The fruits and vegetables are widely acclaimed for their health benefits. The idea of consuming their tops may therefore seem natural, especially when we are looking to reduce food waste… But some leaves and other stems can put your health at riskas explained to us by Dr. Gaël Le Roux, toxicologist pharmacist at the Poison Control Center of the Angers University Hospital and Dr. Magali Labadie, head of the Poison Control Center of the Bordeaux University Hospital.
What are the most toxic vegetable leaves?
You have probably already used leaves beets, carrots, celery, turnip or of radish to make a pesto, a soup, or simply to enhance a dish? These tops, rich in vitamins and minerals, can in fact be used in zero waste kitchen to limit losses, but others should absolutely be avoided because of their toxicity.
“This is particularly the case with the leaves of fruits and vegetables belonging to the nightshade family “, warns Dr. Le Roux. And to recall: “This family of plants includes around 90 genera and more than 2,500 species of plants. It includes toxic plants such as belladonna or mandrake, but also many food plants.”
List: eggplants, peppers, potatoes, tomatoes…
The most toxic nightshade leaves at high doses are:
Why are nightshade leaves toxic?
“Solanaceae contain glycoalkaloids, including solanine and tomatinetwo chemicals that are toxic to humans,” Dr. Labadie replies. She elaborates: “These alkaloids are generally concentrated in the leaves and stems of eggplant, pepper, potato and tomato plants.” They act as natural defenses against insects, bacteria or fungi and can also cause a number of symptoms when ingested in large quantities by humans.
- In detail, the solanine interferes with cellular function by inhibiting acetylcholinesterase, an enzyme needed for the transmission of nerve signals. Its consumption can cause symptoms such as headache, nausea, vomiting, abdominal crampsand in severe cases, neurological disorders such as confusion, hallucinations, convulsions or even coma (very exceptional).
- Tomato is less toxic, but can still cause gastrointestinal and neurological symptoms!
Good to know: “Do not consume either potato fruits ! These types of green cherry tomatoes are very concentrated in glycoalkaloids and can make you sick,” warns Dr. Le Roux.
What about rhubarb?
Only the stems (petiole) of the rhubarb can be eaten as long as they are well cooked. As mentioned above, rhubarb leaves can be toxic. Why? They contain oxalic acid and anthraquinone glycosides which can cause burning in the mouth and throat, nausea, vomiting, abdominal pain, and kidney problems. “Oxalic acid interferes with the absorption of calcium in the body and can cause crystals to form in the kidneys, causing kidney pain and problems “, emphasizes Dr. Le Roux. In addition, anthraquinone glycosides stimulate intestinal mobility, leading to excessive loss of fluids and electrolytes (laxative effect).
Are these leaves really dangerous? Should we be worried?
The toxicity of vegetable leaves is often relative to the quantity consumed ! Accidental or small ingestion does not cause serious consequences, assure our experts. “Most people naturally avoid consuming nightshade leaves and spit them out because of their taste. But cases of food confusion can wreak havoc,” warns Dr. Labadie.
Accidental ingestion of small amounts of toxic leaves is rarely dangerous. However, ingestion of large amounts of leaves or repeated exposure can cause health problems, ranging from mild gastrointestinal disturbances to more serious complications such as kidney stones or neurological symptoms. Dr Gaël Le Roux.
What symptoms should alert you?
Symptoms of poisoning by toxic leaves vary depending on the substance ingested (i.e. the nature of the plant) and the quantity:
- dizziness,
- headache,
- muscular weakness,
- abdominal pain,
- nausea and vomiting,
- diarrhea.
In very rare cases, some patients may also present kidney problems, respiratory problemseven neurological disorders (confusion, hallucinations, etc.).
Complications: Are some people at greater risk?
As you will have understood, the risks are relatively low for the general public, in the event of accidental ingestion of small quantities. However, some people may be more vulnerable to the toxic effects of nightshades or rhubarb. Children, pregnant women, the elderly and people with health problems “People with kidney or gastrointestinal problems are at greater risk of serious complications. Their bodies generally have a harder time handling toxins, which can worsen the effects of poisoning,” warns Dr. Le Roux.
What precautions should be taken to avoid consuming toxic vegetable leaves?
- Buy fresh vegetables from reliable sources.
- Learn to identify the vegetables you eatespecially if you grow your own garden.
- Inform children of the dangers and watch the younger ones when they are near the garden or the kitchen.
- If in doubt about a plant or part of a plant, seek advice from gardeners, botanical societies or toxicologists.
- Use some gardening guidesof the botany books or some specialized applications to identify plants and their edible parts.
- Once in the kitchen, wash your vegetables well to remove any dirt or pesticide residue and remove inedible parts such as leaves.
- Store vegetables in proper conditions to prevent degradation and the formation of secondary toxins. In particular, potatoes should be stored in a dark, cool place to prevent the formation of solanine (which turns the skin of potatoes green).
Don’t try to do something new! Always take pictures of your harvest and only cook fruits and vegetables that you know. And if you have symptoms after eating suspicious leaves, contact a poison control center immediately or go to the emergency room. Dr. Magali Labadie.