TROPICAL MEDICINAL PLANTS

Tropical medicinal plants: effectiveness, risks and current knowledge

Introduction

Tropical regions (Caribbean, Africa, South America, Southeast Asia) host exceptional biodiversity. Medicinal plants play a central role in traditional medicine: they heal wounds, reduce fever, aid digestion, and strengthen immunity.
Today, their use also interests modern medicine, but it raises questions about real effectiveness and safety.

1. Effectiveness of tropical plants

1.1. Recognized traditional uses

For centuries, tropical populations have used these plants to:

Treat infections: cinchona bark (Cinchona) used against malaria → basis of chloroquine.
Relieve pain and inflammation: turmeric, ginger.
Heal and moisturize the skin: aloe vera, coconut oil.
Boost immunity: noni, moringa.
Support digestion: tropical mint, ginger.

1.2. Modern scientific data

Research confirms some effects:

- Hibiscus (Hibiscus sabdariffa, roselle)

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Effectiveness: clinical trials and meta-analyses show a modest reduction in blood pressure.
Risks: generally well tolerated; caution in people with low blood pressure or on antihypertensive medication.
Evidence level: moderate, supported by several studies.

🍃 Papaya leaves (Carica papaya)

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Effectiveness: increased platelet count and faster recovery observed in dengue patients.
Risks: good short-term tolerance; beware of non-standardized homemade preparations.
Evidence level: promising, but more clinical trials are needed.

🍈 Soursop (Annona muricata, graviola)

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Effectiveness: laboratory results only, no solid clinical evidence.
Risks: neurotoxicity signal (atypical parkinsonism reported in the Caribbean).
Evidence level: risks outweigh benefits in chronic use.

🍹 Noni (Morinda citrifolia)

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Effectiveness: few high-quality studies; benefits not confirmed.
Risks: documented cases of severe liver toxicity.
Evidence level: limited; real safety concerns.

🌳 Neem (Azadirachta indica)

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Effectiveness: mainly traditional use; few human studies.
Risks: cases of seizures and encephalopathy after ingestion of oil or powder, especially in children.
Evidence level: safety issues; avoid oral use.

🌿 Moringa (Moringa oleifera)

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Effectiveness: nutrient-rich; some metabolic effects suggested, still under study.
Risks: leaves safe as food; roots and bark potentially toxic.
Evidence level: limited.

🌱 Ginger (Zingiber officinale)

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Effectiveness: modest reduction of nausea (pregnancy, post-surgery).
Risks: possible heartburn; caution with anticoagulants.
Evidence level: moderate.

🍃 Guava leaves (Psidium guajava)

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Effectiveness: one clinical trial showed improvement of acute diarrhea.
Risks: well tolerated in short-term use.
Evidence level: encouraging, but few studies.

🌾 Lemongrass (Cymbopogon citratus)

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Effectiveness: small studies show reduced anxiety and slight blood pressure lowering.
Risks: possible skin irritation with essential oils; ingestion not recommended.
Evidence level: preliminary.

🌵 Aloe vera

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Effectiveness: topical use helps in minor burns and skin conditions; laxative effect of latex.
Risks: oral latex unsafe (cramps, diarrhea, possible carcinogenic effect).
Evidence level: safe for topical use; avoid chronic ingestion.

🍂 Bitter melon (Momordica charantia, cerasee)

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Effectiveness: contradictory results in diabetes (blood sugar, HbA1c).
Risks: risk of hypoglycemia; contraindicated during pregnancy.
Evidence level: uncertain.

2. Risks of tropical plants

2.1. Toxicity and overdose

Some plants contain powerful alkaloids → risk of liver or heart damage.
Example: excessive use of kava (Polynesia) → reported cases of severe liver toxicity.

2.2. Drug interactions

St. John’s Wort (Hypericum): reduces the effectiveness of many drugs (contraceptives, anticoagulants, antidepressants).
Garlic, ginger, ginkgo at high doses: increase bleeding risk with anticoagulants.

2.3. Confusion and home preparations

In rural areas, confusion between two similar plants may cause serious poisoning.
Strong herbal decoctions can cause nausea, vomiting, neurological issues.

2.4. Allergic reactions

Aloe vera may cause skin irritation in sensitive people.
Essential oils from tropical plants are very concentrated and can be irritant.

3. Current state of scientific knowledge

3.1. Confirmed

Several tropical plants are officially recognized in pharmacopoeias: cinchona, aloe vera, turmeric, ginger.
Their effectiveness is validated in specific indications.

3.2. Controversial

Noni: some studies suggest immune benefits, but evidence is limited.
Moringa: nutritive value recognized, but medicinal claims need more research.

3.3. In progress

Hundreds of tropical plants are being studied for active compounds (antiviral, anticancer, anti-inflammatory).
WHO promotes cautious integration of traditional medicine but emphasizes safety and standardization.
Current state of research
- ✅ Some plants have proven clinical benefits (hibiscus for hypertension, ginger for nausea, guava leaves for diarrhea).
- 🔄 Others are promising but still insufficiently studied (papaya in dengue, moringa, lemongrass, bitter melon).
- ⚠️ Some show documented risks (soursop → neurotoxicity, noni → liver toxicity, neem → neurological toxicity, aloe latex → digestive issues).
- 📊 Overall: research is progressing but remains fragmented; more solid clinical trials and standardized products are needed.
👉 In summary: there are interesting prospects, but caution is required since evidence is uneven and some risks are well established.

Conclusion

Tropical medicinal plants are an extraordinary resource for human health.

✅ Some have validated effectiveness.
⚠️ Others pose risks through toxicity, interactions or misuse.
🔬 Research continues: many promises but also uncertainties.

👉 The future lies in balance: respect traditional knowledge, validate through science, and inform the public about risks.