The two original kinds of senna (Cassia senna and Cassia angustifolia) used to make remedies are now mass-cultivated for medicinal purposes – primarily for their laxative properties. Some senna-based medicinals have a long tradition in Northern Africa, where only Cassia senna used to be cultivated. The leaves of the plant were usually shipped from the port of Alexandria on the Nile delta to places all over the world. At the time, this medicinal was referred to as “Egyptian senna”. The fruits were mostly collected from Cassia angustifolia, which was cultivated in the south of India and mainly traded in the city of Tinnevelly (present-day Tirunelveli). This is why it was also called “Tinnevelly senna”.
Today, the leaves and fruits from both Cassia senna and Cassia angustifolia are used and the two varieties are grown in various tropical and subtropical regions. Dried senna leaves and fruits are drunk in tea or consumed in products containing a standard-regulated senna extract that can help relieve constipation.
Where does senna grow and what does it look like?
Senna plants belong to the legume family (Caesalpiniaceae). Senna has a long tradition as a medicinal plant. Even the prophet Mohammed is said to have mentioned its healing effect. Paracelsus recommended senna as a laxative in combination with leek and wormwood. The senna plant is commonly found in hot and dry regions of Africa and Asia. Its stem grows to a height of one to two metres and it has pinnate leaves and yellow flowers. The fruits grow in husks that are around five centimetres in length.
What does senna contain and what are its effects?
The dried leaves and dried fruits are used for the medicinal substances they contain. Both have similar effects, but the fruits are considered to have a milder effect. The active ingredients are anthranoids (which are also called anthraquinones). These are classified as sennosides A to F. Standard-regulated extracts taken from the leaves or fruits are usually measured for a specific quantity of sennoside B. The two drugs also contain mucilage, flavonoids and a small amount of essential oil.
Sennosides are what are referred to as “pro-drugs”, meaning that they only become effective once they are converted to anthrones in the colon. Sennosides and anthrones are not absorbed into the bloodstream and only release their effect in the colon. Anthrones inhibit water absorption from the intestinal contents and stimulate movement of the bowel muscles (peristalsis), making the stool softer and more voluminous and speeding up passage through the colon.
Medical uses for senna
The leaves and fruits of the senna shrub can be brewed into a drinkable tea. They are often among the ingredients in laxative tea blends. Various shop-bought medicinals contain extracts from the senna fruits and leaves in standard dosages. Any preparation should only be taken for a short period of time unless instructed otherwise by a doctor – for example, to treat cases of acute constipation or when the stool needs to be softened due to rectal problems, such as haemorrhoids or anal tearing.
People experiencing prolonged episodes of constipation may find lifestyle changes more effective than taking laxatives: drinking plenty of water, exercising regularly and eating a diet rich in fibre can help stimulate digestion.