Can Vitamin C Upset Your Stomach?

upset stomach

Vitamin C is well known for providing many benefits, including shortening the duration of a cold, boosting the immune system and supporting the natural production of collagen.  But yes, taking high doses of traditional vitamin C – pills, powders, and capsules – can upset your stomach and then some…

Here’s why:

Most traditional vitamin C supplements contain straight ascorbic acid.  Ascorbic acid is recognized as the primary force behind the power of vitamin C, but it is an acid.  A moderate amount of acid in the gastric system helps to digest food and kill bacteria, but too much acid leads to heartburn, bloating, belching, and flatulence.

High quality vitamin C supplements use gentler, less-acidic types of vitamin C to help prevent this gastric upset.  These supplements typically include sodium ascorbate, ascorbic acid with bioflavonoids, ascorbyl palmitate, calcium ascorbate, or mineral forms of ascorbate.

The type of vitamin C you take, however, is only one part of the issue.  Because no matter what type of vitamin C you ingest, it’s primarily absorbed through an active transport system (unless it’s encapsulated in liposomes, but we’ll get to that later).

Active transport of vitamin C relies on sodium-dependent vitamin C co-transporters (SVCTs) to carry each vitamin C molecule through special doorways into the bloodstream, cell or tissue.  SVCTs can only carry one molecule of vitamin C through one door at a time.

This system works efficiently for a healthy person taking small doses of vitamin C, but when you take high doses of vitamin C, the absorption is severely restricted by the number of SVCTs and the number of open doors. If there aren’t enough SVCTs to carry all of the vitamin C into the blood, or all of the doors are closed, the vitamin C that was not absorbed is forced to exit the body.

This forced exit occurs because the most common forms of vitamin C are water soluble – meaning the vitamin C dissolves in water, and cannot be stored by the body for later use.  So when a large dose of water soluble vitamin C is taken and there are not enough SVCTs or open doors, all of the unabsorbed vitamin C is sent to the colon. Water is then drawn into the colon in order to dilute and excrete the vitamin C.  Then… straight to the bathroom.

Unless you are looking for a good cleanse, there are two ways to prevent these unpleasant experiences when taking high doses of vitamin C:

  • Take single doses of <500 mg of sodium ascorbate, several times a day.  Sodium ascorbate is recommended most by vitamin C experts, and it is commonly used in high dose intravenous (IV) infusions.
  • Take vitamin C encapsulated in liposomes.  Liposomes are tiny spheres that form a protective membrane around the vitamin C.  This prevents the vitamin C from being destroyed in the digestive system, while promoting delivery directly into the bloodstream and cells.  And because liposomes do not use the body’s active transport system, you can take high doses of liposomal vitamin C without worrying about where to find the nearest bathroom.


  • Li, Y. and Schellhorn, E. 2007. New developments and novel therapeutic perspectives for vitamin C. Journal of Nutrition. 137: 2171-2184
  • Hickey S., Roberts H, Miller N, (2008), “Pharmacokinetics of oral vitamin C” Journal of Nutritional & Environmental Medicine July 31.

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