The study aims to identify key physiological factors that differentiate older adults with healthy appetites from those experiencing appetite decline. The investigators hypothesize that seniors experiencing appetite decline will exhibit distinct oro-sensory, gastrointestinal, and hormonal profiles compared to seniors with healthy appetites, suggesting underlying biological mechanisms contributing to reduced appetite.
Appetite decline in older adults, or anorexia of aging, is a prevalent geriatric syndrome associated with decreased quality of life, increased risk of malnutrition, and accelerated decline in health. While current nutritional guidelines often emphasize increasing nutrient density, these strategies often fail to address the root causes of diminished appetite. Emerging research highlights the critical role of age-related physiological changes, particularly dysregulation of the gut-brain axis, altered sensory perception, and hormonal imbalances, in suppressing appetite. Notably, existing evidence is largely derived from Western populations, which may not fully reflect the influence of cultural and lifestyle factors on appetite in Asian seniors. This leaves a significant gap in understanding and addressing appetite loss within this specific demographic. This study aims to address this gap by comprehensively investigating the physiological mechanisms underlying appetite regulation in Asian seniors, to identify key determinants that differentiate individuals with healthy appetites from those experiencing a decline. By assessing the relationships between oro-sensory function, gastric dynamics, neuro-hormonal regulation, gut microbiome composition and subjective appetite, this study seeks to provide a deeper understanding of the biological pathways driving appetite differences in this population. The findings of this study will lay the groundwork for future research aimed at developing culturally sensitive and effective interventions that can restore appetite, improve nutritional status, and ultimately enhance the health span and quality of life for older adults in Singapore and beyond. Furthermore, this work has the potential to drive innovation in the food and nutrition industry, leading to the development of tailored products and dietary strategies that effectively address the unique nutritional needs of aging populations, ultimately impacting public health recommendations and policies related to senior nutrition.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
OTHER
Masking
NONE
Enrollment
20
This is a mixed meal tolerance test intended to elicit gut hormone responses reflective of real-world dietary patterns.
Clinical Nutrition Research Centre
Singapore, Singapore
Ad Libitum Lunch
Participants will be asked to eat as much of the stir-fried beehoon as they want until they are comfortably full, to measure the exact calorie intake by weighing the food before and after eating.
Time frame: Participants will be given 30 minutes to consume the meal until they are comfortably full, 180 minutes after the start of the intervention.
Palatability questionnaire
Palatability appetite questionnaire, rated on a visual analogue scale is a psychometric assessment tool where participants rate their subjective sensory experience-such as taste, smell, or pleasantness-by marking a point along a continuous 100 mm line anchored by opposing extremes (e.g., "extremely unpleasant" to "extremely pleasant").
Time frame: Administered after consuming test meal and after consuming the ad libitum meal.
Appetite hormones
GLP-1, PYY and Acyl-ghrelin will be used to measure hormones related to appetite.
Time frame: Blood samples will be collected at timepoints (t = -15 minute (baseline), 30, 60, 90, 120 and 180 minutes)
Subjective Appetite Questionnaire
A subjective appetite questionnaire utilizes a Visual Analogue Scale to quantify a person's current metabolic state by measuring four key sensations: hunger, fullness, desire to eat, and prospective food consumption.
Time frame: Measurement is taken at t = -15 minute (baseline), 10, 30, 60, 90, 120 and 180 minutes
Gastric Ultrasound
Gastric ultrasound will measure the gastric emptying rate postprandially.
Time frame: Measurements will be taken at t = -15 minute (baseline), 15, 45, 105 and 165 minutes
Stool collected using the OMNIgene and OMNImet
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Stool sample will be collected in the OMNIgene-GUT and OMNImet-GUT tube for measurements that may include microbiome profiling, untargeted and targeted metabolome (e.g. bile acids and short-chain fatty acids profiling).
Time frame: Baseline stool sample will be collected once between screening and intervention day.
Olfactory Acuity (SCENTinel)
Olfactory acuity will be assessed using a simple, non-invasive SCENTinel rapid smell test. Participants will be presented with test cards containing various odors, and will be asked to detect, rate, and identify the odors. The test assesses the participant's ability to perceive and recognize smells, providing information on their overall sense of smell.
Time frame: Baseline measurement administered once during screening, takes approximately 5-10 minutes
Taste Acuity Test (WETT)
The Waterless Empirical Taste Test (WETT) is a sensory method for assessing how well participants can recognise and detect basic tastes. Participants will taste pre-moistened, paper-based test strips for the five basic tastes: sweet, sour, salty, bitter, and umami.
Time frame: Baseline measurement administered once during screening, takes approximately 10-15 minutes
Blood plasma (Cytokines)
Blood samples may also be analyzed for indicators of inflammation including cytokines testing
Time frame: t = -15 minute (baseline), 30, 60, 90, 120, 180 minutes
Blood plasma (Bile acids and short-chain fatty acids profiling)
Blood samples collected may be used to analyse biomarkers related to nutrition and digestive health e.g. bile acid and short-chain fatty acids profiling
Time frame: t= -15 minute (baseline), 30, 60, 90, 120, 180 minutes
Bite Strength
Bite strength will be measured using a bite force device (non-invasive) that records the maximum force a participant can exert while biting. Multiple measurements will be taken with rest periods in between to prevent fatigue.
Time frame: Baseline measurement that may be administered once during screening or test session, as schedule and equipment permits. Takes only a few minutes.
Tongue Strength (Tongue Pressure)
Tongue pressure will be measured using a device equipped with a disposable air-filled bulb placed between the tongue and the hard palate. Participants will be instructed to press the bulb with their tongue as firmly as possible for a few seconds. Multiple measurements will be taken with rest periods in between to ensure accuracy and prevent fatigue.
Time frame: Baseline measurement that may be administered once during screening or test session, as schedule and equipment permits. Takes approximately 5 minutes.