The
two major constituents of licorice are glycyrrhizin and
flavonoids. According to test tube studies, glycyrrhizin
has anti-inflammatory actions and may inhibit the
breakdown of the cortisol produced by the body. Licorice
may also have antiviral properties, although this has
not been proven in human pharmacological studies.
Licorice flavonoids, as well as the closely related
chalcones, help heal digestive tract cells. They are
also potent antioxidants and work to protect liver
cells. In test tubes, the flavonoids have been shown to
kill Helicobacter pylori, the bacteria that
causes most ulcers and stomach inflammation. However, it
is unclear whether this action applies to the use of
oral licorice for the treatment of ulcers in
humans.
An
extract of licorice, called liquiritin, has been used as
a treatment for melasma, a pigmentation disorder of the
skin. In a preliminary trial, topical application of
liquiritin cream twice daily for four weeks led to a 70%
improvement, compared to only 20% improvement in the
placebo group.
A
preliminary trial found that while the acid-blocking
drug cimetidine (Tagamet®) led to quicker symptom
relief, chewable deglycyrrhizinated licorice (DGL)
tablets were just as effective at healing and
maintaining the healing of stomach ulcers. Chewable DGL
may also be helpful in treating ulcers of the duodenum,
the first part of the small intestine. Capsules of DGL
may not work for ulcers, however, as DGL must mix with
saliva to be activated. One preliminary human trial has
found DGL used as a mouthwash was effective in
quickening the healing of canker sores.
How much is
usually taken?
There
are two types of licorice, “standard” licorice and
“de-glycyrrhizinated” licorice (DGL). Each type is
suitable for different conditions. The standard licorice
containing glycyrrhizin should be used for respiratory
infections, chronic fatigue syndrome or herpes
(topical). Licorice root in capsules, 5–6 grams per day,
can be used. Concentrated extracts, 250–500 mg three
times per day, are another option. Alternatively, a tea
can be made by boiling 1/2 ounce (14 grams) of root in 1
pint (500 ml) of water for fifteen minutes, then
drinking two to three cups (500–750 ml) per day.
Long-term internal use (more than two to three weeks) of
high amounts (over 10 grams per day) of
glycyrrhizin-containing products should be attempted
only under the supervision of a doctor. Licorice creams
or gels can be applied directly to herpes sores three to
four times per day.
DGL
is prepared without the glycyrrhizin in order to
circumvent potential safety problems (see below), and is
used for conditions of the digestive tract, such as
ulcers For best
results, one 200–300 mg tablet is chewed three times per
day before meals and before bed. For canker sores, 200
mg of DGL powder can be mixed with 200 ml warm water,
swished in the mouth for three minutes, and then
expelled. This may be repeated three or four times per
day.
