Harakeke: a strong digestive medicine

Harakeke (Phormium tenax) sometimes known as New Zealand flax, is a common native plant of Aotearoa New Zealand. It is also cultivated as an ornamental and landscape plant in other parts of the world. Harakeke has a related cousin wharariki (Phormium cookianum) or mountain flax, and several hybrids and cultivars have been bred.

Harakeke is a prized plant in Māori culture and used for a multitude of purposes, particularly to produce fibre for clothing and woven garments such as mats and kete. It also has medicinal properties.

Medicinal Uses

While the nectar from harakeke flowers can be used as a sweetener, and the bitter gel has topical applications, the rhizome and root were mainly used.

Relatively little is known about the phytochemistry of harakeke, although the roots contain anthraquinone glycosides, which are key to its medicinal properties. These include chrysophanol, emodin, dianellidin and stypandrone. It also contains tannins.¹

Use for gastrointestinal conditions:

Harakeke rhizome and root was a popular remedy for constipation in the 19^th century, with many accounts of its use as a purgative appearing in early literature. The red, and probably the anthraquinone-rich portion of the rhizome rather than the more fibrous part of the root, was boiled and the resulting ‘flax water’ was drunk. It has an unpleasant and bitter taste, and was therefore often mixed with sugar.^1,2

Other traditional uses of harakeke root preparations include flatulence, stomach trouble and worms. A decoction of the root was mixed with kōhia (Passiflora tetrandra) fruit or New Zealand passionfruit for flatulence. Several early British explorers reported anthelmintic effects from root decoctions.¹ While drugs are now normally used to treat gut parasites, harakeke combines well with wormwood, tansy and black walnut if it is to be used for this purpose. Research by the New Zealand government research agency AgResearch used chopped harakeke leaves as a cereal feed supplement in heifer calves with high counts of faecal nematode eggs. The results found no effect on these following 10 days of supplementation.³

Somewhat paradoxically, reports also exist of small amounts of the harakeke root or gum being useful for the treatment of dysentery and diarrhoea. There are many other native plants that are more specific for the management of these conditions. But the astringency of the tannins, and antimicrobial actions shown by many plant parts of harakeke, are likely to be contributory to these actions.

Dosage and safety

As with all anthraquinone-containing laxatives, it is important to start with a low dosage when prescribing harakeke. It’s best to anticipate the delayed onset of its action, which is a feature of such remedies. The laxative action, which can be quite sudden and violent, generally appears around 6 to 12 hours after ingestion. Also as is the case with other anthraquinone-containing stimulant laxatives, harakeke can cause griping pains. The risk of pain occurring after consumption is reduced by combining it with carminatives such as aniseed, fennel or peppermint. Also, by adding in a great digestive herb like kawakawa. Other herb combinations include totara, rata, mānuka or tautauā and peach bark.

Finally, long-term use of harakeke root is probably best avoided, due to the possibility of laxative dependency or other unknown effects. Harakeke is best avoided in pregnancy due to potential abortifacient effects. Caution should also be taken in patients with conditions such as inflammatory bowel disease or ulcerative colitis, as well as undiagnosed obstructive bowel conditions.

References:

1. Brooker SG, Cambie RC, Cooper RC. New Zealand Medicinal Plants. 3^rd edition, 1987. Heinemann Publishers, Auckland. ISBN 0 86863 1264.
2. Riley M., “Maori Healing and Herbal: New Zealand Ethnobotanical Sourcebook”, Viking Sevenseas, Paraparaumu, N.Z., 1994.
3. Litherland A, Deighton D, Leathwick D. An evaluation of anthelmintic properties, assessed using faecal nematode egg counts, of New Zealand native flax (Phormium tenax). N Z Vet J. 2008;56(6):339-342.Semwal RB, Semwal DK, Combrinck S, Viljoen A.