Inflammatory responses to meals with varying levels of anti-inflammatory potential: a randomised control pilot study in adults above a healthy weight
The study uses a randomised, controlled, cross over design where participants are randomised to one of three meal orders. Each participant will attend 1 screening visit and three testing visits, with a washout period between testing visits of no less than 1 week.
Screening visit (x 1): Participants will have their height, weight, waist circumference and blood pressure measured. Eligible participants will be given a physical activity questionnaire (IPAQ), a 3-day food diary, and two questionnaires used to explore factors that affect their food choices, to be completed prior to their first testing visit.
Pre-testing procedure: Prior to each testing session participants will be provided with a ready-prepared standardised evening meal comprised of a Healthy Choice spinach and ricotta ravioli, 50 g cheese and crackers, 250 mL 100% apple juice (3MJ, 45-65% total energy (E) carbohydrate, 25-35% E protein, and 15-25% E fat). They will be asked to consume this meal between 7 – 9 pm the night before each testing day, and will be asked to fast for 12 hours prior to their test visit. During this time they will be required to refrain from eating or drinking anything else except for water until they attend the Department of Nutrition, Dietetics & Food at the BASE Facility, Monash University, Notting Hill. They will also be asked to refrain form moderate and vigorous physical activity and alcohol consumption for 24 hours prior to each testing session. To monitor adherence to pre-intervention procedures, participants will be asked to recall at what time they consumed the standardised evening meal, how much of the standardised evening meal was consumed, and any other foods or drinks consumed during the 12 hour fasting period. They will also be asked to recall all physical activity undertaken and alcohol consumed in the 24 hour period prior to their testing visits.
Testing visits (x3): Participants will be asked to come in to the lab at 8 am in the morning following an overnight fast. Their weight and waist circumference will be taken. On the morning of each test session participants will have an indwelling catheter inserted and a baseline blood draw (~15ml taken at time point t = 0). Participants will then be provided with the relevant test meal, and will be supervised to ensure all of the meal is consumed within 15 minutes. They will then remain in the laboratory for five hours, during which time 8 additional blood draws (at time points t 15, 30, 45, 60, 120, 180, 240, 300 m) will be taken, and they will not be permitted to consume any food or drink except water. During each of these testing sessions participants will also be asked to complete 3 visual analogue scales (VAS) for hunger, desire to eat, and fullness. These three VAS scales will be completed at baseline (before consuming the test meal) and then hourly for five hours (at time points t 60, 120, 180, 240 and 300 m). Lastly, participants will be asked to undertake two questionnaires about sensory evaluation and factors affecting their likelihood to prepare each of the test meals at home. Following the final blood draw the indwelling catheter will be removed.
During the first testing visit participants will have their body composition (DXA scan) measured. The DXA scan will be performed prior to catheter insertion. A qualified dietitian will also take a detailed diet history.
Test Meals: There are three isocaloric test meals (2.2 MJ) meals designed to have a low (-6.24, termed the anti-inflammatory meal), moderate (-2.76, termed the neutral meal) or high (+9.36, termed the pro-inflammatory meal) Dietary Inflammatory Index (DII) score.
The pro-inflammatory meal, a cheese and bacon croissant, is a highly processed meal obtained from commercially available products. The neutral meal, a chicken, vegetable, red kidney bean and wholegrain pasta minestrone soup, is a typical healthy meal. The anti-inflammatory meal is an adaptation of the neutral meal, specifically designed to optimise purported anti-inflammatory compounds, including but not limited to ß-carotene, eugenol, fibre, omega-3 fatty acids, vitamin A, vitamin E and flavonoids.
The anti-inflammatory meal is the intervention meal and can be described as a chicken, vegetable and red kidney bean curry, served with brown rice, flaxseeds, and a lemon kefir yogurt (2.3 MJ, with 36% energy from carbohydrate (19 g fibre), 35% energy from fat (3.4 g saturates) and 19% energy from protein).
