Garlic For High Blood Pressure

Garlic is one of the most powerful natural remedies for high blood pressure. Eating two or three fresh garlic cloves (2.7g/0.1oz) every day may not win you many friends, but could lower your high blood pressure enough to cut your risk of a heart attack or stroke by up to 40%.

Garlic lowers a high blood pressure

Garlic is a source of allicin, a unique amino acid which gives crushed garlic cloves their characteristic smell. Allicin and other powerful sulphur compounds formed in aged black garlic have numerous beneficial effects on the circulation.

Researchers have found that garlic can:

  • Dilate blood vessels by relaxing smooth muscle cells so that small arteries (arterioles) expand by an average of 4.2% and small veins (venules) by 5.9%; studies show, for example, that garlic extracts improve blood flow to the skin and nail folds by as much as 55% within 5 hours of taking a single dose.
  • Decrease blood stickiness by increasing the activity of a natural clot busting reaction called fibrinolysis; in one study, fibrinolytic activity was increased by 70% within a few hours of taking raw garlic.
  • Increase blood fluidity through a beneficial effect on sodium and potassium flow across cell membranes.
  • Increase arterial wall elasticity – including that of the largest artery in the body, the aorta – to lower the resistance against which your heart has to pump.
  • Protect circulating fats, such as ‘bad’ LDL-cholesterol from oxidation to reduce their uptake by scavenger cells and protect against hardening and furring up of the arteries (atherosclerosis) to reduce age-related rises in blood pressure.

Together, these actions have a significant, blood pressure lowering effect.

The results from 20 trials, involving almost a thousand people, found that garlic extracts reduced systolic blood pressure (the upper reading) by between 7mmHg and 16mmHg, and reduced diastolic blood pressure (the lower reading) by between 5mmHg and 9mmHg, compared with inactive placebo.

Garlic is therefore at least as effective in reducing blood pressure as many prescribed medications. While its effects start within five hours, and wear off over 24 hours, there is an accumulative benefit so that blood pressure gradually continues to fall over two to three months of treatment.

Interestingly, garlic extracts appear to have little effect on a normal blood pressure, so that side effects related to low blood pressure (hypotension) do not seem to occur.

Aged garlic and blood pressure

Aged garlic appears to have the most consistent blood pressure lowering effect.

Aged garlic is produced by allowing fresh bulbs to mature at room temperature so that allicin degrades into other, more powerful, sulfur-containing substances such as S-allyl-cysteine.

Black garlic is produced by naturally fermenting fresh garlic bulbs under controlled higher temperatures and humidity.  This converts unstable, volatile, smelly sulphurous compounds into stable, odourless substances and also generates dark, melanoidin pigments, which turn the cloves black.

Aged black garlic has at least four times more antioxidant activity per gram.  It therefore offers greater therapeutic benefits while reducing the anti-social element associated with high intakes of garlic.

Garlic reverses atherosclerosis

Exciting research shows that garlic can even reverse hardening and furring up of the arteries. A study in which 152 people were followed for over 4 years showed that taking garlic tablets could reduce and even reverse hardening and furring up of the arteries (atherosclerosis). In those not taking garlic tablets, atherosclerotic plaques built up by 15.6% over the four years, while in those taking garlic, plaque volume decreased by 2.6% – a combined difference of 18.2%. Due to all these beneficial effects on the circulation, taking garlic extracts is estimated to reduce the risk of a heart attack by 50%.

Another study, involving fifty-five people with metabolic syndrome (a combination of high blood pressure, large waist, raised triglycerides and/or poor glucose control) taking 2400 mg aged garlic extracts per day, for 12 months, slowed the accumulation of fatty plaques in the coronary arteries by 80%. What’s more, their degree of measurable soft plaque actually reduced by -1.5%. In those taking placebo, the degree of plaque increased by +0.2% as their arterial disease continued to progress despite all the medications they were taking.

These findings are part of the explanation on why the Mediterranean way of eating is so beneficial for the heart and circulation and for improving blood pressure regulation.

Garlic improves well-being

As well as protecting against heart disease and stroke, garlic also provides emotional benefits. One study assessed volunteers psychological state before and after four months treatment with standardised garlic extracts. They found marked improvements in positive mood characteristics (activity, elated mood, concentration, sensitivity) and a fall in negative mood characteristics (anxiety, irritation) in those taking garlic tablets, while those taking inactive placebo showed no significant emotional changes. These beneficial effects may result from improved blood flow to the brain, and can reduce perceptions of stress to contribute to the overall blood pressure lowering effect.

Cooking with garlic

mediterranean dietOnce garlic is oven-heated (at 200 degrees C) or boiled for more than 3 minutes, its medicinal benefits are reduced. After more than 10 minutes heating, garlic’s ability to reduce platelet clotting is completely suppressed so add garlic towards the end of cooking for maximum effect.

Large doses of fresh garlic of between two to 28 cloves per day are needed to achieve the results seen in clinical trials using garlic extracts, however. While it’s a good idea to include garlic in your daily Mediterranean-style of eating – these high doses are best achieved through supplements.

What is the best dose to lower blood pressure?

Doses depend on the concentration of extracts used in a product. A typical dose supplies 1000mcg – 5000mcg allicin, or the equivalent of 2000mg black garlic whose active component is S-allyl-cysteine.

Enteric coating of dried garlic reduces garlic odour on breath and protects active ingredients from degradation in the stomach. This is not needed with aged black garlic whose odour is much more mild.


If your blood pressure is raised, self-monitoring is key to maintaining good control. 

Click here for advice on choosing a blood pressure monitor to use at home.

See my recommended upper arm blood pressure monitors.

Image credits: gadini/pixabay; 5ph / shutterstock

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2 thoughts on “Garlic For High Blood Pressure

  • James W D

    Thanks for the tip about cooking with Garlic. I had added this into many of the things that I have been cooking over the last couple of years, but it appears that I have been putting it in a tad early at times. I will definitely make some adjustments now and plop it in at the end now. Need to get the benefits of using it!

    • DrSarahBrewer Post author

      The flavour is more intense, then, too. Just make sure anyone you plan to kiss later eats it too as therapeutic amounts can be a bit antisocial – that’s wehre enteric-coated and black garlic tablets come in!