EAL

NNNS: Appetite (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To evaluate whether sweetness increases hunger.

Inclusion Criteria:

Telephone interview informed subjects they would receive $7.50 to chew gum and answer questions for 90 minutes.

Exclusion Criteria:

If the prospective subject had any of the following conditions:

Diabetes
Hypoglycemia
Phenylketonuria.

Description of Study Protocol:

Recruitment

Subjects responded by telephone to advertisements posted on and around the campuses of the University of Pennsylvania and Drexel University
Subjects signed consent to particiate in the study forms. Consent form included brief instructions and reminders of the subject requirements.

Design

Subjects were tested individually
Subjects were assigned at random to one of six groups with 10 males and 10 females. One group received nothing to chew, the other five chewed a single piece (1,150mg) of gum base containing 0%, 0.05%, 0.3%, 0.5% or 1.0% aspartame.
Asparatame was mixed into a commercially prepared gum base that had no flavorants and no other source of sweetness.

Statistical Analysis

Visual analog ratings: Significant effects of each question were determined by three-way analyses of variance between subject factors of sex and group and a within-factor of time bv (0, 15, 30, 45, 60, 75, 90 minutes). If statistical significance was achieved at P<0.05, the difference was located using Tukey's post hoc tests.

Data Collection Summary:

Timing of Measurements

Height and weight were measured and subjects were asked about dietary habits, including when they last had eaten and how frequently they used chewing gum.
In 15 intervals for 60 minutes, they completed a series of 10cm visual analog scales. Except for the group of subjects that was given nothing to chew, all subjects were required to chew during the 15-minute period between the first pre-chewing baseline and second series of analog scales.

Description of Actual Data Sample:

Initial N

60 males and 60 females.

Attrition (final N)

Characteristics of Subjects

Characteristic	Females (N=60)	Males (N=60)
Age (years)	25.5±0.9	26.1±0.9
Height (cm)	165.3±0.9	175.8±1.0
Weight (kg)	61.0±1.8	69.6±1.1

Values are mean and SE.

Summary of Results:

Correlations between subject characteristics and their responses to chewing aspartame were all non-significant, except for a correlation between the time subjects last ate and their initial ratings of hunger (P<0.01).

Effects of chewing aspartame on psychophysical and motivational ratings

Sweetness and Bitterness

Significant differences in response to the question, "How sweet and how bitter is the taste in your mouth?" were present at 15 minutes, immediately after subjects finished chewing
For both sexes combined, subjects who had just chewed gum base containing 0.3, 0.5 or 1.0% aspartame rated the taste in their mouth as sweeter than did subjects who had just chewed the unsweetened gum base (0% aspartame) or did not chew. Subjects who did not chew rated the taste in their mouths sweetener than did those who chewed gum base containing 0% or 0.05% aspartame (group X time interaction, P<0.0001)
For bitterness, subjects given gum base that was unsweetened or contained 0.05% aspartame rated the taste in their mouths as more bitter than those not given anything to chew (group X time interaction, P<0.005)
Chewing 0.5% aspartame produced a sweeter taste in females than males, whereas chewing 1.0% aspartame produced a sweeter taste in males than females (sex X group X time interaction, P<0.05).

Intensity and Pleasantness

For both sexes combined, ratings in response to "How intense is the taste in your mouth?" were monotonically related to aspartame concentration (group X time interaction, P<0.0005). Subjects given 0.3%, 0.5% or 1.0% asparatame indicated a more intense taste than did those given 0.05% aspartame. After chewing 1.0% aspartame, females gave higher ratings of intensity than did males, but the difference was not significant.
In response to the question, "How pleasant is the taste in your mouth?" subjects who had just chewed the gum base gave lower scores than those who had not (group X time interaction, P<0.05).

Hunger

For both sexes combined, chewing the sweetened gum base increased hunger ratings (group X time interaction, P<0.005)
Males and females responded differently to various concentrations of aspartame at different times: Females that chewed 0.05% aspartame reported increased hunger at 75 and 90 minutes; those that chewed 0.3% asparatame showed the largest increase in hunger ratings, which commenced 30 minutes after they started to chew and for the remainder of the test
Females who chewed 0.5% aspartame reported decreased hunger during the first 45 minutes of the test
Only males who chewed 0.5% aspartame reported increased hunger ratings (at 60, 75 and 90 minutes)
Relative to the group given the unsweetened gum base to chew, the groups that chewed 0.5% or 1.0% aspartame had higher ratings
At 15 minutes, males who chewed 0.3% aspartame showed decreased hunger ratings compared to males that received nothing to chew
At 75 and 90 minutes, the hunger ratings of females who chewed the unsweetened gum base were significantly higher (P<0.05) than those of males given the same gum base to chew. Males given either 0.5% or 1.0% aspartame reported greater hunger than did the equivalent males (except at 15 minutes for 1.0% aspartame, where there was no difference).

Other Questions

No effects related to asparatme for:

How thirsty are you?
How anxious are you?
How good does your stomach feel?
How tense are you?
How sick do you feel?
How queasy are you?

Author Conclusion:

Limitations and Biases

The overall effect was complicated by three factors,

The relationship between the concentration of aspartame in the gum base and hunger was not monotonic
Subjects rated themselves more hungry after chewing a moderate (0.3% or 0.5%) than high (1.0%) concentration of aspartame. The highest concentrations of aspartame tended to have a time-dependent biphasic effect, producing a transient decrease followed by a sustained increase in hunger ratings.
The concentration of aspartame to stimulate appetite was different for males and females.

This variability in response may explain why some investigators have found an association between sweetness and hunger, but others have not.

Intense sweetness (as experienced with the higher concentrations of aspartame) may lead to a transient loss of appetite, but a cephalic phase response to sweetness is responsible for an increase in appetite later. These opposite actions of the “sensory” and “cephalic-phase” responses may explain the failure to find a monotonic relationship between aspartame concentration and hunger.

The psychophysical ratings collected may have been inappropriate to measure a monotonic relationship between aspartame concentration and hunger, if such a relationship exists.

Funding Source:

Reviewer Comments:

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
	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
	4.	Is the intervention or procedure feasible? (NA for some epidemiological studies)	Yes

Validity Questions
1.	Was the research question clearly stated?		Yes
	1.1.	Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified?	Yes
	1.2.	Was (were) the outcome(s) [dependent variable(s)] clearly indicated?	Yes
	1.3.	Were the target population and setting specified?	No
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?	No
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
3.	Were study groups comparable?		Yes
	3.1.	Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT)	Yes
	3.2.	Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline?	Yes
	3.3.	Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.)	Yes
	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
	3.6.	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?		Yes
	4.1.	Were follow-up methods described and the same for all groups?	Yes
	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?	Yes
	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
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?	Yes
	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.)	Yes
	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
	5.5.	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
	6.1.	In RCT or other intervention trial, were protocols described for all regimens studied?	Yes
	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?	Yes
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	N/A
	6.6.	Were extra or unplanned treatments described?	N/A
	6.7.	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
7.	Were outcomes clearly defined and the measurements valid and reliable?		Yes
	7.1.	Were primary and secondary endpoints described and relevant to the question?	Yes
	7.2.	Were nutrition measures appropriate to question and outcomes of concern?	Yes
	7.3.	Was the period of follow-up long enough for important outcome(s) to occur?	Yes
	7.4.	Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures?	Yes
	7.5.	Was the measurement of effect at an appropriate level of precision?	Yes
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	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?	Yes
	8.2.	Were correct statistical tests used and assumptions of test not violated?	Yes
	8.3.	Were statistics reported with levels of significance and/or confidence intervals?	Yes
	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)?	Yes
	8.6.	Was clinical significance as well as statistical significance reported?	No
	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
	9.1.	Is there a discussion of findings?	Yes
	9.2.	Are biases and study limitations identified and discussed?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes