There has been some confusion in the U.S. market regarding OPC products containing Pycnogenol® or grape seed extract (GSE), because one of the generic terms for chemical constituents ("pycnogenols") is the same as the patented trade name (Pycnogenol®). Some GSE products were formerly erroneously labeled and marketed in the U.S. as containing "pycnogenols." Although GSE and Pycnogenol® do contain similar chemical constituents (primarily in the OPC fraction), the chemical, pharmacological, and clinical literature on the two products is distinct. The term Pycnogenol® should therefore only be used to refer to this specific proprietary pine bark extract. Scientific literature regarding this product should not be referenced as a basis for the safety or effectiveness of GSE.