Benefits
Supports low-light vision and dark adaptation
Blackcurrant anthocyanins are traditionally used to support the eye's ability to adjust to dim light. In a small crossover study in healthy adults, single doses of 12.5, 20 and 50 mg lowered the dark-adaptation threshold in a dose-dependent way, with the clearest effect at 50 mg. That study was published in 2000 in Alternative Medicine Review, a low-tier journal that no longer publishes. It tested generic blackcurrant anthocyanins, not VitaCurrant.
Helps ease screen-related eye fatigue
Long hours at a computer or phone can leave eyes tired and strained. In that same small 2000 crossover study, blackcurrant anthocyanins reduced the temporary shift in focus measured right after a stretch of intensive computer screen work. It is one small short-term study in healthy adults, published in a low-tier journal, using generic blackcurrant anthocyanins rather than VitaCurrant. Whether that translates into feeling less eye strain day to day was not measured.
Short-term effects on blood flow in small studies
Two small studies looked at blood flow. In healthy young men, a single dose raised forearm blood flow about two hours later during a typing task. In the two-year trial in 38 people with glaucoma who were also using prescription eye drops, eye blood flow increased compared with placebo. Neither study measured heart or artery health, so this is not evidence of a benefit for the heart or blood vessels.
Antioxidant activity shown in the lab
Blackcurrant anthocyanins act as antioxidants in laboratory tests, meaning they can neutralize reactive molecules in a test tube. None of the human studies cited on this page measured antioxidant status, oxidative stress markers or any aging-related outcome, so this is chemistry rather than a proven benefit in people.
Mechanism of action
Rhodopsin regeneration in the retina
In laboratory experiments, cyanidin-based anthocyanins from blackcurrant speed up the regeneration of rhodopsin, the light-sensitive pigment in retinal rod cells. Faster rhodopsin turnover is a proposed explanation for the dark-adaptation findings, but it has not been confirmed in people.
Ciliary muscle relaxation and focusing
Delphinidin-3-rutinoside, a major blackcurrant anthocyanin, relaxes ciliary smooth muscle in laboratory models. Because the ciliary muscle controls the lens's focusing power, this relaxation is a proposed mechanism for reduced eye strain during sustained near work.
Vasomodulation and blood flow
Anthocyanins are thought to influence vascular tone, in part through nitric oxide and endothelin-1 signaling, but that pathway comes from laboratory work. In people, the only related findings on this page are a short-term rise in forearm blood flow in healthy young men and an increase in eye blood flow in the small two-year trial in glaucoma patients who were on prescription drops.
Free-radical scavenging
The polyphenol structure of anthocyanins lets them donate electrons and neutralize reactive oxygen species in laboratory tests. No human study cited here measured oxidative stress, so any reduction in oxidative burden in the body is unproven.
Clinical trials
Double-blind, placebo-controlled crossover trial of blackcurrant anthocyanosides at 12.5, 20 and 50 mg (Nakaishi et al., 2000, Alternative Medicine Review). Component/class evidence on blackcurrant anthocyanins, not on the finished VitaCurrant product.
Healthy adult volunteers
Blackcurrant anthocyanoside intake produced a dose-dependent lowering of the dark-adaptation threshold, significant at 50 mg, and blunted the temporary shift in focus measured after intensive computer screen work compared with placebo. Limitations: small, short-term and single-dose, and published in Alternative Medicine Review, a low-tier journal that has since ceased publication.
Placebo-controlled, double-masked crossover study, blackcurrant anthocyanins 50 mg/day for 4 weeks (Ohguro, Ohguro & Yagi, 2013, Journal of Ocular Pharmacology and Therapeutics). Component/class evidence on blackcurrant anthocyanins, not the finished VitaCurrant product.
12 healthy volunteers and 21 glaucoma patients on standard therapy
This small pilot study measured eye pressure in healthy volunteers and in glaucoma patients who were already on standard treatment, and reported lower eye pressure readings. It is very small, and the larger two-year trial by the same group found no significant change in eye pressure, so this should not be treated as an established effect. Glaucoma is a leading cause of irreversible blindness: nothing here replaces prescribed glaucoma treatment, and anyone with eye-pressure concerns needs an ophthalmologist.
Randomized, placebo-controlled, double-masked trial, blackcurrant anthocyanins 50 mg/day for 24 months (Ohguro et al., 2012, Ophthalmologica). Component/class evidence, not on the finished VitaCurrant product.
38 people with open-angle glaucoma, 19 per group, who were already using prescription antiglaucoma eye drops
Over two years, the anthocyanin group showed less visual-field deterioration than placebo, but the difference was marginal (p=0.039) in a trial of only 38 people, 19 per group. Eye blood flow increased. There was no significant change in eye pressure. The supplement was given in addition to prescribed antiglaucoma medication, never instead of it. This is a report of a trial in people with an eye disease, not a benefit a healthy person should expect, and no one should change glaucoma treatment because of it.
Double-blind, placebo-controlled crossover study, blackcurrant anthocyanin ~17 mg/kg body weight (Matsumoto et al., 2005, European Journal of Applied Physiology). Component/class evidence on blackcurrant anthocyanins, not the finished VitaCurrant product.
Healthy young men
A single dose increased forearm blood flow about 2 hours after swallowing it during a typing task, and was linked with less typing-related muscle stiffness. Very small sample of healthy young men, one measurement session, and blood flow in a forearm muscle during typing says nothing about heart or artery health.