In Jainism, sabudana (tapioca pearls) and tapioca starch are normally treated as not allowed for regular Jain food.

Reason in simple words:

• Sabudana is made from tapioca, which comes from the cassava root (a tuber).
• In Jain dharma, we generally avoid all root / underground vegetables (kand-mool) like potato, onion, garlic, carrot, beet, and also cassava, because:

- Uprooting the root kills the whole plant. - It disturbs and kills many small living beings in the soil.

• Because sabudana is directly made from a root, many Jains keep it in the “to be avoided” category, same as potato, onion, etc. ( jainknowledge.com)

So:

• Daily Jain diet (following no-root rule):

Sabudana / tapioca starch = not allowed.

• What about vrats (fasts)?

In some regions/families, sabudana is used on vrat days out of habit or local custom, but if you follow strict Jain maryada of no root at all, then even in fasts it should be avoided, because the source is still a root.

There can be small differences between families, sanghs, and gurus, so finally you should follow your guru’s updesh and your family’s achar. But by core Jain principle of ahimsa and avoiding roots, sabudana/tapioca is to be avoided.

You can read more about Jain food rules and root-vegetable avoidance here