Tea Extract, Blood Lipid and Dietary Fat
Condition: Lipid Metabolism; Diabetes
Study type: Interventional

Summary: 
      There are numerous factors known to determine the relative rate of lipid metabolism at rest
      between and within individuals, including: biological sex, endogenous carbohydrate
      availability, training status and, in particular, feeding. Recent focus has been placed on
      the potential of alternative nutrients, nutritional supplements and pharmacological agents to
      modify substrate selection in favour of greater lipid oxidation (e.g. caffeine, carnitine,
      green tea) and/or to alter lipid absorption (e.g. caffeine, carnitine, orlistat, green tea
      preparations).

      Polyphenol-rich tea extract can have effects on lipase activity in the pancreas causing
      reduced fat absorption. The present study is to assess the potential for tea extract alone to
      be as effective at the liquid product in a western population.
    

Detailed description: 
      Participants will be asked to visit laboratories at the University of Bath on four occasions,
      with each visit separated by at least 2 days. Each visit will last approximately 5 hours.

      Participants will be asked to provide informed consent to participate in the study and to
      answer a number of questions to confirm that it is safe for them to do so, and to confirm
      eligibility. Participants will be asked to monitor their diet for 48 h before their first
      laboratory visit, and then to replicate this diet before subsequent visits. Participants will
      also be asked abstain from caffeine (i.e tea and coffee), alcohol and strenuous physical
      activity the day before visiting us (e.g. no exercise that causing sweating or heavy
      breathing).

      Participants will be asked to arrive to the laboratory after having not eaten for at least 5
      hours, having drunk one pint of water at least one hour before testing. Upon arrival at the
      laboratory a person trained and experienced in sampling blood will insert a cannula (a small
      plastic tube) into a vein on the participants arm. This is to allow for repeated blood
      sampling every 30-60 minutes during their visit.

      Participants will then be provided with one of the four supplements under investigation (i.e.
      either a placebo or one of the preparations derived from tea) to ingest as fluid along with a
      standard milkshake that provides participants with 40 g of fat, such that the appearance of
      this fat in the bloodstream can be measured. Of the 55 participants in this study, additional
      measurements will be made on a randomly selected sub-group of 15 to directly trace the
      appearance of fat in their blood samples; if participants have been asked and agreed to this
      part of the study then some of the fat in their milkshake would be a stable isotope tracer
      (13C-Tripalmitin). Participants will then rest comfortably, and a 10 ml sample of blood will
      be drawn from participants every 30 minutes for two hours, and at three hours, after
      consumption of the high fat drink.
    

Intervention name(s): Placebo; Tea beverage; Tea extract (medium concentration); Tea extract (high concentration); High fat liquid meal challenge
Intervention type(s): Dietary Supplement; Dietary Supplement; Dietary Supplement; Dietary Supplement; Other
Intervention description(s): Placebo will be matched for flavour, odour, and colour, to a tea beverage, without any active ingredient (tea extract).; Tea beverage; Tea extract (medium concentration) will be matched for flavour, odour, and colour, to a tea beverage, with a medium concentration of tea extract.; Tea extract (medium concentration) will be matched for flavour, odour, and colour, to a tea beverage, with a high concentration of tea extract.; A dairy based standard study meal challenge providing 40 g dietary fat and less than 2 g carbohydrate or 1.2 g protein.
For the tracer test subpopulation (n=15) the test meal will also contain 300 mg [1,1,1-13C3] tripalmitin to trace the incorporation of dietary lipid into plasma fatty acids.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Double-blind, single-centre randomised controlled trial using a cross-over experimental design.
Masking: Double (Participant, Investigator)
Primary purpose: Basic Science
Keywords: Tea extract; Triglycerides; Energy metabolism