Cardiovascular System

A later dose- and duration-stratified meta-analysis of 19 trials confirmed a robust diastolic reduction and a fall in heart rate, but found the systolic effect non-significant and highly heterogeneous, with I² above 90% ^{9Reference 9Foshati et al. · 2022Meta-analysisThe effect of grape (Vitis vinifera) seed extract supplementation on flow-mediated dilation, blood pressure and heart rate: a systematic review and meta-analysis with duration- and dose-response analysisView study →}.

Because it is standardised to a defined procyanidin dose of 100 to 600 mg daily, its trials are more comparable than most. The extracts are still not interchangeable between manufacturers, and juice, wine and whole seed do not deliver the same thing.

It carries a separate and thinner signal in venous and lymphatic congestion.

The effects are consistent in direction and small in size.

Dosing is not standardised, the fixed oil frequently outperforms ground seed powder for the same endpoint, and thymoquinone content varies several-fold with seed origin.

It is a mild, broad cardiometabolic nudge rather than a targeted lipid drug.

The metabolic effect is real but heterogeneous, and most cinnamon trials do not specify the species. Many used C. verum, Ceylon cinnamon, rather than cassia.

That matters because cassia’s high coumarin content is hepatotoxic, which caps how much can safely be taken where Ceylon’s does not.

The lipid effect is a side-benefit of a metabolic-support herb rather than a cholesterol treatment.

The effect is tied to the weak, ERβ-preferring oestrogenic activity of its isoflavones, formononetin and biochanin A.

The benefit belongs to standardised, isoflavone-quantified extracts delivering 40 to 160 mg of isoflavones daily, not to a tea or whole-flower tincture, and it is confined to the menopausal-transition population it was studied in.

Its flagship human indication is chronic stable angina. In a double-blind crossover trial, bark extract reduced anginal frequency and improved treadmill parameters comparably to isosorbide mononitrate ^{25Reference 25Bharani et al. · 2002RCTEfficacy of Terminalia arjuna in chronic stable angina: a double-blind, placebo-controlled, crossover study comparing Terminalia arjuna with isosorbide mononitrate — randomised controlled trialView study →}, though a 2014 systematic review judged the pooled angina trials methodologically weak and inconclusive ^{26Reference 26Kaur et al. · 2014Meta-analysisTerminalia arjuna in chronic stable angina: systematic review and meta-analysisView study →}.

In heart failure the best-powered single trial (n=100) was null on its primary endpoint of ejection fraction, improving only functional and antioxidant secondary measures ^{27Reference 27Maulik et al. · 2016RCTClinical efficacy of water extract of stem bark of Terminalia arjuna in patients of chronic heart failure — a double-blind, randomised controlled trialView study →}. A 2026 meta-analysis of nine trials partly rehabilitates it, finding a consistent reduction in left-ventricular mass and a rise in HDL, which is a signal on cardiac remodelling rather than on pump function ^{28Reference 28Kumar et al. · 2026Meta-analysisEvaluation of the therapeutic potential and safety of Terminalia arjuna in heart failure management — a systematic review and meta-analysis of randomised controlled trialsView study →}.

Nearly all trials used crude water or alcohol stem-bark extract at around 1,500 mg/day, so the results do not transfer to tinctures or teas.

The certainty is low, and almost all of it tests compound formulas, danshen with notoginseng and borneol, or intravenous injections rather than the dried root a Western herbalist would use ^{29,30Reference 29Jia et al. · 2017Meta-analysisHow efficacious is danshen (Salvia miltiorrhiza) dripping pill in treating angina pectoris? Evidence assessment for meta-analysis of randomized controlled trials — meta-analysis with GRADE assessmentView study →Reference 30Luo et al. · 2015Systematic reviewCompound danshen (Salvia miltiorrhiza) dripping pill for coronary heart disease: an overview of systematic reviewsView study →}. No trial shows a benefit on hard endpoints such as mortality or infarction.

Its best-grounded mechanism is antiplatelet and antithrombotic, and the clearest human proof of that is inadvertent. Danshen measurably potentiates warfarin, raising the INR and causing bleeding ^{31Reference 31Chan · 2001Case reportInteraction between warfarin and danshen (Salvia miltiorrhiza) — review of case reportsView study →}, which demonstrates the effect and warns of the interaction at the same time.

The human evidence is large and low-certainty, and mostly on preparations that are not sold as loose root.

Around it sit meta-analyses of a reproducible antiplatelet effect ^{33Reference 33Li et al. · 2017Meta-analysisEffect of Panax notoginseng preparations on platelet function — a meta-analysis of 36 randomised controlled trialsView study →} and of adjunctive benefit in unstable angina, though those are mostly injections of low trial quality with no demonstrated reduction in events.

The herb both stops bleeding and moves blood: the saponins inhibit platelets while the amino acid dencichine promotes clotting. Which side dominates depends on the fraction, and the standardised saponin preparations are the antiplatelet ones.

As with dan shen, nearly all the human data use standardised extracts or injections rather than powdered root. Its haematological side is covered on the blood page.

The 2020 Cochrane review of phlebotonics judged the class to moderately reduce oedema and some venous symptoms, and lists Centella asiatica among the agents assessed ^{38Reference 38Martínez-Zapata et al. · 2020Meta-analysisPhlebotonics for venous insufficiency — Cochrane systematic review and meta-analysisView study →}. The European Medicines Agency accepts the herb as a traditional remedy for minor venous symptoms.

The trials are small and mostly from a single Italian research group.

The effect belongs to the standardised fraction or a defined cream, not to tea or raw powder, whose triterpene content varies enormously.

In chronic venous insufficiency it is the most consistent finding. A double-blind trial at 100 mg three times daily for two months significantly reduced subcutaneous oedema, leg heaviness and pain, with about 60% of treated patients losing oedema entirely while placebo did nothing ^{41Reference 41Arcangeli · 2000RCTPycnogenol in chronic venous insufficiency — randomised placebo-controlled trialView study →}.

A 2020 Cochrane review pooling 27 trials across ten disorders found oedema among the outcomes the bark extract helps, though it graded the certainty low because trials were small and mostly manufacturer-funded ^{40Reference 40Robertson et al. · 2020Systematic reviewPine bark (Pinus spp.) extract for treating chronic disorders — Cochrane systematic reviewView study →}.

The bark extract also carries modest blood-pressure and glycaemic signals. The active fraction is the bark’s oligomeric procyanidins, and a Pycnogenol result does not transfer to a cup of needle tea.

For intermittent claudication, the calf pain of peripheral arterial disease, early meta-analyses showed a small gain in pain-free walking distance, but the 2009 Cochrane review found the effect small and of uncertain clinical significance ^{42Reference 42Nicolaï et al. · 2009Meta-analysisGinkgo biloba for intermittent claudication — Cochrane systematic review and meta-analysisView study →}.

Its circulatory rationale and its bleeding risk share one mechanism: ginkgolide B is a potent antagonist of platelet-activating factor ^{43Reference 43Liu et al. · 2014In vitroGinkgolide B inhibits platelet release by blocking Syk and p38 MAPK phosphorylation in thrombin-stimulated platelets — in vitro studyView study →}.

The data belong to the standardised EGb 761 extract rather than crude leaf or tea, and the antiplatelet action means it is stopped before surgery and used cautiously with anticoagulants.