Vitamin D

Publication Date: 
Tue, 11/08/2011

Vitamin D is a fat-soluble vitamin that promotes calcium absorption in the body. Without sufficient vitamin D, bones can become thin, brittle, or misshapen and together with calcium, vitamin D also helps protect older adults from osteoporosis.1

Where is Vitamin D found?

Few foods contain vitamin D including cod liver oil, fatty fish  such as salmon, mackerel, tuna, sardines and herring, vitamin D-fortified milk and cereal, and egg yolks are among the best sources.1 Many people may also meet some of their vitamin D needs from exposure to sunlight.2 Dietary supplements are also a source of vitamin D, although you should discuss your daily allowance with your doctor.

Interaction with Warfarin?

Concern has been raised about a possible interaction between vitamin D and warfarin, but the potential for increased activity of warfarin due to vitamin D has not been confirmed by any substantial research.3 Normal amounts of vitamin D should not affect INR test results.

As always, discuss all diet and supplements with your doctor.

  1. Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010.
  2. Cranney C, Horsely T, O'Donnell S, Weiler H, Ooi D, Atkinson S, et al. Effectiveness and safety of vitamin D. Evidence Report/Technology Assessment No. 158 prepared by the University of Ottawa Evidence-based Practice Center under Contract No. 290-02.0021. AHRQ Publication No. 07-E013. Rockville, MD: Agency for Healthcare Research and Quality, 2007.
  3. Schrogie JJ. Coagulopathy and Fat-Soluble Vitamins. JAMA. 1975;232(1):19.