Limit Green Vegetables In Diet

Q. I’m taking Coumadin blood thinner after having heart surgery to replace an aortic valve. I discovered that vitamin K, which is in every vegetable that’s green, counteracts with the Coumadin. Can you tell me which foods are highest in vitamin K and how it affects blood clotting? - T.M., Toms River, N.J.

A. Vitamin K, discovered in 1929, is a “fat-soluble” vitamin - along with vitamins A, D and E. What that means is that unlike the “water soluble” vitamins C and the Bs, it needs bile and fats in the digestive tract to help it be absorbed into the bloodstream. It’s actually a group of three K vitamins: K1 which is made by plants; K2 which is made by animals in the liver and by the “friendly” bacteria that live in our digestive tracts, helping us break down some of the foods we eat; and K3 which is a synthetic, man-made form of vitamin K.

Why do we need vitamin K? Its main job is to stimulate the formation of proteins critical for creating the meshwork repair involved in a blood clot. These proteins, as well as vitamin K, are made within the liver. That’s why a person with liver disease such as cirrhosis or severe hepatitis often has bleeding problems. Coumadin purposely interferes with the formation of these clotting proteins and with vitamin K’s role in encouraging clotting to occur. An artificial valve like you have (as well as conditions like the heart rhythm irregularity “atrial fibrillation”) creates a new condition where blood can form an undesired clot. That clot could lead to a fatal embolism, so Coumadin in precisely the right dosage to affect clotting is pretty important in your case.

Two other lesser known roles for vitamin K are in reducing osteoporosis and decreasing the risk of forming kidney stones. Vitamin K is involved in activating the bone protein osteocalcin - involved in new bone creation and bone repair. In the kidneys, it’s involved in the production of a urinary protein which attempts to block the formation of calcium oxalate kidney stones - the most common type of kidney stone. This may explain why vegetarians, whose plant diet is rich in vitamin K, have a much lower incidence of kidney stones.

What are good sources of vitamin K? Some of the highest sources are swiss chard, kale, parsley, spinach, Brussels sprouts, broccoli, watercress, turnip greens and endive.

Keep in mind that half of the daily recommended amount of vitamin K we need comes from the production within our own bodies - those friendly intestinal bacteria and the liver.

If you’re on Coumadin, these veggies could give you unwanted extra vitamin K and make your level of blood thinning inadequate. It would be a good idea to consume these veggies sparingly (if at all). Perhaps you might try salads made of veggies low in vitamin K - such as cabbage, beans, carrots, lentils, cucumbers, and tomatoes. Olive, canola and soybean oils are good sources of vitamin K, so watch how much of them you use.

Freezing of veggies does tend to destroy vitamin K, but steaming veggies doesn’t result in much loss of vitamin K. What can cause a person to become vitamin K deficient?

As I’ve described earlier, any form of liver disease can affect vitamin K production. Folks with severe, prolonged diarrhea can get a malabsorption of vitamin K. Prolonged use of antibiotics can kill off those friendly bacteria, leading to a transient vitamin K deficiency. Most folks who take antibiotics occasionally need not worry about this.

Signs of deficiency are easy bleeding and bruising, frequent nosebleeds, gastrointestinal bleeding, and blood in the urine.

Generally speaking, unless there’s an obvious illness present, a person should not be at risk for becoming vitamin K deficient.