Kola nut

Synopsis

Kola Nut (Cola nitida and Cola acuminata)

1. Identity: Botanical Classification, Source, and Common Forms

Botanical and Chemical Names

Kola nut is a caffeine-containing nut of evergreen trees of the genus Cola, primarily the species Cola acuminata and Cola nitida. The kola nut, or bitter cola, (Cola vera, Cola acuminata, Cola nitida) is a seed part from a tree of the Sterculiaceae family. The genus Cola encompasses a large number of tropical tree species. Kola nut belongs to the plant family Sterculiaceae, having about 125 species of trees native to the tropical rainforests of Africa. The two commercially and medicinally significant species, Cola acuminata and Cola nitida, are closely related but show some variation in chemical composition and traditional applications.

Common names and synonyms for kola nut include: Arbre à Cola, Bissey Nut, Bissy Nut, Cola acuminata, Cola nitida, Guru Nut, Gworo, Kolatier, Noix de Cola, Noix de Gourou, Noix de Kola, Soudan Coffee, Sterculia acuminata, Sterculia nitida. In Jamaica and the broader Caribbean, the nut is widely known as "bissy." The term "bichy" or "bissy" is derived from the Akan (from present-day Ghana) term for kola nut; it is the local name for kola nuts in Jamaica, and bissy tea is still drunk in the Caribbean.

It is important to note that C. acuminata should not be confused with Garcinia kola (Clusiaceae family), a distinct species also sometimes called "bitter kola," with a different phytochemical profile and different pharmacological activity.

Botanical Description

Cola acuminata is an evergreen tree about 20 meters in height, with long, ovoid leaves pointed at both ends with a leathery texture. The trees have cream-white flowers with purplish-brown striations, and star-shaped fruit consisting of usually five follicles. Inside each follicle, about a dozen prismatic seeds develop in a white seed-shell. The nut has a reddish or white color flesh on the inside, and has a sweet and rose-like aroma.

The trees are native to Central and Western Africa, but are now found in the West Indies and Brazil, where they were introduced by African slaves. Originally a tree of the tropical rainforest, it needs a hot humid climate, but can withstand a dry season on sites with a high ground water level.

Common Forms and Preparations

All three species are used as a stimulant and are prepared in the same manner. The fresh seed (cotyledon) is the part consumed. The star-shaped fruits contain follicles that hold the bean-like seeds, the cotyledon of which is the sweet-smelling, bitter, brown kola nut. After drying, the nut is milder and aromatic.

Forms of preparation include:

Fresh whole nut (chewing): In African countries, people chew kola nuts because of their high caffeine content, which can increase energy to provide a boost during the workday. People also chew kola while socializing.
Dried powdered cotyledon: Used in capsule form or decoctions. The German Commission E Expanded Monograph specifies a dose of 2–6 g/day of powdered cotyledon; 1–3 grams of dried powdered cotyledon two to three times daily; or 1–3 grams in 150 mL water two to three times daily as a decoction.
Tincture and fluid extract: A fluidextract at 2.5–7.5 mL, a tincture at 10–30 mL, and a cola wine at 60–180 mL are among the preparations listed.
Dry extract: A dry extract at 0.25–0.75 grams is also referenced.
Infusion (tea): In herbal medicine, the nut is usually soaked in alcohol to make tinctures, may be taken as tea although bitter, and the powder can be taken as a capsule.
Food-grade extract: Kola nut extract is used in the food industry as a flavoring ingredient.

Herbal medicinal preparations of kola nut extract are typically standardized for methylxanthine (e.g., caffeine and theobromine) content, usually 1.5–2.5%.

2. Traditional and Historical Use

Origins and Cultural Significance in West Africa

The origins of the kola nut, like other caffeine-containing plants, are also ancient; with evidence of it being chewed in many West African cultures, either by individuals, in social settings, or at significant life events like weddings, naming ceremonies, and funerals. Kola nuts are an important part of the traditional spiritual practice, culture, and religion in West Africa, particularly Ghana, Niger, Nigeria, Sierra Leone, Democratic Republic of Congo, and Liberia.

The kola nut is of particular importance in the social life and religious customs of people in the tropics of West Africa. Kola is prized throughout West Africa by the poor and the affluent; by men and women; by Muslims, Christians, and animists.

Used in cultural traditions of the Igbo people, the presentation of kola nuts to guests or in a traditional gathering shows goodwill. It is implemented in Yoruba religion both as an offering to orishas and as an instrument of divination. The Igbo, a tribe in southern Nigeria, consider the kola nut tree to be the first tree (and fruit) on earth.

In Ghana and other African countries, the kola nut is essential in many traditional ceremonies, including marriage rituals, chieftaincy installations, and religious practices. It is often used as an offering to ancestors and deities, representing a link to traditional spirituality.

Trade and Economic History

The nut was a major trade commodity in intra-African trade, being imported from the Ashanti region of Ghana by large caravans heading to further inland markets such as Kano and Bornu where their primary consumers were aristocrats and scholars. It has cultural significance in various West African societies, where it is chewed during social events and traditional practices, and has historically served as a form of currency.

Medicinal Uses in Traditional African Practice

Traditionally, in West African cultures, kola was essential to spiritual rituals, ceremonies, medicinal practices, and everyday life. Traditional medicinal uses include:

Stimulant and anti-fatigue: Kola nuts are commonly chewed by local laborers as a stimulant to diminish sensations of hunger and fatigue.
Digestive aid: The bitter and astringent flavor of kola nut is used as a digestive aid before meals to stimulate gastric juice and bile production.
Cough remedy: In traditional medicine, kola nut and bitter kola are dried, ground, and mixed with honey to make a traditional cough mixture.
Water purification: A French voyager named Chevalier Des Marchais, who traveled to West Africa in the late 1720s, noted that the nut made the "bitterest, our sourest things taste sweet after it." Kola nuts were used to improve the taste of poor-quality drinking water on ships sailing to the Americas, including those used in the transatlantic slave trade.
Uses in the Caribbean and Brazil: In Brazil and the West Indies, the astringent-tasting nuts are used as a botanical drug to combat intoxication, hangover, and diarrhea.

Introduction to Europe and the Pharmaceutical Industry

The nut was introduced to Europe in the mid-16th century by Portuguese traders. Early explorers of West Africa quickly took notice of the region's native kola nut. One Portuguese explorer visiting the region in 1587 observed that many people he had encountered on his travels used the nut to relieve thirst and improve the taste of water.

Pharmaceutical company Wellcome Burroughs & Co. developed a range of products derived from plant-based chemicals, including a kola-nut/coca-leaf stimulant. Their "Forced March Tabloids" contained the "active principles of Kola Nut and Coca Leaves" to "allay hunger and prolong the power of endurance." The product was aimed at explorers, travellers, and the military.

A formulation of kola nuts and coca leaves as a remedy for headache led to the commercial carbonated cola drink, Coca-Cola, in the 1880s. Kola nuts were used as an ingredient within Coca-Cola and Pepsi-Cola in 1886 and 1893, respectively. The cola drink recipe no longer contains kola nut extract; however, kola nut extract continues to be used in the food industry as a flavoring ingredient.

3. Key Constituents and Active Compounds

Methylxanthine Alkaloids

The defining pharmacologically active constituents of kola nut are the methylxanthine alkaloids. Preliminary studies of phytochemicals in kola nut indicate the presence of various constituents: caffeine (2–3.5%), theobromine (1.0–2.5%), theophylline, methylliberine, polyphenols, catechins, and phlobaphens (kola red), among others.

Chemical compounds in the leaves and plant parts of C. acuminata have been identified and include tannoids (catechol and epicatechol), caffeine (1,3,7-trimethylxanthine; up to 3% of dry weight), theobromine, and theophylline. Flavonoids, anthocyanins, and tannins have also been described.

Polyphenols and Catechins

Varieties of kola nuts (Cola nitida alba, Cola nitida rubra A. Chev, and Cola acuminata Schott & Endl), a group of popular Nigerian and West African stimulants, were analyzed for their content of secondary plant metabolites. The three varieties of the kola nuts contained appreciable levels of (+)-catechin (27–37 g/kg), caffeine (18–24 g/kg), (−)-epicatechin (20–21 g/kg), procyanidin B1 (15–19 g/kg), and procyanidin B2 (7–10 g/kg).

Additional Phytochemicals Identified by GC-MS

A total of 78 diverse compounds were identified in kola nut seeds, spanning alkaloids, flavonoids, fatty acids, and carbohydrates. Fifteen bioactive compounds, including scopolin, picropodophyllin, catechin, yohimbine, squalene, campesterin, epicatechin, stigmasterol, p-coumaric acid, quinoline, methyl linoleate, methyl oleate, theobromine, and caffeine, were shortlisted for further study.

The presence of cardiac glycosides has also been suggested. Polyphenols and other compounds with biological activity are present in higher quantities in the seeds than the leaves.

Effect of Processing on Composition

The composition of fresh kola nuts differs from that of processed or dried nuts, and heat treatment may deactivate certain enzymes involved in the release of caffeine.

Amine Content

Three varieties of kola nut, Cola acuminata, C. nitida, and Garcinia cola, were analyzed for their content of primary and secondary amines. Primary and secondary amines were determined by gas chromatography. Dimethylamine, methylamine, ethylamine, and isopentylamine were detected in all kola nut varieties, while pyrrolidine, piperidine, and isobutylamine were detected in one or more varieties. Estimated average total daily intake of aliphatic amines by a typical kola nut chewer varied from 260 to 1040 μg/day for secondary amines and from 2430 to 9710 μg/day for primary amines.

4. Mechanisms of Action

Central Nervous System Stimulation via Adenosine Receptor Antagonism

Caffeine is naturally found in coffee beans, tea leaves, kola nuts, cocoa beans, and guarana berries. Because of its high degree of lipid solubility, caffeine can easily cross the blood–brain barrier and reach the brain where it exerts a variety of behavioral effects, including physical endurance, stimulating wakefulness, decreasing the sensation of fatigue, and enhancing mental alertness and concentration. Caffeine is structurally similar to adenosine and it has the potential to occupy adenosine A1 and A2A receptors. The A1 receptors are located densely in the cerebral cortex and hippocampus. The stimulation of A1 receptors inhibits ACh release from pyramidal hippocampal neurons. Caffeine can enhance ACh release in the hippocampus by its antagonism of A1 receptors, resulting in an improvement of memory and learning skills.

Cardiovascular and Respiratory Stimulation

The most widely used food stimulants are xanthic bases (caffeine in coffee, tea, cocoa, and kola nuts; theophylline in tea; and theobromine in cocoa). Coffee is probably the most popular beverage all over the world. The xanthic bases, especially caffeine, have stimulant effects on the nervous and cardiorespiratory systems.

Phosphodiesterase Inhibition and Catecholamine Release

The methylxanthine alkaloids inhibit cellular phosphodiesterase, causing an increase in cyclic AMP (cAMP), and stimulate the release of catecholamines from the adrenal medulla. These two mechanisms together account for the thermogenic, alertness-promoting, and cardiovascular effects attributed to the methylxanthine fraction of kola nut.

Anticholinesterase Activity

Anticholinesterase activity of aqueous C. acuminata seed extract has been demonstrated in vitro, leading to claims regarding potential protective effects against neurodegenerative disease. Clinical studies are lacking. In laboratory studies, kola nut extracts inhibit enzymes such as acetylcholinesterase and butyrylcholinesterase, which could theoretically slow neuronal degradation.

Antioxidant Activity

Antioxidant capacity of the extracts and purified metabolites of kola nuts was assessed by two HPLC-based and two colorimetric in vitro assays. Extracts of all varieties exhibited antioxidant capacity with IC50 values in the range 1.70–2.83 and 2.74–4.08 mg/mL in the hypoxanthine/xanthine oxidase and 2-deoxyguanosine HPLC-based assays, respectively. Antioxidant activities showed that ethanol extract was the most effective in scavenging nitric oxide and ferric reducing power compared to chloroform and water extracts.

5. Scientific Evidence by Area of Use

Important framing note: Clinical trials are lacking to support use; however, CNS stimulation is evident, likely due to the caffeine content. The following sections distinguish available human/clinical evidence from animal and in vitro studies, and characterize evidence strength honestly.

5.1 CNS Stimulation, Fatigue, and Mental Performance

Limited animal and in vitro studies suggest kola nut extract and caffeine exert similar neurological effects. The CNS stimulant effects of one nut have been reported to be equal to or greater than the effects of the caffeine content of two large cups of coffee.

No dedicated randomized controlled trials (RCTs) using isolated kola nut preparations in humans were identified. The evidence base for cognitive and performance enhancement rests on the well-established pharmacology of caffeine, which constitutes 2–3.5% of the dry nut by weight. Caffeine is the most frequently consumed central nervous stimulant in the world, and its behavioral effects include physical endurance, stimulating wakefulness, decreasing the sensation of fatigue, and enhancing mental alertness and concentration.

Evidence strength: No kola nut–specific human clinical trials identified. Biological plausibility is high via the established pharmacology of caffeine. The stimulant effect is considered established by regulatory and expert bodies as attributable to caffeine content.

5.2 Cardiovascular Effects

Primarily dose-dependent increases in blood pressure were observed in both normotensive and hypertensive rats, with diastolic pressure more sensitive to dose. Researchers also examined effects on isolated rat heart, noting increases in both force of contraction and rate with low doses of kola nut extract, with higher doses resulting in decreases in contraction and rate, until heart failure occurred.

Evidence strength: Animal and in vitro data only. No human cardiovascular trials using kola nut as a test agent were identified.

5.3 Gastrointestinal Effects

Kola may contribute to gastrointestinal health thanks to tannins that are gastroprotective. However, studies have also reported stimulant properties of kola on gastric and salivary secretion. A 1986 study published in the Scandinavian Journal of Gastroenterology Supplement examined the effects of Cola acuminata and Cola nitida on gastric acid secretion, though details of its findings are not fully captured in available secondary sources.

Evidence strength: Extremely limited. The single human gastric secretion study is old and insufficiently detailed in publicly available summaries. The digestive stimulant effect claimed in traditional use (stimulation of gastric juice and bile) has pharmacological plausibility from the bitter taste receptor mechanism and caffeine's known pro-secretory effects, but no modern RCTs exist.

5.4 Diuretic Activity

A 2017 study found that methanolic extract of Cola nitida elicits dose-dependent diuretic, natriuretic, and kaliuretic activities without causing electrolyte impairment, hepatotoxicity, or nephrotoxicity in rats.

Evidence strength: Preclinical (animal) only. No human studies identified.

5.5 Metabolic Rate and Weight Management

Increases in metabolic rate were noted in a rat study examining three species of kola nut, with C. acuminata having the greatest effect. The thermogenic effect is consistent with caffeine's established ability to increase basal metabolic rate, and kola nut extract has historically appeared in weight-loss supplement formulations due to its caffeine content.

Evidence strength: No kola nut–specific human studies on weight management were identified. The metabolic rate effect is attributed to caffeine content, for which there is a broader evidence base, but no dedicated kola nut RCTs exist.

5.6 Antimicrobial Activity

Extracts (chloroform, n-hexane, and ethanol) of the kola nut (Cola acuminata) were analyzed for their phytochemicals, physicochemical properties, antibacterial activity, and antioxidant potential, with the antibacterial efficacy of the extracts being tested. Extracts of the kola nut were effective against pathogens at 50, 100, and 200 mg/mL concentrations.

Evidence strength: In vitro only. No human clinical antimicrobial trials with kola nut have been identified.

5.7 Cognitive Function and Neuroprotection

A narrative review examined the potential benefits of Cola nitida in several areas of health, including its role in cognitive function, cardiovascular health, immune system function, gastrointestinal health, and metabolic and endocrine health. In vitro evidence points to two potential mechanisms: anticholinesterase activity of aqueous C. acuminata seed extract has been demonstrated in vitro, leading to claims regarding potential protective effects against neurodegenerative disease. Furthermore, the caffeine present in the kola nut appears to protect dopamine-related neurons, which could be useful in diseases like Parkinson's.

Evidence strength: Preliminary. All findings are from in vitro or animal experiments. No human trials on kola nut for cognitive or neuroprotective outcomes have been identified.

5.8 Anticancer Potential (Computational/In Silico)

A study explored the anticancer potential of kola nut seeds extract by first identifying its chemical constituents through gas chromatography–mass spectrometry (GC-MS), followed by molecular docking of selected compounds against the cancer-associated target PI3Kα. Molecular docking of 15 kola nut bioactive compounds against PI3Kα revealed that squalene, campesterin, epicatechin, yohimbine, and scopolin exhibited favorable binding energies, engaging key residues. Fatty-acid esters showed moderate binding, while small compounds such as theobromine and caffeine displayed weak interactions.

Evidence strength: Computational (in silico) only. These findings are hypothesis-generating and far from clinical application.

6. Body Systems and Health Areas Associated with Kola Nut

The examined potential benefits of Cola nitida in health encompass cognitive function, cardiovascular health, immune system function, gastrointestinal health, and metabolic and endocrine health. In practice, the substantiated associations, based on evidence available as of August 2025, are confined primarily to:

Central nervous system: Stimulation, alertness, reduced fatigue — attributable to caffeine content, with pharmacological support but no kola-specific RCTs.
Cardiovascular system: Dose-dependent blood pressure effects and cardiac chronotropy in animal models; no human clinical trial data specific to kola nut.
Gastrointestinal system: Traditional use as digestive aid; limited older human data on gastric acid secretion; tannins are gastroprotective in preclinical models.
Metabolic/thermogenic: Metabolic rate increases in animal studies; plausible via caffeine pharmacology.
Renal/diuretic: Dose-dependent diuresis in animal models.

7. Regulatory Status and Dosage

Regulatory Status

Kola nut extract has been approved for use in food by the Council of Europe (CoE), FDA, FEMA, and the IOFI. The CoE has classified kola nut extract as Category 4, defined as plants or animals not normally consumed as food items in Europe that contain defined active principles or other chemical components requiring limits on use levels. The FDA and FEMA have determined kola nut extract to be GRAS for use as a flavoring ingredient. The FDA has also approved kola nut extract for use as an inactive ingredient in certain oral and rectal pharmaceutical preparations. Kola extract is approved by the German Commission E.

Dosage Forms and Reported Dosages

Clinical studies are lacking to provide dosing guidance. The dosages below come from the German Commission E Expanded Monograph as cited in secondary literature:

Powdered cotyledon (internal use): 2–6 g/day total; alternatively 1–3 grams two to three times daily as dried powder.
Decoction: 1–3 grams in 150 mL water, two to three times daily.
Dry extract: 0.25–0.75 grams per dose.
Fluidextract: 2.5–7.5 mL per dose.
Tincture: 10–30 mL per dose; Cola wine: 60–180 mL per dose.

Herbal medicinal preparations of kola nut extract are typically standardized for methylxanthine (caffeine and theobromine) content at 1.5–2.5%.

8. Safety Considerations and Interactions

General Safety and Regulatory Status

Kola nut has US Food and Drug Administration (FDA) generally recognized as safe (GRAS) status; however, information regarding safety and efficacy in pregnancy and lactation is lacking. Case reports and clinical studies are lacking to identify potential adverse reactions.

Although limited biological data are available for kola nut extract specifically, the published data of the major constituents of kola nuts suggest the pharmacological/toxicological properties of kola nut extract parallel those of a roughly equivalent dose of caffeine.

Adverse Effects

Kola nut is contraindicated in gastric and duodenal ulcers. Side effects include sleep disorders, over-excitability, nervous restlessness, and gastric irritation. Its use is restricted in pregnancy and lactation, and in hypertensive and cardiac patients. It is classified as a CNS stimulant and GI irritant.

The side effects of kola nut and kola nut extract parallel the effects of a comparable dose of caffeine.

Pregnancy and Pediatric Use

The American Herbal Products Association includes kola nut on a list of caffeine-containing substances that should not be used by pregnant or breastfeeding women or those under the age of 18.

A preclinical safety signal from animal research warrants note: kola nut administered repeatedly at certain doses to pregnant dams was shown to disrupt normal postnatal cerebellar development in their pups. The findings suggest potential deleterious effects of excessive kola nut consumption on human brain development and warrant further studies to understand the wider implications.

Oral and Gastrointestinal Cancer Risk (Habitual Chewing)

It has been suggested that the high amine content is possibly related to oral and GI cancers observed among habitual chewers of kola nut. This concern derives from the amine analysis by Atawodi et al. (1995), which found nitrosatable secondary and primary amines in kola nut. Dimethylamine, methylamine, ethylamine, and isopentylamine were detected in all kola nut varieties, while pyrrolidine, piperidine, and isobutylamine were detected in one or more varieties. Estimated average total daily intake of aliphatic amines by a typical kola nut chewer varied from 260 to 1040 μg/day for secondary amines and from 2430 to 9710 μg/day for primary amines.

This safety signal is important to distinguish from the extensively studied carcinogenicity of areca nut (Areca catechu), a botanically distinct species. The amine- and nitrosamine-related cancer concern for Cola species remains based on chemical analysis and epidemiological observation in habitual chewers, not on the same scale of prospective or mechanistic human evidence that exists for areca nut.

Drug Interactions

Because the pharmacologically active constituents of kola nut are predominantly caffeine-class methylxanthines, clinically relevant interactions are those established for caffeine:

Caffeine may lower the effects of carbamazepine. Taking cola nut with carbamazepine might increase the risk of seizures in some people.
Caffeine in cola nut can decrease the effects of ethosuximide, and taking cola nut with ethosuximide might decrease the effects of ethosuximide and increase the risk of seizures in some people.
Caffeine in cola nut might decrease the effects of felbamate, and taking cola nut with felbamate might decrease the effects of felbamate and increase the risk of seizures in some people.
Caffeine might increase the amount of pioglitazone that the body absorbs. Taking caffeine might increase the effects and adverse effects of pioglitazone.
Kola nut has a strengthening action on psycho-analeptic drugs and caffeine-containing beverages.

A number of drugs, including certain selective serotonin reuptake inhibitors (particularly fluvoxamine), antiarrhythmics (mexiletine), antipsychotics (clozapine), psoralens, idrocilamide and phenylpropanolamine, bronchodilators (furafylline and theophylline), and quinolones (enoxacin), have been reported to be potent inhibitors of the CYP1A2 isoenzyme. Drugs metabolized by, or bound to, the same CYP enzyme have a high potential for pharmacokinetic interactions due to inhibition of drug metabolism. Thus, pharmacokinetic interactions at the CYP1A2 enzyme level may cause toxic effects during concomitant administration of caffeine and certain drugs used for cardiovascular, CNS, gastrointestinal, infectious, respiratory, and skin disorders.

Labeling Requirements

The American Herbal Products Association (AHPA) requires caffeine warning labels on products containing more than 5 milligrams of caffeine per serving. Kola fruit, coffee, tea, guarana fruit, yerba mate leaf, and cacao seed require a caffeine label. Only the AHPA follows these labeling guidelines.

No-Observed-Effect Level

A NOEL/NOAEL cannot be defined for repeated oral exposure to kola nut extract from available data.