It's easy to get answers about health and nutrition! Just send your question by email to firstname.lastname@example.org and Dr. Harlan will respond to selected questions of general interest. Answers will be posted in the Ask Dr. Gourmet newsletter (sign up now!) and archived in the Ask Dr. Gourmet section of the website.
I am concerned about the accuracy of the Vitamin K information in the foods you report on your website to Coumadin takers. You report that pistachios have 0mcg of Vitamin K, but on the USDA website and several other dietitian and hospital websites, it shows that pistachios do have Vitamin K. Specifically, from the USDA, "Nuts, pistachio nuts, dry roasted, with salt added," 1 ounce (47 nuts) has 3.7mcg of Vitamin K. I think this is very important because if someone thinks there is none in a food, then they might eat several throughout a day or week thinking they are a "safe" food, but then wonder why their INRs cannot balance.
Sometimes the information from the USDA web site can be challenging and it is key to make sure one is looking carefully at the choice of ingredient - comparing apples to apples and not apples to oranges.
You are correct that an ounce of dry roasted pistachios is reported as having 3.7 micrograms (mcg) of Vitamin K. Raw pistachios are, however, reported as having no Vitamin K.
The difference is likely due to the addition of other oils in the dry roasting process (dry roasting isn't always "dry"). We don't know for sure what products that the USDA may have tested at the time, but many dry roasted nuts contain other oils which do contain Vitamin K. For example, soybean oil is reported by the USDA as containing 8.3 mcg of Vitamin K per teaspoon and is a common oil used in processing foods.
All of the information on the Dr. Gourmet web site is taken directly from the USDA database. We don't use any other source for our nutrition information, whether that is in our lists for Coumadin users or other handouts for nutrients such as calcium, magnesium and iron. Likewise, our meal planning software is powered by the most recent version of the USDA information.
Thanks for writing,
Timothy S. Harlan, MD, FACP, CCMS