Bananas vs. liquorice!

Should you have a banana with your liquorice? It might be a good idea and here we explain why. But first let’s start with the liquorice, and we are talking about the real stuff with the characteristic liquorice taste provided by glycyrrhizin and not sweets flavoured with aniseed or other similar flavourings.

Liquorice is the common name given to a flowering plant (Glycyrrhiza glabra) that grows in parts of Asia and Europe. The root of the liquorice plant is the source of a sweet, aromatic compound called glycyrrhizin, which is used as a flavouring in confectionery and drinks. It is over 50 times sweeter than succros. The root itself may also be used as a dietary supplement with claimed health benefits like anti inflammatory activities and respiratory health support.

Liquorice consumption considered safe

For most of us, the liquorice found in food is generally considered safe to eat and safe when consumed as a medicine for short periods of time. However, when taken in large amounts over an extended period, it may cause potassium levels in the body to fall and this may impact your blood pressure. Some people may be particularly sensitive to these effects, such as those with heart disease, kidney disease and high blood pressure. Daily consumption of 50 g or more of liquorice candy for as little as two weeks may increase blood pressure by a small amount. This in turn can trigger abnormal heart rhythms, oedema (swelling), lethargy, and congestive heart failure in some people.

The component glycyrrhizin is responsible for many of these side effects. Although the amount of glycyrrhizin varies depending on the manufacturer of the confectionary and country preferences, a recent Danish study established a typical mean content of around 2 mg/g. Safe intakes recommended by the European Union and the World Health Organization (WHO) are specified as up to 100 mg glycyrrhizin a day, equivalent to about 50 g of confectionary. The US FDA allows soft candy to contain a maximum of 3.1% of glycyrrhizin so a 100 mg limit would be reached after the consumption of only 4 g of confectionary.

Swedish study issues a warning

However, in a study published in 2024, Swedish researchers suggested that the safe limit for liquorice might need to be reconsidered after discovering a significant impact on blood pressure in healthy adults. The researchers recruited 28 healthy participants with an average age of 24 years. The study used a randomised crossover design, with participants either starting with a liquorice product containing 100 mg of glycyrrhizin or a control product. The first block consisted of a 1-week run-in, followed by the 2-week liquorice intervention, a 2-week washout, a 2-week control period and a further 2-week washout period. The second block reversed the sequence of 2-week periods.

The researchers observed significant increases in systolic blood pressure during the liquorice intervention period when compared to measurements in the control period. Blood pressure readings were found to show increases from day five, with a mean increase in systolic blood pressure of 3.1 mm Hg at day 14. In addition, renin and aldosterone were found to be suppressed during the liquorice intervention. Renin is a hormone made by the kidneys. It controls the production of aldosterone, a hormone made in the adrenal glands. Aldosterone helps manage blood pressure and maintain healthy levels of potassium and sodium in the body. These effects have not previously been demonstrated for such moderate amounts of daily intake of liquorice.

Thus the researchers indicated that liquorice seems to be a more potent substance than previously thought and that currently advised safe levels might need to be reconsidered.

And here is the saviour

So now we come to potential counter measures in case you cannot resist the temptation posed by liquorice candy. And bananas could be part of the answer.

Researchers at The George Institute of Global Health at Imperial College London analysed data from a five year monitoring study of 20,995 people in China where half of the participants had replaced the use of normal table salt in cooking with a “salt substitute” containing potassium-enriched salt. They found that a one gram increase in daily potassium intake lowered systolic blood pressure levels by 2 mm Hg on average.

As it happens consuming an extra gram of potassium is the equivalent of eating two medium-sized bananas, a cup of spinach or a large sweet potato. So eating bananas can actually be an effective way of reducing blood pressure similar to cutting down on salt intake.

A global collaboration of researchers from Australia, the US, Japan, South Africa and India have called for potassium to be added to international health guidelines, with just Chinese and European guidelines currently suggesting it as an effective way to reduce blood pressure.

So what are the lessons learned?

First up be careful with your liquorice intake. Maybe eating 50 g every day for two weeks is overdoing it a bit. And also we are talking about mean levels of glycyrrhizin in liquorice sweets while some products may have much higher levels.

On the other hand, it is possible to balance the potassium reducing effects of liquorice by consuming other potassium-rich foods. Bananas is a good choice as they have other beneficial health effects as well. And why not a cup of spinach on she side?

As always a balanced diet without excesses either way is the solution to a long and healthy life.

New liquorice warnings

Liquorice is a popular sweetener found in many soft drinks, food products, snacks and herbal medicines. It has a rich history as an old remedy that was used by ancient Egyptians and Assyrians made into a sweet liquid drink. There is a traditional belief that liquorice is a healthy natural substance without side effects driving its liberal consumption that can occasionally be hazardous.

If you have followed this blog for a while you might remember that we have covered the good and the bad of liquorice before. Now we also cover the ugly.

The good

Liquorice is extracted from the roots of the plant Glycyrrhiza glabra, a member of the pea family. Most liquorice roots are wild-harvested with collection occurring mainly in Central Asia (Iran, Turkmenistan, Afghanistan and China). Liquorice extract is produced by boiling liquorice root and subsequently evaporating most of the water. Large-scale extraction is limited to China and Iran. Glycyrrhizin, that is 50 times sweeter than sugar, is the main active component in liquorice extract and apart from sweetness also provides the desirable liquorice flavour. Moderate consumption of liquorice is associated with several health benefits in that it can quickly soothe sore throats and coughs among some other positive effects.

The bad

Unfortunately, it has long been known that excessive and prolonged consumption of glycyrrhizin intensifies the effects of the stress hormone cortisol by inhibiting the enzyme that inactivates cortisol and may interfere with the sodium and potassium balance. High levels may increase hypertension. Thus, it has been suggested to limit consumption of glycyrrhizin to 100 mg per day, the approximate amount found in 60–70 g of liquorice candy. However, it is not that easy to estimate intake of glycyrrhizin as various forms of candies, beverages, supplements and extracts contain very different amounts of the active components.

The ugly

Recently new warnings were issued by the Finnish National Institute for Health and Welfare to women to avoid consuming large amounts of liquorice during pregnancy as it can have long-term harmful effects on the development of the foetus. A new Finnish study had shown that youths previously exposed to large amounts of liquorice in the womb performed less well than others in cognitive reasoning tests carried out by a psychologist. The difference was equivalent to approximately seven IQ points.

Those exposed to liquorice also performed less well in tasks measuring memory capacity, and according to parental estimates, they had more ADHD-type problems than others. With girls, puberty had started earlier and advanced further.

In this study a large amount was defined as daily consumption of more than 70 mg and compared to consumption of less than 35 mg glycyrrhizin.

The lesson

Although cortisol is essential to the development of a foetus, large increases initiated by excessive consumption of liquorice can be detrimental.

Devilish liquorice

I admit it, I am a liquorice junkie. The other day I bought a small packet of liquorice candy at IKEA of the strong and salty Swedish variety and emptied the 150 g in 15 minutes. Each year around Easter time, Sydney puts on the Easter Show with animal exhibits, entertainment and, above all, showbags. Most showbags are full of toys and candy and are mainly targeting kids, but there is always one full of 1 kg of liquorice. That is my favourite and I buy it each year and empty it in less than a week. That is not good for me, I know. Do you want to know why?

What is liquorice?

Liquorice is extracted from the root of the Glycyrrhiza glabra plant

First a few words about the plant Glycyrrhiza glabra. It is a herb belonging to the pea and bean family native to the Mediterranean region from which the confectionary liquorice is produced. Liquorice is extracted by boiling the root of the Glycyrrhiza plant in water and evaporating most of the water to produce a solid extract or a syrup. The name Glycyrrhiza is derived from the ancient Greek term ‘glykos’, meaning sweet, and ‘rhiza’, meaning root. The active compound in liquorice is glycyrrhizin, a sweetener between 30 to 50 times as sweet as sucrose, and which also has pharmaceutical effects. The sweetness is very different from sugar, being less instant and lasting longer.

The liquorice extract is used to flavour a wide variety of candies or sweets. In most of these candies the taste is reinforced by aniseed oil, and the actual content of liquorice might be very low or even absent. However, in the Netherlands and in the Nordic countries in particular a stronger variety is very popular, often containing ammonium chloride to give it a salty taste that partly masks the sweetness.

Liquorice flavouring is also used in soft drinks, and in some herbal infusions where it provides a sweet aftertaste. Chinese cuisine uses liquorice as a culinary spice for savoury foods. It is often employed to flavour broths and foods simmered in soy sauce. The flavour is common in medicines to disguise unpleasant flavours.

Liquorice is popular in Italy and Spain in its natural form. The root of the plant is simply dug up, washed and chewed as a mouth freshener. Throughout Italy liquorice is consumed in the form of small black pieces consisting  of pure liquorice extract. In Calabria a popular liqueur is made from liquorice extract. Liquorice is also very popular in Syria where it is sold as a drink.

The beneficial effects of liquorice

Liquorice has a rich history and has been used in various forms in food and as medicine for thousands of years. Liquorice is special because it can quickly soothe sore throats and coughs and was used centuries ago to treat coughing, hoarseness and asthma by Ancient Greek and Egyptian physicians. It is an old beneficial remedy used by Egyptian prophets and pharaohs as a sweet liquid. Liquorice extracts were also commonly used in the battlefields. Alexander the Great supplied his troops with rations of liquorice root whilst marching, because of its thirst-quenching qualities.

Liquorice candy should be enjoyed in moderation (Photo: U.S. Government)

Spanish monks introduced liquorice into Pontefract in West Yorkshire in 1562 and a local chemist added sugar to it and named it Pontefract cake. England began using the extract and turned it into liquorice candy which then became well known throughout the country. Liquorice recipes were brought by the early settlers to America which have been producing and importing liquorice products ever since, often called “black licorice”.

It is clear that glycyrrhizin in liquorice possesses various beneficial pharmaceutical properties. It is an expectorant (facilitating removal of mucus from the lungs by coughing) and a mild laxative since it increases prostaglandin levels. It is used in Japan for the treatment and control of chronic viral hepatitis and in China to treat tuberculosis. There are indications that glycyrrhizic acid disrupts latent Kaposi’s sarcoma exhibiting a strong anti-viral effect. As it inhibits Helicobacter pylori, it is used as an aid for healing stomach and duodenal ulcers, and in moderate amounts may soothe an upset stomach.

Pretty convincing don’t you think, and the list of beneficial effects of liquorice goes on and on to also include lowering of blood sugar levels in type-2 diabetics, treatment of ileitis, leaky gut syndrome, irritable bowel syndrome and Crohn’s disease as it is antispasmodic in the bowels.

The downside of liquorice consumption

If that is all it is to it you might be able to enjoy a daily dose of liquorice, but unfortunately there are also downsides. Consuming large amounts of liquorice is known to be toxic to the liver and cardiovascular system and can lead to hypokalemia and serious increases in blood pressure. The latter effect can become significant with a daily consumption of 50 g or more of liquorice candy for as little as two weeks. Studies of pregnant women suggest that 100 g of liquorice a week may adversely affect both IQ and behaviour traits of offspring.

And the side effects are real. Here are the case history of two females.

In 2004, a 56-year-old woman was admitted to hospital after overdosing on liquorice. The woman from Yorkshire went into muscle failure, a potentially fatal condition, after eating too much Pontefract cake. She had been eating a packet of sweets a day, about 200 g, to relieve chronic constipation. Her potassium levels were dangerously low and her muscles were very weak. She also had high blood pressure, which is dangerous because it can lead to stroke. The hospital restored her potassium levels, by intravenous drip and tablets, allowing her to recover after 4 days.

Similarly, a report published in 2010 described a 59-year-old female with headaches and malaise seeking medical help. She was found to have a very high blood pressure and a haemorrhagic lesion in the right temporal lobe of the brain. As it happened, she had been drinking five cups of liquorice tea per day over 18 months before seeking help. Following a vomiting illness she stopped liquorice tea consumption and her blood pressure normalised.

Enjoy liquorice in moderation

Drinking too much liquorice tea can be bad for you (Photo: Joi Ito)

Despite its apparent use in a few clinical scenarios, daily consumption of liquorice is best avoided because its benefits are minor compared to the adverse outcomes of chronic consumption.

An opinion by the European Commission published in 2003 suggested that people should not consume any more than 100 mg of glycyrrhizic acid a day since it can raise blood pressure or cause muscle weakness, chronic fatigue, headaches or swelling, and lower testosterone levels in men.

Likewise the U.S. Food and Drug Administration advised in 2011 that an excessive amount of black licorice consumption can cause potassium levels in the body to fall. This will cause some people to experience abnormal heart rhythms, as well as high blood pressure, oedema, lethargy, and congestive heart failure.

On the other hand, liquorice was named as the medicinal plant of 2012 by some environmental organisations in Germany noting that there are myriad medical indications for the use of liquorice, recommended since ancient times.

So remember that like most other things, liquorice might be good for you in moderation. But too much of it can be dangerous.

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