Benefits
Cardiorespiratory endurance improvement
A manufacturer-run trial of Oxyjun® (500 mg/day for 4 weeks) reported higher VO2 max versus placebo in healthy adults. This trial is not indexed in PubMed and has not been independently replicated, so the size of the effect cannot be confirmed. In a separate small study, generic arjuna bark extract (500 mg/day) also raised VO2 max in a group of about 10 healthy young adults.
Circulatory and heart-function support
In one small crossover trial in 58 men with stable angina, generic arjuna bark extract (500 mg three times daily, each arm lasting about one week) reduced angina frequency and improved treadmill exercise tolerance to a degree similar to isosorbide mononitrate, and was well tolerated. That study enrolled men only, did not measure ejection fraction, and used generic arjuna rather than Oxyjun. A separate manufacturer-run trial of Oxyjun (400 mg/day for 8 weeks) reported a small rise in left-ventricular ejection fraction in healthy adults.
Blood pressure and arterial health
In a small study of healthy young adults, generic arjuna lowered resting systolic blood pressure. Controlled trials in people with high blood pressure are lacking, so a specific millimetre-of-mercury effect cannot be stated.
Exercise-induced oxidative stress reduction
Arjuna bark is rich in tannins and flavonoids that scavenge free radicals in laboratory tests. Whether oral arjuna lowers exercise-induced oxidative stress, muscle damage, or recovery time in people has not been shown in the trials cited here.
Lipid profile improvement
Some early studies suggest arjuna may modestly affect blood lipids, but the trials cited here did not establish a clear cholesterol-lowering effect in people. The proposed mechanisms come from laboratory work.
Mechanism of action
Endothelial nitric oxide enhancement
Arjunolic acid and arjunic acid stimulate endothelial nitric oxide synthase (eNOS) activity and increase bioavailable nitric oxide — improving vascular tone, reducing blood pressure, and enhancing blood flow to working muscle tissue during exercise. This mechanism underlies both cardiovascular protection and performance enhancement.
Cardiac muscle calcium channel modulation
Arjuna glycosides modulate cardiac L-type calcium channels, improving cardiac contractility and stroke volume without the proarrhythmic risks associated with pharmaceutical calcium channel modulators. This proposed effect comes from laboratory work and has not been confirmed as the cause of any clinical benefit in people.
Free radical scavenging and antioxidant enzyme induction
Arjuna's dense tannin matrix (including arjunagenin and terminic acid) directly scavenges reactive oxygen species and induces endogenous antioxidant enzyme expression (SOD, catalase, GPx), providing both immediate and sustained antioxidant protection in cardiac and vascular tissue.
Clinical trials
Randomized, double-blind, placebo-controlled trial of Oxyjun® (500 mg/day) vs. placebo in 30 healthy adults for 4 weeks. (Manufacturer-sponsored; not indexed in PubMed.)
30 healthy adults. 4-week intervention.
Oxyjun® supplementation was reported to increase VO2 max versus placebo. Significant improvements in cardiorespiratory fitness markers and exercise performance indices. Well-tolerated with no adverse effects. This trial is manufacturer-sponsored and is not independently published or PubMed-indexed, so the effect size should be viewed with caution.
Randomized double-blind crossover trial comparing generic arjuna bark extract (500 mg three times daily) vs. isosorbide mononitrate (40 mg/day) vs. placebo in 58 men with stable angina, each treatment given for about one week separated by a washout.
58 men with stable angina. Each treatment arm lasted about one week in a crossover design. Generic arjuna extract, not Oxyjun.
Arjuna extract significantly reduced angina frequency and improved treadmill exercise tolerance compared with placebo, to a degree similar to isosorbide mononitrate, and was well tolerated. Ejection fraction was not measured. Because this trial used generic arjuna in men only, it does not establish the branded Oxyjun product's effects.