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fullscreen Watch out for licorice if you’re worried about blood pressure. Archive photography Photo: Anders Wiklund/TT
Just three grams of licorice a day raised blood pressure in healthy Swedes in a study. It is less than previously thought.
It is well known that licorice can raise blood pressure. This is because the substance glycyrrhizic acid, which is naturally found in licorice, affects hormones in the body, which in turn affects blood pressure.
Now researchers at Linköping University have investigated how much, or rather how little, licorice is required for the pressure to rise.
According to today’s recommendations from both the World Health Organization (WHO) and the EU, the limit of what is stated as a safe amount is 100 milligrams of glycyrrhizic acid a day.
– We saw that those who ate 100 milligrams a day for two weeks had an elevated blood pressure, says Peder af Geijerstam, ST doctor in general medicine and the study’s lead author.
Licorice for two weeks
In the study, 28 men and women between the ages of 18 and 30 were given either licorice or another product that contained salmiak but not licorice. All were healthy and had normal blood pressure before the start of the study.
Participants were randomly assigned to eat either licorice or the control product for two weeks, then take a two-week break and then eat the other variety for two weeks. In this way, the participants became their own controls.
The licorice contained exactly 100 milligrams of glycyrrhizic acid, i.e. the limit that was considered safe until now. After two weeks of licorice eating, the participants’ blood pressure rose by an average of 3.1 mmHg (millimeters of mercury).
– If you have that increase for a long time, it can increase the risk of heart attack and stroke. Especially if the blood pressure is on the higher side already before. In comparison, it is the same level that someone who has started taking blood pressure medication can lower their blood pressure, says Peder af Geijerstam.
Gained weight
The participants reacted differently to the licorice they ate. A quarter of them gained a slightly increased body weight, which the researchers believe is due to an increased amount of fluid in the body.
– It is a small study that needs to be repeated, but we think there is reason to review today’s recommendations. We also know that it is very variable how much glycyrrhizic acid is in the licorice that is sold, so it is difficult to know how much you ingest, says Peder af Geijerstam.
He advises anyone who eats licorice regularly to mention it to the doctor, nurse or other healthcare professional when having their blood pressure checked.
– If you have high blood pressure, a reduced licorice intake can help lower blood pressure.
The study was led by Fredrik Nyström, professor at Linköping University and has been published in the American Journal of Clinical Nutrition.