Irvingia gabonensis

Irvingia gabonensis (African Wild Mango)

1. Identity: Botanical Name, Classification, and Natural Source

Irvingia gabonensis (Aubry-Lecomte ex O'Rorke) Baill. is a species of fruit-bearing tree classified within the family Irvingiaceae. The tree is considered one of the African bush mango trees (ABMTs), valued as a source of traditional food, medicine, and economic benefits, and is native to the West and Central African humid zones. It should not be confused with Irvingia wombolu Vermoesen, a closely related species with a bitter, inedible pulp; taxonomically, these two species are difficult to distinguish morphologically — I. gabonensis possesses fruits with a sweet and edible pulp, whereas I. wombolu has inedible bitter pulp, though both have been utilized for human consumption in Africa.

Common names include African mango, wild mango, bush mango, and dika nut. In local languages, the plant is also known as "manguier sauvage" and "chocolatier" (French), Ogbono (Igbo), Oro and Oyin (Yoruba), and Ogwe and Ohere (Edo). Although its fruit is superficially similar to the mango (Mangifera indica), the two are unrelated: true mango belongs to the family Anacardiaceae.

I. gabonensis grows straight, reaching up to 40 m in height and 1 m in diameter, with buttresses to a height of 3 m. The outer bark is smooth to scaly with grey to yellow-grey coloration. The crown is evergreen, spherical, and dense; leaves are elliptic, dark green, and glossy on the upper surface. The bisexual flowers are yellow to greenish-white and form small panicles. The fruit is a broad, green-colored, sweet-smelling, ellipsoid drupe with a thin outer skin and an edible, fleshy, orange juicy pulp (mesocarp) when ripe. The hard, stony nut encloses a soft, oil-rich, dicotyledonous kernel. Fruit production occurs in July to August.

Common Forms and Preparations

• Whole dried seed/kernel (dika nut): Kernels, after being dried and crushed, are generally used to prepare a sticky and aromatic soup widely consumed in Cameroon and West African countries.
• Seed (dika) fat/butter: The fat extracted from the seeds has been investigated for use in the preparation of margarine, kitchen oil, soap, and pharmaceutical products, including as a base for suppositories or as a lubricant for granules or tablets.
• Standardized seed extract (IGOB131): IGOB131 is a proprietary, standardized extract of I. gabonensis seed developed and patented by Gateway Health Alliances, Inc. It is the extract used in two of the three published clinical trials and is the form most commonly found in commercial African mango supplements marketed in the United States and internationally.
• Seed gum/mucilage: The use of I. gabonensis polysaccharides as thickeners or as sources of carbohydrates for diabetics in food products and as thickeners or binders in the pharmaceutical industry has been documented.
• Fruit pulp: The ripe fruit pulp was consumed fresh or processed into juice and wine.

2. Traditional and Historical Use

Irvingia gabonensis has a rich history of medicinal use in West and Central Africa, where indigenous communities have valued its seeds, bark, and leaves not only as food but also for their therapeutic properties. Different parts of the plant have been employed in traditional medicine.

The plant is used medicinally in most parts of tropical Africa for the treatment of a number of ailments; in West Africa, the Mende tribe of Sierra Leone specifically uses the stem bark to relieve pain.

In Senegal, decoctions of the stem bark are used in the treatment of gonorrhea, gastrointestinal or hepatic disorders, and as a purgative; root barks are prescribed in poultice form to treat wounds, and their decoctions are used to treat diarrhea and as a mouth bath for dental neuralgias.

The ripe fruit pulp was consumed fresh or processed into juice and wine, and it was documented in folk tradition for anti-diarrheal, anti-diabetic, anti-ulcer, hepatoprotective, antimicrobial, and anti-inflammatory purposes. The kernels are widely traded and incorporated into traditional dishes, and the seeds have folkloric uses for weight loss and are popular as blood thinners and anti-diabetics.

Fever, scabies, toothache, inflammation, and liver and gastrointestinal disorders are among the pathological conditions addressed by Irvingia plants through traditional preparations.

The aqueous maceration of the leaves is also used as an anti-poison. In combination with palm oil, leaves have been used to stop hemorrhages in pregnant women.

Preparations recorded across these traditions include decoctions of bark and roots, poultices, aqueous macerations of leaves, and the consumption or application of the ground seed kernel mixed with water or condiments. The seeds, crushed and mixed with water, pepper, or other condiments, are widely used in Africa as a thickener in the preparation of soups.

3. Key Constituents and Active Compounds

Seed Fat (Dika Butter)

The fruit kernel is rich in oil, comprising 63%–69% crude fat, consisting mostly of myristic and lauric acids. Dika nut oil primarily consists of two saturated fatty acids: lauric acid (40.70%) and myristic acid (49.05%). These two fatty acids, along with capric acid (1.54%), palmitic acid (5.06%), and stearic acid (2.38%), account for 98.86% of the saturated fatty acids; oleic acid is the single unsaturated fatty acid identified.

Polyphenols and Ellagic Acid Derivatives

Irvingia gabonensis is a plant rich in polyphenols, including ellagic acid, mono-, di-, and tri-O-methyl-ellagic acid, and their related glycosides as the major constituents. Seventeen compounds of diverse classes have been isolated from the methanolic extract of the defatted seed kernel, including four flavonoid glycosides, five ellagic acid derivatives, and eight other metabolites; among the isolates, quercetin 3-O-methyl-4′-[α-L-rhamnopyranosyl-(1→3)]-O-α-L-rhamnopyranoside and a novel ellagic acid sulfate ester were found to be previously undescribed.

Terminalin

A phytochemical investigation of I. gabonensis using liquid chromatography–mass spectrometry (LC/MS)-based analysis led to the isolation of terminalin as a major component from the extract of the seeds. LC/MS-based analysis also confirmed ellagic acid as a major component in the crude extract.

Other Secondary Metabolites

Phytochemical analysis of I. gabonensis seed extract has identified the presence of diverse constituents including steroids, flavonoids, alkaloids, cardiac glycosides, volatile oils, terpenoids, tannins, and saponins; moreover, the seeds have been reported to contain a significant amount of gallotannins with high antioxidant capacity.

Reports on phytochemical analysis of Irvingia plants have revealed the presence of a number of secondary metabolites including flavonoids, phenolic compounds, tannins, saponins, and alkaloids.

From the stem bark, isolated compounds include 3-friedelanone, betulinic acid, oleanolic acid, 3,3′,4′-tri-O-methylellagic acid, 3,4-di-O-methylellagic acid, and hardwickiic acid.

Seed Soluble Fiber (Gum/Mucilage)

The water-soluble fibers of I. gabonensis have been suggested to act as "bulk-forming" agents. These fibers are also expected to delay stomach emptying, potentially bringing about a more gradual absorption of dietary sugar. Like other soluble fibers, they are expected to bind bile acids in the gut and facilitate their excretion with feces, which in turn would cause the body to convert more cholesterol into bile acids.

4. Mechanisms of Action

Adipogenesis Inhibition via PPARγ, Leptin, and Adiponectin Pathways

IGOB131 favorably impacts adipogenesis through a variety of critical metabolic pathways including PPARγ, leptin, adiponectin, and glycerol-3-phosphate dehydrogenase. An in vitro study in adipocytes showed that the flavonoid-containing extract inhibits the expression of PPARγ and leptin, thus acting on adiposity signaling and energy intake regulation, while simultaneously causing an increase in the expression of adiponectin.

These effects appear to be mediated through down-regulated expression of the adipogenic transcription factor (PPARγ) and adipocyte-specific protein (leptin), together with up-regulation of adiponectin. These two hormones produced by fat cells are at the center of current mechanisms controlling fat metabolism and obesity. The decrease in leptin levels observed in obese individuals on IGOB131 parallels the decrease in body fat stores, suggesting a possible reversal of leptin insensitivity.

Inhibition of C/EBP Expression

Ellagic acid, as a bioactive component of IGOB131, has been reported to decrease adipogenesis by inhibiting C/EBP (CCAAT/enhancer-binding protein) expression.

Inhibition of Protein Tyrosine Phosphatases (PTPs)

Protein tyrosine phosphatases (PTPs), along with protein tyrosine kinases, control signaling pathways involved in cell growth, metabolism, differentiation, proliferation, and survival. Several PTPs, such as PTPN1, PTPN2, PTPN9, PTPN11, PTPRS, and DUSP9, disrupt insulin signaling and trigger type 2 diabetes, indicating that PTPs are promising drug targets for the treatment or prevention of type 2 diabetes. Terminalin, isolated from I. gabonensis seeds, has been studied for its ability to stimulate glucose uptake through inhibition of these phosphatases (in vitro evidence).

Soluble Fiber / Gastric Mechanisms

The water-soluble fibers of I. gabonensis have been suggested to act as bulk-forming laxatives and to delay stomach emptying, bringing about more gradual absorption of dietary sugar.

5. Scientific Evidence by Area of Use

5.1 Body Weight, Obesity, and Body Composition

Overview of clinical evidence: The human clinical evidence base for I. gabonensis and weight management consists of a small number of randomized controlled trials (RCTs) and subsequent systematic reviews and meta-analyses. Three RCTs have been identified and all were included in one systematic review; all RCTs had flaws in the reporting of their methodology.

Ngondi et al. (2009) — IGOB131 RCT: The study enrolled 102 healthy, overweight and/or obese volunteers (BMI > 25 kg/m²), randomly divided into two groups. Each group received either 150 mg of IGOB131 or a matching placebo in a double-blind fashion, administered 30–60 minutes before lunch and dinner. At baseline and at 4, 8, and 10 weeks, subjects were evaluated for changes in anthropometrics and metabolic parameters including fasting lipids, blood glucose, C-reactive protein, adiponectin, and leptin. Significant improvements in body weight, body fat, waist circumference, plasma total cholesterol, LDL cholesterol, blood glucose, C-reactive protein, adiponectin, and leptin levels were observed in the IGOB131 group compared with placebo. This was described as the first double-blind, randomized, placebo-controlled clinical trial of the anti-obesity and lipid profile modulating effects of an I. gabonensis extract.

Systematic review (Onakpoya et al., 2013): The RCTs all had flaws in the reporting of their methodology; however, all RCTs reported statistically significant reductions in body weight and waist circumference favoring I. gabonensis over placebo, and the results also suggested positive effects on the blood lipid profile. Adverse events included headache and sleep difficulty. Due to the paucity and poor reporting quality of the RCTs, the effect of I. gabonensis on body weight and related parameters was judged to be unproven. Therefore, I. gabonensis could not be recommended as a weight loss aid, and future research should be more rigorous and better reported.

Systematic review and meta-analysis (Lee et al., 2020): Five RCTs met the eligibility criteria for this review; four of the five RCTs were rated as having a high risk of bias (ROB), and only one RCT was rated as having a low ROB. Random-effects meta-analysis of the five RCTs showed that a significant decrease in body weight, body fat, and waist circumference was observed in relation to I. gabonensis seed extract supplementation; however, the only low-ROB trial did not have significantly different outcomes. Meta-analysis also showed beneficial effects on total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides. The authors concluded that overall efficacy on weight loss seems positive but is limited due to poor methodological quality and insufficient reporting of clinical trials.

Across studies: Studies involving a total of 214 subjects receiving I. gabonensis at various doses alone or in combination with other dietary supplements versus placebo over four to ten weeks demonstrated a decrease in weight ranging from 4–12 kg (p<0.05). Body fat percentage and waist circumference were also significantly decreased; improvements were seen in total cholesterol, LDL, and fasting blood glucose.

Important limitation: The three short-term studies from a single research group in Cameroon were all funded by the ingredient supplier and patent holder; independent replication is lacking, and no established long-term dosing, safety, or bioavailability data exist.

Regulatory recognition: The Korean Ministry of Food and Drug Safety approved wild mango seed extract (IGOB131) as a health/functional food in 2015, considering ellagic acid to be the functional component and permitting the claim "reduction in body fat."

5.2 Metabolic Syndrome and Insulin Sensitivity

Méndez-del Villar et al. (2018): A randomized, double-blind, placebo-controlled clinical trial was performed in 24 patients with metabolic syndrome (MetS) as defined by International Diabetes Federation criteria. Twelve patients received I. gabonensis (150 mg) twice a day for 90 days, and 12 patients received placebo. Seven patients (58.3%) in the I. gabonensis group showed remission of MetS, compared to only two patients (16.7%) in the placebo group (P = 0.045). I. gabonensis significantly decreased waist circumference, post-challenge glucose (at 90 and 120 minutes), triglycerides, VLDL, and the area under the curve for glucose. This was a small study (n=24) and must be interpreted with caution.

5.3 Blood Lipid Profile (Dyslipidemia)

Meta-analysis showed beneficial effects of I. gabonensis seed extract supplementation on total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides. Only the low-ROB trial showed a trend of increasing HDL-cholesterol levels (net percent change = 11.61%; 95% CI: −6.12%, 29.34%) and decreasing triglyceride levels (net percent change = −29%; 95% CI: −76%, 19%), with confidence intervals crossing zero, indicating these specific results were not statistically significant in the highest-quality trial. The totality of evidence is promising but methodologically weak.

5.4 Blood Glucose and Antidiabetic Effects

Treatment with I. gabonensis seed extract in obese patients had a positive effect on obesity management including reducing total cholesterol, triglyceride, LDL, and blood glucose levels, and increasing HDL-cholesterol. The in vitro and preclinical evidence base is broader: the methanol extract of seeds produced hypoglycemic effects in streptozotocin-diabetic rats. The isolated compound terminalin was studied for its ability to stimulate glucose uptake through PTP inhibition; this work is in vitro only and cannot be extrapolated to clinical outcomes without further study.

5.5 Analgesic and Anti-inflammatory Properties

The analgesic effects of water and ethanol extracts of the stem bark were studied; the analgesic effects of the water extract and morphine were blocked by the opioid receptor antagonist naloxone in both tests, whereas the ethanol extract's analgesic effects were not antagonized by naloxone, suggesting the active principle in the water extract has an analgesic profile similar to that of a narcotic analgesic, while the ethanol extract may contain non-narcotic analgesic compounds. These findings provided for the first time a pharmacological basis for the folkloric use of I. gabonensis in pain relief. This evidence is limited to preclinical (animal) models.

5.6 Antimicrobial Activity

The antimicrobial activity of the methanolic extract from the stem bark of I. gabonensis, and fractions and compounds isolated from it — including 3-friedelanone, betulinic acid, oleanolic acid, 3,3′,4′-tri-O-methylellagic acid, 3,4-di-O-methylellagic acid, and hardwickiic acid — was evaluated against Gram-positive bacteria (6 species), Gram-negative bacteria (13 species), and three Candida species using dilution methods. The lowest MIC values (78.12 μg/ml) were obtained with the methanolic extract on 13 of the 22 microorganisms tested; the corresponding value of 1.22 μg/ml for compound 6 (hardwickiic acid) was recorded on Neisseria gonorrhoeae. All antimicrobial evidence is from in vitro laboratory studies; no human trials have been conducted in this area.

5.7 Antiprotozoal Activity

In antiprotozoal assays, I. gabonensis demonstrated antiplasmodial and anti-Trypanosoma brucei activity (IC₅₀ <8 µg/mL); the stem bark and leaves were the plant organs tested. This evidence is limited to in vitro assays; no human clinical data exist in this area.

6. Body Systems and Health Areas of Association

• Adipose tissue and weight regulation: The most extensively studied area; seed extract is associated with modulation of adipogenesis, fat mass, and body weight.
• Cardiovascular/lipid metabolism: Meta-analysis showed beneficial effects on total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides.
• Endocrine/metabolic (insulin and glucose): Human and preclinical studies associate the extract with improvements in fasting blood glucose, insulin sensitivity, and metabolic syndrome components.
• Gastrointestinal: Traditional use and pharmacological investigation have implicated bark, root, and seed extracts in managing diarrhea, dysentery, gastric disorders, and as a bulk-forming fiber agent.
• Musculoskeletal and pain: Stem bark extracts have demonstrated pharmacological analgesic activity in preclinical models, corroborating traditional pain-relief uses.
• Immune/antimicrobial: In vitro evidence for antimicrobial and antiprotozoal activity, primarily from stem bark fractions and isolated compounds.
• Antioxidant: The seeds contain a significant amount of gallotannins that have high antioxidant capacity.

7. Dosage Forms and Dosages Reported in Studies

The following dosages are reported as used in published research and should not be interpreted as recommendations:

• IGOB131 seed extract — 150 mg twice daily (300 mg/day): In the primary double-blind RCT (Ngondi et al., 2009), groups received either 150 mg of IGOB131 or matching placebo daily in a double-blinded fashion, 30–60 minutes before lunch and dinner (total 300 mg/day).
• IGOB131 — 150 mg twice daily for 90 days: In the MetS trial (Méndez-del Villar et al., 2018), twelve patients received I. gabonensis 150 mg twice a day for 90 days.
• Various doses in systematic review pool: Studies reviewed involved 214 subjects receiving I. gabonensis at various doses alone or in combination with other dietary supplements versus placebo over a period of four to ten weeks.
• Preclinical toxicology — up to 2500 mg/kg/day: In the subchronic toxicity study, Sprague Dawley rats were gavaged with IGOB131 at dose levels of 0, 100, 1,000, and 2,500 mg/kg body weight/day for 90 days.

8. Safety Considerations

Subchronic Toxicology and Genotoxicity (IGOB131)

No adverse effects of I. gabonensis extract were noted in subchronic toxicity studies in rats at doses up to 2,500 mg/kg/day, and the extract was not genotoxic as evaluated by in vitro and in vivo studies. No treatment-related changes in clinical signs, functional observations, mortality, ophthalmologic observations, body weights, body weight gain, or feed consumption were noted. Hematological, clinical chemistry, urinalysis parameters, and organ weights did not reveal any toxicologically significant treatment-related changes. No treatment-related macroscopic and microscopic abnormalities were noted. Mutagenicity as evaluated by the Ames assay, in vitro and in vivo chromosomal aberration test, and in vivo micronucleus assay did not reveal any genotoxicity of IGOB131. The no-observed-adverse-effect level (NOAEL) for the extract was ≥2,500 mg/kg bw/day, the highest dose tested.

Adverse Events Reported in Human Trials

Three RCTs in one meta-analysis reported adverse events including headache, sleep difficulty, gas, intestinal flatulence, and intestinal constipation. The reported adverse events were minor across these five RCTs. There were no significant differences between I. gabonensis and placebo for adverse events.

Case Report: Renal Failure

A case report published in the International Journal of Clinical and Experimental Medicine (2015) described renal failure developing in association with African mango consumption. This represents a single case report and does not establish causality, but it has been noted in the medical literature as a potential safety signal warranting attention.

Pregnancy and Lactation

There is insufficient reliable information to know if I. gabonensis is safe to use when pregnant or breastfeeding; clinical studies have not addressed this population.

Conflict of Interest in the Evidence Base

The three short-term clinical studies originate from a single research group in Cameroon and were all funded by the ingredient supplier and patent holder. This concentrated and commercially linked evidence base is a key limitation in evaluating safety and efficacy independently. The National Evidence-based Healthcare Collaborating Agency (NECA) in Korea conducted a systematic review of the safety and efficacy of I. gabonensis seed extract on weight-related outcomes in 2016.

Duration of Use

When taken by mouth, I. gabonensis seed extract is possibly safe when used short-term. The longest published RCT durations are 10–12 weeks; long-term safety data in humans are absent.

References

• ScienceDirect Topics — Irvingia gabonensis overview
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• Onakpoya I et al. (2013). The efficacy of Irvingia gabonensis supplementation in the management of overweight and obesity: a systematic review of RCTs. Journal of Dietary Supplements. PMID: 23419021.
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