According to Jainism, the principle of ahimsa (non-violence) guides dietary choices. Jains strive to minimize harm to all living beings, including microorganisms. This is why many Jains avoid foods that involve killing or harming even the smallest life forms, such as root vegetables (which disturb soil organisms) and fermented foods.

Curd (yogurt) does contain bacteria, but traditional Jain dietary guidelines allow its consumption under certain conditions:

• Freshness: Jains typically eat only freshly set curd, made from boiled and cooled milk. It should be consumed within a few hours and not after sunset, as the number of bacteria increases with time.
• Intent and Awareness: The making of curd does not involve the intentional destruction of higher forms of life. The bacteria in curd are considered one-sensed beings (ekindriya jiva), and the harm is minimized by ensuring freshness.
• Fermented Foods: While fresh curd is permitted, other fermented products like old curd, cheese, or yeast-based foods are generally avoided because they contain a much higher concentration of living organisms and involve greater microbial proliferation.

In summary, Jains eat fresh curd as a practical allowance, balancing the principle of non-violence with day-to-day living, while taking care to minimize harm by consuming only freshly prepared curd and avoiding more harmful or older fermented foods.