In Jainism, the dietary principles are very strict to avoid harm (ahimsa) to living beings. Most Jains, especially followers of the Shvetambara and Digambara traditions, avoid eating root vegetables like onions, garlic, and potatoes. This is because these vegetables grow underground and their harvesting causes harm to small organisms and the entire plant, which goes against the principle of non-violence.

So yes, the majority of Jains do not eat onions. This practice helps in minimizing harm to life and is part of their commitment to non-violence and purity in diet. However, there may be some minor variations in individual practices, but traditionally, onions are avoided by all strict Jains.