In continuation of information sharing about Khat, the following paragraphs focus on cultivation, mode of consumption  and the global levels of demand for this plant substance of abuse. As always your feedback and comments are most welcomed.

Where is Khat cultivated?

The Catha edulis plant, or Khat is a member of the Celastraceae, which includes about 350 species of trees and shrubs in 15 genera, and grows wild, but often cultivated, in the east of a region extending from Yemen in the Arabian Peninsula to much of eastern and southern Africa. It also grows in Uganda, Tanzania, and Madagascar. In central Asia the plant largely grows in the wild and its distribution extends as far as Afghanistan and Turkistan. It grows at an altitude of 1670-2600 meters adapting to a range of soil and climatic conditions. Khat tree is hardly ever affected by diseases, takes two years to be ready for harvest and can live up to 75-100 years (Kennedy et al., 1983). Figure 1 shows a map of  the geographical area of the Khat-belt countries from Yemen across the Red Sea to eastern Africa. In Kenya it grows well on fairly moist slopes of between 1220-2750 meters on Nyambene Hills, in the northeast of Mount Kenya (Carrier, 2005). In Ethiopia it is farmed in almost every region, although traditionally cultivation was confined to Harerghe area in eastern Ethiopia (Lamessa, 2001) and on either semi-humid lowlands or lower highland forests 1400-2000 meters above sea level. In Yemen it is cultivated all over the country in mountainous and flat lands but not in coastal area with hot climate (Al-Motarreb et al., 2002). Although several varieties are cultivated within each of the khat-belt countries, the varieties grown in different cultivation areas with different climate conditions differ in appearance; in the colour of the leaves and twigs that is either red or green; in the length of the twig (Geisshusler and Brenneisen, 1987a) and in the size of the leaves as well as in taste (Al-Motarreb et al., 2002).

Figure 1

Figure 2

The Kenyan type, the Mira (Figure 2) appears to be generally shorter with slender and softer twigs. The leaves are also smaller and softer than the Herari type (Figure 3), from Ethiopia, which often has a bigger twig size and larger, slightly leathery, leaves.

Figure 3

Khat is harvested in the same way regardless of type or growing location. During harvesting only young shoots (stems and leaves) are picked then bundled together (200-300 grams equivalent to 20-30 stems) and wrapped in green, dry banana leaves. This is done in order to preserve freshness while the plant is en route to the market destination. 

How is Khat used?

The commonest mode of administration is by chewing the plant through mastication, with some buccolingual absorption of active material. However, in countries where Khat is illegal, e.g. USA a dried or a freeze-dried form of the plant known otherwise as garaabo is used. Garaabo is boiled and the resulting infusion is used as a tea. Flowers are also used among Khat users to prepare a tea with stimulating properties (Krizevski et al., 2007). Khat chewing involves picking leaves (one by one) from each twig and chewing them thoroughly, while the juice extracted is swallowed. Altogether, each person takes some 200 to 400g of the leaves; with young leaves being most favoured, mainly because they are more potent, but also because they are tenderer to chew. When chewing, the macerated quid material is pushed back and kept in the cheek as a bolus that is later spat out. During the session, the group may smoke from water pipes or smoke cigarettes and there is usually a generous supply of beverages. The gathering context, place and the time for the actual slow consumption by chewing is known as a Khat session and can last between 3-24 hours. Drinking hot tea or soft drinks, all belong to the complex ritual of a Khat chewing setting (Nencini et al.,1986). Another feature of this ritual that is common involves the shutting of all windows to exclude draughts and increase temperature in the room where Khat is being chewed, in order to speed up optimum stimulant effect. Furthermore, as the plant is used in its natural form without processing, it is almost exclusively required to be used fresh for an optimum stimulating effect. It is usually not considered acceptable if harvested more than 3 days before use because the leaves and soft shoots, which are the parts used, lose their potency. For these reasons Khat consumption in the past was limited to areas close to where it's grown. Hence when it was not available beyond the geographical cultivation areas, its use was unknown in the global markets. It was only since late 1980s and with the advent of rapid air transport coupled with network of distribution facilities that fresh Khat became available in distant places such Europe and North America (Kalix, 1991). 

What is the level of global consumption?

It is estimated that over 20 million people (Saha and Dollery, 2006) chew Khat in the world today, while its consumption is not only increasing but also rapidly spreading (Kalix, 1992) across continents to Europe (Nencini and Ahmed, 1989), Australia (Jager and Sireling, 1994), USA and Canada. Following the migration in the last two decades of communities originating from war-torn areas of the Horn of Africa, Khat has become a widely available commodity in the West. Levels of Khat use in cultivating countries are said to be comparable. In Somalia a large survey found 31% of respondents admitting current use, in Ethiopia this was 50%, and in Yemen 82% of men and 43% of women (ACMD report 2005). However there are variations in cultural attitudes towards usage, even among the two major Khat consumer societies; the Somalis and the Yemenis, where Khat use is culturally sanctioned and common practice. Nonetheless use has been evolving along with the dynamics in societal psychosocial changes. For the Yemenis, Khat consumption is a deeply rooted tradition. A recent large survey of 2500 people estimated current adult users in Yemen at 61.1% of total population (Ali et al.,2004). In comparison, for Somalis, habitual Khat use is fairly new and has only been developed as rapid cultural phenomena, growing out of urban communities in the 1970s, and later, as a result of the civil war of the 1990s, spiraled into deviant patterns of misuse.

Reference list

ACMD (Advisory Council on the Misuse of Drugs): Report on Khat (Qat): Assessment of Risk to the Individual and Communities in the UK. Home Office Publications 2005

Ali AA, Al-Sharabi AK, Aguirre JM, Nahas R (2004) A study of 342 oral keratotic white lesions induced by qat chewing among 2500 Yemeni. Journal of Oral Pathology and Medicine 33: 368-372

Al-Motarreb A, Baker K, Broadley KJ (2002) Khat: pharmacological and medical aspects and its social use in Yemen. Phytother Res 16: 403-413

Geisshusler S, Brenneisen R (1987a) The content of psychoactive phenylpropyl and phenylpentenyl khatamines in Catha edulis Forsk. of different origin. J Ethnopharmacol 19: 269-277

Jager AD, Sireling L (1994) Natural history of khat psychosis. Australian and New Zealand Journal of Psychiatry 28: 331-332

Kennedy JG, Teague J, Rokaw W, Cooney E (1983) A medical evaluation of the use of qat in North Yemen. Social Science and Medicine 17: 783-793

Kalix P (1991) The pharmacology of psychoactive alkaloids from ephedra and catha. J Ethnopharmacol 32: 201-208

Kalix P (1992) Chewing khat, an old drug habit that is new in Europe. International Journal of Risk and Safety in Medicine 3: 143-156

Krizevski R, Dudai N, Bar E, Lewinsohn E (2007) Developmental patterns of phenylpropylamino alkaloids accumulation in khat (Catha edulis, Forsk.). Journal of Ethnopharmacology 114: 432-438

Lamessa D: Khat (Catha edulis) Botany, Distribution, Cultivation, Usage and Economics in Ethiopia, Addis Ababa 2001.

Nencini P, Ahmed AM, Elmi AS (1986) Subjective effects of Khat chewing in humans. Drug and Alcohol Dependence 18: 97-105

Nencini P, Ahmed AM (1989) Khat consumption: A pharmacological review. Drug and Alcohol Dependence 23: 19-29

Saha S, Dollery C (2006) Severe ischaemic cardiomyopathy associated with khat chewing. J R Soc Med 99: 316-318