Black currant (Ribes nigrum) is a shrub whose leaves are used in herbal teas and whose dark berries are sold as anthocyanin-rich extracts, often from New Zealand.
Also known as: blackcurrant, Ribes nigrum, New Zealand blackcurrant, blackcurrant leaf.
Berry extract trials used 300 mg a day of an extract with 105 mg of anthocyanins for 7 days (Cook 2015), or two 300 mg capsules a day for 7 days (Okamoto 2020). These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling. In the EU, EMA concluded that black currant leaf preparations can be used for minor joint pain and to increase urine flow for minor urinary complaints, in adults only. EMA bases this on long-standing ("traditional") use: there is not enough evidence from clinical trials, but the effect is plausible and the herb has been used safely this way for at least 30 years, including at least 15 years in the EU. EMA says no studies in patients have been done with the leaf (EMA).
What studies show for the berry extract: in 14 trained male cyclists, 7 days of extract improved a 16.1 km time trial by 2.4% and raised fat burning during moderate cycling by 27% (Cook 2015). In 14 older adults, 7 days lowered arterial stiffness and central blood pressure more than placebo, with no effect on blood lipids (Okamoto 2020). Both were small, short crossover trials.
Safety: EMA had no reports of side effects with the leaf, and says leaf medicines for urinary complaints should not be used when a doctor has advised less fluid, as in severe heart or kidney disease (EMA). The sources here do not describe drug interactions.
We could not find a single published half-life or time to peak for black currant that applies to a supplement dose, so we do not list one. Plant extracts are mixtures of many compounds, so no single figure would describe them.
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