By Dr. Anthony Watson
Like any good story, this one starts a long time ago in a land far away. It was in 2011 when I embarked on an industry focussed PhD with Northumbria University and the New Zealand Institute for Plant and Food Research. My memories of my time in New Zealand are very fond but this bog is about science. Since I had the freedom, I thought would write about research many, at least at Newcastle Uni, wont know me for. But it’s a research focus which has been trundling on in the background for a while (my current main projects can be found here).
This research broadly focussed around conducting research to evidence the health benefits of berry fruit, with a specific focus on blackcurrants and their surprising impact on the brain.

It has long been established that blackcurrants contain phytochemicals such as anthocyanins, the compounds which are responsible for their deep purple colour. These compounds have been linked to numerous health benefits, ranging from cardiovascular support to anti-inflammatory effects. But a report by Borman in 1999 outlined that in test tubes, anthocyanins from blackcurrants could inhibit a class of enzymes called monoamine oxidase (MAO). A potential mechanism with potential to be explored (there’s a twist later on).
What is Monoamine Oxidase?
MAO is an enzyme responsible for breaking down key neurotransmitters in the brain, like dopamine, serotonin, and noradrenaline. These chemicals help regulate mood, motivation, and emotional balance. There are two types of MAO A and B.
MAO inhibitors (MAOIs) are a class of drugs historically used to treat depression, anxiety and neurological disorders, because they block this enzyme’s activity, leading to higher levels of these neurotransmitters in the brain. But nonselective and non-reversable inhibition can come with serious side effects and dietary restrictions.
Blackcurrants and MAO Inhibition
As mentioned earlier, there was previous test tube data which showed that anthocyanins from blackcurrants could inhibit MAO. So, we set out to test this in people. A randomised, double-blind, placebo-controlled, crossover study was conducted using 36 healthy young participants. Participants consumed two different blackcurrant extracts (a fresh blackcurrant juice or a commercially available blackcurrant powder fortified with anthocyanins) and a placebo across three separate sessions. The study also aimed to assess the effects on cognitive performance, mood, and circulating neurotransmitters. Participants improved in tasks requiring attention and mental flexibility after consuming blackcurrant extracts when compared to the placebo. Interestingly only the freshly juiced blackcurrant juice and not the anthocyanin fortified powder inhibited MAO. This was a little odd since the original hypothesis was based around anthocyanins, illustrating that compounds other than anthocyanins may be responsible for the observed in vivo MAO inhibition. But, this showed for the first time that the Blackadder variety of blackcurrants (now marketed under the name of Neuroberry) could inhibit both MAO-A and MAO-B in healthy people. The serving size of the juice was about 140ml. You can find the paper here.
I mentioned earlier that there are potentially negative effects of MAO-Is, especially if they are irreversible. For example, hypotensive crisis can occur If someone eats foods high in tyramine (like aged cheeses, cured meats, soy products, red wine, etc.), it can cause a dangerous spike in blood pressure.
Next we set out to assess the pharmacodynamics (time course) of the inhibition to understand if this inhibition is reversible. Just like the first study, we used a double-blind, placebo-controlled, randomised crossover design. Eight healthy male participants consumed a single serving of blackcurrant juice or a placebo. Blood samples were collected at multiple intervals up to 24 hours post-consumption to assess changes in monoamine oxidase activity. The outcome was a fast and absolute inhibition MAO. This was seen from the first measurement at 15 minutes post dose, through to the final day 1 measurement at 4 hours. The inhibition had disappeared by 24 hours. This showed that the inhibition was nonselective, absolute and reversable. Great news! The paper is here and contains some cool effects of blackcurrant on prolactin which may indicate dopamine modulations.
Blackcurrants and Brain activity

I then wanted to understand if blackcurrants were affecting brain activity; the idea was to combine cognitive tests and physiological measurements. Now at Newcastle, I ran a pilot study with nine healthy young adults. The goal was to see if drinking a single serving of blackcurrant juice would acutely brain wave activity in the prefrontal cortex, as measured by electroencephalography (EEG). This time the blackcurrant juice used was made from the UK ‘Ben Hope’ cultivar. Participants visited the lab twice, at least a week apart. On the study days, they arrived fasted, did some baseline tests, drank either the blackcurrant juice or a placebo drink, rested for 45 minutes, and then completed a set of cognitive tasks while their brain waves were recorded. Outcomes of this study were also pretty interesting, an increase delta and theta brain waves was seen after consuming the blackcurrant drink. Changes in these brain waves are an indication of relaxation, suggesting an anxiolytic (anxiety-reducing) effect of the blackcurrant juice. The paper can be found here. My most recent paper which is under review in nutritional neuroscience also showed increases in blood flow in the pre frontal cortex during cognitive demand after consuming blackcurrants. This is potentially mediated by increased neurovascular coupling.
All of this evidence is quite compelling with measurable and repeatable inhibition of MAO, improvements in cognitive performance and effects on brain activity after consumption of New Zealand and UK blackcurrant cultivars. But, there was still the issue of which compound was actually driving the MAO inhibition. The papers which we based the whole research idea on described anthocyanins as the molecule responsible, but our research showed that anthocyanin enriched powders did not have the same effect as a standard juice. Scientists at Plant and Food Research carried on this work and recently found the molecule responsible. It was not anthocyanins but sarmentosin, a glycoside and that is found in several plant species. The paper can be found here.

Back to the original question, “can blackcurrants boost your brain”? Definitely! And there is plenty more great research emerging showing similar results to mine. How much do you need to eat? The studies all focussed on 140ml of Juice, which is about 200g of berries.
What is exiting is the potential application of MAO inhibition in clinical populations, and that will probably be where this line of research goes next.