More than thirty years ago, I proposed a theory about sweet and bitter molecules’ recognition by protein helical structures. Unfortunately the papers could not go to public platform until now. The sweet and bitter taste theory is updated and presented in separated papers1,2. The sweet taste theory conveys that sweet molecules are recognized by receptor protein helical structures and the recognition process is a dynamic action, in which the sweet receptor protein helix has a torsion-spring-like oscillation between helical structures of 3.6 and 3 amino acids per turn. To help this kind of oscillation, there are two kinds of hydrogen donor and hydrogen acceptor DH-B entities for both receptor and sweet molecules: H-bond or non-H-bond. The distances between DH and B could be up to ~ 8.5 Å. The receptor H-bond type DH-B entities are the NH-O pairs forming H-bonds in protein helices; the receptor non-H-bond type DH-B entities are the ones from two pairs of NH-Os forming H-bonds which are about one turn away. To facilitate this kind of movement, the interaction of DH-Bs of a sweet molecule with those of sweet receptor, through a pair of complementary hydrogen bonds, must have hydrogen bond complementarities, which means Hbond type of ligands’ DH-Bs reacts on non-H-bond type of receptor’s O-NHs, and vice versa. As the oscillation may have different extent, it translates to sweet intensity. As recognition sites are only associated with a small fraction – helix structure of whole sweet receptor, multiple binding sites or multiple receptors are well expected.