• 24-Hour Immune Support

    Clinical studies show that Ester-C® increases vitamin C levels in the body for up to 24 hours.

  • Quick Absorption

    Better absorbed and more bioavailable due to the active vitamin C metabolites only found in Ester-C®.

  • Gentle on the Stomach

    Ester-C® is non-acidic and gentle, making it gentle on the digestive system unlike regular vitamin C.

  • Backed by Science

    The patented Ester-C® has been studied for decades and is better researched than all other buffered forms of vitamin C.

How it Works

Ester-C® is a unique and patented form of calcium ascorbate, which is created when ascorbic acid (vitamin C) is buffered with calcium.


Ester-C® takes calcium ascorbate and, using a proprietary, water-based manufacturing process, produces a pH neutral product that contains active vitamin C metabolites (that do not exist in any other form of vitamin C, including calcium ascorbate).


These natural metabolites provide quick absorption.


Ester-C® also functions biologically like other forms of vitamin C, providing benefits for skin, joint and vision health, cardiovascular support, antioxidant protection and immune system wellness.

Sisu vitamins and supplements are available in stores and online from retailers across Canada