Tea Extract, Blood Lipid and Dietary Fat

University of Bath52 enrolled

Overview

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.

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.

Interventions

PlaceboDIETARY_SUPPLEMENT

Placebo will be matched for flavour, odour, and colour, to a tea beverage, without any active ingredient (tea extract).

Tea beverageDIETARY_SUPPLEMENT

Tea beverage

Tea extract (medium concentration)DIETARY_SUPPLEMENT

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 (high concentration)DIETARY_SUPPLEMENT

Tea extract (medium concentration) will be matched for flavour, odour, and colour, to a tea beverage, with a high concentration of tea extract.

High fat liquid meal challengeOTHER

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.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 60 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: 1. Consent- Demonstrates understanding of the study and willingness to participate as evidenced by voluntary written informed consent and has received a signed and dated copy of the informed consent form. 2. Age- Aged between 18 and 60 years. 3. Compliance- Understands and is willing, able and likely to comply with all study procedures and restrictions. 4. General Health - Good general and mental health with, in the opinion of the investigator or medically qualified designee: 1. No clinically significant and relevant abnormalities of medical history or physical examination. 2. Absence of any condition that would impact on the subject's safety or wellbeing or affect the individual's ability to understand and follow study procedures and requirements. 5. No anticipated changes in diet and/or physical activity or lifestyle habits during the study period (e.g. pre-planned holidays, diets/exercise plan, smoking etc.) 6. Contraception- Females of childbearing potential who are, in the opinion of the investigator, practising a reliable method of contraception. Adequate contraception is defined as abstinence, oral contraceptive, either combined or progestogen alone OR injectable progestogen OR implants of levonorgestrel OR estrogenic vaginal ring OR percutaneous contraceptive patches OR intrauterine device or intrauterine system OR double barrier method (condom or occlusive cap \[diaphragm or cervical vault caps\] plus spermicidal agent \[foam, gel, film, cream, suppository\]) OR male partner sterilization prior to the female subject's entry into the study, and this male is the sole partner for that subject. Exclusion Criteria: 1. Pregnancy- Women who are known to be pregnant or who are intending to become pregnant over the duration of the study. 2. Breast-feeding- Women who are breast-feeding. 3. Allergy/Intolerance- Known or suspected intolerance or hypersensitivity to the study materials (or closely related compounds) or any of their stated ingredients. 4. Blood donation- More than 400ml of blood within 3 months of the screening visit and more than 1500ml of blood in the previous 12 months. Any reported bleeding disorder 5. Clinical Study/Experimental Medication 1. Participation in another clinical study or receipt of an investigational drug within 90 days of the screening visit) to allow full recovery of blood volume 2. Previous participation in this study. 6. Any reported recent (within 6 months) shift (\>3 kg) in body mass 7. Substance abuse- Recent history (within the last 2 years) of alcohol or other substance abuse and / or Any reported use of substances which may pose undue personal risk to participants or introduce bias into the experiment as deemed by the Principal Investigator 8. Any reported condition or behaviour deemed by the Principal Investigator either to pose undue personal risk to the participant or introduce bias into the experiment 9. Exclusion criteria assessed after taking measurements- Those with body mass index \< 18 or \> 35 kg/m\^2. Medical history of diabetes.