Soybeans are one of the few plant-protein sources that offer all of the essential amino acids. The protein is concentrated or isolated after the soybeans have been hulled and dried into soy flour (which also makes for delicious pancakes!).
Pros: Protein from the soybean may help improve the body's immune function and promote bone health. Soy may also help prevent cardiovascular disease and reduce the risk of certain cancers.
Cons: In recent years, soy has come under heavy scrutiny because it is often genetically modified to produce greater crop yields. Some research has also singled out soy due to its effects on hormone levels. Many foods are already full of soy due to its extremely low-cost protein. This has led some to question whether adding even more dietary soy (via protein supplements) is a wise choice.
News flash: There is protein in rice! Although often thought of as a carbohydrate only, brown rice is becoming a standard source for vegetarian protein powder.
Pros: Protein aside, brown rice protein is considered a good source of complex carbohydrates, vitamin B and fiber. It's also hypoallergenic, meaning it's easily digestible and therefore almost entirely used by the body, not relieved as waste.
Cons: Unlike soy, rice protein is a plant-based option that's deficient in some amino acids and therefore should not comprise the main source of dietary protein.
Hemp protein is derived from the seeds of the cannabis plant that's gained popularity in recent years. (And yes, we are talking strictly about hemp as a food source here!)
Pros: Often referred to as a superfood due to its mix of essential fatty acids, hemp has been shown to improve metabolism, brain function, and circulation, and can help treat a host of medical conditions.
Hemp also includes all 21 amino acids (making it a complete protein). The vegan-friendly supplement is also extremely hypoallergenic, high in fiber (read: excellent for digestion and filling), which makes it a fantastic weight-loss food.
Cons: Since hemp is only harvested in mass quantities in select countries due to its association with cannabis, it is often the most expensive protein powder available.