Does garlic help with high blood pressure or cholesterol?
Garlic supplements can moderately lower blood pressure and cholesterol, but are not a replacement for medication and are not a proven protection against heart attacks or strokes.
Garlic supplements can moderately lower your blood pressure and cholesterol. Multiple large review studies of randomised trials show this consistently. The effect is greatest when your blood pressure is already elevated (above 140/90 mmHg): in that case systolic pressure drops by an average of around 8.7 mmHg and diastolic pressure by 6.1 mmHg. Across all participants combined the effect is smaller: 5.1 mmHg and 2.5 mmHg. That sounds modest, but it is comparable to exercising more or eating less salt. This emerged from 20 studies with 970 participants1,2,3.
Aged garlic extract has been studied separately in 9 studies with 584 people. Systolic pressure dropped by an average of 4 mmHg, diastolic pressure by almost 1.5 mmHg. Pay attention to the dose: the effect on diastolic pressure only occurred at more than 1200 mg per day. Lower doses had barely any measurable effect2.
For cholesterol too, the picture is more positive than was long assumed. Garlic supplements can lower total cholesterol and 'bad' LDL cholesterol by around 10%, but only if your cholesterol is already mildly elevated (above 200 mg/dL) and you take it for longer than 2 months. This emerged from a review study of 39 trials with 2300 participants1. A broader analysis also confirms favourable effects on triglycerides and 'good' HDL cholesterol4. Older research from 2002 was more sceptical about the practical significance of this effect5, but more recent and larger analyses therefore paint a slightly more positive picture.
The active compound allicin has clearly demonstrated mechanisms by which it can influence blood pressure and cholesterol in laboratory research6. But what works in the lab does not automatically translate to humans. All available studies measure intermediate variables such as blood pressure and cholesterol, not hard outcomes such as heart attacks, strokes or mortality. Whether garlic actually reduces those risks therefore remains unknown.
Garlic should therefore never replace regular blood pressure or cholesterol medication. If you want to use it as a supplement, discuss this with your doctor first. Stopping prescribed medication on your own initiative based on garlic supplements is not responsible3,1.
Based on multiple review studies of randomised trials, covering up to 39 studies and 2300 participants. One study had industry funding. Older research from 2002 differs somewhat from more recent findings. No long-term studies are available that look at cardiovascular disease or mortality.