What is Yeast Beta 1,3/1,6 Glucan? Yeast Beta-1,3/1,6-glucan is derived from baker’s yeast (Saccharomyces cerevisiae), made up of a string of glucose molecules, with fats, proteins, and other polysaccharides removed.It’s a 100%-natural, food-based dietary supplement. Different Sources of Beta Glucan Beta Glucan can be found in other sources such as