Pygeum

Prunus africana (Hook.f.) Kalkman belongs to Rosaceae, the rose family, which also gives us plums, cherries, peaches, apricots, and almonds; Bodeker and colleagues note that it and P. crassifolia are the only wild Prunus species in Africa. Kew’s Plants of the World Online records that it was first published as Pygeum africanum in 1863 and moved to Prunus by Kalkman in the journal Blumea in 1965, with Laurocerasus africana as a further synonym. Kew gives the native range as Ghana to Ethiopia and South Africa, the Comoros, and Madagascar, taking in Cameroon, the islands of the Gulf of Guinea, the Democratic Republic of the Congo, Kenya, Uganda, Tanzania, Malawi, Zimbabwe, and others, and classes it as a tree of the montane tropics. The range is broad but broken: Vinceti and colleagues (PLOS One 2013) describe the species as confined to mountain regions with low colonization potential, and South Africa’s national Red List assessment (SANBI 2022) describes ‘islands’ of Afromontane forest, with trees growing up to 2,100 m. Common names include African cherry, African plum tree, red stinkwood, bitter almond, and wild almond, and EMA lists dozens of local names, from inkhokhokho to tendwet.

EMA’s assessment report describes an evergreen tree usually 10–25 m tall, with a straight, cylindrical trunk and a dense, rounded crown. The leaves are alternate, elliptic, leathery, and glossy deep green, 8–12 cm long, with shallow rounded teeth, reddish stalks, and an almond smell when bruised. Small, fragrant white or cream flowers hang in spikes 3–8 cm long from the leaf axils. Vinceti and colleagues add that the flowers are bisexual and insect-pollinated, and that although the tree can fertilize itself it usually outcrosses; its fruits, cherry-like, red to purplish-brown, 8–12 mm across, with very bitter flesh (EMA), are spread by birds and monkeys. Bodeker and colleagues note that the tree provides habitat and food for endemic birds, rare primates, and epiphytes such as orchids, ferns, and mosses. The pale red wood gives off a strong smell of cyanide when freshly cut and darkens to mahogany-brown; it is very hard and heavy, and has been used for axe handles (Rubegeta and colleagues 2023). The medicinal part, the trunk bark, is red to blackish-brown and deeply fissured, with a characteristic almond-like odor, fitting names such as bitter almond and red stinkwood.

EMA describes the bark’s main constituents as fat-soluble: phytosterols such as beta-sitosterol, its glucoside, and beta-sitostenone; pentacyclic triterpenes, mainly ursolic and oleanolic acid derivatives, at about 14%; long-chain fatty acids; and the long-chain alcohols n-docosanol and n-tetracosanol with their ferulic acid esters. In one lipophilic extract it cites, fatty acids made up 62.3%, beta-sitosterol 15.7%, ursolic acid 2.9%, friedelin 1.4%, and n-docosanol 0.6%. Beta-sitosterol (PubChem CID 222284, C29H50O) is the same plant sterol found in saw palmetto; ursolic acid is PubChem CID 64945 (C30H48O3). Atraric acid and N-butylbenzenesulfonamide (NBBS), isolated from the bark, blocked the androgen receptor in cell tests (EMA). The bark varies with its origin: Kadu and colleagues (Phytochemistry 2012) sampled 20 populations across Africa and found average levels of 743 mg/kg of ursolic acid and 490 mg/kg of beta-sitosterol, with ursolic acid varying most between populations. Products differ again: Thompson and colleagues (Journal of Pharmaceutical and Biomedical Analysis 2019) found some supplements with more than 10,000 µg/g of beta-sitosterol against about 680 µg/g in bark, about a quarter of the bark’s ferulic acid, and no NBBS in any sample. EMA concluded that no constituent with known therapeutic activity, and no reliable marker, can be identified.

Long before it reached European pharmacies, the African cherry was a working tree. Bodeker and colleagues (Journal of Alternative and Complementary Medicine 2014) list traditional uses of the bark for fevers, gonorrhea, stomach pain, chest pain, kidney disease, urinary symptoms, and malaria, as well as an arrow poison and a purgative for cattle, and note that its Fulani name, dalehi, means “plant that has many uses.” A 2023 review by Rubegeta and colleagues in the Journal of Ethnopharmacology describes stem-bark decoctions taken by mouth for prostate enlargement, stomach ache, chest pain, malaria, heart conditions, gonorrhea, and urinary and kidney diseases. EMA’s assessment report states that Africans used the powdered bark for urinary problems and that traditional healers have used the tree for genitourinary disorders for centuries. Its many names, such as umkhakhazi and umdumizulu in Zulu and Xhosa and rooistinkhout in Afrikaans, recorded by SANBI, reflect how widely it was known. In South Africa the bark remains part of the traditional medicine trade, where SANBI’s 2022 assessment reports its popularity increasing.

The bark’s modern career began in France. EMA notes that French scientists became interested in pygeum in the 1960s, and Bodeker and colleagues record a mid-1960s patent by J. Debat, whose company, Laboratoires Debat, set up the Cameroonian subsidiary Plantecam Medicam. In the early 1970s Plantecam obtained a monopoly on the commercial harvest in Cameroon, at first using partial debarking designed to spare the trees, and from 1976 to 1996 it received yearly permits to harvest more than 500 tons. EMA’s market survey found a chloroform-extracted soft extract sold in France since 1969 as 50 mg capsules taken twice daily, with related products in Greece, Poland, and the Czech Republic, some since withdrawn. Tadenan, the Debat product, became the most studied, and Levin and Das (Urological Research 2000) wrote that plant preparations were the most widely used drugs for BPH in France and made up about a third of BPH drug sales in Europe. Monographs from the World Health Organization and the European Scientific Cooperative on Phytotherapy followed, and EMA adopted its own on 12 July 2016, confirmed by a periodic review in 2023.

Success brought overexploitation. Stewart (Journal of Ethnopharmacology 2003) estimated world exports of dried bark at 3,225 tons in the peak year of 1997, falling to 1,350–1,525 tons in 2000, almost all of it collected from the wild, with two companies, Groupe Fournier of France and Indena of Italy, making 86% of the world’s extract. Bodeker and colleagues describe an outbreak of illegal harvesting on Mount Cameroon in 1994, when trees were felled or completely stripped, and cite a survey that found 68% of exploited trees dead or with dying crowns. On Kenya’s proposal the species entered CITES Appendix II on 16 February 1995, so exports need permits. In 2006 the CITES Plants Committee rated populations in Burundi, Cameroon, the Democratic Republic of the Congo, Equatorial Guinea, Kenya, Madagascar, and Tanzania as ‘of urgent concern’, and the EU banned bark imports from Cameroon from November 2007 to December 2010, when trade resumed under a quota of 150,000 kg a year, compared with 2 million kg in 2005 (Vinceti and colleagues). By 2012 Cameroon supplied 72.6% of world trade, 658.6 tons, while harvesters in Mount Cameroon National Park earned less than US$1 a day (Cunningham and colleagues, Journal of Ethnopharmacology 2016).

No one knows exactly how pygeum might ease urinary symptoms, and EMA found no data on how its constituents are absorbed or eliminated in people. Most mechanistic work has used Tadenan-type extracts on the stromal (connective tissue) cells that make up much of an enlarged prostate. Yablonsky and colleagues (Journal of Urology 1997) found that the extract inhibited the growth of rat prostate fibroblasts driven by the growth factors EGF, IGF-I, and bFGF at concentrations of about 5–13 µg/ml without killing the cells. Boulbès and colleagues (BJU International 2006) saw a dose-dependent effect at 5–100 µg/ml in fibroblasts and myofibroblasts grown from human BPH tissue. Quiles and colleagues (The Prostate 2010), using cells from three men with BPH and three without, found the extract more potent against BPH cells, inducing apoptosis (programmed cell death) mainly in myofibroblasts, lowering TGF-β1, and blocking FGF2 signaling. In an unusual experiment, Larré and colleagues (Asian Journal of Andrology 2012) found that serum from a man taking the extract slowed the growth of prostate myofibroblasts in culture, suggesting that active material can reach the blood, though one volunteer is a thin basis. All of this is laboratory evidence.

Anti-inflammatory and hormonal effects have also been proposed. Paubert-Braquet and colleagues (Journal of Lipid Mediators and Cell Signalling 1994) found that the extract inhibited production of leukotrienes and other 5-lipoxygenase products by human white blood cells at concentrations as low as 3 µg/ml, and EMA summarizes rat studies in which a lipophilic extract reduced paw swelling. MSKCC suggests that phytosterols may reduce inflammation by blocking prostaglandin production. Any effect on 5-alpha-reductase, the enzyme finasteride blocks, appears weak: in work cited by EMA, a lipophilic extract inhibited the human prostate enzyme with an IC50 (the concentration giving half the maximum effect) of 63 µg/ml, against 1 ng/ml for finasteride, more than 60,000 times weaker. Atraric acid and NBBS blocked the human androgen receptor in cell tests, and atraric acid slowed the growth of androgen-sensitive prostate cancer cells and reduced their PSA gene activity (EMA), but Thompson and colleagues found no NBBS in the bark or products they analyzed. Rubegeta and colleagues observe that activity has mainly been ascribed to the phytosterols, yet isolated compounds have generally been less active than the whole extract.

A second line of research looks at the bladder, and EMA notes that pygeum’s benefits on urinary symptoms have been ascribed to a protective action there. In rats and guinea pigs, lipophilic extracts reduced bladder contractions provoked by drugs or electrical stimulation. In rabbits with a partly obstructed bladder outlet, an animal model of BPH, pretreatment with the extract preserved the bladder’s ability to contract, and in one study treated animals had bladders weighing 4.2 g against 8.8 g without treatment; in rats whose prostates were enlarged with dihydrotestosterone (DHT), 100 mg/kg a day reduced urination frequency (all summarized by EMA). In people, the extract has not been shown to shrink the prostate: in an open study by Breza and colleagues (Current Medical Research and Opinion 1998), prostate volume did not change, and a Polish product label summarized by EMA stated that it does not affect prostate size and only relieves symptoms. EMA concluded that the laboratory findings give some rationale for traditional use, while the EAU notes that the effects of plant extracts in the body remain uncertain.

Symptoms of an enlarged prostate are pygeum’s only recognized use. EMA’s Committee on Herbal Medicinal Products adopted its monograph on 12 July 2016, accepting one chloroform soft extract as a traditional herbal medicine for lower urinary tract symptoms related to BPH in adult and elderly men, after a doctor has excluded serious conditions, “exclusively based upon long-standing use.” Its assessors counted 12 trials of this extract involving 825 men in France, Italy, Poland, and the Netherlands, mostly at 100 mg a day for six to 12 weeks, and wrote that in many cases final conclusions were not at all clear. They judged that there were not enough data from well-designed trials to support well-established use, though the results supported plausibility, and noted that the placebo effect in BPH can be large and two months is a short time. A periodic review adopted on 20 September 2023 screened 31 newer references and found nothing that would change the monograph. Pygeum therefore sits alongside pumpkin seed as an EU traditional remedy, a step below the hexane extract of saw palmetto, which EMA accepts as well established.

The main evidence is the Cochrane review by Wilt, Ishani, and colleagues (2002), also published by Ishani and colleagues in the American Journal of Medicine (2000). It included 18 randomized trials with 1,562 men. Seventeen were double-blind, but only one reported how treatment allocation was concealed; 12 were published in languages other than English, none was run in the United States, the mean duration was 64 days (range 30–122), and daily doses ranged from 75 to 200 mg. Pooling six placebo-controlled trials with 474 men gave a combined improvement in symptoms and flow of 0.8 standard deviations, which the authors called moderately large. In five trials with 430 men, 65% on pygeum were rated as improved overall, against 30% on placebo. Peak urine flow rose by 2.5 ml per second (23%) and leftover urine in the bladder fell by 13 ml (24%), while the 19% reduction in night-time urination, 0.9 fewer trips a night, was not statistically significant. The authors concluded that a standardized extract may be a useful option, but that the trials were small, short, varied in doses and preparations, and rarely used validated symptom scores. Cochrane now marks the review as out of date and withdrawn.

The largest single placebo-controlled trial, by Barlet and colleagues (Wiener klinische Wochenschrift 1990), randomized 263 men at eight centers in Germany, France, and Austria to 50 mg of extract or placebo twice daily for 60 days. Urination improved in 66% of men on pygeum and 31% on placebo. Chatelain and colleagues (Urology 1999) compared 50 mg twice daily with 100 mg once daily in 209 men for two months, double-blind but without placebo: International Prostate Symptom Scores (IPSS), starting around 17, fell by 38% and 35%, and peak flow rose by about 1.6 and 2.0 ml per second. In a 10-month open extension with 174 men taking 100 mg daily, scores fell from 16 to 9. In an open study of 85 men in the Czech Republic, Slovakia, and Poland, Breza and colleagues reported a 40% fall in IPSS and 32% fewer night-time trips after two months. Without a placebo group, these open studies cannot separate pygeum’s effect from the placebo response and natural fluctuation, and EMA’s assessors flagged dropout rates of 47% and 31% in two of the older placebo-controlled trials.

How does pygeum compare with standard treatment? No randomized trial has tested it against an alpha-blocker or 5-alpha-reductase inhibitor. In the observational TRIUMPH study, Hutchison and colleagues (European Urology 2007) followed 2,351 men treated for urinary symptoms in six European countries for a year: 43% of men on phytotherapy with saw palmetto or pygeum improved significantly, against 57% on finasteride and 68% on alpha-blockers, though men were not randomized to treatments. Saw palmetto offers a cautionary parallel: a 1998 review of its short trials by Wilt and colleagues found modest benefits, but the larger and longer STEP and CAMUS trials and Cochrane’s 2023 update found little or no benefit, a test pygeum has never faced. Guidelines reflect the uncertainty. NICE’s guideline on men’s urinary symptoms says not to offer homeopathy, phytotherapy, or acupuncture, and the 2026 EAU guideline lists the EU pygeum monograph but recommends only hexane-extracted saw palmetto, warning that extracts of the same plant from different makers are not interchangeable. MSKCC says pygeum may relieve BPH symptoms but that long-term effects are unknown and larger studies against standard treatments are needed.

Other uses are unproven. Many products combine pygeum with nettle root, saw palmetto, or pumpkin seed. Krzeski and colleagues (Clinical Therapeutics 1993) gave 134 men a nettle root and pygeum combination at full or half dose for eight weeks and found similar improvements with both, but there was no placebo group. Coulson and colleagues (Complementary Therapies in Medicine 2013) reported that symptom scores fell by 36% with a five-ingredient product containing pygeum, saw palmetto, pumpkin seed, willow herb, and lycopene, against 8% with placebo, in 57 men over three months; the benefit cannot be credited to pygeum alone. In laboratory studies, pygeum extracts slowed the growth of prostate cancer cells, and in mice genetically prone to prostate cancer, those fed an extract developed tumors less often, 35% against 62.5% (EMA), but there are no human data, and pygeum is not a treatment for prostate cancer. MSKCC finds no evidence that pygeum improves sexual performance, and its anti-inflammatory effects have not been shown in people.

The EMA monograph covers a single preparation: a soft extract of the bark made with chloroform (stabilized with 1.2% ethanol) at a drug-to-extract ratio of 114–222:1, meaning more than 100 kg of bark for each kilogram of extract, in solid oral forms such as capsules. Adults and elderly men take a single dose of 50 mg, for a daily dose of 100 mg; long-term use is possible, and there is no relevant use in children, adolescents under 18, or women. The bark must meet the European Pharmacopoeia standard. The French product on which the monograph rests is a 50 mg capsule taken twice daily in courses of six weeks, extendable by two weeks and renewable, and an American reference cited by EMA describes 100 mg a day in six- to eight-week cycles, with some extracts standardized to 14% triterpenes and 0.5% n-docosanol. Trials used 75–200 mg a day, and Chatelain’s trial found 100 mg once daily as effective as 50 mg twice daily. MSKCC notes that it may take several weeks to see an effect. EMA advises seeing a doctor if symptoms worsen or if fever, spasms, blood in the urine, painful urination, or urinary retention occur.

Pygeum sold in the United States is a dietary supplement rather than the EU-registered extract, and products vary. When Thompson and colleagues analyzed seven commercial pygeum products and four bark samples, some products contained more than 10,000 µg/g of beta-sitosterol against about 680 µg/g in bark, and on average a quarter of the bark’s ferulic acid, so they were chemically quite unlike the bark they came from. Kadu and colleagues found that the bark itself varies between populations, particularly in ursolic acid. The EAU warns that extracts of the same plant from different manufacturers do not necessarily have the same effects. Many prostate formulas combine small amounts of pygeum with saw palmetto, nettle root, pumpkin seed, or lycopene, which makes doses hard to compare with the trials: the nettle and pygeum capsule in Krzeski’s trial contained only 25 mg of pygeum extract. Traditional African bark decoctions have not been tested in clinical trials. Check the label for the extract type, the amount in milligrams, and the daily dose, and treat a product that lists only bark powder as an unknown quantity.

See a doctor first, since EMA’s indication applies only after serious conditions have been excluded, and NICE recommends that men with urinary symptoms have a history, an examination including a digital rectal exam, a urine dipstick test, and information about PSA testing. A symptom score or a simple diary of daytime and night-time trips, kept before and during use, makes it easier to judge any change, since trials lasted about two months and placebo responses are large. Do not stop a prescribed alpha-blocker or 5-alpha-reductase inhibitor in favor of pygeum without your doctor’s agreement. Consider the tree, too. Stewart found that bark was almost entirely wild-collected, and Cunningham and colleagues argue that cultivated, traceable supply chains are needed; about 625 hectares with some 1.5 million trees were planted in western Cameroon between 1976 and 2008 (Bodeker and colleagues). Buyers can ask manufacturers where and how their bark was harvested. Bodeker and colleagues go further, suggesting that the industry shift toward other, more renewable plants used for BPH, and for a man choosing a remedy with equally uncertain evidence, that is worth weighing.