Licorice is a popular treat with a long history, but eating it regularly may affect the heart more than many people realize.
A study from Linköping University in Sweden found that even an amount close to the commonly accepted daily limit can raise blood pressure in healthy young adults.
The research was published in the American Journal of Clinical Nutrition. The findings challenge the idea that small or moderate amounts of licorice are harmless for most healthy people and suggest that some people may be especially sensitive to its effects.
Licorice is made from the root of plants in the Glycyrrhiza family and has been used for centuries in foods and traditional remedies. It contains glycyrrhizic acid, a naturally sweet substance that can change the way the kidneys and hormones control salt and water in the body.
When this system is disturbed, the body may hold on to more sodium and water while losing potassium. The extra fluid can increase the pressure inside blood vessels, which may push blood pressure higher and place more strain on the heart over time.
International health guidance has often treated about 100 milligrams of glycyrrhizic acid a day as an amount unlikely to cause harmful effects in most adults. However, the researchers wanted to test whether this level was truly harmless when consumed every day.
The study included 28 healthy adults between 18 and 30 years old. During one part of the experiment, they ate licorice containing 100 milligrams of glycyrrhizic acid each day, while during another period they received a control product containing salty licorice flavor but no licorice extract.
After a two-week break, the participants switched to the other product. This design allowed the researchers to compare each person’s response to real licorice with their response to the control product, reducing the effect of natural differences between people.
Participants checked their blood pressure at home every day. The research team also tested substances in the blood that help control salt and fluid levels and looked for signs that the heart was working harder.
The researchers found that daily licorice increased systolic blood pressure by an average of about 3.1 mmHg. Systolic pressure is the top number in a blood pressure reading and measures the pressure in the arteries when the heart contracts.
Licorice also lowered levels of renin and aldosterone, two hormones involved in controlling blood pressure and the body’s balance of salt and water. People who showed the strongest hormone changes also tended to retain more fluid and gain a small amount of weight.
Some of these more sensitive participants also had higher levels of NT-proBNP, a substance that can rise when the heart is under extra strain. The changes were small in these healthy young adults, but they suggest that the effects of licorice can reach beyond a simple change in a blood pressure reading.
A rise of a few points may not be dangerous for every healthy person. However, repeated increases could matter more for older adults or people who already have high blood pressure, heart disease, kidney problems, or other conditions that make fluid balance harder to control.
Another problem is that consumers may not know how much glycyrrhizic acid they are getting. Licorice sweets, herbal teas, extracts, supplements, and some traditional remedies can contain different amounts, and the exact level is not always clearly shown on the label.
The study was small and involved only healthy young adults, so larger studies are needed to understand how licorice affects different age groups and people with existing health conditions. Still, the results suggest that the current daily limit may not protect everyone equally.
For people who enjoy licorice occasionally, the findings do not mean that it must be avoided completely. But people who eat it frequently, especially those concerned about their blood pressure, may want to limit how much they consume and pay attention to licorice in candies, teas and supplements.
If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and natural coconut sugar could help reduce blood pressure and artery stiffness.
For more health information, please see recent studies about How to eat your way to healthy blood pressure and results showing that Modified traditional Chinese cuisine can lower blood pressure.
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