The one dietary prohibition stated plainly in the Sikh Rehat Maryada, the code of conduct maintained by the Shiromani Gurdwara Parbandhak Committee, is against kutha meat, meat from an animal killed slowly by ritual bleeding, the method used in both Muslim halal and Jewish kosher slaughter. What the code names instead as acceptable, for a Sikh who chooses to eat meat, is jhatka, a single strike meant to kill the animal instantly, a distinction about method rather than about the animal itself.
The prohibition is read by Sikh institutions as a marker of independence rather than a borrowed rule: rejecting kutha meat distinguished the Khalsa, the Sikh order founded by Guru Gobind Singh at the end of the seventeenth century, from the ritual slaughter customs of the Mughal court and from Islamic dietary law more broadly, at a period when Sikh and Mughal authority were in open conflict. The Nihang order, historically associated with Khalsa militancy, has been particularly linked with jhatka meat as a matter of identity rather than simple diet.
The Rehat Maryada was given its present written form in 1945, codifying practices and disputes that had circulated among Sikh reformers for decades before, and the kutha prohibition is the clause of it that speaks most directly to food.