The food is cassava (also called yuca/manioc). Raw or improperly processed cassava can release cyanide, causing outbreaks of acute poisoning and a disabling neurological condition called konzo. The World Health Organization (WHO)–linked summaries report ~200 deaths per year worldwide from cassava poisoning, while hundreds of millions of people—especially across Africa, Asia and Latin America—depend on it daily. With proper processing (peeling, soaking/fermenting, drying and thorough cooking), cassava is safe to eat.
What exactly is cassava—and why do so many people eat it?
Cassava (Manihot esculenta) is a drought-tolerant root crop that thrives in poor soils, making it a lifeline in tropical regions where other staples struggle. It’s the third-largest source of carbohydrates in the tropics and a primary energy source for roughly 500 million people. In many countries, it’s boiled or fried like potatoes, fermented into gari, ground into flour, or processed into tapioca starch.
Why is cassava sometimes called “the world’s deadliest food”?
Cassava’s roots and leaves naturally contain cyanogenic glycosides (mainly linamarin). When plant tissue is damaged and then chewed or digested, enzymes can split these molecules to release hydrogen cyanide (HCN)—a potent toxin. WHO’s expert committees and Codex Alimentarius set a safety guideline of ≤10 mg HCN per kg (10 ppm) in cassava flour to prevent acute toxicity. When cassava isn’t processed correctly, cyanide exposure can cause headache, dizziness, vomiting, rapid breathing, seizures, coma, and death.
How many people die from cassava each year?
Several reputable science outlets summarizing WHO figures report “upward of 200 deaths per year” attributed to cassava poisoning globally. While that’s a small fraction of the ~420,000 annual deaths from all unsafe food of every cause combined, the tragedies are largely preventable with correct preparation and community education.
Real-world outbreaks: In 2017, an outbreak in western Uganda tied to cassava flour from wild high-cyanide cultivars caused 98 poisonings and two deaths—a reminder that processing steps can fail under pressure (e.g., food shortages, displacement, drought).
Not just acute poisoning: the long-term risk called konzo
Beyond sudden poisonings, chronically eating inadequately processed “bitter” cassava—especially during drought/famine when detox steps are skipped—can lead to konzo, a sudden-onset, irreversible spastic paralysis that primarily affects children and women of child-bearing age. Studies repeatedly find cassava flours far above the 10-ppm safety limit in affected communities.
So…why do nearly half a billion people still eat it?
Because cassava keeps growing when other crops fail. It’s hardy, stores in the ground, and yields reliable calories with minimal inputs. For families facing climate stress and market volatility, that resilience can literally mean survival—even as it raises safety stakes if processing shortcuts are taken.
The good news: simple, proven ways to make cassava safe
Traditional processing methods dramatically reduce cyanide by letting enzymes work and allowing volatile HCN to escape:
- Peel deeply and discard peels (they’re richer in cyanogens).
- Grate/slice to rupture cells and expose linamarin to enzymes.
- Soak or ferment for 1–3 days (e.g., heap fermentation for gari).
- Sun-dry thoroughly (or roast), then sieve/mill into flour.
- Boil/fry thoroughly and discard soaking/boiling water—never reuse it for cooking or feeds.
- Avoid eating cassava raw in any form.
- Pair with protein-rich foods (sulfur-containing amino acids help detoxify cyanide), and diversify the diet when possible.
What about nutrition—does cassava have upsides?
- Energy: Cassava is calorie-dense and gluten-free, but low in protein; its leaves (properly cooked/processed) can be surprisingly rich in protein and micronutrients (vitamin A, vitamin C, iron, calcium)—a valuable complement to the starchy root.
- Blood sugar: Cassava and tapioca starches tend to have a high glycemic index, so people managing blood sugar should watch portions and pair cassava with fiber, protein, and healthy fats.
How to reduce community risk (a holistic view)
- Promote safer varieties & training. Encourage cultivation of lower-cyanide (“sweet”) varieties and share standardized detox methods through extension services, women’s groups and schools.
- Measure and monitor. Community kits and simple picrate-paper tests can screen flours; local mills and co-ops can adopt quality checks to meet the 10-ppm safety target.
- Support during climate shocks. Drought and conflict increase reliance on bitter cassava and short-cuts. Emergency rations, fuel for cooking, and clean water reduce the temptation to skip soaking/fermenting.
- Nutrition pairing. Promote legumes, eggs, fish, and leafy greens alongside cassava to improve protein intake and overall diet quality.
Is “yuca” the same as “yucca”?
“Yuca” is cassava—the edible tropical root. “Yucca” is a different (ornamental) genus. Stick with cassava/yuca in recipes. (General usage)
Can I safely use tapioca flour (cassava starch) at home?
Yes—commercial tapioca starch is produced from fully processed cassava and is safe. The risk lies in raw roots or home-processed products that skip detox steps.
How do outbreaks happen if people know how to prepare it?
During famine, drought or displacement, families may harvest bitter varieties and rush processing to meet urgent food needs—exactly the pattern seen in multiple outbreaks.
Key takeaways
- The “world’s deadliest food” label refers to cassava because of its cyanide risk when improperly processed. Estimated ~200 deaths/year occur globally, but most are preventable.
- ~500 million people still eat cassava because it’s resilient, affordable and reliable where other crops fail.
- Correct processing—peeling, soaking/fermenting, drying and cooking—makes cassava safe; public-health standards target ≤10 ppm HCN in cassava flour.