Lupin poisoning

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. 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.

Safe preparation

Safe preparation involves the following steps:

1. Soaking the bean overnight in four parts water to one part beans.
2. Draining, boiling in the same ratio of water to beans with salt for two hours.
3. Draining the beans and putting them in a bucket in an unused shower or laundry sink under a quickly running cold tap for seven to fourteen days until the bitter taste is gone from the beans and they are enjoyable to eat.
4. Boiling the beans with salt for two hours until the bean is no longer crunchy.
5. Pickling the beans in salt and vinegar and water brine, and keeping them refrigerated if proper canning hygiene is not followed.

The Italian and Portuguese tradition is to soak the beans for a week or two in a pillowcase or fabric bag in a stream.^[3]

Lupin alkaloid poisoning symptoms

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, in-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]

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.^[7]

Other toxic legumes

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.

• Grass pea, also known as chickling vetch – cause of lathyrism paralysis, and subject of Goya's painting Thanks to the Grass Pea, of starving and paralyzed peasants in the Peninsular War. Grass pea is now beginning to be sold in west coast North American health food stores along with spelt/farro as an artisanally produced, trendy ancient protein source. Do not eat this as a major part of your diet. It resembles a tiny flattened chick pea a little larger than a lentil, and is a great source of protein and neurotoxin. While the neurotoxic effects may not be obvious unless the pea is eaten as a large part of the diet for several months, it is not clear whether the effects are cumulative at lower consumption levels.
• Fava beans – rarely toxic to people, especially males, of Cretan origin, susceptible to favism, a rare genetic form of fatal hemolytic anemia.
• The castor bean – is not a legume but is instead a member of the spurge family, the Euphorbiaceae. It is often confused with legumes because of its common name. It is never sold for food as it contains an immensely toxic protein known as ricin, but is a source of castor oil for industrial use.

See also

• Alkaloids:
  • Lupinine
  • Sparteine
• Anticholinergic
• Lupin milk
• Sodium channel blockers
• Antiarrhythmic agents

References

External links

• Lupini beans recipe
• Lupini beans ???
• Agricultural research in lupins
• Lupin poisoning on Google Books – 1
• Lupin poisoning on Google Books – 2