The appearance of blackcurrant compounds and the inhibition of MAO-B enzyme activity in blood after consuming a single dose of two different blackcurrant beverages in healthy adults

This study will investigate the effect of food format (freeze dried powder or juice concentrate) on inhibiting platelet monoamine oxidase-B activity and bioavailability of blackcurrant anthocyanins and sarmentosin. We will implement a two-arm, randomised, placebo-controlled repeated measures study design. Individuals who have passed the study’s inclusion/exclusion criteria will be asked to attend a familiarisation session (approximately 40 minutes) where they will meet with the study’s principal investigator. During this session the study’s trial coordinator (Research Associate, approx. 6 years experience in human studies) or the principal investigator (Research Scientist, PhD) will explain the logistics of the trial to them and answer any questions they may have. Enrolled participants (n = 12) will be evenly assigned to the two blackcurrant food formats tested in this study - blackcurrant powder (n = 6; 7.8 mg anthocyanin/kg bodyweight) and blackcurrant juice (n = 6; 78.8 mg anthocyanins). Participants will complete two trial days – one for each treatment (blackcurrant or placebo). Participants will be given a list of foods (e.g. blackcurrants and blackcurrant-containing foods and supplements) to abstain from consuming 24 hours prior each trial day. Participants will be also be asked to refrain from eating any food or drink (other than water) 10 h before the start of their scheduled trial day except for their supplied breakfast (one Almond One Square Meal bar [Cookie Time Ltd.]) that will be provided for them to consume approximately 2 h before your scheduled arrival at the research facility for their trial day. Upon arriving on site, participants will be asked what time they consumed their standardised breakfast and self report whether they consumed any of the restricted foods in the list that they were given in the last 24 h. Participants will complete a mood questionnaire, and donate a venous blood sample first blood sample (approximately 18 mL). They will then be given a single serve of their allocated intervention (blackcurrant or placebo) served as a 300 mL drink to consume. Participants will the be asked to complete a mood questionnaire prior donating a venous blood sample at 10 min, 20 min, 2 h, 4 h and 8 h after consuming the intervention. A small meal will be provided to them after the 4 h blood sample collection timepoint. After the blood collection at 8 hour timepoint the Trial Day is finished. At least five days after their first trial day, participants will complete a second trial day. The second trial day will be the same as the first, except participants will be give the intervention that they did not receive on their first trial day (i.e. the blackcurrant or placebo drink). The blackcurrant juice and powder are commercially source and prepared in a food-safe facility. Doses used in this study have been used in previous used in nutritional intervention studies (blackcurrant powder) or the current dose of anthocyanins in a commercial blackcurrant juice product (blackcurrant juice).