The Texture, Eating Rate and Glycaemic Index (TERAGI) Study
Condition: Adults
Study type: Observational

Summary: 
      Rationale: It is now recognized that diet plays a critical role in the etiology and
      management of chronic diseases such as type-2 diabetes, obesity and cardiovascular diseases.
      Evidence shows an increasing prevalence of type-2 diabetes as well as obesity, whereby large
      consumptions of carbohydrate foods is one of the leading contribution to these diseases. Food
      structure and texture can be modified to control oral processing behaviour, which would have
      subsequent impact on total energy intake and glycaemic response through altering the food
      breakdown path. Whilst it has been demonstrated that foods which are eaten at a faster rate
      leads to more food consumed ad-libitum and therefore higher energy intake, they are also
      eaten at fewer chews per bite, resulting in larger food particle sizes and hence slower
      digestion. Therefore it is important to understand the overall net effect of the opposing
      outcomes of food texture and oral processing behavior, bolus properties and glycaemic
      response, and identify the key factors which has the biggest influence on glycaemic response.
      The findings from this study can be used as guidelines on meal planning and making better
      informed choices between foods which are of the same composition/nutrition but with different
      health outcomes.

      Study Aims: The aim of this study is to understand how food texture and saliva
      characteristics influences oral processing behavior, bolus characteristics and postprandial
      glycaemic response.

      Study Design: Randomised crossover design where participants receive 2 treatments (i.e. 2
      test meals) over 2 test sessions. Test sessions will include bolus characterisation of foods
      where participants chew and expectorate test foods (5g each) based on a fixed chew protocol.

      Study Population: Up to 40 healthy males aged 21-50 years with BMI between 18-25 kg/m2

      Intervention: For test session 1 and 2, participants will receive 2 treatments (i.e. 2 test
      meals) in randomised order over 2 sessions. The test meals contain 50g carbohydrate load of
      different textures. Participants will be video recorded while consuming the test meals to
      derive oral processing behaviour (bites, chews, time food spent in mouth). Blood samples will
      be collected at baseline and post consumption (5, 10, 15, 30, 45, 60, 90, 120 minutes) to
      measure glycaemic responses to the test meals. For test session 3, participants will be asked
      to follow a fixed chew protocol to chew and expectorate 3 test foods while being video
      recorded. Similarly, oral processing behaviours will be analysed from the recorded videos.
      The spat out food samples (i.e. bolus samples) will be analysed for saliva uptake and bolus
      particle size indicating extent of food breakdown.
    

Detailed description: 
      Study Aims:

      The aim of this study is to understand how food texture and saliva characteristics influences
      oral processing behavior, bolus characteristics and postprandial glycaemic response.

      The study hypothesizes that foods with a more elastic texture are eaten slower and requires
      more chewing, resulting in smaller bolus particle sizes and therefore higher postprandial
      glycaemic response due to an increased surface area for enzymatic digestion. Participants
      with higher saliva flowrate and/or alpha-amylase activity would also have shorter eating
      times and higher postprandial glycaemic responses.

      Study Design:

      Oral processing behaviours have high individual variances (Bolhuis et al 2013; Ketel et al
      2019) and a large sample size is required in order to get significant differences between
      treatments. Based on previous papers on food texture and oral processing, a minimum of 20
      healthy young male Chinese participants will be recruited in this study.

      The study will require participants to attend 1 screening session (1 hour) and 3 test
      sessions (3 hours for test sessions 1 and 2; 1 hour for test session 3).

      Screening (1 hour):

      All potential participants will be asked to give informed consent before taking part in any
      of the research activities. Baseline measurements including anthropometric (height, weight,
      percentage body fat using a Bioelectrical Impedance Analyser), fasting blood glucose via
      finger prick and blood pressure will be taken to access eligibility.

      Successfully screened participants will proceed to complete intraoral volume capacity
      measured using simple sip-and-spit measures, as well as provide stimulated and unstimulated
      saliva sample (approximately 4 x 5 ml each) via passive drooling to assess their saliva
      flowrates and saliva alpha-amylase activity.

      Test Foods:

      Commercially available and commonly consumed foods (e.g. white rice, korean rice cake,
      carrot, biscuits, etc.) are safe for human consumption and prepared in line with safe
      hygienic food preparation

      Test session 1 and 2 (3 hours each):

      Participants will be informed to fast 10 to 12 hours prior to test session 1 and 2. They are
      required to arrive the test centre between 08:00 - 09:00 a.m.

      Participants will be asked to consume a test meal during each session, consisting of a 'fast'
      (less elastic texture and eaten more quickly) or 'slow' food (more elastic texture and eaten
      more slowly) in total. The order of test foods presented will be randomised. These test foods
      will be of the same carbohydrate load (50g carbohydrate) with different textures (i.e. white
      rice vs. rice cakes).

      A baseline finger prick blood sample will be taken. After obtaining the baseline blood
      samples, test meal will be given to the participant to consumed within 15 minutes while being
      video recorded using a laptop webcam at face level. Following consumption of the test meal,
      finger prick blood samples will be taken for the next 5, 10, 15, 30, 45, 60, 90 and 120
      minutes. The amount of blood that will be collected at every time point will be about a drop
      of blood (approximately 0.5ml per time point and 5 ml in total).

      Sensory and textural ratings of the test meal will be taken using a visual analogue scale on
      a laptop. Post-meal satiety responses using a visual analogue scale will also be collected on
      a laptop every 15 minutes.

      After completion of blood collection and satiety responses, the participant will be asked to
      chew on a separate portion of test meal (5g) until ready to swallow, and will be asked to
      expectorate the food bolus to assess their bolus properties including saliva uptake and
      particle size distribution. Video-recordings of the participant chewing the test foods will
      be taken.

      A set of ad-libitum snacks will be provided to participants after all the measurements have
      been completed.

      Test sessions 1 and 2 will be interspaced by a minimum of 5 days.

      Test session 3 (1 hour):

      Participants will be asked to chew on 3 test foods (white rice, rice cake, raw carrot) using
      a fixed chew protocol (i.e. 15 chews, 30 chews and chew until point of first swallow) and
      then expectorating the bolus to assess their bolus properties including saliva uptake and
      particle size distribution. Video-recordings of the participant chewing the test foods will
      be taken.

      Sessions 2 and 3 will be interspaced by a minimum of 1 day.
    

Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Males of Chinese ethnicity and aged between 21 to 40 years old.
      
Keywords: Eating behaviour; Eating rate; Glycaemic response; Texture; Satiety