A. Sarah L. Booth, PhD, associate director of Tufts USDA Human Nutrition Research Center on Aging (HNRCA) and director of its Vitamin K Laboratory, replies: The issue with vitamin K and vitamin D is that there is a hypothesis that in the situation of low vitamin D, calcium accumulates in places where you dont want it and that vitamin K prevents that from happening. The data are not there to support it so, at best, it is a hypothesis. As for taking vitamin K2, it is found in fermented foods, such as cheese, milk and natto. It is not found in yogurt, tofu, etc. At the moment there are no recommended intakes for vitamin K2, so its best not to use supplements for intake.
