Abstract: Thioredoxin, a small dithiol protein, is a specific reductant for allergenic proteins and particularly allergenic proteins present in pollen and animal and plant sources. All targeted proteins contain disulfide (S—S) bonds that are reduced to the sulfhydryl (SH) level by thioredoxin. The proteins are allergenically active and less digestible in the oxidized (S—S) state. When reduced (SH state), they lose their allergenicity and/or become more digestible. Thioredoxin achieved this reduction when activated (reduced) either by NADPH via NADP-thioredoxin reductase (physiological conditions) or by lipoic acid chemical reductant. Skin tests carried out with sensitized dogs showed that treatment of the pollens with reduced thioredoxin prior to injection eliminated or decreased the allergenicity of the pollen. Studies showed increased digestion of the pollen proteins by pepsin following reduction by thioredoxin.