Is liquorice good for you, or can it raise blood pressure? 

What is liquorice?

Liquorice comes from the root of a plant called Glycyrrhiza glabra and has been used as a flavouring and in herbal medicine for thousands of years.

Within the liquorice root, there’s a chemical called glycyrrhizin which, if eaten (even in modest amounts), can raise blood pressure.

Glycyrrhizin is 50 times sweeter than sugar and this root extract is used to make black liquorice sweets, herbal teas, throat lozenges and herbal supplements.

Does liquorice have any health benefits?

It is claimed that liquorice has a wide range of health benefits including helping digestion, treating coughs, improving immunity and reducing inflammation and infections.

While there have been some studies looking at the effects of liquorice on health, there’s not enough good quality evidence to show that it should be used for any specific health condition.

Despite these potential health benefits, there is good evidence that eating liquorice and drinking liquorice teas, even in modest amounts, may raise your blood pressure.

How does glycyrrhizin in liquorice raise blood pressure?

Glycyrrhizin (an active chemical in liquorice) can alter the body’s levels of potassium and sodium which help regulate fluid balance.

Consuming too much liquorice or liquorice products can cause high blood pressure, fluid retention, muscle weakness and abnormal heart rhythms (arrhythmias), increasing your risk of cardiovascular disease.

The good news is that if liquorice has this effect on you, the changes are not normally permanent. Stop consuming liquorice and your levels of sodium, potassium and fluid should return to normal.

However, if you have experienced any symptoms that may be triggered by liquorice, it’s important to let your doctor know, so they can make sure there is no other possible cause.

How much liquorice is safe to eat?

European and World Health Organization guidelines suggest that a maximum of 100mg glycyrrhizin per day is safe for most people, although some susceptible people may be affected by lower intakes.

One small study of young, healthy people showed that 100mg glycyrrhizin per day, in the form of 3.3g liquorice for 2 weeks did raise blood pressure.

Although it did not cause high blood pressure (hypertension), but some people showed signs of fluid retention and heart strain.

Unfortunately, there’s no way of knowing how much glycyrrhizin there is in liquorice products because it is not reported on food labels. 

However, UK labelling guidelines require that liquorice sweets containing 400mg glycyrrhizin per 100g (or more) and herbal teas, or other drinks, containing 50mg glycyrrhizin per litre or more must have a warning on the label saying, “contains liquorice – people suffering from hypertension should avoid excessive consumption”.

It remains unclear, however, what excessive consumption is, as it is likely that different brands of liquorice sweets or teas contain very different amounts of glycyrrhizin.

One survey of different brands of liquorice teas found the average glycyrrhizin content to be 126mg per litre, so an average 250ml cup could be expected to contain about 31mg glycyrrhizin.

There is very little data on the glycyrrhizin content of UK liquorice products, but regularly eating even modest amounts could exceed the suggested 100mg/day limit.

Is liquorice fattening?

Liquorice root extract is mixed with other ingredients like treacle or molasses (sugars), flour and aniseed to make black liquorice sweets.

Most brands will contain 50 per cent sugar or more, and a 28g (1oz) portion of black liquorice will give you 14g sugar.

This is about half the recommended maximum of 30g per day and nearly 100 calories.

As with other sugary sweets, eating too many of them can lead to weight gain. Eat small amounts as an occasional treat as part of a balanced diet.

The takeaway on liquorice

For people with high blood pressure or cardiovascular disease, it’s probably sensible to avoid or limit consumption of liquorice and liquorice products.

Even people who do not have high blood pressure may be at risk of raising their blood pressure if regularly consuming liquorice sweets or liquorice tea.

Check if there is a liquorice warning on the ingredients list to give you an indication of a product’s glycyrrhizin level.

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