A randomised 3-period cross-over trial will be carried out to assess the acute and chronic effects of a large dose of apple PA compared with a low dose of apple PA (negative control) and aspirin (positive control), on platelet function (flow cytometry) and other risk factors of CVD (endothelial function, plasma antioxidants, inflammatory markers, lipid profile). Once recruited, volunteers will be assigned at random to consume 230g of low PA apple puree or high PA apple puree or aspirin (75mg) each day for 14 days in period 1. Following a minimum 14 day wash-out volunteers will then be crossed over for period 2 and after another 14-day wash-out volunteers will be crossed over to complete period 3 of the intervention (flow chart I). The acute effect of each treatment will be investigated on day 15 of each period. A fasting blood sample will be obtained prior to consumption of a standard breakfast and the apple puree or aspirin. Further blood samples will then be obtained at 2, 6 and 24 hours post-dosing. The chronic effect of all three treatments will be determined by measuring CVD risk factors in fasting blood samples obtained on day 1, 15 and 29. Flow chart II provides a more detailed overview of the design of each period which is identical for the apple puree treatments and differs only in the omission of urine collections and PWV measurements for the aspirin period. During the apple puree interventions phenolic acids will be analysed in 24-hour urine pools collected on the day prior to the start of each period, as well as on day 14, 15, and 28. PWV measurements will be carried on day 15 and 29 after a 12-hour overnight fast for each of the 2 apple intervention periods.
For the intervention to be successful it is necessary to exclude some food sources that contribute significantly to total PA intake (e.g. cocoa, berries, grapes, red wine, apples, legumes) and limit other PA food sources (tea/coffee) to levels that support compliance and are unlikely to mask any effects of the intervention. Because of its well documented effect on platelet function alcohol will be restricted to a maximum of 2 units per day and excluded completely for the 48 hours prior to blood sampling appointments. Oily fish consumption will be limited to 2 portions per week and will not be allowed for 48 hours prior to blood sampling. These dietary restrictions may have significant effects on platelet function in individuals that consume these foods regularly. Therefore, dietary restrictions will apply during a 14-day run-in diet prior to and for the duration of each intervention period. Platelet function will be assessed prior to the start of the run-in diet as well as at the start and end of each PA/aspirin intervention (flow chart II).
Male and female volunteers aged 19 to 64 will be recruited and screened for eligibility for up to 2 months prior to the start of the intervention. Those meeting the study criteria will be randomly assigned to one out of the six possible treatment orders, i.e. ABC, ACB, BAC, CAB, BCA, CBA. Randomisation will be stratified by sex.
Volunteers will be given a user friendly booklet (Run-in diet/Apple/Aspirin diary) for each intervention period to record apple puree/aspirin consumption and volunteers will also be prompted to record their alcohol, tea/coffee and oily fish intake (Annex 2). Foods not allowed during each intervention period are listed. Volunteers will be reminded not to consume oily fish (as listed), alcohol, coffee and tea 48 hours prior to a blood sampling appointment.
