In Jainism, the primary reason for dietary restrictions is the principle of ahimsa (non-violence) and the desire to minimize harm to all living beings, including tiny and unseen life forms.

Onion and garlic belong to the category of root vegetables. When these are harvested, the entire plant is uprooted, which results in the destruction of the plant and potentially many small organisms living in the soil around the roots. Additionally, Jain scriptures mention that root vegetables like onion and garlic contain an infinite number of microscopic life forms (nigodas), and consuming them causes greater harm to these lives.

Moreover, onion and garlic are considered tamasic (promoting darkness, ignorance, and passion) foods in Jain philosophy. They are believed to excite passions and hinder spiritual progress.

Groundnuts (peanuts), on the other hand, are seeds or legumes, not roots. They grow underground, but the plant itself is not destroyed when the pods are harvested; only the fruits (pods) are removed. The harm caused is considered significantly less compared to harvesting root vegetables. Also, groundnuts do not have the same tamasic properties as onion and garlic.

Thus, the distinction comes from both the degree of violence involved in harvesting and the spiritual effects of the foods, according to Jain teachings.