The Toxic Culprit: ODAP and Its Conditions
At the core of the toxicity concern surrounding khesari dal is a naturally occurring neurotoxin known as beta-N-oxalyl-L-α,β-diaminopropionic acid, or ODAP. This amino acid analogue, found in varying concentrations within the seeds of Lathyrus sativus, acts as an excitotoxin that can damage motor neurons in the spinal cord and motor cortex. The risk of developing neurolathyrism is primarily tied to the following conditions:
- Chronic and Excessive Consumption: Lathyrism is not a result of occasional or moderate consumption. It historically surfaced during severe droughts and famines when poor, food-insecure populations relied on khesari dal as a staple, constituting more than 30% of their daily caloric intake for months.
- Genetic and Environmental Factors: The concentration of ODAP in khesari dal seeds is not static. It can vary significantly based on the specific variety of the legume, growing location, soil composition, and environmental stress like drought.
- Malnutrition: A malnourished state, particularly one lacking sufficient sulfur-containing amino acids like methionine and cysteine, appears to increase an individual's susceptibility to ODAP's toxic effects.
The Historical Context: The 1961 Ban and Its Reversal
India's blanket ban on the sale and storage of khesari dal in 1961 was a direct response to widespread outbreaks of lathyrism, particularly in regions like Madhya Pradesh, Uttar Pradesh, and Bihar, where it was a 'famine food'. However, the ban's effectiveness was limited, as cultivation often continued for personal consumption or as animal fodder. The ban's legacy highlighted the need for a more nuanced approach.
Following decades of research and a significant decrease in lathyrism cases due to improved food security, the Indian Council of Medical Research (ICMR) recommended lifting the ban. By 2015, the Food Safety and Standards Authority of India (FSSAI) was advised to approve the sale and storage of specific low-toxin varieties developed by agricultural research institutions. This move marked a shift towards harnessing the crop's nutritional benefits while mitigating risk through modern agricultural science and food safety protocols.
Mitigating the Risk: Safe Preparation and Modern Farming
While the historic risk is undeniable, several modern practices have emerged to make khesari dal consumption significantly safer. The key lies in reducing the ODAP content before it reaches the consumer.
Safe Preparation Techniques
- Boiling and Soaking: Research has shown that soaking the seeds in hot water for several hours followed by thorough washing and boiling can leach out a significant portion of the water-soluble ODAP toxin. Repeating this process, as traditionally done in some areas, can increase the removal efficiency.
- Steeping in Lime Water: A traditional detoxification method involves steeping the dal in a 2% slaked lime solution, which can also significantly reduce the ODAP content.
- Germination: Sprouting the seeds has also been shown to reduce the concentration of the neurotoxin.
Modern Agricultural Advances
- Low-ODAP Varieties: Agricultural scientists have successfully developed and released low-toxin varieties of khesari dal that retain its hardiness and nutritional value. These include varieties like 'Ratan' (Bio L 212) and 'Prateek' (LS 157-14).
- Intercropping and Mixed Diets: Promoting dietary diversity and avoiding monoculture farming of khesari dal ensures it is not consumed as the sole staple, a primary risk factor for lathyrism. Intercropping with cereals or other legumes helps ensure a balanced diet.
Khesari Dal's Nutritional and Therapeutic Potential
Beyond its reputation for causing lathyrism, khesari dal is a highly nutritious legume with several potential benefits now being explored by modern science.
Comparison: Khesari Dal vs. Other Pulses
| Feature | Khesari Dal (Lathyrus sativus) | Other Pulses (e.g., Masoor, Toor) |
|---|---|---|
| Protein Content | Very high (26-49%), often exceeding other pulses | High, but typically lower than khesari dal |
| Hardiness/Drought Resistance | Exceptionally high, thrives in harsh, low-input conditions | Varies by variety, generally less hardy than khesari dal |
| Waterlogging Resistance | Resistant, making it a valuable crop in flood-prone areas | Not typically tolerant of waterlogged conditions |
| ODAP Neurotoxin | Contains ODAP, requiring careful preparation | ODAP not present, generally safer for chronic consumption |
| Medicinal Potential | Contains L-homoarginine, shown to support cardiovascular health | Varies by pulse; rich in various minerals and fiber |
| Cost | Historically a low-cost, 'poor man's pulse' | Pricing fluctuates based on market and harvest |
L-homoarginine, a non-toxic amino acid in the pulse, shows promise as a vasodilator, potentially benefiting cardiovascular health by regulating blood pressure. Furthermore, some studies suggest that ODAP itself, in controlled doses, may possess neuroprotective properties, though this is still an area of research.
Conclusion
The question of whether khesari dal causes lathyrism is not a simple 'yes' or 'no.' Historical evidence shows that chronic, heavy consumption during famines, particularly without proper preparation and in a state of malnutrition, was the cause of widespread neurolathyrism outbreaks. However, modern agricultural advancements have produced low-toxin varieties, and scientific research has outlined effective detoxification methods like soaking and boiling.
Today, with increased food security and awareness, khesari dal can be considered safe for consumption as part of a diversified diet and with appropriate preparation. It presents a valuable, protein-rich resource, especially for regions prone to drought and flooding where it can serve as a resilient and nutritious food source. The demonization of khesari dal is giving way to a more balanced and scientific understanding, allowing its potential benefits to be responsibly utilized while effectively managing its risks.
