EE: Caffeine and Other Stimulants (2014)

Citation:

Arciero PJ, Bougopoulos BC, Nindt, Benowitz NL. Influence of age on the thermic response to caffeine in women. Metabolism. 2000;49(1):101-107.

 
Study Design:
Randomized Crossover Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  1. To determine whether older and younger women demonstrate a siilar thermic response to caffeine as previously observed in older and younger men
  2. Identify the relationships between aerobic fitness, body composition, and hormone and substrate concentrations with age-related thermic effect of caffeine.

Definitions

  • Caffeine-dosing was: 5 mg/kg fat-free mass.
Inclusion Criteria:
  1. Understand and give written consent
  2. Regularly consume moderate amounts of caffeine :
  3. Healthy, indicated by normal ECG at rest and during an exercise test, normal BP
  4. Nonsmoker
  5. Weight stability during the past year
  6. Postmenopausal not on ERT or hormone-regulating contraceptives OR premenopausal during the follicular phase and NOT taking oral contraceptives for one month prior to testing.
Exclusion Criteria:
  1. Refusal to consent
  2. Not meeting inclusion criteria
  3. Diseases excluded included CVD history, diabetes mellitus, renal failure or liver disease
  4. Excessive intake of caffeine (>4 cups coffee/day):
  5. Medications excluded were those that could influence CV function or metabolic rate.
Description of Study Protocol:
  • Testing order: Before the frist test day, FFM & FM determined by skinfold analysis; VO2 fitness test on treadmill.
  • W/in 1 month of initial test: IC measure with placebo or IC measure w/caffeine; and the other exposure the next day.

ANTHROPOMETRIC

  • Ht measured? Yes
  • Wt measured? Yes
  • Fat-free mass measured? Yes via sinfold thickenesses; Waist:hip circumference.

CLINICAL

  • Monitored heart rate? Yes
  • Body temperature? Not specified
  • Medications administered? No; only caffeine via pill vs placebo (lactose).

Resting energy expenditure

  • IC type: VacuMed with facemask
  • Equipment of Calibration: Not specified
  • Coefficient of variation using std gases: NA
  • Rest before measure (state length of time rested if available): 30 mins
  • Measurement length: 1st measure: 30-45 minutes
  • After exposure to placebo or caffeine: Was measured in 15-minute intervals for the next 90 mins
  • Steady state: Not specified
  • Fasting length: 12 hrs food; 48 hrs caffeine and alcohol
  • Exercise restrictions XX hr prior to test? Yes, 24 hours
  • Room temp: Human Performance Laboratory
  • No. of measures within the measurement period: 1 measure for baseline; 1 measure per 15 mins following exposure
  • Were some measures eliminated? No
  • Were a set of measurements averaged? NA
  • Coefficient of variation in subjects measures? Intraclass correlation was 0.90 between day 1 and day 2
  • Training of measurer? Not specied
  • Subject training of measuring process? Yes.

DIETARY

  • Energy intake and caffeine consumption using a 3-day food diary.
Data Collection Summary:

Outcome(s) and other measures

  1. Measured REE [(VO2, l/min), VCO2 (l/min; ml/kg/min), VO2peak, ventilation (l/min)].
  2. Blood sampling: fasting plasma glucose, insulin, FFA, caffeine
  3. Independent variables of weight, height, age, BMI, and fat-free mass, fat mass.

Blinding used: Yes.

Description of Actual Data Sample:
  • N=10 younger healthy women, aged 18-22 yr (mean 19.0±1.5)
  • N=10 older healthy women, aged 50-67 yr (mean 55.0±5).

Statistical tests

  • 3x2 repeat-measures ANOVA to test effects of caffeine ingestion, age group, and time course of insulin, gluxose and FFA levels during the 2 treatment test days.
  • ANCOVA with initial baseline RMR serving as the co-variate between younger and older women to test effects of caffeine ingestion on RMR; Correlation coefficient to estimate associations; Mean±SD.

Summary of Results:

ANTHROPOMETRIC

Younger Women

Mean±SD

Range

Wt, kg

62.5±7.3 50-74

Ht, cm

168.5±6.7 159-184

Body fat, %

23.5±5.1 15.8-34.1

Fat-free
body mass

48.7±4.8

39.9-55.2

Older Women

Mean±SD

Range

Wt, kg

72.1±9.4 58-86

Ht, cm

168.5±6.7 159-184

Body fat, %

31.9±5.8

24.5-40.1

Fat-free
body mass

48.8±5.2

37.2-55.6

MEASUREMENT PROCESS

  • Number of measurements: 7 (baseline plus 6 after exposure)
  • Length of measurements: 1st measure 30-45 minutes; 15 minute measures after exposure
  • Steady state: Not specified
  • RQ: Not specified.

MEASUREMENT TIMING

  • Rest; 24-hr fast from physical activity; Food intake.

THERMIC EFFECT OF CAFFEINE RMR RESULTS

  • Baseline RMR was statistically significant (P<0.05) between older and younger groups (0.98±0.14 vs. 1.09±0.14 respectively).
  • The magnitude of increase in energy expenditure (±SD) was 7.8±6.0% and 15.4±7.0% over baseline in older and younger women, respectively and was statistically significant (P<0.05) above placebo group within both age groups.
  • The change in RMR (0-90 minutes) reported as kcal/ min was 0.173±0.06 vs 0.075±0.05 in younger and older women, respectively (P<0.05 compared to placebo).
  • The group mean total thermic response to caffeine (kcal/90 min) was 15.6±7.0 kcal/90minutes in the younger women and 6.9±5.0 in the older women.

LONGITUDINAL RMR (kcal/min) DATA (Taken from Figure 2)

Younger Women (Mean±SEM) Older Women (Mean±SEM)

Baseline

1.09 0.98

15-30 min

1.2

1.05

45-60 min

1.24

1.10

75-90 min

1.35

1.05

Author Conclusion:

As stated by the author in body of report:

  • The major findings in our study:
    1. Younger & older healthy women exhibit a significant thermogenic response to caffeine, but older women have a blunted response [over 90 minutes];
    2. Body weight and waist circumference in younger women and aerobic fitness level in older women are significant correlates of the thermogenic response to caffeine
    3. IN response to caffeine ingestion, younger and older women show similar increases in FFAs and no significant change in insuling and glucose concentrations.”
  • "These findings imply that age is an important parameter to consider when comparing the thermogenic response to caffeine, as it is associated with different physiological factors in younger and older women.”
  • Another important highlight is that the thermic response to caffeine was still significantly elevated in the younger women and not in the older women at the termination of the 90 minute test period.
  • “One limitation of our study is that the study underestimated the total thermic response to caffeine in younger women and may not have detected actual age-related differences in the thermic response to caffeine. Our older women were significantly fatter than the younger women, possibly explaining the tency for the lower thermic effect of caffeine in older female subjects."
Funding Source:
Government: National Institute of Drug Abuse
University/Hospital: Skidmore College
Reviewer Comments:

Strengths

  • “Researchers eliminated confounding variables of nicotine, prior weight loss, fasting, and medication effects."

Generalizability/Weaknesses

  • “Generalizable to US-residing women; No generalizability to “old” and “very old” women since oldest person was only 66 years; No generalizability to females ages 31-49 years; Researchers do not report ethnicity;”
  • “Study biases include: convenience sampling; modest coffee drinkers; it does not apply to caffeine-naïve and excessive caffeine consumers."
  • An intervening variable not measured or discussed: the placebo was lactose (a sugar that would have impacted thermogenic response in placebo groups of younger and older women) and a group mean RMR increase (kcal/min) is seen 15-30 mins after placebo ingestion
  • These are important variables on REE measurement accuracy: did not report steady state
  • Did not discuss the clinical significance of total RMR change (i.e., 16 kcal/90 minutes and 7 kcal/90 minutes).

NOTE:  This paper was published in 2000 and not completed at the University of Vermont, and was not supported by any of Poehlman’s grants so we kept this paper.

Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? N/A
  1.3. Were the target population and setting specified? N/A
  1.3. Were the target population and setting specified? N/A
  2. Was the selection of study subjects/patients free from bias? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? N/A
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.2. Were criteria applied equally to all study groups? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? N/A
  3. Were study groups comparable? N/A
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
  4. Was method of handling withdrawals described? No
4. Was method of handling withdrawals described? No
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
  5. Was blinding used to prevent introduction of bias? Yes
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
  6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
  7. Were outcomes clearly defined and the measurements valid and reliable? No
7. Were outcomes clearly defined and the measurements valid and reliable? No
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.1. Were primary and secondary endpoints described and relevant to the question? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.5. Was the measurement of effect at an appropriate level of precision? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.6. Were other factors accounted for (measured) that could affect outcomes? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
  7.7. Were the measurements conducted consistently across groups? N/A
  8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.1. Were statistical analyses adequately described and the results reported appropriately? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.2. Were correct statistical tests used and assumptions of test not violated? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.3. Were statistics reported with levels of significance and/or confidence intervals? N/A
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.6. Was clinical significance as well as statistical significance reported? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
  9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? N/A
  9.1. Is there a discussion of findings? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
  9.2. Are biases and study limitations identified and discussed? N/A
  10. Is bias due to study's funding or sponsorship unlikely? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.1. Were sources of funding and investigators' affiliations described? N/A
  10.2. Was the study free from apparent conflict of interest? N/A
  10.2. Was the study free from apparent conflict of interest? N/A