Blood Pressure and Licorice – The Facts

Blood Pressure - About one million years ago (OK, 25 years ago really) when I was studying herbal medicine, one of the first things we learned was that you need to take care of prescribing licorice because it raises blood pressure.  I found that interesting seeing so many millions of people have consumed real licorice lollies, which was full of the medicinal herb licorice. I figured that if it was that bad, surely some of the millions of doses consumed would have killed someone and we would have known about it by now. Anyway, I was good and during herbal medicine exams, dutifully noted that licorice can increase BP.

History of Licorice

Licorice has a number of functions. The most amazing aspect of licorice is an amazing taste. It dates back to King Tut as it was found in 3,000-year-old tombs so humans have liked it for thousands of years. I must ask the question again…if the herb has been consumed as a sweet treat, or a tea, for this many years, why has licorice’s alleged blood pressure problems surfaced?

Effects of blood pressure changes from licorice

A group of researchers back in 2001 had the same curiosity as I did (back in 1995 as a long-haired herbal medicine student) regarding BP effects of licorice. Researchers gathered 3 groups of people together and decided to give each group ever-increasing doses of glycyrrhetinic acid (otherwise known as glycyrrhizin). The first group consumed 75mg, the second group consumed 270mg and the third group received a massive 540mg of glycyrrhetinic acid.

What happened was interesting with regard to the changes in blood pressure. The first group that received 75mg had no significant changes in their blood pressure after four weeks. However, the group that consumed 270mg glycyrrhetinic acid had a slight rise in their blood pressure (on average, up by a relatively small 5.4mmHg). The group consuming 540mg of glycyrrhetinic acid had increases of an average of 7mmHg.

Blood Pressure - What does the research say?

This research now gives us a clear indication of what level of licorice we can consume before our blood pressure is affected. For example, a cup of licorice tea contains around 15mg of glycyrrhetinic acid, which is highly unlikely to affect your blood pressure. Even consuming 3 cups per day of licorice tea is likely to be safe and not affect your BP. Having said that, if you do have any BP issues, you may want to check with your health care professional before you consume licorice in any form.

REFERENCES:
Liquorice-induced rise in blood pressure: a linear dose-response relationship. HA Sigurjonsdottir, L Franzson, K Manhem, J Ragnarsson, G Sigurdsson and S Wallerstedt. Journal of Human Hypertension (2001) 15, 549–552

Liquorice-induced rise in blood pressure: a linear dose-response relationship. HA Sigurjonsdottir, L Franzson, K Manhem, J Ragnarsson, G Sigurdsson and S Wallerstedt. Journal of Human Hypertension (2001) 15, 549–552