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Commonly overlooked sources of vitamin K

Primary Care Resident in Family Medicine College of Pharmacy and Department of Family Medicine The University of Iowa, Pomerantz Family Pavilion 200 Hawkins Drive Iowa City, Iowa 52242-1009 FAX 319/384-8515 E-mail shella-johnson{at}uiowa.edu

Michael E Ernst, PharmD BCPS

Assistant Professor (Clinical) College of Pharmacy and Department of Family Medicine The University of Iowa

Mark A Graber, MD

Associate Professor of Family Medicine and Emergency Medicine Departments of Family Medicine and Emergency Medicine The University of Iowa

Published Online, January 3, 2003. www.theannals.com, DOI

This reaction led us to examine the vitamin K content of other health and sports bars and some other common supplements. We found that many of them contain significant amounts of vitamin K. For example, Viactiv soft calcium chews, labeled as "a unique blend of vitamins D & K," contain 40 µg of vitamin K in each chew. Since the recommended dose for a postmenopausal woman is 3 chews daily, an individual taking the recommended amount of this supplement will receive 120 µg of vitamin K intake (roughly equivalent to 1/2 cup broccoli). Likewise, 8 fluid ounces of Boost or Ensure nutritional supplement will provide 30 µg. Some energy/protein bars such as Balance or Clif bars may deliver as much as 40 µg of vitamin K per bar, while each Luna bar contains up to 65 µg. The recommended daily allowance of vitamin K, based on a 2000-calorie daily diet, is 60–65 µg for women or 70–80 µg for men. This recommended daily allowance is met or exceeded by some available supplements and health bars.

It is important to note that not all sports bars contain vitamin K. Some, such as Met-Rx, Power Bars, and Power Harvest Bars, do not include vitamin K. Nevertheless, as the use of nutritional supplements continues to grow across all age groups, practitioners who monitor anticoagulation therapy must be aware of the impact that these products may have on their patients. While patients receiving anticoagulation are routinely encouraged to maintain a stable diet low in vitamin K, they are rarely counseled about significant nontraditional sources of vitamin K they may unknowingly ingest.

We recommend that, as part of their routine warfarin education, clinicians also advise their patients that many of these products are significant sources of vitamin K, and periods of increased intake may result in unstable INR values. Furthermore, when a patient with a previously stable INR appears to require escalating doses of warfarin, clinicians should remember to inquire about intake of nutritional supplements and/or health or sports bars in addition to their routine questions about recent dietary changes.

This Article PDF Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Articles Ahead of Print [Order Reprint] Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Johnson, S. R Articles by Graber, M. A Search for Related Content PubMed PubMed Citation Articles by Johnson, S. R Articles by Graber, M. A