Silicon dioxide

Silicon dioxide, also known as silica, is added to capsule and tablet formulations to reduce clumping 1. Silica is found in many foods, particularly whole grains (oats and barley), sugar beets, sugar cane, soybeans, turnips, green beans 2. The average intake of silica in adults is 14-21 mg/day 3. The bioavailability of silicate additives is low 4. Silica that occurs in food and water has not been shown to cause any adverse effects 3.

This ingredient can be found in the following products in United States:


  1. The Merck Index. Whitehouse Station, NJ: Merck & Co., 2006.
  2. Nutritional Biochemistry and Metabolism. New York, New York: Elsevier, 1991.
  3. Natural Medicines: Comprehensive Database. Stockton, CA: Therapeutic Research Faculty, 2000.
  4. Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, D.C.: National Academy Press, 2002.