Friday 29 January 2010

Health and Fitness: Liquorice Root (2nd Suggested Cure for Mouth Ulcers)

Liquorice Root
Image from

WARNING: consult a doctor or a medical expert before trying!

Traditional Chinese medicine is widely appreciated, even by some westerners. Westerners travelling across the oceans to China to study Chinese medicine and to become doctors in mainland is no longer news. Nowadays, tough diseases which are seemingly incurable are facing strong challenges from Chinese herbology. Just to list one example, Shikimic acid, a primary feedstock used to create Tamiflu which is largely used to fights SARS virus, is produced from Chinese star anises. [1]
Chinese Star Anise
Image from
It seems almost magical to me to find that apart from expensive Manuka honey, there is yet another low-cost natural herb that can cure my oral ulcers -- the slightly-sweet Liquorice /ˈlɪk.ər.ɪs/ Root.
Liquorice's sweetness comes partially from glycyrrhizic acid (GA), which is an anti-viral compound significantly sweeter than sugar. It is this acid that plays an important part in curing the mouth ulcers.[2]

From my personal experience, Manuka Honey works well before and when the mouth ulcers are first formed, while Liquorice root (brewed in hot water and then drinking the water) is effective even after trauma.

Liquorice is widely used in food and medicine worldwide. It is used in candies in the UK and the Netherlands, used in cakes in some parts of England such as Yorkshire and Lancashire, used in soft drinks in the Netherlands and Egypt, used as natural mouth-freshener in Italy and Spain, used in soy sauces, broths and medicine in China.[3]

In traditional Chinese medicine, liquorice is commonly used in herbal formulae to "harmonize" the other ingredients in the formula. [4]

In modern medicine, it is shown that the glycyrrhizic acid(GA) in liquorice inhibits liver cell injury caused by many chemicals and is used in the treatment of chronic hepatitis and cirrhosis in Japan. It also inhibits the growth of several DNA and RNA viruses, inactivating herpes simplex virus particles irreversibly[5]

Despite the benefits, one should strongly note the toxicity of liquorice. Excessive consumption of liquorice or liquorice candy is known to be toxic to the liver and cardiovascular system, and may produce hypertension and oedema.[6]

The European Union suggests that people should not consume any more than 100 mg of glycyrrhizic acid(GA) a day, equivalent to approximately 50g of liquorice sweets[5] (assuming a content of 0.2% glycyrrhizic acid)[7]

But does the concentration of glycyrrhizic acid(GA) in the liquorice roots varies with cultivated areas? Yes. Here's the study done by a group of researchers in China. A preview can be read from here.

Then how much glycyrrhizic acid(GA) is there in 1 gram of liquorice root I bought from the medical store? Unknown.

So it is fair to say that it is very hard to tell how much liquorice root we should use in brewing the water, thus we had better be careful. One indicator is how sweet the brewed liquorice water is.

Since glycyrrhizic acid(GA) is 30-50 times as sweet as table sugar[5], then 1 gram of GA will taste like 30-50 grams of sugar. When I drink milk tea, I add 5 grams of sugar (a packet) only and I already find it sweet enough, therefore, in order not to exceed the maximum suggested intake of GA, which is 100mg / 0.1 g, then the brewed liquorice water (in my milk tea standard) should not be more than a tea cup (around 250ml), and should not be sweeter than 3 - 5 grams of sugar -- meaning not be sweeter than the milk tea.

In simple words, you should not drink more than a cup a day and it should be less sweeter than milk tea. (There are other ingredients in the liquorice root that will give the sweetness and not just from GA, but in the case of safety, it is better less than more.) Of course, it is better to consult a doctor or a medical expert before taking any actions, since you are dealing with medicine... but I just don't think they know the content of GA in the liquorice roots I bought.

trauma -- specialized (a) severe injury, usually caused by a violent attack or an accident
harmonize -- originally means "to add harmonies to a music tune", hereby used in a metaphorical way, which means "lowering the sharpness or great medical strengths of some other herbs"
inhibit -- to prevent someone from doing something, or to slow down a process or the growth of something
toxicity -- the level of poisonous substance