Olestra, a fat substitute - Can it affect your INR?

Publication Date: 
Fri, 09/06/2013
By: Alere Staff

Olestra is a food additive approved for use by the U.S. Food & Drug Administration (FDA) in 1996. It is added to many ready to eat and prepackaged snack foods as a zero-calorie fat substitute. Often used in place of high-fat cooking oil, shortening and butter, olestra is processed in a way that mimics ordinary fat. It prevents the body from absorbing fat and is not ingested by the body, which in turn lowers the calorie content of the snack.1

Lower calorie snacks may be good but be aware; olestra also prevents the body from absorbing the fat soluble vitamins which are vitamin A, D, E, & K.1 In an attempt to make up for blocking this absorption of these important vitamins, the FDA requires companies using olestra in their products to add additional amounts of these vitamins to the product.2 In the case of vitamin K, 8 micrograms is added for every 1 gram of olestra used in the product.2

Vitamin K can influence your INR and since olestra blocks the absorption of vitamin K and extra vitamin K is added to the product it is difficult to know exactly how much vitamin K you are actually absorbing. If you decide to eat lower calorie foods containing olestra, you may see a change in your INR due to the change in how much vitamin K you are eating and absorbing. To be safe, let your doctor know if you significantly increase eating products containing olestra. You may need to test your INR more often.

Increasing testing frequency is recommended when making any changes to your diet, medication, etc. Studies have shown that increasing testing frequency with weekly testing of INR improves patient safety and helps keep the drug in its therapeutic effective zone.3,4 Weekly testing was shown to be the most effective testing frequency.3 Medicare and many private/commercial insurance reimburse patients for weekly patient self-testing.5 Go to the Getting Started page or call Alere at 1.800.504.4032 for more information about testing your INR at home.

  1. Jandacek RJ. The effect of nonabsorbable lipids on the intestinal absorption of lipophiles. Drug Metab Rev 1982;13:695-714.
  2. U.S. Food and Drug Administration. Federal Register. Vol. 68, No. 150. Rules and Regulations. August 5, 2003.
  3. Am J Manag Care. 2014;20(3):202-209.
  4. Heneghan C., et al. Self-monitoring of oral anticoagulation: a systematic review and meta-analysis. 2006. Lancet, 367, 404-11.
  5. Center for Medicare and Medicaid Services. Decision Memo for Prothrombin Time (INR) Monitor for Home Anticoagulation Management  (CAG-00087R) [Memorandum]. 2008. Baltimore, MD.