Supplemental protein was previously used only by bodybuilders but now even most common eaters add more protein to their diet.

Manufacturers opt for protein sources for their ingredients rather than to animal sources such as dried egg whites or milk-derived casein and whey.
Executives of companies such as DuPont, Solazyme, and Roquette say the choice of ingredients has many causes such as rising dairy prices, demand for new ingredients in food and beverages, concerns about sustainability, and the popularity of heart-healthy diets based on plants.
Apart from soy, the king among plant proteins, there is demand for new ingredients derived from peas, other oil seeds, and even algae. A switch to plant proteins by those who can afford meat would go a long way to feeding the growing global population while using fewer of the planet’s resources.
Source-Medindia