What foods cause neurolathyrism?

December 30, 2025 •

4 min read

Epidemics of neurolathyrism often followed periods of famine throughout history, when the drought-resistant grass pea (Lathyrus sativus) became the primary or sole food source for impoverished populations. This debilitating neurological disease, causing irreversible paralysis of the legs, is a historical and modern-day reminder of the dangers posed by toxic compounds within certain food plants.

Quick Summary

Neurolathyrism is a neurological disease resulting from the excessive and prolonged consumption of legumes from the Lathyrus genus, particularly the grass pea. It is caused by the neurotoxin β-ODAP, leading to spastic paralysis. Risk factors include high intake, poor nutrition, and inadequate food preparation.

Key Points

The Main Culprit: Prolonged and excessive consumption of the grass pea (Lathyrus sativus), particularly during famine, is the primary cause of neurolathyrism.
The Neurotoxin: The neurotoxin β-ODAP, found in grass pea seeds, is responsible for the motor neuron damage that leads to paralysis.
Preparation is Key: Simple processing methods like soaking and boiling can significantly reduce the concentration of the water-soluble toxin in grass pea seeds.
Balanced Diet is Protective: Mixing grass pea flour with other cereals, especially those containing sulfur amino acids, can lower the risk of developing the disease.
Higher Risk from Immature Seeds: Immature grass pea seeds contain a higher concentration of the β-ODAP toxin and should be avoided.
Avoid Misinformation: Neurolathyrism affects the nervous system, while the sweet pea (Lathyrus odoratus) causes a different condition, osteolathyrism, which impacts connective tissues.
Modern Challenge: Although largely historical in many regions, neurolathyrism still poses a risk in food-insecure parts of the world.

The Primary Culprit: Lathyrus Legumes

Neurolathyrism is primarily associated with the prolonged overconsumption of specific legumes belonging to the genus Lathyrus, especially the grass pea (Lathyrus sativus). This crop is also known by other names, including chickling pea, Indian pea, or kesari dal. Due to its hardiness and ability to thrive in harsh, drought-prone environments, it has historically been an important "insurance crop" for poor farming communities.

While Lathyrus sativus is the most notorious, other species in the genus, including Lathyrus cicera, Lathyrus ochrus, and Lathyrus clymenum, also contain the causative neurotoxin and can cause neurolathyrism if consumed in large enough quantities.

The Neurotoxin: β-ODAP

The toxicological cause of neurolathyrism is the neurotoxic amino acid β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP).

How β-ODAP Damages the Nervous System

β-ODAP acts as an excitotoxin and an analog to the neurotransmitter glutamate. In the brain, β-ODAP overstimulates glutamate receptors on motor neurons, a process known as excitotoxicity. This overstimulation leads to an influx of calcium into the cells, disrupting their normal function and ultimately causing them to die. This selective death of motor neurons, particularly in the spinal cord and motor cortex, leads to the characteristic symptoms of spastic paralysis.

Factors Influencing β-ODAP Concentration

Several factors can influence the level of β-ODAP in Lathyrus seeds:

Environmental Stress: Plants grown under drought conditions or other environmental stresses tend to produce higher concentrations of β-ODAP.
Growth Stage: Immature seeds can have a higher level of the toxin than mature ones.
Preparation Method: Cooking and processing can reduce the toxin content, while consuming raw or roasted seeds poses a greater risk.

Historical Context and Modern Relevance

Neurolathyrism is not a new disease. The first recorded instance may go back to ancient India, and Hippocrates also reportedly mentioned a neurological disorder linked to Lathyrus consumption in Greece. In Spain, during periods of famine, excessive consumption of almorta (grass pea) flour led to outbreaks of lathyrism, famously depicted in a print by Francisco de Goya. More recent epidemics occurred during famines in Ethiopia and Bangladesh, particularly in the 1970s and 1990s.

While largely eradicated in Western countries due to diversified diets, neurolathyrism remains a threat in certain impoverished and food-insecure regions of Ethiopia, Bangladesh, and Afghanistan. In these areas, persistent drought and poverty can force populations to rely on the resilient grass pea as a primary food source for months, leading to outbreaks.

Prevention and Mitigation Strategies

Given the irreversible nature of neurolathyrism, prevention is crucial. The risk can be significantly reduced through a combination of dietary and food-processing measures:

Diet Diversification: The most effective way to prevent neurolathyrism is to avoid prolonged, exclusive consumption of grass peas. A balanced diet that includes other cereals and protein sources minimizes the intake of β-ODAP and provides essential sulfur-containing amino acids (like methionine and cysteine), which are thought to have a protective effect.
Proper Processing: Since β-ODAP is water-soluble, cooking methods are key.
- Soaking: Soaking the seeds for several hours or overnight and then discarding the water can remove a significant portion of the toxin.
- Boiling: Boiling the seeds in fresh water is another effective method. Combining soaking and boiling provides the best results.
Breeding Low-Toxin Varieties: Agricultural researchers have developed new, low-toxin varieties of grass pea through selective breeding. Promoting the cultivation and use of these safer strains is an important long-term strategy for prevention.
Avoiding Immature Seeds: Because immature grass pea seeds have higher β-ODAP concentrations, they should be avoided for consumption.

Neurolathyrism vs. Osteolathyrism

It is important to distinguish neurolathyrism from osteolathyrism, another condition caused by the consumption of a different Lathyrus species. While neurolathyrism affects the nervous system, osteolathyrism affects connective tissues and the skeleton.


Feature	Neurolathyrism	Osteolathyrism
Causative Legume	Lathyrus sativus and related species	Lathyrus odoratus (sweet pea)
Toxic Compound	β-ODAP	β-aminopropionitrile (BAPN)
Primary Symptoms	Irreversible spastic paralysis, muscle rigidity	Skeletal deformities, aortic damage
Affected Tissue	Central nervous system, motor neurons	Connective tissues (bone, blood vessels)

Conclusion

The foods that cause neurolathyrism are primarily legumes of the Lathyrus genus, most notably the grass pea (Lathyrus sativus). The neurotoxin β-ODAP within these seeds can cause irreversible spastic paralysis of the legs, but only with prolonged, high-volume consumption, often exacerbated by malnutrition and poor food preparation. The risk of developing this devastating disease can be effectively mitigated through a combination of proper food processing techniques, dietary diversification, and the use of low-toxin varieties of the plant. As a highly resilient crop, the grass pea's potential to provide food security in challenging environments depends on continued efforts to manage and reduce its toxic effects safely.

Learn more about the research into β-ODAP and its properties here.

Frequently Asked Questions

The primary cause of neurolathyrism is the excessive and prolonged consumption of legumes from the Lathyrus genus, most notably the grass pea (Lathyrus sativus).

β-ODAP is a neurotoxin found in grass peas. It acts as an excitotoxin, overstimulating and causing the death of motor neurons in the spinal cord, which leads to spastic paralysis.

No, neurolathyrism typically occurs from prolonged and high-volume consumption of grass peas over a period of months, especially during times of famine when it forms a major part of the diet.

Processing methods such as prolonged soaking in water and thorough boiling can significantly reduce the water-soluble β-ODAP toxin from grass pea seeds.

Yes, combining grass pea flour with other cereals like wheat or maize dilutes the toxin concentration and provides compensating nutrients that help mitigate the toxic effects.

Neurolathyrism affects the nervous system and causes paralysis, while osteolathyrism is caused by a different toxin (BAPN) in sweet peas and affects connective tissues and bones.

Although rare in many developed regions, neurolathyrism still occurs in some areas prone to drought and famine, particularly in parts of Ethiopia, Bangladesh, and Afghanistan.