Blood Pressure and Garlic

Garlic is said to lower high blood pressure - this is a claim that is often repeated. Should patients with hypertension really reach for the pungent bulb or the powders and granules made from it more often?

Contrary to popular belief, the studies on the blood pressure-lowering effect of Allium sativum - the botanical name for garlic - are not so clear-cut.

In 2008, eleven different studies on the topic of blood pressure reduction through garlic were evaluated. Some studies did show improved blood pressure reduction with garlic compared to placebo products (the higher the initial blood pressure, the greater the possible reduction in blood pressure values), but no consistent results could be found. This was partly due to the insufficient methodological quality of the studies. For example, there was a lack of information on how the blood pressure measurement was conducted during the observation period of the respective studies.

In 2010, Australian researchers investigated the effect of so-called black garlic on patients suffering from difficult-to-control hypertension. Black garlic is normal garlic that has been "aged" through fermentation. The 50 participants received four capsules daily containing extract from black garlic (960 mg with 2.4 mg S-Allylcysteine) or a corresponding placebo over twelve weeks. The results showed a reduction in blood pressure, which, however, cannot be classified as significant.

A meta-analysis from 2016 also showed a reduction in blood pressure values, but about one-third of the study participants did not respond to garlic.

In 2019, a new meta-analysis was published that examined 12 studies in which garlic was taken by participants in the form of powder or capsules or as aged garlic.
It was found that garlic could lower the systolic blood pressure of participants by an average of 8 10 mmHg and the diastolic value by about 5-6 mmHg. However, this was not achieved by all participants; some fell short of these average values, meaning their blood pressure decreased less. This is attributed to the fact that the response to the garlic preparation apparently depends on how well the respective participant is supplied with B vitamins.
It was also shown that aged garlic positively affects the arteries, specifically their stiffness. It was also found that, like other garlic preparations, it has a blood-thinning effect but does not increase the risk of bleeding.

It is important to mention that garlic is not without interaction with various medications. It can enhance the antiplatelet ("blood-thinning") effect of platelet aggregation inhibitors, such as aspirin. Since an enhancement of effect, in this case an increased tendency to bleed, is also possible with the simultaneous intake of oral anticoagulants like Marcumar, as well as newer generation preparations like Xarelto, Eliquis, etc., garlic preparations are also discouraged in this context. However, garlic can weaken the effect of protease inhibitors in HIV-infected individuals.

A blood pressure-lowering effect of garlic was demonstrated in the 2019 meta-analysis. However, this was not observed in all participants. Some people respond to garlic with lower blood pressure, while others do not. As this meta-analysis showed, this may also depend on the supply of B vitamins. Considering the mentioned possible interactions, one can enjoy fresh garlic as a food. However, whether to use a garlic preparation for lowering blood pressure should be discussed with one's treating physician, especially if one is already taking medications for hypertension.

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By Sabine Croci. This article is medically reviewed. Last updated by Sabine Croci (03/2024).
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Blood Pressure and Garlic

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