Effect of blackcurrant consumption on sugar metabolism in healthy adults

This trial is aimed at assessing how ‘timed’ blackcurrant consumption influences sugar metabolism and energy production. The trial is a parallel design consisting of three trial arms. This design was selected since the influence of blackcurrant on sugar metabolism is currently unknown; a parallel trial design will eliminate any potential problems from a cross-over design. In all three trial arms, participants will be asked to fast for 12 hrs the night before and eat a set breakfast (One Square Meal Bar [Cookie Time Ltd.]) 2 hrs before the start of the trial. Participants will be randomised into 3 trial arms; arm 1 will consume a 200 mL drink containing fruit sugar (equivalent to the amount in the blackcurrant extract, i.e. for 2.2 g glucose, 2.6 g fructose, 0.36 g sucrose) diluted in water and then 1 hr later a 200 ml sugar drink containing 40 g sucrose diluted in water, arm 2 will consume a 200 ml fruit sugar drink (as described above) and then 1 hr later a blackcurrant / sugar drink (containing a whole blackcurrant extract equivalent to 3.2 mg polyphenolic compounds /Kg and 40 g sucrose) diluted in water, and arm 3 will consume a 200 mL blackcurrant drink (containing a whole blackcurrant extract equivalent to 3.2 mg polyphenolic compounds /Kg) diluted in water and then 1 hr later a 200 mL sugar drink containing 40 g sucrose diluted in water. The blackcurrant extract was commercially sourced from Sujon Berries (New Zealand) and the sugars purchased from Healtheries (New Zealand) and dinks were prepared under New Zealand food safety requirements. The trial will take place in designated clinical facilitates within PFR and will be conducted by experience trial co-ordinators, who are also First Aider and trained phlebotomist. The trial co-ordinator will monitor the welfare of participants and ensure that they adhere to trial arm protocols. Participants will be randomised into one of the trial three arms. In all three trial arms a small amount of blood (capillary samples) will be taken prior to the start of the trial, after the consumption fruit sugar, blackcurrant + / - sugar drinks and then 1 hr later at specific times over a 4 hr period; 0, 15, 30, 45, 60, 90, 120, 150, 180, 240 mins after the consumption of the sugar or blackcurrant/sugar drink.