim Horton's, McDonald's) and/or websites that aggregate nutrition
information (http://www.cspinet.org/new/cafchart.htm).
A paper version of a caffeinated beverage questionnaire (CBQ) from the Fred Hutchison Cancer
Centre, adapted slightly for use in Canada (e.g., mL measures were included in addition to
fluid ounces), was also administered.The CBQ included 13 beverage categories, including
caffeinated and decaffeinated coffee (brewed and instant) and tea, energy drinks and highly
caffeinated sodas, regular colas and root beer, and caffeine-free colas and root beer. Nine
frequency categories were included: Never or less than once per month; 1-3 per month; 1 per
week; 2-4 per week; 5-6 per week; 1 per day; 2-3 per day; 4-5 per day; 6+ per day. A
reference for a 'medium' size for each type of beverage category was provided; respondents
stated whether each drink size was small, medium or large in comparison to the reference
amount. Responses to the CBQ were used to calculate average daily caffeine consumption for
each respondent. First, the number of annual servings consumed for each questionnaire item
was calculated by multiplying the reported frequency by the reported portion size. A 'small'
size was multiplied by a serving ratio of 0.5, and a 'large' size was multiplied by 1.5.
Next, the average annual volume of each beverage consumed was divided by 365 to estimate the
daily intake of each beverage. The caffeine database that accompanies the tool was used to
calculate the amount of caffeine consumed in milligrams. In cases in which frequency data for
items were missing, we assumed that none was consumed, and when a frequency was entered but
no portion size was indicated, the 'medium' size was assumed.
For each participant, all urine samples were combined, and the total volume of the entire
24-hour sample was recorded. A sample from each participant was aliquoted into a 2 mL
cryovial, and immediately frozen at -80°C. Samples were moved for 8 days to a -20°C freezer
due to logistical issues, and were later returned to -80°C. At the end of the study period,
all samples were transported in insulated containers with dry ice to the CDC Nutritional
Biomarkers Branch in Atlanta, GA for analysis.
Urine concentrations for caffeine (1,3,7-trimethylxanthine) and 8 caffeine metabolites
(1,7-dimethylxanthine (Paraxanthine or 17X); 1,3-dimethylxanthine (theophylline, 13X);
1,3,7-trimethyluric acid (137U); 1,3-dimethyluric acid (13U); 1,7-dimethyluric acid (17U);
1-methyluric acid (1U); 1-methylxanthine (1X); and 5-acetylamino-6-amino-3-methyluracil
(AAMU)) were quantified by use of a high performance liquid chromatography-polarity switching
electrospray ionization-tandem quadrupole mass spectrometry with stable isotope labeled
internal standards based on a method reported previously.(26) Existing studies indicate that
these metabolites have moderate correlation with caffeine intake (14). The limits of
detection were: 0.05 μmol/L for 1U; 0.01 μmol/L for theophylline; 0.02 μmol/L for 13U and
17U; 0.005 μmol/L 137U; 0.03 μmol/L for 1X; 0.003 mmol/L for caffeine; 0.006 μmol/L for 17X;
and, 0.1 μmol/L for AAMU. Samples that had amounts below the limits of detection were
excluded for that particular metabolite.
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