HYD: Effect of Thickened Beverages on Fluid Intake (2007)

Philip KEA, Greenwood CE. Nutrient Contribution of Infant Cereals Used as Fluid Thickening Agents in Diets Fed to the Elderly. Journal of the American Dietetic Association, 2000; 100: 549-554. PubMed ID: 10812380
Study Design:
Non-Randomized Controlled Trial
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To determine if the use of Pablum as a fluid thickening agent would replace the nutrient loss associated with the food or energy displacement caused by such agents, thereby preventing nutrient inadequacy.

Aims Used to Meet Objective

  • To determine if nutrients offered to patients consuming pureed diets differed, depending on whether the individuals could tolerate regular fluids or required the use of thickened fluids
  • To evaluate the magnitude of nutrient displacement associated with the thickening agent
  • To assess the overall adequacy of nutrient intake and the contribution of Pablum to attaining nutrient adequacy in people who consume thickened-fluid diets.
Inclusion Criteria:

Two subject groups requiring texture modification of diet were included:

  1. Those consuming pureed foods, but able to tolerate regular fluids (regular-fluid diet group)
  2. Those consuming a diet of thickened fluids and pureed foods (thickened-fluid diet group).
Exclusion Criteria:
  • Persons consuming mixed food textures or energy-controlled diets
  • Persons consuming specialized diets, such as diabetic or renal diets
  • Persons not consuming at least two pureed entrees per day.
Description of Study Protocol:
  • Recruitment: All residents older than 65 years at the chronic-care hospital (245 beds) or the home for the aged (372 beds) at Baycrest Centre for Geriatric Care (North York, Ontario, Canada) were considered.
  • Design: Non-randomized trial; subjects were grouped according to diet order of regular-fluid diet or thickened-fluid diet.
  • Blinding used: Caregivers responsible for feeding the subjects in the thickened-fluid group were unaware that food intake was being measured to ensure that food consumption was representative of normal intake patterns.


  • Regular-Fluid Diet Group
    • Seven days of tray-delivery data collected (including all foods, snacks and supplements)
    • Days were selected randomly from a 28-day cycle
    • Individual fluid deliveries, including beverages and fluid supplements such as Ensure, were used to determine the amount of thickener required for each subject
    • Formula used: 75ml (20g) of Pablum per 100ml of fluid
    • Theoretical impact on nutrient delivery with Pablum was determined. The energy values of the total amount of the thickening agent required were calculated for each individual.
    • Data collected from subjects consuming the regular-fluid diet were limited to food and nutrient delivery.
  • Thickened-Fluid Diet Group
    • Seven days of tray-delivery data collected (including all foods, snacks and supplements)
    • Actual nutrient contribution associated with the use of Pablum was determined
    • Seven days of weighed-food intake data was obtained to determine actual intake
    • Data for subjects consuming the thickened-fluid diet included food and nutrient delivery and consumption.

Statistical Analysis

  • Power analyses were performed to determine the number of days of data collection necessary to estimate true average intake of these subjects at a probability of 0.05, given a fixed sample size. Seven days of intake data as sufficient for all nutrients except vitamin A.
  • Probability analysis was used to estimate the prevalence of nutrient inadequacy for micronutrients and protein
  • Energy intake was evaluated relative to basal metabolic rate
  • Basal metabolic rate was estimated using the Harris-Benedict equations.
Data Collection Summary:

Timing of Measurements


  • Seven days of tray-delivery data collected (including all foods, snacks and supplements) for the regular-fluid diet group and thickened-fluid diet group
  • Seven days of weighed food intake data was obtained to determine actual intake for the thickened-fluid diet group.

Dependent Variables

Weighed food intakes were linked to these data to provide estimates of nutrient intake:

  • Protein
  • Calcium
  • Iron
  • Thiamin
  • Riboflavin
  • Niacin
  • Vitamins A and C
  • Fluid*
  • Folate
  • Water*

*Data for water are expressed as either fluid (free fluids, such as drinks, soups, fluid supplements) or total water (also includes the water content of solid foods)

  • The nutrient content of a single portion of each recipe (prepared on site) was calculated based on individual ingredients using a software package, Foodman, which assesses the Canadian Nutrient File.
  • Water content of individual foods was estimated by subtracting the sum of the carbohydrate (including fiber), protein, and fat weights from the weight of the cooked portion for each recipe.

Independent and Control Variables

Nutrient delivery to the subjects consuming the thickened-fluid diet (independent variable) was compared with delivery to subjects consuming the regular-fluid diet (control variable).

Description of Actual Data Sample:
  • Initial N: Forty-four patients
  • Attrition (final N): Not described
  • Ethnicity: Not described
  • Relevant demographics: All subjects required full feeding assistance.


Age (Mean)

Age Range

BMI (Mean)

BMI Range


4 men





Diet Group

19 women





Thickened Fluid

2 men

88 and 90


27.2 and 20.6


Diet Group

19 women





  • Location: North York, Ontario, Canada.
Summary of Results:


  • The theoretical impact of thickening all fluids resulted in daily delivery of 906±274kcal of Pablum (mean±SD) or 34% of total energy delivery
  • If an unfortified thickener were used at the same level as Pablum, nutrient inadequacies (even at the level of delivery) would occur
  • Fluid delivery to subjects consuming the thickened-fluid diet was 48% lower than that to subjects consuming the regular fluid diet (T=6.5, P<0.001)
  • Despite fluid-reduced delivery, the overall level of water delivery surpassed the 1,500-ml recommendation
  • Total energy delivery was comparable between the two groups of elderly persons (T=1.02, P<0.3), which suggests that the projected displacement of energy was occurring even at the level of delivery
  • Nutrients offered, with the exception of folate, were sufficient to eliminate the risk of inadequacy. Pablum protected against potential inadequacies of calcium and thiamin.
  • Mean energy intake was only 62% of that delivered.

Thickened-Fluid Diet

(Assuming Initial N)

Estimated Basal Metabolic Rates

Average Energy Intake Times Metabolic Rate









  • On average, subjects consumed 51% of delivered fluids and Pablum provided 228±23kcal per day or 15% of total energy
  • More than 5% of the sample experienced nutrient inadequacy for protein, calcium, folate and water
  • Pablum prevented inadequacy of thiamin, riboflavin and niacin and reduced that for calcium and protein.
Author Conclusion:

The relative protection Pablum offered fell into three categories:

  1. Food sources of certain nutrients, including iron and vitamins A and C, were sufficient to meet the needs and Pablum played no role
  2. Nutrients found in extremely low levels of Pablum, such as folate, were unable to overcome dietary inadequacy
  3. For other nutrients, including protein, calcium, thiamin, riboflavin and niacin, the levels contributed by Pablum were able to partially or completely overcome risk of inadequacy.

Thus, the use of infant cereals as fluid-thickening agents in the diet of elderly who require thickened fluids has merit, yet the current formulation of Pablum is unable to offset all inadequacies and water intake remained sub-optimal.

Funding Source:
University/Hospital: University of Toranto
Reviewer Comments:

This research relies on several assumptions:

  1. Total fluid delivery would not change during the transition from a regular-fluid to a thickened-fluid diet
  2. Total daily energy intake would not change. Rather, the equivalent energy value of pureed foods would be displaced.
  3. Displacement of food would occur equally across all foods delivered.

There is no discussion as to why the total energy delivery was comparable between the two groups if the Pablum would theoretically provide 34% of the total energy delivery.

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? 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? Yes
  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? 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
  4.3. 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? ???
  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? Yes
  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? Yes
  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? ???
  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? ???
  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? ???
  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)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? No
  8.6. Was clinical significance as well as statistical significance reported? Yes
  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? ???
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? Yes