Bitter kola

Bitter kola is an evergreen tree of the humid forests of West and Central Africa, producing smooth, orange to reddish, round fruits about the size of a small orange. Inside the pulp are several seeds, often fused together, with a hard, yellowish-brown, lobed shape.

The seed is hard and fibrous, with a bitter, astringent and slightly resinous flavour, followed by a mild sweetness and a cooling, lingering aftertaste, quite different from true kola nuts.

It is sold fresh or dried in African markets, chopped or split into pieces, and increasingly as powder, extract or capsules in the supplement trade.

Garcinia kola is native to the tropical forests of West and Central Africa, from Sierra Leone through Nigeria and Cameroon to Gabon and the Democratic Republic of Congo. It is often found near villages, where it has been protected or planted.

Bitter kola is usually described as a semi-cultivated tree. Wild populations are under pressure from habitat loss, and efforts to cultivate it have increased.

Names in Nigerian languages are widespread, and the common name bitter kola reflects both its taste and a superficial use similar to that of the unrelated kola nut, Cola nitida, which contains caffeine.

In Nigeria and neighbouring countries, bitter kola seeds are an important social food. They are presented to guests, shared at naming ceremonies, weddings and funerals, and used in prayers and oaths among several peoples, often alongside kola nuts.

Traditional healers have used the seeds, bark, roots and sap for coughs, throat complaints, stomach disorders and as chew sticks for teeth. It is commonly said in West Africa that bitter kola prolongs life and clears the voice, and singers and public speakers chew it before performing.

Trade in the seeds links forest producers with city markets across West and Central Africa, and it is a source of income for rural women.

In recent decades, scientists have studied its biflavonoids, such as kolaviron, with laboratory work on antioxidant, anti-inflammatory and antimicrobial effects, and the seed has attracted commercial interest in the herbal supplement market.

Bitter kola is chewed as a snack or offered to guests, usually a piece at a time. It is also used as a traditional remedy for cough, hoarseness, fever and stomach upset and sometimes added to herbal infusions or local alcoholic drinks.

The seed extract is used in food flavouring and in supplements marketed for wellness. Twigs have long been used as chewing sticks for oral hygiene.

The wood, bark and latex have local uses in carpentry and medicine. The tree also serves as shade in cocoa and farm systems.

Laboratory and animal studies have identified biflavonoids and other compounds in bitter kola with antioxidant, anti-inflammatory and antimicrobial activity, and the plant has been the subject of many research papers in West Africa. High-quality human trials are very scarce.

Reports that it treats infections, cancer, diabetes or viral diseases are not supported by solid clinical evidence. It is best viewed as a traditional food and social nut.