Cassava (Yuca): Nutrients, What Research Shows and Safety

Cassava, also called yuca or manioc (Manihot esculenta Crantz), is a woody shrub in the spurge family (Euphorbiaceae). The starchy root is the part eaten, and it is a staple food for hundreds of millions of people in the tropics. [3] Tapioca is a starch made from the same root. People eat cassava for energy and for its vitamin C and minerals. This page keeps the whole food apart from supplements and from hype, and it puts safety first, because raw or poorly prepared cassava can contain a natural poison.

Read this first

• Never eat raw cassava. Cassava roots contain natural compounds (cyanogenic glycosides) that release cyanide. The World Health Organization (WHO) lists cassava among the important foods containing them. [2] Poisoning cases, some fatal, have followed cassava ingestion. [3]
• Bitter versus sweet: "bitter" cassava has much more of the compound and needs special traditional processing (grating, soaking, fermenting, roasting). Cassava sold as an everyday vegetable (often called yuca) is usually the "sweet" kind, but the European Food Safety Authority (EFSA) notes that cooking whole roots does not remove all of it. [3]
• Konzo: a lasting paralysis of the legs linked to long-term reliance on poorly processed bitter cassava, mainly in parts of Africa. [5][6] It is not a risk from an occasional dish of well-prepared cassava, but it shows why processing matters.
• Poisoning emergency: for dizziness, vomiting, trouble breathing, confusion or seizures after eating cassava, call 911 (or your local emergency number). In the US you can also call Poison Help at 1-800-222-1222. [15] For an allergic reaction (trouble breathing, swelling of the face or throat) call 911 as well.
• Evidence in one line: cassava is a useful energy food; we found no good evidence that it prevents or treats any disease, and the small studies on blood sugar and starch are about specific processed products.

What is in it (USDA values)

Raw cassava, USDA FoodData Central item 169985 (SR Legacy). [1] USDA household portion: 1 cup = 206 g (1 whole root = 408 g).

% Daily Value uses the FDA 2016 Daily Values; values vary with variety, ripeness and storage. [1] These numbers are for the raw root; peeling, cooking and processing into flour or starch change them, and USDA lists no values for those in this item.

Plant compounds. The main compounds in cassava that matter for health are the cyanogenic glycosides, mostly linamarin, with a smaller amount of lotaustralin. EFSA reports both in a roughly 20 to 1 ratio, and says the leaves have about ten times more than the root. [3] This is human toxicology, covered in the safety section. White cassava, the common kind, has almost no vitamin A (USDA lists 8 µg of beta-carotene per 100 g). [1] Yellow, biofortified varieties bred to contain more beta-carotene exist and have been tested in children (see the table). The starch itself can contain resistant starch, a starch that is not fully digested in the small intestine; in one laboratory study of fufu and gari dough (processed cassava foods), resistant starch was 1.1 to 2.1 g per 100 g in fufu. [8] That is a lab measurement, not a health outcome.

What research says

Eaten as food vs taken as a supplement or extract. The USDA values and the glycemic-index findings above are about food. The resistant maltodextrin trial used a manufactured ingredient made from tapioca, so it cannot be used to judge cassava as a vegetable. We did not find any trial that tested a cassava supplement or extract for a health outcome in people; the review of "pharmacological activities" is mostly laboratory work. [12]

How much is a normal serving

There is no official serving size for cassava in the sources we read. As information, not a prescription: USDA lists 1 cup of raw cassava as 206 g and one whole root as 408 g. [1] WHO says people over 10 should get at least 400 g of fruits and vegetables a day. [13] The NHS says potatoes do not count toward 5 A DAY because they are starchy, but sweet potatoes, parsnips and turnips do; it does not name cassava on the page we read, so we make no claim about how it counts. [14] Cassava is much higher in energy than most vegetables (160 kcal per 100 g). [1]

Processing changes the picture. Cooked cassava, flour, gari, fufu and tapioca are different foods from the raw root. USDA gave no values for them in the item we used, and the cyanide content depends on the variety and on how the product was made (see safety below).

Safety, allergy and medicines

• Why cassava is different from most vegetables. WHO says cyanogenic glycosides occur in at least 2,000 plant species and names cassava among the important food sources. Eating the plant can release cyanide, and whether it reaches toxic levels is the main question. [2]
• Acute cyanide poisoning. WHO describes symptoms that can include rapid breathing, a drop in blood pressure, dizziness, headache, stomach pain, vomiting, diarrhea, mental confusion and convulsions, followed by coma; death can occur when the cyanide exceeds what the body can detoxify. [2] In Mozambique, 70 patients were hospitalized with vomiting, abdominal pain, headache and in severe cases altered consciousness and breathing trouble after eating bitter cassava. [3]
• A real-world flour outbreak. In Kasese District, Uganda, in September 2017, 33 people who attended a funeral were admitted with diarrhea, vomiting and abdominal pain. The cause was a dish made from cassava flour with high cyanogenic content, traced to one wholesaler. [4]
• How much is too much (official figures, not advice). EFSA set an acute reference dose of 20 µg of cyanide per kg of body weight, meaning an amount people can take in one day without expected harm, and says it applies whatever the food source. EFSA calculated that, depending on body weight, only 0.7 to 8.5 g of raw cassava root at a high cyanide level (235 mg/kg) could reach that figure. For cassava flour at the Codex limit of 10 mg total cyanide per kg, the figure is reached with 17 to 200 g of flour; for gari at the 2 mg/kg limit, 87 to 1,000 g. [3]
• Sweet versus bitter. Codex defines "sweet cassava" as having less than 50 mg total cyanide per kg, and EFSA says sweet cassava is usually just sold as "cassava." [3] In retail samples measured in Australia and New Zealand, total cyanide in raw cassava ranged from about 16 to 81 mg/kg, in boiled cassava from 7.3 to 23, steamed from 9.0 to 26 and fried from 5.4 to 37. [3] So some retail raw roots exceeded 50 mg/kg, and cooked cassava still contained measurable cyanide. Food Standards Australia New Zealand concluded that properly processed cassava was not of concern because no adverse effects were reported, with worst-case assumptions in the estimates. [3]
• What processing does. According to the review in EFSA's opinion, boiling, steaming, baking or frying fresh roots is not very effective, often leaving 50% or more of the cyanide, because heat disables the enzyme that breaks it down. Sun or oven drying of roots usually does not cut it by half. Crushing, pounding or grating, or soaking in water for several days, then fermenting and finally roasting, can lower cyanide by more than 90%, and traditional foods made this way (gari, fufu, akyeke) kept only about 2% of the original. Prolonged soaking removes some of it. [3] These are descriptions of traditional food production, not a recipe.
• Home fix for flour. The "wetting method" (spreading a thin layer of wet cassava flour in the shade for several hours) reduces cyanide in flour three- to six-fold. [3] In a Democratic Republic of Congo village where konzo had occurred, women kept using it, no new konzo cases appeared over 14 months, and the average flour cyanide was 9 ppm. [7]
• Konzo. Konzo is a permanent, irreversible leg paralysis (spastic paraparesis) seen mostly in children and women of childbearing age in several African countries, associated with a monotonous diet of insufficiently processed bitter cassava. [5][6] A 2021 systematic review found cassava cyanide and protein malnutrition to be well-documented risk factors, but could not show a direct causal link to cyanide alone, and notes other factors may be involved. [5] There is no cure, so prevention (processing) is the focus. [6] EFSA also notes tropical ataxic neuropathy has been linked to cassava as a main calorie source. [3]
• Thyroid. EFSA says thyroid problems from cassava cyanide have only been reported where poorly processed cassava was eaten in areas of iodine deficiency with too little protein. [3]
• Allergy. The sources we read do not describe cassava allergy or cross-reactions (including with latex). Proper evidence not found in the sources we read. Any food can cause an allergic reaction; see food allergy basics and emergency signs.
• Medicines. We did not find a source we could read describing interactions between cassava and medicines. Proper evidence not found; a pharmacist can check. See foods and medicine interactions.
• Potassium. Cassava has 271 mg of potassium per 100 g (558 mg in a cup). [1] People with kidney disease or on potassium-affecting medicines should read kidney disease, potassium and oxalates and ask a clinician.
• Pregnancy and young children. The sources we read give no cassava-specific advice for pregnancy. We did not find a safe-amount statement for children, and children are among those affected by konzo and by flour poisoning outbreaks. [4][6] Ask a clinician.
• Tapioca. Tapioca is a starch from the same root. The sources we read do not give cyanide levels for tapioca pearls or starch, so we make no claim. Proper evidence not found.

Choosing, storing and food safety

• Do not eat raw cassava, and do not eat cassava leaves or bitter cassava from an unfamiliar source without traditional preparation. WHO and EFSA treat the raw root and insufficiently processed bitter cassava as the hazard. [2][3]
• Buy flour, gari and similar products from regulated sources. In Uganda, a single wholesaler's flour caused the outbreak. [4] Codex has limits for flour (10 mg/kg) and gari (2 mg/kg). [3]
• General storage and food-safety basics for produce are on our fresh, frozen and canned produce page. The sources we read do not give storage times for cassava: Proper evidence not found.

Related pages

• Foods and medicine interactions
• Food allergy basics and emergency signs
• Sweet potatoes, carrots and orange vegetables
• Resistant starch foods
• Fresh, frozen and canned produce
• Foods for blood sugar control