What is actually being researched now, how Nigeria regulates traditional medicine and where the regulation stops, who owns knowledge that becomes a drug, and the contamination data that make the contemporary trade a public health problem in its own right.
Yoruba medicine is not a survival. It is a large, active, commercial sector with contemporary products, contemporary advertising, contemporary regulation and contemporary failures. A herbal preparation bought in a Lagos market today is likelier to come in a branded plastic bottle with a NAFDAC number on it than in a calabash, and it may contain lead. This file is about that sector, and about the three questions that decide its future: whether the pharmacopoeia yields drugs, who owns the knowledge if it does, and whether the products people are currently swallowing are safe.
The last question has the clearest answer, and it is the worst one. Confidence on this file is high because the safety and regulatory claims rest on published measurement and on published policy documents.
Ethnobotanical documentation is the strongest and most active part of the literature. Surveys record what practitioners use, for what, in what preparation, with voucher specimens and species identification in the better work, and inventories now cover the southwestern states in some depth . This documentation is urgent for a reason that has nothing to do with drug discovery: the transmission chain is thinning as practitioners age, forest habitat is lost, and apprentices go to school instead. Knowledge that is not written down in the next generation will not exist.
Pharmacological screening is active but lopsided, and the shape of the lopsidedness is set by funding. It concentrates on malaria, is dominated by in vitro and rodent work, rarely reaches clinical trial, and uses non-standardised extracts that make results incomparable across studies. Toxicology is under-investigated relative to activity, which is the wrong way round for substances people are already consuming in quantity. File 03 sets out what has and has not been established plant by plant.
Clinical and health systems research is where the real results are. This is worth stating plainly because it cuts against the expectation that the interesting work is in the laboratory. The two strongest pieces of evidence produced anywhere in this field in the last decade are both health systems trials rather than pharmacology: the COSIMPO trial showing that collaborative care between traditional and faith healers and primary health workers improves psychosis outcomes, with an adjusted mean PANSS difference of -15.01 ; and the Ondo Agbebiye programme evaluation showing a 61.8 percent increase in facility births after traditional birth attendants were incorporated into the maternal health system . Neither required isolating a compound. Both changed outcomes at scale.
What is missing. The intermediate layer: standardised preparations, dose-response characterisation, interaction studies with the pharmaceuticals patients take concurrently, and clinical evaluation of the actual traditional preparations rather than of solvent extracts of single plants. Until that exists, the honest position on most Yoruba herbal medicine is that a sophisticated knowledge system has identified plants with real pharmacological activity, and that whether the medicines as actually prepared and administered work in humans is open rather than answered.
The precedent is genuine. Quinine from Cinchona and artemisinin from Artemisia annua both came out of traditional medical traditions, and artemisinin is described in the review literature as the most noteworthy achievement of twentieth-century ethnopharmacological research . Reserpine, from Rauvolfia, a genus with Yoruba medicinal use, entered world medicine as an antihypertensive and early antipsychotic . The proposition that ethnobotany can yield drugs is established, not speculative.
The pipeline reality is harsher. Ethnopharmacology has been an active field for decades and the number of new drugs it has delivered is small. The attrition points are ordinary drug development attrition points: activity in vitro does not survive to animals, activity in animals does not survive to humans, the active compound is too toxic or too poorly absorbed, or the effect size is real but too small to matter. None of that is specific to African plants.
Two structural problems are specific to this setting. Nigerian pharmacology is under-resourced relative to the size of the pharmacopoeia, so most of the screening that gets done is done by whoever has the equipment, which is frequently not in Nigeria. And extracts vary so much between studies that positive results cannot be replicated even in principle, because the second team is not testing the same material.
NAFDAC is the principal regulator: the National Agency for Food and Drug Administration and Control regulates herbal medicinal products, tests ethnomedicinal preparations, and operates a registration regime . NAFDAC has published guidelines for the registration of herbal medicines and dietary supplements made in Nigeria, and issued Herbal and Fruit Infusion Regulations in 2024 covering infusions other than those for medicinal purposes . Full registration of a herbal product is granted only after the product has shown satisfactory efficacy and a convincing safety profile .
Two further bodies exist. A Department of Traditional Medicine has been established within the Federal Ministry of Health to conduct research into traditional medicines, and a Council for Traditional, Alternative and Complementary Medicine Practice has been approved, though the operational detail is thin .
The decisive gap is practitioner licensing. The 2024 review in African Health Sciences states the position directly: there is no national agency responsible for licensing practitioners of traditional medicine . Products are regulated; the people are not. A practitioner may treat anyone for anything with no licence, no accreditation, no scope-of-practice limit, no complaints mechanism and no means of being struck off. Everything in file 02 about verification resting on reputation and lineage remains true because nothing has replaced it.
Education is the second gap. Institutionalised training in complementary and alternative medicine is essentially absent in Nigeria, with most herbal medicine teaching confined to pharmacology departments, and the knowledge otherwise passed orally without formal documentation . The review proposes a six-year Doctor of Traditional African Medicine degree with six months of hospital training, plus shorter diploma and certificate routes, together with a dedicated licensing agency, a government portal for regulations, standardised product testing, expanded university programmes and government-funded training for existing rural practitioners .
How much of this reaches the actual market is the open question. A registration regime constrains the manufacturer who seeks registration. It does not touch the market herb stall, the itinerant vendor, the radio-advertised preparation sold from a car boot, or the practitioner compounding for a patient in front of him, and that is where most of the trade happens.
This is the part of the file with the hardest numbers and it should not be softened.
Heavy metals, the national picture. The study by Obi, Akunyili, Ekpo and Orisakwe, published in Science of the Total Environment in 2006, characterised cadmium, copper, iron, nickel, selenium, zinc, lead and mercury in a random sample of Nigerian traditional products purchased on the open market, digested and measured by atomic absorption spectrometry . The result: 100 percent of samples contained elevated amounts of heavy metals, with levels of iron, nickel, cadmium, copper, lead, selenium and zinc sufficient to cause adverse health effects when taken regularly as recommended .
That study deserves attention for an additional reason. Dora Akunyili, one of its authors, was at the time Director-General of NAFDAC, the regulator itself. This is the regulator's own leadership publishing a finding of universal contamination in the sector it regulates.
Heavy metals in a Yoruba market specifically. Ten commonly consumed herbal plants sold in Ado Ekiti urban market were analysed with a full health risk assessment . Estimated daily intakes for lead, nickel, chromium, copper and manganese were above the upper tolerable daily intake reference for all studied species, in both children and adults . Health risk indices for lead exceeded 1 in children for Alstonia congensis, Terminalia avicennioides, Aframomum melegueta, Cymbopogon citratus and Napoleona vogelii, with copper and manganese also unusually high; the risk index order was Mn > Cu > Ni > Pb > Cr, and cadmium was not detected in any sample . Estimated cancer risk for lead, nickel and chromium ranged from 10⁻⁶, low, to 10⁻³, high, in children, and from 10⁻⁵, acceptable, to 10⁻², unacceptable, in adults . The authors conclude that consumption of these plants poses a long-term cancer risk .
Note that two of those plants, Aframomum melegueta and Cymbopogon citratus, appear in the pharmacopoeia table in file 03 as plants with documented traditional use and laboratory-demonstrated activity. The same plant can be both pharmacologically interesting and, as actually sold, a lead exposure. These are not competing facts about the tradition; they are facts about different things, the plant and the product.
Guideline violations. A separate study reported percentage violations of WHO and EU limits across six metals in Nigerian herbal remedies: arsenic 0 percent, cadmium 58.3 percent, chromium 4.16 percent, cobalt 0 percent, lead 54.1 percent and nickel 54.1 percent, with the highest concentrations in solid dosage forms and the lowest in liquid preparations .
Microbial contamination. Organisms isolated from herbal remedies include Escherichia, Salmonella, Pseudomonas, Streptococcus, Staphylococcus, Klebsiella, Bacillus and Enterococcus species along with various fungi . Fungal contamination carries the additional aflatoxin risk in material dried and stored in humid conditions.
Where the contamination comes from. Uptake from contaminated soil, roadside drying, contamination during grinding and processing, contact with metal implements and containers, adulteration, and in some cases deliberate addition. The mechanisms are mundane and each is addressable by ordinary manufacturing controls.
Adulteration with pharmaceuticals is a documented problem in herbal products globally, with corticosteroids, NSAIDs and antidiabetics the usual additions, since these produce the rapid symptomatic effect that sells the product. This compiler did not locate a Nigeria-specific prevalence figure and does not supply one.
The honest summary. The contamination evidence is not a marginal quality issue. It indicates that a substantial proportion of the herbal products sold in Nigeria carry a measurable toxic exposure on top of whatever the plant does, and that the exposure is largest in exactly the products a patient takes daily over long periods. This is a public health problem independent of whether the traditional indications are correct, and it would remain a problem even if every plant in the pharmacopoeia worked perfectly.
The question is real and it has a legal answer that does not resolve it.
The framework. The Nagoya Protocol to the Convention on Biological Diversity entered into force on 12 October 2014 and establishes an international legally binding framework for access to genetic resources and the fair and equitable sharing of the benefits arising from their use . It gives each country sovereign rights over its biological resources, which is what makes biopiracy illegal as a matter of international law, and it covers traditional knowledge associated with genetic resources and the benefits from using it .
The scenario it addresses. A researcher records that a Yoruba herbalist uses a particular plant for a particular condition; a compound is isolated; a patent is filed; a drug is sold. The traditional knowledge was indispensable, since without it nobody would have screened that plant out of tens of thousands of candidates, and under the pre-Nagoya regime the community that held the knowledge received nothing. Scholars have argued specifically for stronger protection of Nigerian traditional medicine on these grounds .
Why the framework does not settle it. Four difficulties, and they are practical rather than theoretical.
Who is the holder? Nagoya contemplates benefit sharing with indigenous and local communities. Yoruba plant knowledge is held by practitioners across two countries and a diaspora, is transmitted through lineages rather than through corporate bodies, and has no representative institution that could receive a payment or give consent on anyone's behalf.
Prior publication. Verger's Ewé and hundreds of ethnobotanical surveys have placed much of the pharmacopoeia in the public domain. Published knowledge is generally unpatentable as such, which cuts both ways: it blocks the crudest appropriation, and it also removes the leverage a community would need to negotiate.
Enforcement. Nagoya obliges parties, and the value is captured in the jurisdictions where drugs are developed and sold. Nigeria's practical capacity to detect and pursue a violation is limited.
The counterproductive equilibrium. Practitioners aware of appropriation risk become less willing to disclose to researchers, which slows the documentation that file 03 identifies as urgent. Restriction protects against a rare, high-value harm at the cost of a common, ongoing one, and the balance is genuinely difficult.
The framing that survives scrutiny. The stronger recent argument in this literature is that the biopiracy frame is itself a colonial relic, and that what is needed is collaborative concepts in which African institutions are principals in the research rather than sources of material for it . That reframing is not a legal solution and it points at the right thing: the durable answer to appropriation is African-led pharmacology with African institutional ownership of the results, not tighter restrictions on what can leave.
Three cases in this section have moved measurable outcomes, and they share a structure worth naming.
The Ondo Agbebiye programme raised facility deliveries by 61.8 percent over three years by registering traditional birth attendants and paying them to refer, rather than by training them to deliver better . The COSIMPO trial improved psychosis symptoms substantially by having healers and primary care workers deliver a shared protocol together . The bone-setting literature has converged on training and integration rather than prohibition, on the arithmetic that traditional bone-setters treat most of Nigeria's fractures and cannot be replaced .
The common structure: none of these attempts to validate or to eliminate traditional practice. Each treats the traditional practitioner as an existing part of the health system, because he is, and works on the interface. That is the approach with evidence behind it.
The trade will grow, because the biomedical system's capacity is not growing fast enough and because the herbal product market is commercially attractive.
The contamination problem will not solve itself. It requires manufacturing standards and enforcement reaching the informal trade, which is where the products are.
Documentation is a closing window. Practitioners are ageing, habitat is being lost and apprenticeship is competing with schooling.
The drug discovery yield will probably be modest, as it has been from every other traditional pharmacopoeia, and this should be said in advance so that a modest yield is not later read as a verdict on the tradition. The knowledge system's value does not depend on producing a blockbuster.
The health systems results are the ones to watch. They are where the evidence is strongest, the effects largest and the implementation cheapest.
Who actually practises Yoruba medicine, how the specialisms divide, how a practitioner is trained and how long it takes, and how expertise is checked among practitioners themselves rather than by any outside body.
The traditional bone-setter's method, what the published outcome studies actually show about which injuries he treats well and which he maims, why patients keep going to him anyway, and the current argument about training rather than banning him.
Yoruba categories for mental disturbance, what traditional treatment consists of including the restraint that is its worst feature, Lambo's village system at Abeokuta and why it changed community psychiatry worldwide, and the trial evidence on collaboration with healers.
What traditional birth attendants do and what the outcome evidence shows, the real demographic explanation for the Yoruba twinning rate and what it is not, infant care practice, and an honest division between what helps, what is neutral and what kills.
What the Yoruba word for medicine covers, how physical and spiritual causation work together inside one diagnostic act rather than in separate compartments, and why calling this system "traditional" as opposed to "scientific" describes it wrongly.
The scale of the documented Yoruba pharmacopoeia, how plants are classified and named, the tonal wordplay that makes a plant's name a mnemonic for its use, and a worked table of named plants against what pharmacological research has and has not established.