Procyanidin C1 as a Senolytic Therapy - Quick Reference Sheet
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Procyanidin C1 as a Senolytic Therapy

Created on 09/17/2026 – Quick Reference based on Evidence Review created using AI4L / Opus 5 – Audit

A single molecule from grape seed that quiets worn-out cells at low intake and kills them at higher intake. Animal and laboratory evidence is broad; no human result exists, and how much reaches human tissue is unmeasured. Plausible harms are modest: stomach upset, headache, allergic reaction in grape-sensitive people, blocked plant-source iron absorption, added blood-thinning and blood-pressure lowering. (Full Review)

Protocol

Continuous low-dose oral regimen
2.5–5 mg once daily
For 12 weeks — the two active arms of the only registered human study
Intermittent high-dose oral regimen
2–3 consecutive days every 2–4 weeks
The pattern favoured by senolytic researchers; neither schedule is established as the default
Best time of day
Morning with a meal
No time-of-day dosing study exists; the only human trial did not fix the hour
Time to effect
Time to effect
Unknown in humans
No biomarker confirms an effect within days
Rodent function and organ change
2–4 months
Emerged over two to four months of intermittent dosing in rodents
Human skin endpoints
6 and 12 weeks
Measurement points of the single human study, which has reported nothing

Benefits

Contraindications
  • Pregnant or breastfeeding women
  • Active bleeding, inherited bleeding disorders, or platelet count below 100 × 10⁹/L
  • Warfarin with INR above 3.0, or unstable anticoagulation control
  • Within 14 days of planned surgery or an invasive procedure, including dental extraction
  • Active malignancy on chemotherapy or radiation therapy, unless scheduled by the treating oncologist
  • Severe hepatic impairment (Child-Pugh Class C)
  • Iron-deficiency anaemia or ferritin below 30 ng/mL, until iron stores are repleted
  • Known hypersensitivity to grapes, grape seed or other grape-derived products
  • Anyone under 18 years of age
    •
Key Interactions
  • Anticoagulants, or blood thinners (warfarin, apixaban, rivaroxaban, dabigatran)
  • Antiplatelet agents, or clot-blocking drugs (aspirin, clopidogrel, ticagrelor, prasugrel)
  • Antihypertensives, or blood-pressure medications (lisinopril, amlodipine, losartan, hydrochlorothiazide)
  • BCL-2 family inhibitors (navitoclax, venetoclax)
  • CYP3A4 substrates with narrow margins (simvastatin, tacrolimus, ciclosporin)
  • Over-the-counter analgesics, or painkillers (ibuprofen, naproxen, high-dose aspirin)
  • Over-the-counter iron supplements (ferrous sulfate, ferrous bisglycinate)
  • Other senolytics and senomorphics (fisetin, quercetin, dasatinib, apigenin, pyrroloquinoline quinone)
  • Antiplatelet supplements (fish oil, high-dose vitamin E, ginkgo, garlic extract, nattokinase, curcumin)
  • Blood-pressure-lowering supplements (beetroot or dietary nitrate, magnesium, hibiscus, coenzyme Q10, aged garlic)
  • Structured exercise and heat exposure
    •

Risk & Side Effects

  • Low: Gastrointestinal intolerance; reduced absorption of plant-source iron; additive blood-pressure lowering on blood-pressure medication; headache; hypersensitivity reactions
  • Speculative: Loss of beneficial senescent-cell functions; pro-oxidant injury to healthy cells at high exposure; platelet inhibition and bleeding; mistimed interaction with cancer therapy; unknown consequences of sustained inflammatory-signal suppression

Monitoring

Marker Target Why
High-sensitivity C-reactive protein <0.5 mg/L Tracks the inflammatory load the compound targets
Interleukin-6 No established target; track change from own baseline Core component of the inflammatory secretion pattern of senescent cells
Seated and standing blood pressure <120/80 mmHg seated, <20 mmHg systolic drop on standing Detects additive blood-pressure lowering on existing therapy
Platelet count 175–250 × 10⁹/L Bleeding margin for the platelet-inhibition risk
International normalised ratio Within the prescribed anticoagulation target Catches destabilised anticoagulation, the most consequential interaction
Alanine aminotransferase 10–26 U/L women, 10–30 U/L men Hepatic reserve against strain from concentrated botanical extracts
Ferritin 50–100 ng/mL Iron status before and during tannin exposure
Estimated glomerular filtration rate >90 mL/min/1.73 m² Baseline renal function, the organ with the largest fibrosis dataset
Grip strength No established target; track change from own baseline Human analogue of the rodent functional endpoint

Cadence: At 4 weeks, at 12 weeks, then every 6 months while use continues. Clotting-time check brought forward to within 1–2 weeks of the first dose on anticoagulants; blood pressure logged at home twice daily for the first 4 weeks.

Qualitative Assessment

  • Daytime energy and endurance across the working day
  • Joint comfort and morning stiffness duration
  • Skin texture, hydration and visible fine lines
  • Recovery time after hard exercise sessions
  • Gastrointestinal comfort, stool consistency and appetite
  • Bruising frequency and duration of bleeding from minor cuts
  • Dizziness or unsteadiness on standing
Not medical advice. Educational distillation of a single evidence review. Confirm any decision with a qualified clinician, especially in the presence of prescription drugs or chronic conditions.