Ester-C Plus is exclusively formulated by Solgar and provides a patented method of supplementing pH neutral ( non-acidic) vitamin C to prevent stomach irritation. In addition, Easter-C Plus includes the vitamin C metabolites, L-Threonic acid, L-Lyxonic Acid and L-Xylonic Acid, that occur alone with vitamin C in nature. A special manufacturing process is employed to form a unique calcium ascorbate metabolite complex. Solgar's Ester-C Plus offers the additional benefits of acerola, Citrus bioflavonoids, rutin and rose hips in the Easter-C Ascorbate metabolite complex.