Clinical manifestations, such as swelling of the throat and difficulty swallowing, several hours after a meal, are reported to Poison Control Centers after consumption of wild asparagus. The study of the possible causes and mechanisms of this toxicity is ongoing. Be vigilant!
As a vinaigrette or as an accompaniment to a dish, wild asparagus, also called asparagus or Pyrenees ornithogale (Loncomelos pyrenaicus, Ornithogalum pyrenaicum), is a wild plant with almond green foliage, which is part of the Asparagaceae family. We eat its flower bud, shaped like a spike, for its flavor combining the aromas of asparagus, peas and artichoke. Between the end of April and the beginning of June, it is found in meadows, on embankments and in woods almost everywhere in mainland France and Corsica. This plant can also be grown in home gardens from commercially available seeds. For several years, it has been offered for sale in markets and in certain supermarkets. The first alerts were notified to the National Agency for Food, Environmental and Occupational Health Safety (ANSES) in 2019.
Wild asparagus is considered edible… until a possible ban
Although no studies have yet demonstrated toxicity in humans, Poison Control Centers have received reports of symptoms occurring after consumption in recent years. In May 2019, that of Nancy launched the alert after serious poisoning threatening the vital prognosis of an individual. Two hours after consuming wild asparagus, the man experienced a tight throat sensation with difficulty swallowing, followed by angioedema and generalized urticaria. Identical symptoms in his wife, but less intense. All this reinforced the hypothesis of food poisoning.
In total, after digging into the files, between 2010 and 2020 the Poison Control Centers recorded 37 meals of wild asparagus linked to poisoning. Of 66 guests, 73% experienced symptoms, mainly oropharyngeal pain (42%), a feeling of swelling in the mouth or throat (29%) and difficulty swallowing (29%). These symptoms appeared on average three hours after consumption, which differs from allergic reactions or immediate irritations.
In search of toxic compounds in a plant never before studied
To find out more about these poisonings, a study was carried out from 2022 to 2023 by the Nancy Poison Control Center and the pharmacognosy laboratory of the Faculty of Pharmacy in Paris, funded by ANSES. The wild asparagus consumed had all been freshly picked, then cooked in boiling water, steamed or sautéed in a pan. The quantities ingested, difficult to estimate precisely, varied between half an asparagus and 30 units. None of the patients had a history of food allergy. Symptoms appeared on average four hours after the meal. The signs reported were otorhinolaryngeal, such as difficulty swallowing, a feeling of pharyngeal or mouth edema. Angioedema was confirmed in one patient. Digestive, skin and respiratory symptoms were also observed.
Under the microscope…
Microscopic examination revealed a large quantity of mucilage, plant substances composed of polysaccharides (complex carbohydrates) which swell on contact with water and take on a viscous consistency. But the analysis highlighted the abundant presence of calcium oxalate raphides, microscopic crystals in the shape of fine needles, characteristic of many plants, particularly indoor plants (Araceae), which cause irritation upon contact with the skin. and mucous membranes is well known.
We also find sugars, fatty acids and sitosterol, a non-toxic sterol (a type of lipid) very common in plants.
Here is the researchers' hypothesis: the raphides, in the form of tiny needles, by planting themselves in the oropharyngeal mucosa, would cause mechanical irritation facilitating the entry of inflammatory or toxic substances. A high concentration of raphides would damage the mucosa, reducing its protection and causing inflammation, swelling and difficulty swallowing. These substances would not be destroyed by cooking. At this stage, the active compounds responsible for the inflammation have not been identified.
An explanation for the delayed protests
Asparagus mucilages may first trap raphides, gradually releasing them during digestion. This would explain why they are not immediately in contact with the oral and pharyngeal mucous membranes, hence the delayed symptoms after ingestion.
Researchers consider individual susceptibility to explain why some develop symptoms and others do not. Some people who have consumed wild asparagus in previous years without problems may either have been “sensitized” to certain substances or exposed to a higher concentration of irritants in the plant.
Should we continue to eat wild asparagus?
The growing sale of wild asparagus could lead to an increase in poisoning. ANSES is urging public authorities to consider specific measures, or even an outright ban on their sale. In the meantime, informing the general public and health professionals will help improve the reporting and documentation of poisonings.
If you experience symptoms after consuming wild asparagus, ANSES recommends contacting a Poison Control Center or consulting a doctor. And, in case of vital distress, to call 15 or 112 mentioning the consumption of wild asparagus.
