What is it about Liquorice?

Love it or hate it liquorice has a range of health benefits. The ingredient of one of the world’s favourite sweets, including the North’s famous Pontefract Cakes, it is used in plant medicine for fatigue, particularly adrenal stress, but it also has memory boosting and protective effects on brain cells. Scroll down to find liquorice recipes and the science behind the root’s energising effects.

Can a plant really increase energy?

Plants have been shown to be energisers that reduce fatigue, tonics that strengthen relevant body systems or adaptogens that restore stress systems that go out of kilter. Certain plants are also nerve tonics that can combat mental fatigue and increase mental clarity. Few plants have been tested in human trials for mental fatigue, because apart from chronic fatigue syndrome (CFS or myalgic encephalopathy, ME), multiple sclerosis (MS) and to a lesser extent depression, mental fatigue is not recognized as a symptom in Western mainstream medicine. Lab-based scientific studies however, do show the impact of energiser plants, or their chemical ingredients, on the brain and nervous system.
Core energisers include two traditional medicinal plants, astragalus and ginkgo, which have origins in China, two European plants, one sweet and the other with a sting (liquorice and nettle), a Chinese and Indian spice (ginger) and then a fiery Asian vegetable (garlic) and the celebrated ‘superfood’ green tea. Other botanical brain balms that improve energy and mental fatigue include ashwaghanda an adaptogen which clinically boosts mood, memory, stamina and much more, and cocoa which lowers fatigue and relieves symptoms of CFS. And other traditional energising plants which have attracted scientific attention are European oak (Quercus robur) and bilberry (Vaccinium myrtillus), the Chinese angelica (Angelica sinensis) and the famous but endangered snow lotus (Saussurea involucrata) from the Himalayas and Mongolia.

Traditional Chinese medicinal plants and energy
Traditional Chinese medicine (TCM) continues to be practised on an equal basis alongside orthodox medicines in China today. TCM sees the concept of “vitality” as an essential component of health and healing. Chinese people understand good health as being critically dependent on what they term qi, or energy. They describe qi as a natural life force which, if not flowing freely due to obstruction or block results in a weaker body.
Ginseng and astragalus are used in traditional Chinese medicine to maintain or restore qi, and traditional ideas on the difference between the two plants are fascinating. Ginseng is said to “nourish vitality” and rescue energy collapse by restoring “yang” and is often used to treat shock. Men in particular recognize it as an energiser and as an aphrodisiac too. Astragalus, on the other hand, is said to reinforce loss of vitality in what is referred to as “insecurity of the exterior” and is used to help patients counter signs of weakness and debilitating physical conditions. Sometimes called female ginseng, it is used to help fight stress and disease too.
Trying to understand how these plants work in terms of conventional Western medicine, especially biological mechanisms is challenging! Ideas range from the mopping up of tissue-damaging free radicals (antioxidants) and increasing blood flow to countering the adrenal stress response or strengthening brain functions. We have no research of our own to back up reports on the revitalising qualities of energising plants, but love the seasonal plants in the physic garden which act as tonics. Nettle tea or soup, made in spring with added wild garlic, seems to be both energising and restorative, while combating mental fatigue and sharpening mental clarity too – but these are our subjective, not scientific, observations.



Today we look at the use of liquorice as an energiser, though the root has many other medicinal uses from liver complaints to as an anti-inflammatory, spasmolytic, laxative, anti-ulcer, anti-diabetic and anti-depressive.

Historical medicinal use

Used in Europe since prehistoric times, the botanical name comes from the Greek for sweet and root. Around 2000BC the Egyptian pharaohs chewed sticks and took it as a sweet drink. It was used in the 1st century by physician Dioscorides, who told Roman soldiers to chew the root to allay thirst. Also known as gan cao in traditional Chinese medicine, it is believed to harmonize other ingredients in a formula.

Used in traditional Japanese medicine and in Ayurvedic medicine for rejuvenation and by Western medical herbalists for adrenal insufficiency and as a restorative tonic – being immunostimulant, anti-inflammatory, anti-viral and anti-bacterial. Researched since the 1950s for its major clinical efficacy in gastric and duodenal ulceration.

What scientists say
In humans Studied in clinical trials for many for its effects (including aiding treatment of Helicobacter pylori), as an energiser, part of a traditional Chinese medicine formula (baoyuan dahuang), liquorice extracts relieve fatigue in patients with kidney disease. In controlled trials it is more effective than HRT in reducing hot flushes in menopausal women. Was successful in a case study for chronic fatigue syndrome.

In the lab Inhibits fatigue and enhances memory in lab models as well as protecting against oxidative stress and inflammation. Neuroprotective in cultured cells and in models of brain injury (such as restricted blood flow). Reduces oxidative stress in the hippocampus (a key memory area in the brain). Also active as an antidepressant and in generating new nerve cells (neurogenesis).

Key chemicals The major bioactive ingredients are the triterpene glycosides (saponins) like glycyrrhizin acid which also account for its sweet flavour – said to be 50 times sweeter than sugar. Also contains active flavonoids such as liquiritin, responsible for the root’s yellow colour, as well as sterols, coumarins and an essential oil.

How to take it Note the safety precautions below. Decoction (which is just a way to extract chemicals from tougher plant material like bark and roots) of peeled or unpeeled root (20g per 750ml water, simmered to 500ml) is commonly taken daily for short-term effects. Fresh root is also made into a paste or dried juice stick and dried root can be chewed, and fresh or dried root made into a tincture or liqueur and other recipes – scroll down. Also taken as capsules and tablets (see product for dose and duration).

As an ingredient of confectionery, its sweetness is less harsh and longer-lasting than sugar and it doesn’t damage teeth (liquorice lollipops actually protect children’s teeth!) or raise blood glucose.

Safety Considered safe within upper dose limit of 400mg active ingredient glycyorrhizin per day. Caution in long-term use when taken at a medicinal level since glycyrrhetic acid can accumulate. Contraindicated heart disease, high blood pressure, kidney disorders, hypokalemia, fluid retention, with oral and topical corticosteroids and, in theory, with anticoagulants and with oral contraceptives in a high dose or with long term use (glycyrrhetic acid can accumulate). An awareness of steroid effects (elevated blood cortisol) is advised. Caution at a medicinal level in pregnancy and breast feeding. Side-effects at higher doses include hypertension and hypokalemic-induced secondary disorders.

CAUTION Always consult an NIMH affiliated medical herbalist before taking any plant at a medicinal level, inform your health care provider if you are taking medication or have any medical condition and do not stop taking prescribed medication. Be sure of the identity of your plant and take only at the recommended dose.


Guo, Jie; Yang, Chunxiao; Yang, Jiajia; Yao, Yang (2016): ‘Glycyrrhizic acid ameliorates cognitive impairment in a rat model of vascular dementia associated with oxidative damage and inhibition of voltage-gated sodium channels.’ In CNS & Neurological Disorders – Drug Targets 15 (8), pp.1001–8.
Singh, Paramdeep; Singh, Damanpreet; Goel, Rajesh K. (2016): ‘Protective effect on phenytoin-induced cognition deficit in pentylenetetrazol kindled mice: a repertoire of Glycyrrhiza glabra flavonoid antioxidants.’ In Pharmaceutical Biology 54 (7), pp.1209–18. DOI: 10.3109/13880209.2015.1063673.
Baschetti, R. (1995): ‘Liquorice and chronic fatigue syndrome.’ In The New Zealand Medical Journal 108 (1002), p.259.

Bredin CP. (2019) Liquorice (Glycyrrhiza glabra): the journey of the sweet root from Mesopotamia to England. J R Coll Physicians Edinb. Jun;49(2):171-174.

Harding V, Stebbing J. (2017) Liquorice: a treatment for all sorts? Lancet Oncol. 2017 Sep;18(9):1155. doi: 10.1016/S1470-2045(17)30628-9.

This is taken from Botanical Brain Balms, Filbert Press 2018. Available buy at Dilston Physic Garden and bookshops. Look out for our new book out soon! GROW YOUR OWN PHYSIC GARDEN Use the Power of Medicinal Plants Grounded in Science.