Capsaicin Energy Expenditure and Glucose Metabolism

Overview

The aim of the study is to investigate the effects of capsaicin rich foods on resting energy expenditure and substrate oxidation. We plan to recruit 30 healthy lean and overweight individuals age 18-45 (women) and age 18-50 (men) who will undergo two test days in random order. During one day they will receive a breakfast of toast, orange juice and an omelette with 4tsp of cayenne pepper while on the other day they will receive the same breakfast without the cayenne pepper. Metabolic rate and Respiratory quotients is measured for 30 minutes before the meal and for 2 hours after the meal. Capillary glucose levels and heart rate and blood pressure are measured before the meal and every 30 minutes thereafter for 2 hours.

Participants will be recruited by posters distributed on campus bulletin boards and asked to contact the investigator by phone or e-mail. Participants will complete a screening questionnaire by phone to determine eligibility. Once they pass the screening, they will be invited to the laboratory to sign the consent form, which will be administered by Rafia Virk. They will also be given a demographic survey. The survey will inquire about height, weight, medical conditions, medications and inclusion/exclusion criteria and availability. This survey will be used for screening purposes only and will not contribute to the research data. The survey is included in this application and inclusion and exclusion criteria are outlined. If participants are determined eligible, they will be contacted to set up with two study visits, pre-test instructions will be provided. \*For both appointments, participants will arrive to the test location after a 12-hour fast. Appointment 1: Participants will arrive at the Nutrition Assessment Laboratory between 7:00am and 7:30am. Details of the study will be re-iterated and informed consent will be obtained first thing on the morning of the first appointment. Eligibility will then then be confirmed by measuring height and weight and BMI calculation, and a over the counter pregnancy test will be performed on women. Demographic survey and 24-hour dietary recall will be obtained for 2 week days and 1 weekend day. Baseline measurements will then be obtained which include: Waist circumference, body compositition by Dual Energy X-ray Absorptiometry (DXA) scan (performed by Dr. de Jonge or Rafia Virk, who will be trained by Dr. de Jonge). The DXA scan involves lying on a table while wearing lose fitting, comfortable clothing. The scanner uses a low dose x-ray to determine the amount of fat, muscle and bone in your body. After lying down for 30 minutes, a metabolic cart will be used to measure resting energy expenditure by indirect calorimetry. For this procedure, a plastic dome will placed over the participants head that will measure their resting energy expenditure (REE). Baseline REE will then be measured for 30 minutes. After getting a baseline measure participants will consume a standard meal. We will continue to measure resting energy expenditure for 120 minutes. Blood glucose using a glucometer will also be determine before and 2 hours after the standardized meal. The REE measurements will be performed by Ms. Rafia Virk. Ms. Virk will be trained in the use of the metabolic cart by Dr. Lilian de Jonge who has over 20 years experience in the use of indirect calorimetry for the assessment of REE. After this test, the subjects will undergo a capsaicin threshold test. For this test, deionized water with red food coloring will serve as the blank. The testing compound will be cayenne pepper. The target samples, containing very low concentrations of cayenne pepper (0-1mg/g), will also have red food coloring so that they will only be distinguishable to participant by sense of taste rather than taste and sight. There will be nine sets of rows, each with 3 sets of samples. Each set will contain 2 blanks and one target sample. The target sample increase in concentration as the participant moves along the row. The participant will be asked to taste test the samples and pick the target sample out of the three. This appointment will take about 3 hours. The second test day will occur within one week of the first day. The participant will arrive with a 12 hour fast during the first week of the study. They will consume the same standardized meal (provided by Dr. de Jonge) from first appointment but with the addition of capsaicin (cayenne pepper powder form) (4tsp). They will then undergo a metabolic cart test (120 mins). Their blood glucose will also be determined using a glucometer for the following 3 hours post consumption. This appointment will last about 3 hours.