Anthocyanin-rich plum juice reduces ambulatory blood pressure but not acute cognitive function in younger and older adults: a pilot crossover dose-timing study
- 24 participants (12 18-45 yo, 12 65+ yo) attended two 6-hour clinic visits
- To avoid any external variables affecting results, participants were instructed to avoid consuming purple/red fruits and vegetables in the 24-hour periods before and after the clinic visits
The 6-hour clinic visits entailed:
- Upon arrival in the morning after fasting for 12 hours, participants were fitted with an ambulatory blood pressure monitor for blood pressure monitoring over 24 hours (every 15 minutes over the 6 hours at the clinic and then once every hour while at home afterwards)
- Urine samples were collected upon arrival and at intervals after QG Nectar consumption to measure the anthocyanin levels
- Cognitive tests were carried out in format of an interview: tasks assessed higher executive function, verbal learning and memory, speed of processing, and general alertness
- Low-flavonoid breakfast cereal provided with QG nectar (either single dose 300 mL or 3 x 100 mL over 3 hours)
- 4 hours in, a ham and cheese sandwich was provided
- They were also provided with two 250 mL water bottles to consume as they pleased over the course of the 6 hours
 Flavonoids: the class of antioxidants that the Queen Garnet’s anthocyanins come under
- Blood pressure reduced significantly at 2 hours after QG nectar consumption for both groups, evidencing the absorption and bioavailability of the anthocyanin and metabolites that occur within 2 hours post-consumption
- The anthocyanins can make it to the large intestine where the gut bacteria turn them into metabolites that get absorbed
- No observed significant dose-timing effect as a result of QG nectar consumption
- No observed significant difference in cognitive performance when comparing baseline (before nectar) and after
 Bioavailability: refers to the proportion of a substance that enters the blood circulation (where it can actually have an effect on the body)
 Metabolite: substances involved in the metabolism
Why does QG lower BP?
- May be a result of the molecular structure of the anthocyanin
- As antioxidants, the anthocyanin and other polyphenols in the QG are able to inhibit the oxidation of low-density lipoproteins (LDL). Inhibiting this process is important because LDL is responsible for carrying the ‘bad’ cholesterol from the liver and other sources into the cells. The cholesterol gets oxidised, builds up, and forms plaque which narrows your arteries and increases blood pressure.
- The potassium in the QG may also influence this blood pressure reduction.
 Low-density lipoprotein: a class of lipoprotein (a fat transporter) that is primarily made up of cholesterol. Instead of removing harmful cholesterol from areas of the body where it shouldn’t be (this is the role of high-density lipoproteins), LDL often deposits cholesterol in places that can lead to disease