|
It's fascinating to me that some toxic plants can be eaten, if prepared in just the right way. I mean, how many people died before they figured out the right method of preparation? How hungry were these people, that they were even eating poisonous stuff? Human ingenuity can be pretty breathtaking, especially in times of great need. I got the idea for this webpage when flipping through the Joy of Cooking one day. It opened to the page about akee, a fruit that is poisonous unless it has ripened to the point of opening up. That got me to wondering how many other foods are potentially toxic. After a few hours of Googling, I had a good chunk of information on the subject, and it might as well be open for public viewing. If you want to add some information, correct something, ask questions, etc, go ahead and mail me. Disclaimer One: All information is copyrighted by its listed source. The text is mostly copy-and-pasted from its source, but I have tweaked and rewritten sentences here and there, for brevity and clarity. Disclaimer Two: Please do not use this page as a guide on how to eat random wild plants. I've tried to present accurate information, but I'm not absolutely certain that the preparation guidelines listed here will result in non-toxic food. I don't want people to get sick from trying stuff on this page. Please use a proper plant guide, manual, survival handbook, recipe book, etc. Also... PLEASE do not try to poison yourself or anyone else with this information. I am not responsible for misuse of the information on this page that might lead to injury or death. The information here is intended to help people protect themselves from unintentional poisoning. page last modified: May 21, 2004. Index:
how to find out if an unknown plant is edible An excerpt from Ken Larson's book, "God's Free Harvest - Successful Harvesting Nature's Free Wild Foods".
"I do use the following methods when I am trying a newly identified plant. To begin with, do not use an unidentified plant unless nutrition needs have become a matter of life and death. If ever in this situation, various military manuals recommend the following general guidelines of testing the unidentified plant: Inspect - Ensure plant is not slimy. Smell - Crush a small portion. If it smells like bitter almonds or peaches, do not try. Skin Irritation - Rub the plant or its juice on a small tender skin area. Do not use if a rash or swelling is experienced. In the case of poison ivy or oak, the rash takes several days to leave. Eating - Cook all plants if there is a question as to edibility. At each of the following steps stop if there is any unpleasant reaction. First, prepare a cooked sample and take a very small amount and place on the lips. Wait 5 seconds. Then take a small amount and chew it. Hold it in your mouth for 5 minutes. If it still tastes okay, go ahead and eat a small quantity. If the taste is disagreeable, do not eat it. Remember that olives are bitter and grapefruit is sour, so an unpleasant taste does not, in itself, mean poison. A burning, nauseating, or bitter taste is a warning of danger. A small quantity of even a poisonous food is not likely to prove fatal, where a larger quantity may be. (Does not apply to mushrooms). Finally, wait five hours before proceeding further and do not drink or eat anything else. Remember to cook all plants when in doubt about their edibility. Obviously, for medical help in an urban situation you will call 911 but in a remote area, the following emergency tips may be useful: When away from a doctor, should stomach trouble occur, drink plenty of hot water and do not eat again until pain goes away. If the pain is severe, induce vomiting by tickling the back of the throat with your finger. Swallowing some crushed charcoal will induce vomiting while the charcoal may also absorb the poison. Wood ashes mixed to a paste with water and swallowed will relieve stomach pain and diarrhea." Morton, J. 1987. Akee. p. 269-271. In: Fruits of warm climates. Julia F. Morton, Miami, FL. "[This fruit is called] ackee, akee apple, or vegetable brain (seso vegetal in Spanish). Other Spanish names are arbol de seso, palo de seso (Cuba); huevo vegetal and fruto de huevo (Guatemala and Panama); arbor del huevo and pera roja (Mexico); merey del diablo (Venezuela); bien me sabe or pan y quesito (Colombia); akí (Costa Rica). In Portuguese, it is castanha or castanheiro de Africa. In French, it is arbre fricassé or arbre a fricasser (Haiti); yeux de crabe or ris de veau (Martinique). In Surinam it is known as akie. On the Ivory Coast of West Africa, it is called kaka or finzan; in the Sudan, finza. Elsewhere in Africa it is generally known as akye, akyen or ishin, though it has many other dialectal names. The akee is indigenous to the forests of the Ivory Coast and Gold Coast of West tropical Africa where it is little eaten but various parts have domestic uses. In Ghana, the fruiting tree is admired as an ornamental and is planted in villages and along streets for shade. The akee was brought to Jamaica in 1793 by the renowned Captain Bligh to furnish food for the slaves. It was readily adopted and became commonly grown in dooryards and along roadsides and, to some extent, naturalized. The arils still constitute a favorite food of the island and the fruit is featured in a calypso despite the health hazards associated with it. The akee must be allowed to open fully or at least partly before it is detached from the tree. When it has "yawned", the seeds are discarded and the arils, while still fresh and firm, are [cooked and eaten]. The toxicity of the akee was long misunderstood and believed to reside in the membranes attaching the arils to the jacket, or only in the overripe and decomposing arils. There have been intensive clinical and chemical studies of the akee and its effects since 1940, and it is now known that the unripe arils contain hypoglycin, a-amino-B-(2-methylenecyclopropyl) propionic acid, formerly called hy poglycin A. This toxic property is largely dispelled by light as the jacket opens. [...] The seeds are always poisonous." from bagelhole.org: "Oak trees have alternate leaves and acorn fruits. They are found in many habitats throughout North America, Central America, and parts of Europe and Asia. All parts of the acorn are edible, but often contain large quantities of bitter substances. White oak acorns usually have a better flavor than red oak acorns. Gather and shell the acorns. Soak red oak acorns in water for 1 to 2 days to remove the bitter substance. You can speed up this process by putting wood ashes in the water in which you soak the acorns. Boil the acorns or grind them into flour and use the flour for baking. You can use acorns that you baked until very dark as a coffee substitute. CAUTION: Tannic acid gives the acorns their bitter taste. Eating an excessive amount of acorns high in tannic acid can lead to kidney failure. Before eating acorns, leach out this chemical." from "The Joy of Cooking" by Irma S. Rombauer and Marion Rombauer Becker: "Almonds come in two varieties, sweet and bitter. Sweet almonds (the usual kind you can buy) are good to eat. Bitter almonds are only used in small quantities for flavouring, as they can be harmful to your health." Another source, "Food in History", says: "People have been poisoned by [...] the prussic acid in bitter almonds." Judi & Carl Manning, Owashtanong Islands Audubon Society.
"Even though bracken ferns are eaten by many people, they have been found to contain many cancer-causing substances and toxins. This fern may be responsible for the high incidence of stomach cancer in Japan, New Zealand, and the U.S." Time-Life Encyclopedia of Gardening: Bulbs. James Underwood Crockett. New York, 1971. p. 67. "A bulb that flowers in late spring and early summer, it is rarely seen in American gardens, although it was here to greet the first colonists and was prized by the Indians, who fried its bulbs, which are poisonous when raw, and ate them. (The name "camassia" derives from the Indian word "quamash," which is still used as one of its common names.) It grows everywhere from Pennsylvania to the Pacific Coast and from Minnesota to Texas; it produces starlike blue, purple or white blossoms atop stalks 1 1/2 to 3 feet tall." from SurvivalIQ.com, based on 'U.S. Army Survival Manual', a public domain work published by the U.S. Department of Defense. "The cashew is a spreading evergreen tree. Its fruit is very easy to recognize because of its peculiar structure. The fruit is thick and pear-shaped, pulpy and red or yellow when ripe. This fruit bears a hard, green, kidney-shaped nut at its tip. This nut is smooth, shiny, and green or brown according to its maturity. The cashew is native to the West Indies and northern South America, but transplantation has spread it to all tropical climates. In the Old World, it has escaped from cultivation and appears to be wild at least in parts of Africa and India. The nut encloses one seed. The seed is edible when roasted. The pear-shaped fruit is juicy, sweet-acid, and astringent. It is quite safe and considered delicious by most people who eat it. CAUTION: The green hull surrounding the nut contains a resinous irritant poison that will blister the lips and tongue like poison ivy. Heat destroys this poison when roasting the nuts." Another source, D. Weinberger at http://www.hyperorg.com/blogger/mtarchive/002011.html, says: "Handling the cashew shell or eating a nut with shell oil on it can cause a reaction. You really don't want to touch the stuff between the two layers of shell... it is extremely caustic and can cause blistering of the skin upon contact. It is used in the making of varnish, insecticide, paint, and even rocket lubricant." cassava / manioc / tapioca (Manihot utillissima) Joan & David Peterson. "Eat Smart in Brazil: How to Decipher the Menu, Know the Market Foods & Embark on a Tasting Adventure." Ginkgo Press, Inc. "When the Portuguese arrived in the early 1500s, the main staple of the natives was manioc, a carbohydrate-rich food that is easy to propagate but difficult to process, at least for the bitter variety, which is poisonous when raw. It is astonishing that the Indians determined these tubers were edible at all. To be detoxified, tubers had to be peeled and grated and the pulp put into long, supple cylinders, called tipitis, made of woven plant fibers. Each tube was then hung with a heavy weight at the bottom, which compressed the pulp and expressed the poisonous juice. The pulp could then be removed, washed and roasted, rendering it safe to eat. The product was a coarse meal or flour known as farinha de mandioca (manioc meal), which is as basic to the diet of Brazilians today as it was to the early Indians. It is a ubiquitous tabletop condiment. Starch settling out from the extracted juice was heated on a flat surface, causing individual starch grains to pop open and clump together into small, round granules called tapioca. The extracted juice, boiled down to remove the poison, was used as the basis of the sauce known as tucupi. The non-poisonous tubers of sweet manioc, which are somewhat fibrous but considerably easier to prepare; are pared, boiled for several hours to soften them and eaten like potatoes. Strips of manioc are also deep-fried and eaten like French fries." Another source, Barbara Mikkelson from Urban Legends Reference Pages (snopes.com), says: "The cassava root, a vegetable favored by many in Africa, is a natural source of cyanide. (Westerners know this plant best as tapioca.) Drying, soaking, and baking cassava roots renders its cyanide precursor, linamarin, harmless, but if that process is not carried out properly the cassava can remain poisonous." Another source, bagelhole.org, says: "Manioc is a perennial shrubby plant, 1 to 3 meters tall, with jointed stems and deep green, fingerlike leaves. It has large, fleshy rootstocks. It is widespread in all tropical climates, particularly in moist areas. Although cultivated extensively, it maybe found in abandoned gardens and growing wild in many areas. The rootstocks are full of starch and high in food value. Two kinds of manioc are known: bitter and sweet. Both are edible. The bitter type contains poisonous hydrocyanic acid. To prepare manioc, first grind the fresh manioc root into a pulp, then cook it for at least 1 hour to remove the bitter poison from the roots. Then flatten the pulp into cakes and bake as bread. Manioc cakes or flour will keep almost indefinitely if protected against insects and dampness. CAUTION: For safety, always cook the roots of either type." from http://t230.com/poison_plants.htm: "Cow parsnip is often confused with wild celery. Important note: In some plant texts this plant is listed as a wild edible, because if harvested with gloves using extreme care the non-flowering stalks are edible in the very early spring. Very irritating; may cause itching and rash, and small blisters are possible. People's sensitivity varies; some aren't bothered at all. Burning cow parsnip may irritate the lungs; breathing the burning smoke can result in internal blisters and can possibly lead to death; children have been severely affected by throwing stalks on campfires and by handling the foliage. This plant is dangerous."
from CDC MMWR Weekly, May 17, 1996; 45(19); 389-391 . "The order Tetraodontoidea includes ocean sunfishes, porcupine fishes, and fugu, which are among the most poisonous of all marine life. These species inhabit the shallow waters of the temperate and tropical zones and can be exported from China, Japan, Mexico, the Philippines, and Taiwan. The liver, gonads, intestines, and skin of these fish contain tetrodotoxin, a powerful neurotoxin that can cause death in approximately 60% of persons who ingest it. Tetrodotoxin is heat-stable and blocks sodium conductance and neuronal transmission in skeletal muscles. Paresthesias begin 10-45 minutes after ingestion, usually as tingling of the tongue and inner surface of the mouth. Other common symptoms include vomiting, lightheadedness, dizziness, feelings of doom, and weakness. An ascending paralysis develops, and death can occur within 6-24 hours, secondary to respiratory muscle paralysis. Other manifestations include salivation, muscle twitching, diaphoresis, pleuritic chest pain, dysphagia, aphonia, and convulsions. Severe poisoning is indicated by hypotension, bradycardia, depressed corneal reflexes, and fixed dilated pupils. Diagnosis is based on clinical symptoms and a history of ingestion. Treatment is supportive, and there is no specific antitoxin. Although personal importation of fugu into the United States is prohibited, FDA has permitted fugu to be imported and served in Japanese restaurants by certified fugu chefs on special occasions. A cooperative agreement with the Japanese Ministry of Health and Welfare ensures fugu is properly processed and certified safe for consumption before export by the government of Japan. If cleaned and dressed properly, the fugu flesh or musculature is edible and considered a delicacy by some persons in Japan, who may pay the equivalent of $400 U.S. for one meal. Despite careful preparation, fugu remains a common cause of fatal food poisoning in Japan, accounting for approximately 50 deaths annually." grapefruit juice (mixed with medicines) from fitresource.com: "According to the National Consumers League and the FDA, there are potential problems with mixing medicines with common foods and supplements. These interactions aren't commonly known, but can be serious. Some examples: Grapefruit juice and blood pressure medicines known as calcium channel blockers. These drugs include but are not limited to Sular, Adalat, Procardia and Plendil. Grapefruit juice should be avoided for 2 hours before and 5 hours after taking these medications. Can be deadly. Grapefruit juice with immunosuppressants such as FK-506 and cyclosporin. Causes confusion and trembling. Grapefruit juice with antihistamines such as Hismanal. Grapefruit juice with benzodiazepines. These include Halicon (sleeping pill), Xanax (anxiety drug) and Versed (a sedative). Grapefruit juice and HIV/AIDS drugs known as protease inhibitors including Crixivan, Invirase and Norvir." Janet Raloff. "When Drought Reigns, Diets Can Turn Poisonous."
"Due to severe drought, some people in Ethiopia are making the grass pea-a cousin of the sweet pea-a dietary staple. Patak is the local name for grass pea. Although that sounds benign, it could be dangerous. Ordinarily, herders plant this legume as forage for their livestock. And in small quantities, the grass peas-the plant's seeds-are safe ingredients of recipes of cuisines from Afghan to Chinese. As such, the legume serves as a low-cost base for stews, breads, and gruel. However, when eaten to excess-as happens in arid Ethiopia and many other regions of the world when drought persists-grass-pea consumption may lead to permanent paralysis because the seeds contain an unusual neurotoxin. Although many people in sub-Saharan Africa and elsewhere are aware of the grass pea's hazard, during drought they confront a Hobson's choice: starve or eat more of one of the only foods available. The enduring irony is that the protein-rich grass pea is one of the few arid-region crop plants to thrive when drought sets in. Moreover, when food is scarce, robust men usually receive the biggest portions to support their breadwinning activities. So, the individuals most important to a community's survival are often the first ones felled by the grass pea's poison. The grass pea (Lathyrus sativus) produces an unusual amino acid known as beta-N-L-alpha-beta-diaminopropionic acid, or ODAP. While this compound may provide the legume some resistance to pests or climatic extremes, it is a potent neurotoxin. It appears to kill mammalian nerve cells-especially those in the legs-through overstimulation. One of the first symptoms of ODAP poisoning-or lathyrism-is weakening and spasticity of the legs. If the condition is allowed to progress, the victim will eventually be reduced to crawling. Wheel chairs aren't an option for most lathyrism sufferers, as they tend to live in dirt-floor huts in rural communities with no paved roads. Writing in the Nov. 29 Lancet, Fernand Lambein of Ghent (Belgium) University and his colleagues show that even when large quantities of grass peas are regularly consumed, mixing them with other cereals can substantially diminish the risk that the grass-pea toxin will paralyze people. Many studies have shown that soaking grass peas prior to cooking can leach out ODAP. So, nutritionists have recommended that cooks pretreat the legumes this way and pitch the water. Unfortunately, areas suffering from drought can't spare the water to do this." Judi & Carl Manning, Owashtanong Islands Audubon Society.
"The following common species contain volatile oils and could be harmful in large doses (over 0.4 oz): nutmeg, cinnamon, cloves, mint, black pepper, rosemary, sage, and sassafras." malanga (Xanthosoma caracu) from bagelhole.org: "Malanga has soft, arrow-shaped leaves, up to 60 centimeters long. The leaves have no aboveground stems. It grows widely in the Caribbean region. Look for it in open, sunny fields. The tubers are rich in starch. Cook them before eating to destroy a poison contained in all parts of the plant. WARNING: Always cook before eating." marsh marigold (Caltha howellii, Caltha palustris) Edible Sierra Nevada Plants (www.backcountryrangers.com) "Marsh marigold leaves are best collected in springtime. Cooking destroys the poison helleborin which is contained in the leaves." Another source, bagelhole.org, says: "This plant has rounded, dark green leaves arising from a short stem. It has bright yellow flowers. It is found in bogs, lakes, and slow-moving streams. It is abundant in arctic and subarctic regions and in much of the eastern region of the northern United States. All parts are edible, but only if boiled." from the USDA meat and poultry hotline: "The only mouldy foods that are safe to use are hard cheeses and hard fruits/vegetables, and only if you cut off all of the mould plus 1 inch around it." from Poisonous Plants of California: "Of all poisonous plants in California, toxic mushrooms cause the most serious illnesses and nearly all the fatalities to humans. Those who gather and eat mushrooms should use every precaution to ensure that their mushrooms are correctly identified and known to be edible." Another source: information from a sheet on Poisonous Mushrooms, handed out in the mid-1990s to my high-school biology class. "Mushrooms may contain a whole bunch of toxic substances. These are just a few. Deadly toxins: these stop the cells from making messenger RNA, so they can't produce proteins anymore. It takes 5-24 hours to start showing symptoms. It can lead to liver and kidney failure, and heart lesions. No antidote exists. Monomethyl-hydrazines: these interfere with vitamin B6, involved in amino acid metabolism. There is no antidote. Symptoms take 7-10 hours to show. Death is inevitable in two to four days, but at least you can reduce the convulsions with some medication. Coprines: they block some enzyme activity, leading to a rise then drop in blood pressure, dizziness, nausea, vomiting, and fainting. Muscarines: affect the autonomic nervous system. They may lead to coma due to a lack of oxygen to the brain. Ibotenic acid/muscimol: interferes with important amino acids connected to the central nervous system. This leads to drunken/deranged/delirious activity, and a death-like sleep accompanied by visions." In other words, if you're not ABSOLUTELY sure that a mushroom is edible, don't eat it. http://www.manataka.org/page171.html "The cooked young shoots of this plant are edible, but the raw leaves and berries can cause a severe reaction. Only the YOUNG shoots are edible once cooked. Toxicity increases as the plant grows older. Symptoms: Stomach cramps, nausea, vomiting, diarrhea, hard breathing, weakness, spasms, convulsions and death." from "The Joy of Cooking" by Irma S. Rombauer and Marion Rombauer Becker: "Don't use sprouted potatoes that are green from exposure to light, as the green portions as well as sprouts are poisonous." Another source: Matthew Rabuzzi, www.urbanlegends.com : "Green potatoes contain solanin. W3NI describes a solanin as a bitter toxic alkaloid like the soapy saponins. It comes from potato sprouts and eyes, and other members of the nightshade family such as belladonna, bittersweet, and henbane. Oh, as far as the greenness of potatoes goes, it's not a vivid viridian, it's just a greenish cast to the skin (and perhaps a millimeter deep of the flesh), so examine 'em carefully. Better yet, keep 'em in the dark, as it is exposure to light that produces the solanins." Judi & Carl Manning, Owashtanong Islands Audubon Society.
"Rhubarb leaves contain oxalic acid. Eating large amounts causes an accumulation of oxalic acids and salts in the body, which causes mechanical damage in the kidneys and other organs." Judi & Carl Manning, Owashtanong Islands Audubon Society.
"Sassafras contains safrole, a volatile oil, which ingested in large concentrations causes liver tumors. Consequently, it is no longer used to flavor root beer." seeds and pits (apple, apricot, cherry, peach, plum) Barbara Mikkelson, Urban Legends Reference Pages (snopes.com ): "Apple pips (seeds) contain amygdalin, a cyanide and sugar compound that degrades into hydrogen cyanide (HCN) when metabolized. Cyanide itself is a poison that kills by denying blood the ability to carry oxygen and thereby causes its victims to die of asphyxiation. At least within the realm of murder mysteries, cyanide is the darling of poisoners because it acts quickly and irrevocably - once a fatal dose has been ingested, there is no effective antidote, and death takes place within minutes. Cyanide is sometimes described as having a bitter almond smell, but it does not always give off an odor, nor can everyone detect the scent. The body can detoxify cyanide in small doses, and the number of apple seeds it takes to pack a lethal punch is therefore huge. Cherry, peach, and apricot pits also contain amygdalin; the latter two, at least, in potentially harmful amounts." Another source: Judi & Carl Manning, Owashtanong Islands Audubon Society.
"Apricots, cherry, plums - avoid eating the seed kernels. Peach -- the pits release cyanide, if chewed." Alan K. Done, M.D. "Malevolent Edibles." Emergency Medicine, volume 10 number 2, February 1978, p. 256-258. Spinach contains nitrates. Once spinach is cooked, its nitrates are converted to nitrites over time. Adults are able to process these compounds just fine, but infants 2 to 10 months old may be unable to process large quantities of them. If infants eat too much nitrites, the hemoglobin in their blood might be altered. This makes their blood temporarily less able to do its job of transporting oxygen. Infants can usually eat freshly cooked spinach with no problems. However, leftover spinach, eaten a day or more after it was cooked, could lead to problems. Judi & Carl Manning, Owashtanong Islands Audubon Society.
"The green parts of the tomato plant cause digestive upset and can be fatal." From www.geocities.com/WahyaUdoi/POISON.html: "Even though the berry pulp of the yew is edible, all other parts of this evergreen tree or shrub are poison, especially the seeds." Send me some email, why don't you. Or, take a look at some of the other content here on my website.
|