New Delhi, Sept. 28 -- The latest US-Canada trade tensions are hitting an unlikely corner of the food market: whey protein.

Whey, a by-product of cheese-making, is a key ingredient in protein powders, shakes, snacks, and increasingly popular high-protein foods. Now, manufacturers on both sides of the border are scrambling to deal with tariffs and restrictions that could make the ingredient more expensive and harder to source.

The US is set to prohibit imports of several Canadian dairy products, including certain whey products, from 29 September. The move follows Washington's decision to impose additional duties on Canadian dairy products, while Canada has responded with its own tariffs on US goods.

The Canadian government has listed wh...