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Bitter yucca

January 15, 2021
Characteristics of bitter cassava

The yuca , also known as manioc or cassava is a tuber originating in the central region of South America, specifically Brazil. Its use as food has spread around the world, as it is a good source of starchy carbohydrates and several essential nutrients; however, its content of toxic compounds can be dangerous, and even fatal, for man. Scholars have observed that the greatest amount of poisonous substances is found in bitter cassava , hence the importance of knowing how to recognize and handle this variety.

Below we explain what its main characteristics are, why it is considered a dangerous food, what are the symptoms of intoxication and what we can do to avoid its harmful effect on the body.

Characteristics of bitter cassava

So far, two varieties of cassava have been identified , sweet cassava and bitter cassava.1 . Like the sweet variety, the latter grows in the form of long tuberous roots, has a fibrous brown skin and a hard pinkish-white flesh.

Due to its starchy carbohydrate content, bitter cassava is a caloric food . A 100-gram serving of boiled yucca root contains 112 calories; 98% of these correspond to carbohydrates and the rest to a small amount of protein and fat. Likewise, it provides a small amount of other essential nutrients such as fiber, vitamins (thiamine, riboflavin, niacin, vitamin C) and minerals (phosphorus, calcium, iron).2

Besides taste, bitter cassava also differs from sweet cassava by its level of toxicity. It has been found to have a higher concentration of toxic substances, not only in the peel of the tuber, but in its meat . This concentration tends to increase if bitter cassava is grown in areas with dry, desert or low fertile soil.

Although neither of the two types of cassava is suitable for consumption in its raw form, it is recommended to exercise greater caution when preparing a bitter variety.


Why is bitter yucca poisonous?

The cause of its poisonous potential is due to a class of substances known as cyanogenic glycosides . These are a group of chemical compounds that occur naturally in more than 2000 species of plants (leaves, stems, edible parts). It is said that there are at least 25 cyanogenic glycosides, linamarin being the most abundant in cassava3.

By themselves, they are relatively non-toxic, but as a result of enzymatic hydrolysis that occurs after maceration of tissues during consumption, or the action of the intestinal microflora, cyanogenic glycosides break down and release hydrogen cyanide , a highly toxic to animals and man4.

The potential toxicity of a cyanogenic plant depends mainly on its ability to produce hydrogen cyanide, but in the case of cassava, it also contains a certain amount of free cyanide, thus increasing its detrimental effect. 5.

What are the symptoms of poisoning from eating bitter cassava?

In humans, clinical signs of acute cyanide poisoning include6:

  • Fast breathing
  • Drop in blood pressure
  • Dizziness and weakness
  • Headache
  • Stomach ache
  • Joint pain
  • Vomiting and diarrhea
  • Mental confusion
  • Contractions and seizures
  • Numbness of limbs
  • Vision problems
  • Swelling of the tongue

Other symptoms of poisoning from eating bitter yucca can be:

  • Dilated pupils
  • Clammy skin
  • Slower, shallower breaths
  • Weaker pulse, faster

If the condition remains undiagnosed and untreated , it can lead to:

  • Slow and irregular heart rate
  • Bluish discoloration of the lips, face and extremities
  • Coma
  • Death

Chronic cyanide poisoning can lead to the development of certain conditions, including impaired thyroid function and neurological disorders. This condition usually affects those who maintain a regular and long-term consumption of cassava with a poor nutritional status.7

Cyanide poisoning can cause death when the level of cyanide exceeds the limit that our body can detoxify. The acute lethal dose of hydrogen cyanide for humans is reported to range from 0.5 to 3.5 mg per kilogram of body weight (50-60 mg for an adult). Children are particularly at risk due to their smaller body size.8

Note : raw sweet cassava contains less than 50 mg of hydrogen cyanide per kilogram, while bitter cassava roots can contain up to 400 mg per kilogram.

How to differentiate bitter yucca from sweet yucca?

To identify when a yucca is bitter and when it is not, you can take into account the following characteristics:

  • Difficult separation from the shell . Unlike the sweet variety, which can be peeled easily, bitter yucca has a thick, hard rind that is difficult to remove. Sometimes it is necessary to scrape it to remove the shell completely.
  • Very bitter taste . This cassava has a significantly bitter taste; To check it, it is enough to split a small piece of the tuber and taste it with the tip of the tongue. If it tastes bitter, it is almost certainly a bitter variety.
  • Tonality of the skin and inner flesh . Raw sweet cassava is completely white, however bitter cassava tends to have a slight pink hue to its skin and flesh.
  • Tonality after cooking . Most of the time, cooked bitter yucca has a yellowish color in the central part of the root and a whitish color towards the outer edges. In the case of sweet cassava, the hue is uniform throughout the tuber.
  • Cooking time . The bitter variety takes much longer to soften. While sweet cassava can be fully cooked in 20 minutes, bitter cassava can take up to 1 hour to soften.

How to prepare bitter cassava to consume it safely?

Sweet cassava can be safely eaten after the roots are thoroughly peeled and cooked (see;  How to consume cassava in a healthy way? ), However, consuming bitter cassava requires a bit more caution. Below we suggest several steps to facilitate the elimination of its toxic compounds and guarantee the safety of its preparation.910

  • Peel the cassava . This is the first step in removing the highest amount of cyanogenic glycosides. The peel contains more toxic substances than the meat .
  • Grate the tuber . With the help of a fork, make furrows along the yucca; This will promote the release of glycosides out of the food.
  • Cut into small pieces . It is best to cut the roots into small or medium-sized pieces to promote uniform cooking.
  • Soak the roots . Soak the bitter yucca pieces in water for several hours, preferably 24 hours before cooking and consuming; This reduces the amount of harmful chemicals it contains. Change the soaking water every so often.
  • Cook thoroughly . Lastly, cook the yuca thoroughly, whether it’s boiled, roasted, or baked. Cassava should not be eaten raw or partially cooked.
  • Combine with proteins . Considering that proteins help the body to get rid of toxic cyanide, it is recommended to accompany bitter cassava with a good source of protein.
  • Maintain a balanced diet . Another way to prevent the adverse effects of cassava is to eat a varied diet (rice, potatoes, sweet potatoes, corn, vegetables). Relying on it as the sole source of carbohydrates is not recommended.

In general, any cassava can be eaten safely, as long as it is prepared properly and consumed in moderation. A reasonable serving can be the equivalent of half a cup of bitter cassava.

An important clarification to take into account is that cassava-derived products, such as cassava or tapioca flour, are safe for human consumption, since they contain very few cyanide-inducing compounds. This flour is usually used to make breads, chips, sweets, among other products.

Is there an antidote?

Yes. How you manage a case of cyanide poisoning often depends on how sick the patient is. 11 For example:

  • If the patient is completely unconscious, every attempt will be made to save his life. Several invasive measures may need to be performed to closely monitor and evaluate the person. The basic life support includes immediate administration of high flow oxygen, respiratory protection and cardiopulmonary resuscitation. Oxygen effectively counteracts the action of cyanide at the mitochondrial level. For its part, advanced life support includes mechanical ventilation, catecholamine, and infusion of sodium bicarbonate.
  • If the patient’s condition is not serious, a thorough investigation will be needed. If there is a strong suspicion of cyanide poisoning, a cyanide antidote kit (CAK) or hydroxocobalamin can be used. Although not a 100% successful cure, these antidotes can often prevent cyanide from further poisoning the victim. Hydroxocobalamin is considered the first-line antidote to manage cyanide poisoning, either from inappropriate ingestion of bitter cassava or from another cause.
  • When no alternative treatments are available, dicobalt edetate, an intravenous chelator of cyanide, is commonly used in some countries that helps remove this substance from the body (cobalt compounds work efficiently by transforming cyanide into stable non-toxic derivatives). It can have serious side effects such as seizures, anaphylaxis, low blood pressure, and abnormal heartbeats, hence it is only used when the diagnosis of cyanide poisoning is almost certain.
  • If the risk of actual cyanide ingestion is determined to be very low, the patient can be monitored for a few hours. If you look good enough, you may be sent home with instructions to return if any of the suspicious signs or symptoms occur.

Frequent questions

Besides cassava, what other edible plants contain cyanogenic glycosides?

These compounds are usually present in:

  • Plants of the Rosaceae family (seeds and internal pits in stone fruits or pips such as apricot, bitter almond, cherry, plum, peach, peach, pear and apple)
  • Bamboo shoots
  • Some legumes (chickpeas, limes)
  • Ground flaxseed
  • Anacardos
  • Alcoholic beverages made from stone fruits, among other examples. 12

Fortunately, only chronic or massive ingestion of any of these foods can cause serious cyanide poisoning.

Can acute poisoning after eating bitter cassava be treated at home?

No. Cyanide poisoning should never be treated at home. It is necessary to seek immediate medical attention.

What is the prognosis for a person who has suffered cyanide poisoning after eating bitter cassava?

It is difficult to determine the prognosis of a person who has been poisoned by eating cassava incorrectly, but this usually depends on how quickly they were taken to the hospital and how sick they were upon arrival. If timely medical care is provided and the patient is still awake and talking, the prognosis is almost always very good. It should be noted that there is still the possibility of developing late neurological problems.


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My name is Louise Hammond, and I am the creator of this website, a place to find information about tubers, bulbs and medicinal roots. In I show the properties, benefits, characteristics, photos and images, ways of growing and how to make delicious meals from starchy vegetables.