Lupin poisoning affects people that eat incorrectly prepared lupin beans.
Mediterranean cultures prefer the historic bitter lupin beans with the required toxin-removal by traditional leaching in water preparation methods due to the better flavour that results. Improper preparation of bitter lupini with insufficient soaking allows pharmacologically significant amounts of the anticholinergic alkaloids to remain in the beans, and poisoning symptoms result.
While the alkaloids found in raw and dried beans are bitter and unpalatable to many, with merely insufficient soaking the level is reduced. Some people like bitter herbs and may mistakenly prepare and eat lupini without enough soaking if they haven't learned of its unique preparation requirements. There are several references in medical literature to poisoning caused by errors in lupini preparation.[1][2] Dry lupini beans are rarely sold with instructions.
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Safe preparation involves the following steps:
The Italian tradition is to soak the beans for a week or two in a pillowcase or fabric bag in a stream.[3]
Symptoms of lupin bean poisoning (from excess alkaloid in cooked food) include dilated unresponsive pupils, confusion, slowed thought and disorientation, flushed face and/or fever, high heart rate and blood pressure, tremors, difficulty with or slurred speech, un-coordination, dizziness, burning dry mouth, stomach pain, and anxiety or "malaise".
Some of the symptoms are described in Biodiversity Canada's Lupin Bean listing:[4]
Many human symptoms are described in the Australian government's evaluation of lupin food and livestock fodder export safety standards in the medical literature review section:[5]
Current media describes the symptoms when referring to recent Australian Medical Journal reports of poisoning from overly bitter lupin flour used in foods reported in the media.[6][7]
Lupin bean poisoning is uncommon enough that poison control responders may not suspect it in Canada and the US. It is important to store dry lupini beans in their original container so that the label is present in case it must be identified if someone becomes ill from eating poorly prepared beans. The poisoned person may not remember what they ate during poisoning episode, and the bean preparation is long enough that confusion may result from the time lag alone.
White lupin beans closely resemble fava and lima beans and may be confused with a new variety of these by people who are not from the cultures familiar with traditional lupini preparation methods that ensure safety and minimize bitterness. Given increased public interest in multicultural ingredients, Mediterranean diets and legume eating for health (in a world where most legumes are safe to eat cooked as a major source of dietary protein without special preparation), a requirement for preparation instructions on lupin bean packaging at the retail level might be a good public health idea and avert accidental poisonings.
Lupins are very attractive flowering plants, and are often referred to as ornamental plants causing human poisoning in the legume family.[8]
The following legumes are part of food and fodder crops in many parts of the world and are toxic even when cooked. There are no known methods of preventing these toxicities other than avoiding consumption of the offending legume.