The use of yeast and products based on them in biotechnology continues to be a fast-growing field. Recent attention to improving human health by extracting more benefits from yeast products has led to increased recognition of the nutraceutical potential of many modern products and renewed emphasis on research demonstrating the effectiveness of new and existing products. Historically, yeast products are supplied in the form of yeast suspension or yeast paste, dried active yeast, yeast autolysates, yeast extracts, individual components such as protein isolates, amino acids, cell wall glucans and mannoproteins, vitamins, enzymes, nucleic acids, polysaccharides, physically or enzymatically modified components.