What is lathyrism due to intake of?

January 2, 2026 •

4 min read

According to the National Institutes of Health, devastating neurolathyrism epidemics have occurred during major famine crises, where a lack of alternative food sources leads to the overconsumption of toxic legumes. Lathyrism is an irreversible neurological condition caused by the prolonged intake of seeds from certain plants of the genus Lathyrus, such as the grass pea.

Quick Summary

Lathyrism is a crippling neurological disorder stemming from the long-term, excessive consumption of legumes containing neurotoxins, such as the grass pea (Lathyrus sativus). The condition, which can be irreversible, affects motor functions and is often associated with famine conditions.

Key Points

Cause: Lathyrism results from the excessive, long-term intake of legumes from the Lathyrus genus, particularly the grass pea (Lathyrus sativus).
Toxins Involved: Neurolathyrism is caused by the neurotoxin ODAP, while osteolathyrism and angiolathyrism are caused by BAPN.
Neurological Damage: ODAP acts as an excitotoxin, leading to the permanent and irreversible degeneration of motor neurons, causing paralysis.
Connective Tissue Damage: BAPN inhibits an enzyme critical for collagen cross-linking, resulting in skeletal deformities and fragile blood vessels.
High-Risk Groups: The disease is most prevalent in areas with food insecurity, famine, or drought, where access to a diverse diet is limited.
Prevention is Key: Detoxification methods like soaking and boiling, and mixing grass pea with other cereals, can significantly reduce the risk.
No Cure: Once established, the paralysis and physical deformities caused by lathyrism are typically permanent and irreversible.

What is Lathyrism?

Lathyrism is a serious and irreversible medical condition resulting from the consumption of specific plants belonging to the Lathyrus genus, particularly the grass pea (Lathyrus sativus). While humans are the most commonly reported victims, the disease can also affect animals such as horses and cattle. This condition is primarily associated with regions of the world where famine or drought forces populations to rely on drought-resistant crops like the grass pea as a primary food source. The severity of lathyrism depends on the quantity of legumes consumed, their toxin content, preparation method, and the individual’s overall nutritional status.

The Toxic Culprits: ODAP and BAPN

The root cause of lathyrism lies in the naturally occurring toxins found within certain species of the Lathyrus genus. The type of toxin ingested determines which form of lathyrism develops.

ODAP (β-N-oxalyl-L-α,β-diaminopropionic acid): This excitatory neurotoxin is found primarily in the grass pea (Lathyrus sativus) and is responsible for neurolathyrism. ODAP acts on the central nervous system, particularly the spinal cord and motor cortex, leading to the selective degeneration of motor neurons. The neurotoxic effects are aggravated by a diet deficient in sulfur-containing amino acids, such as methionine and cysteine, which are normally involved in detoxification.
BAPN (β-aminopropionitrile): This toxin is found in the seeds of the sweet pea (Lathyrus odoratus) and is the cause of osteolathyrism and angiolathyrism. BAPN inhibits the copper-containing enzyme lysyl oxidase, which is crucial for forming strong cross-links in collagen and elastin. This results in weak and fragile connective tissues.

How Neurotoxins Damage the Body

The specific mechanism of action for each toxin targets different physiological systems, leading to distinct symptoms.

ODAP and the nervous system: As an excitotoxin, ODAP overstimulates glutamate receptors in the brain and spinal cord, causing neuronal damage. This leads to the progressive death of motor neurons, which control muscle movement. The longest nerve pathways, which lead to the legs, are often the most severely affected. The damage is permanent and results in spastic paralysis.
BAPN and connective tissue: BAPN disrupts the formation of stable collagen and elastin, affecting bones, cartilage, and blood vessels. In osteolathyrism, this leads to weakened bones and skeletal deformities. In angiolathyrism, the same toxin can damage the blood vessels, with severe cases leading to aortic aneurysms.

Comparison of Lathyrism Types


Feature	Neurolathyrism	Osteolathyrism / Angiolathyrism
Primary Cause	Overconsumption of grass pea (Lathyrus sativus) seeds.	Overconsumption of sweet pea (Lathyrus odoratus) seeds.
Toxic Compound	ODAP (β-N-oxalyl-L-α,β-diaminopropionic acid).	BAPN (β-aminopropionitrile).
Affected Tissues	Motor neurons of the central nervous system, especially the spinal cord and motor cortex.	Bones, cartilage, and blood vessels (connective tissues).
Key Symptoms	Spastic paralysis of the legs, weakness, muscle atrophy, and a scissoring gait.	Skeletal deformities, bone pain, aortic aneurysms, and weakened connective tissue.
Reversibility	Irreversible and non-progressive once consumption is stopped.	Generally irreversible.
Associated Factors	Famine, drought, and malnutrition, particularly diets low in sulfur amino acids.	Malnutrition and excessive intake of sweet peas.

Prevention and Management

As there is no cure for lathyrism once the neurological damage has occurred, prevention is paramount. For at-risk populations dependent on Lathyrus legumes, several strategies can mitigate the danger:

Awareness and Education: Educating communities on the risks associated with excessive consumption of these legumes is a crucial first step. The toxic effects are often not known to the people most at risk.
Detoxification Methods: Proper food preparation can significantly reduce the toxin levels. Methods include soaking the seeds in water overnight, boiling them, and discarding the water. Roasting the seeds can also be effective. However, in drought-stricken areas, water scarcity can make these processes difficult.
Dietary Diversification: Mixing grass peas with other cereals or legumes, or consuming a diet rich in sulfur-containing amino acids, can help counteract the toxic effects. This reduces the overall concentration of toxins in the diet and provides protective nutrients.
Breeding Low-Toxin Varieties: Agricultural research has focused on developing low-toxin strains of Lathyrus legumes. These new varieties provide the same drought resistance and nutritional benefits without the high risk of toxicity.

Conclusion

Lathyrism is a severe and irreversible condition caused by the excessive, long-term intake of certain legumes containing specific toxins, such as ODAP and BAPN. This disease is a public health issue in regions facing famine and food insecurity, where people are forced to rely on drought-resistant crops like the grass pea. Understanding the toxins and their different effects—neurological in the case of ODAP and connective tissue-related for BAPN—is essential for prevention. While there is no cure, proper food preparation, dietary diversification, and the development of low-toxin plant varieties offer effective strategies for protecting vulnerable populations. By addressing the socio-economic factors that lead to overconsumption of these legumes, it is possible to prevent the permanent disabilities caused by lathyrism.

To learn more about the role of diet and nutrition in public health crises, visit the World Health Organization (WHO) website.

Frequently Asked Questions

Lathyrism is a disease caused by the long-term, excessive consumption of legumes from the Lathyrus genus, particularly the grass pea (Lathyrus sativus), which contains the neurotoxin ODAP.

Neurolathyrism is caused by the neurotoxin β-N-oxalyl-L-α,β-diaminopropionic acid (ODAP), which is found in the grass pea (Lathyrus sativus).

Symptoms typically include muscle weakness and rigidity in the legs, a scissoring gait, and spastic paralysis. Other forms can cause bone pain and skeletal deformities.

No, once the neurological or connective tissue damage has occurred, lathyrism is considered irreversible. Discontinuing the intake of the toxic legume can prevent the condition from worsening.

The toxins can be reduced through proper food preparation methods, such as soaking the seeds overnight, boiling them in water, and discarding the water.

During famine and drought, populations may rely heavily on drought-resistant crops like the grass pea. Without other food sources, this leads to the prolonged overconsumption of the toxic legumes.

Neurolathyrism affects the motor neurons and nervous system due to the toxin ODAP. Osteolathyrism affects the connective tissues and bones due to the toxin BAPN, which is found in sweet peas (Lathyrus odoratus).