Supplement analysis backed by scientific evidence · PT

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Moderate evidenceHeart & metabolic

Garlic Extract

Garlic reliably produces a small blood-pressure reduction in people who are actually hypertensive — roughly the effect of a low-dose drug in some trials — plus a modest cholesterol drop. Its reputation as a cold preventer rests on a single unreplicated trial.

What the science says

  • Lowering blood pressure in hypertension Moderate evidence

    A 2020 review and meta-analysis of 12 trials in 553 hypertensive participants found aged garlic extract lowered systolic pressure by about 8.3 mmHg and diastolic by about 5.5 mmHg over 8-12 weeks — comparable to a standard first-line antihypertensive in these trials. Effects are much smaller or absent in people with normal blood pressure, so this is a population-specific result.

  • Cholesterol and lipids Moderate evidence

    An updated meta-analysis of 39 trials (2,300 participants) found garlic reduced total cholesterol by roughly 17 mg/dL and LDL by about 9 mg/dL in people with total cholesterol above 200 mg/dL treated for more than 2 months, with no meaningful effect on HDL or triglycerides. That is a real but clinically modest change — a fraction of what a statin delivers.

  • Preventing colds Limited evidence

    The claim rests almost entirely on one 146-person UK trial in which allicin-containing garlic cut cold episodes over 12 weeks. It has never been replicated, and Cochrane has repeatedly noted the evidence base for garlic and the common cold is a single trial of uncertain quality.

Dosage & safety

Studied doseAged garlic extract: 600-2,400 mg/day (typically 1.2 g/day) in divided doses, the form used in most blood-pressure trials. Garlic powder tablets: 600-900 mg/day standardized to about 1.3% alliin, delivering roughly 3.6-5.4 mg potential allicin. Raw garlic equivalents used in lipid trials are around 4 g/day (one to two cloves). Minimum 8-12 weeks for blood-pressure effects.
SafetyBreath and body odour are near-universal with allicin-yielding forms; aged garlic extract is largely odourless. GI upset, heartburn and, occasionally, allergic contact dermatitis occur. The clinically important issue is bleeding: garlic inhibits platelet aggregation, and case reports link it to spontaneous bleeding and to potentiation of warfarin — stop at least 7-10 days before surgery and use caution with warfarin, clopidogrel, aspirin and DOACs. Garlic induces CYP3A4 and P-glycoprotein and has been shown to significantly reduce saquinavir levels, so it is a real concern with protease inhibitors and other narrow-therapeutic-index drugs. It may add to antihypertensive and antidiabetic drug effects.

Scientific references

Where to buy

Kyolic, Aged Garlic Extract™, Cardiovascular Health, Original Formula 100, 300 Capsules (300 mg per Capsule)

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