According to the FAO and WHO, half of the world’s population (nearly eight billion people) is protein deficient. Protein deficiency is the most important nutritional problem in the world. Proteins can be animal- (meat and offal, fish, milk, eggs) or plant- (cereals, legumes, oilseeds) based, microbiologically synthesized (from yeast and a variety of bacteria), and synthetic or artificial (produced after amino acid synthesis). Animal proteins are the most expensive. The systematic incorporation of alternative proteins in the human diet is becoming increasingly urgent as global meat costs rise. Legumes, cereals, seeds, and nuts can all provide protein to the human body. Microalgae are considered to be an excellent source of functional and biologically active nutrients for human nutritional needs. Arthrospira platensis and Chlorella vulgaris are the most popular microalgae on the global market today, both of which are marketed as standalone functional foods containing proteins, vitamins, and minerals. Insects, as a source of dietary protein, differ in protein content from 20 to 75%. Investments in plant-based meat companies exceeded $350 million in 2020. The FAO predicts that the market for edible insects will reach $1.2 billion by 2023. All of these alternative protein sources are becoming more popular in the modern food industry for the production of high-protein foods and dietary supplements. This review aims to be a state-of-the-art study of new and potential sources of dietary proteins.