Blackcurrant powder and juice reduced an enzyme linked to mood in adults
What it found
Freeze-dried blackcurrant powder and blackcurrant juice both strongly reduced a blood enzyme called MAO-B in healthy adults.
A compound called sarmentosin was identified as the main active ingredient responsible.
What they found
Studies in people
Enzyme blocked by blackcurrant
Both the freeze-dried powder and the juice blocked more than 80% of platelet MAO-B activity within two hours. The effect faded after four to eight hours. Placebo drinks had no meaningful effect on this enzyme.
Pure sarmentosin tested
In a small trial, five healthy men drank 42 mg or 84 mg of pure sarmentosin extracted from blackcurrants. Both amounts significantly lowered platelet MAO-B activity after two hours, and the effect wore off by four hours.
Mood and alertness links
When the enzyme was most blocked, participants reported feeling more alert and less mentally tired. These positive mood ratings were strongest in the first 20 minutes after drinking blackcurrant.
Blood sugar unchanged
Drinking the blackcurrant powder, the juice, or the placebos made no significant difference to blood sugar levels during the study.
Studies in people and animals
Sarmentosin identified as key
Lab tests on blackcurrant juice fractions found that a compound called sarmentosin was the main substance blocking the MAO enzymes. It also blocked the enzyme when tested using pig liver enzymes in the lab.
What the authors conclude
- They conclude that sarmentosin is the main compound in blackcurrants responsible for blocking the MAO enzyme in people.
- They note that freeze-drying keeps this compound intact, so powder works just as well as juice.
- The authors suggest that eating or drinking blackcurrant products may support a better mood in healthy adults.
How it was done
Earlier work showed blackcurrant juice could lower levels of an enzyme that breaks down brain chemicals linked to mood, but scientists did not know which part of the fruit caused this. They wanted to find the specific compound and see if freeze-dried powder worked as well as juice.
Thirteen healthy adults aged 26 to 39 drank either freeze-dried blackcurrant powder mixed with water, blackcurrant juice, or matching placebos on separate days at least 7 days apart. Blood samples and mood questionnaires were taken over 8 hours. In a second trial, five healthy men drank isolated sarmentosin or a placebo to test its effect directly.
What it can’t tell you
- This trial only looked at single doses over one day, so it cannot show what happens if you eat blackcurrants every day.
- The mood findings came from a very small group, so they need checking in larger studies.
- The lab tests used pig liver enzymes, which might behave differently from human ones.
Who paid
- Conflicts
- The authors declare no competing financial interest.
- Authors work at
- The New Zealand Institute for Plant and Food Research Limited, New Zealand
The paper
- Title
- Identification of Sarmentosin as a Key Bioactive from Blackcurrants ( Ribes nigrum ) for Inhibiting Platelet Monoamine Oxidase in Humans
- Type
- Randomised controlled trial
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Lomiwes D, Günther CS, Bloor SJ, et al (2024). Identification of Sarmentosin as a Key Bioactive from Blackcurrants ( Ribes nigrum ) for Inhibiting Platelet Monoamine Oxidase in Humans. Journal of agricultural and food chemistry. doi:10.1021/acs.jafc.4c03802Free full textPubMed 39028868DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error