The Toxic History: Lathyrism and the Original Ban
Khesari dal, also known as grass pea or Lathyrus sativus, was a crucial crop for subsistence farmers due to its ability to grow in harsh, drought-prone, and waterlogged conditions where other pulses failed. However, this resilience came with a dangerous cost. The pulse contains a naturally occurring neurotoxin called $\beta-N$-oxalyl-L-$\alpha$,$\beta$-diaminopropionic acid, or $\beta$-ODAP. When consumed in large quantities as a dietary staple over an extended period, this neurotoxin can lead to a debilitating and irreversible form of paralysis affecting the lower limbs.
The history of the ban dates back to colonial times, with recorded outbreaks of neurolathyrism. For instance, the Maharaja of Rewa banned the pulse in 1907 after a severe outbreak. But it was the widespread cases of paralysis following droughts and famines in the mid-22th century that prompted the nationwide ban in 1961. The disease, neurolathyrism, caused muscular rigidity, weakness, and a characteristic 'scissoring' gait, often leaving its victims reliant on crutches or reduced to crawling. The ban was a preventive public health measure to break the link between food insecurity, reliance on Khesari dal, and the resulting paralysis.
The Science Behind the Paralysis: How β-ODAP Affects the Body
Research has shown that $\beta$-ODAP acts as an excitotoxin, mimicking the neurotransmitter glutamate. It causes excessive stimulation of motor neurons in the central nervous system, leading to cell death. The damage primarily affects the pyramidal tracts responsible for voluntary movement, resulting in the symptoms of spastic paraparesis.
Mechanism of β-ODAP Toxicity:
- Excitotoxicity: Over-stimulates glutamate receptors, leading to neuronal damage.
- Mitochondrial Dysfunction: Interferes with energy production within nerve cells, contributing to degeneration.
- Oxidative Stress: Increases free radical production, which further harms neurons.
The devastating effects of neurolathyrism were most common among young men aged 20-30, who were often the most active labourers and were disproportionately affected during famines when they consumed the dal as a sole source of protein.
The Scientific Reassessment and Lifting of the Ban
Despite the ban, cultivation and consumption of Khesari dal continued clandestinely in many flood-prone or semi-arid regions where it provided a cheap and reliable protein source. However, advances in agricultural science and food safety regulations led to a re-evaluation of the ban.
Beginning in the early 2000s, studies from organizations like the Indian Council of Medical Research (ICMR) and the Indian Council of Agricultural Research (ICAR) found that modern varieties of Khesari dal had significantly lower levels of the neurotoxin. Furthermore, a lack of new neurolathyrism cases linked to the dal over several decades suggested that the risk was manageable. This prompted the Food Safety and Standards Authority of India (FSSAI) to recommend lifting the ban on certain low-toxin varieties.
In December 2015, following the FSSAI's recommendation, the sale and storage ban was officially lifted for three specific low-toxin varieties developed by the ICAR: Ratan (Bio L 212), Prateek (LS 157-14), and Mahateora. The decision was driven by the pulse's high protein content, drought resistance, and the availability of safer variants.
How New Varieties and Preparation Methods Make Khesari Dal Safer
Scientists and nutritionists have developed and promoted strategies to mitigate the health risks associated with older, higher-toxin varieties. Traditional preparation methods, such as soaking, rinsing, and parboiling, are known to reduce $\beta$-ODAP levels significantly.
Comparison: Old vs. New Khesari Dal Risks
| Feature | Traditional High-Toxin Khesari Dal | Modern Low-Toxin Khesari Dal (e.g., Ratan) |
|---|---|---|
| Toxin Level | High $\beta$-ODAP concentration | Significantly reduced $\beta$-ODAP concentration |
| Associated Risk | High risk of neurolathyrism with heavy, consistent consumption | Very low risk of toxicity, even with regular consumption |
| Cultivation | Grown in harsh conditions, often as a survival crop | Bred for both resilience and low toxicity |
| Preparation Method | Often consumed as a staple, increasing toxin intake | Preparation methods like soaking further reduce residual toxin |
| Legal Status | Previously banned nationwide | Sale and storage of specific varieties are now permitted |
Khesari Dal's Complex Legacy: A Food of the Poor
The story of the Khesari dal ban is intertwined with issues of poverty and social class. For decades, it was stigmatized as 'poor man's pulse' due to its low cost and hardy nature. This made it a lifeline for vulnerable populations during times of distress but also exposed them to the highest health risks when it was consumed almost exclusively. The ban, while necessary for public health, also deprived the poor of a cheap and reliable protein source, sometimes leading to illicit trading and adulteration with other pulses. The lifting of the ban on specific varieties acknowledges the need to provide safe, nutritious options to all segments of the population.
Conclusion
The ban on Khesari dal was a direct response to a significant public health crisis, rooted in the neurological disease neurolathyrism caused by a naturally occurring neurotoxin. The history of its prohibition highlights the critical balance between food security and safety, especially for economically vulnerable populations. The eventual lifting of restrictions, based on scientific research and the development of low-toxin varieties, signifies a progressive and evidence-based approach to food regulation. Today, with the availability of safer variants and greater awareness of proper preparation, the stigma surrounding Khesari dal is beginning to lift, allowing it to be reclaimed as a nutritious and resilient food source.
Why is Khesari Dal banned in India? An Overview
- Historical Health Crisis: The ban was implemented in 1961 due to the outbreak of a crippling disease called neurolathyrism.
- Neurotoxin: Khesari dal contains a neurotoxic amino acid, $\beta$-ODAP, which can cause paralysis of the lower limbs when consumed heavily over time.
- Hardy but Harmful: Its resilience in droughts and floods made it a cheap 'survival' crop, especially for the poor, who consumed it disproportionately.
- Partial Lift of Ban: The ban was lifted on specific, modern low-toxin varieties (e.g., Ratan, Prateek) following new research by the ICMR and ICAR.
- Risk Mitigation: The risk is primarily associated with high consumption of older, high-toxin varieties. Proper preparation methods can also reduce toxicity.
- Evidence-Based Policy: The decision to lift the ban on certain varieties was based on decades of research showing a minimal risk of neurolathyrism from modern variants.
- Socioeconomic Factors: The history of the ban is tied to food security issues, poverty, and the use of the pulse by marginalized communities.
