In Jainism, the principle of ahimsa (non-violence) is central, and it guides dietary restrictions. Jains avoid eating foods that involve killing living beings or harming many life forms in the process of obtaining or consuming them.

Jackfruit is generally avoided by many Jains, especially among the stricter sects (like the Śvetāmbara and Digambara traditions), for the following reasons:

1. Many Seeds and Potential Life: When a jackfruit is opened, it contains numerous seeds, each of which is considered a potential life. Consuming jackfruit often involves destroying many such life forms, which goes against the Jain vow of ahimsa.

1. Multiple Organisms: The fruit also harbors many micro-organisms and insects within its sticky flesh, increasing the possibility of inadvertently killing small life forms during handling and consumption.

1. Rooted Plants: While jackfruit itself is not a root, Jains also avoid root vegetables because uprooting them kills the entire plant and disturbs many small organisms in the soil. Jackfruit, though a fruit, is similarly avoided due to the reasons above.

1. Traditional and Scriptural Guidance: Jain texts and traditional practices have identified certain fruits and vegetables as unsuitable for consumption due to the above concerns, and jackfruit is among them.

Therefore, jackfruit is not allowed in Jainism because eating it is believed to cause more harm to living beings, which directly contradicts the foundational Jain principle of non-violence.