Tribune Media Services

If you want to preserve your bones as you age, don't skimp on vitamin-K rich foods, such as deep-green vegetables. While we usually think of calcium - found in dairy products, greens, and fortified products such as soy products - as the main nutrient essential for bone health, it's not the only one you need to maintain healthy bones.

Recent attention has focused on the potential for vitamin K (best known for its critical role in blood clot formation), to protect bones from osteoporosis, which can lead to fractures and disability as we age.

Researchers have observed that people with low levels of circulating vitamin K tend to have low bone mineral density, and vitamin K supplementation improves markers of bone health. Data from the Nurses' Health Study, which included more than 72,000 women, found those who got at least 110 micrograms (mcg) of vitamin K per day were 30 percent less likely to break a hip than women who got less.

U.S. Department of Agriculture researchers also found low vitamin K intake was associated with low bone mineral density in women involved in the Framingham Heart Study. And in a 2012 study that investigated data from the Postmenopausal Health Study II, groups receiving dairy products supplemented with two forms of vitamin K had more favorable changes in bone metabolism compared to the group that received nonsupplemented dairy products.

For optimal bone health, it's a good idea to achieve the recommended amounts of vitamin K in your diet through daily consumption of vitamin-K rich foods. The Institute of Medicine established the Adequate Intake for vitamin K at 90 mcg per day for women and 120 mcg for men.

However, if you're taking blood-thinning medications such as warfarin (Coumadin), you need to be careful about maintaining a consistent level of vitamin K in your diet. You don't need to cut vitamin K out of your diet all together, but try to avoid abrupt increases and decreases in food sources.

Foods high in vitamin K

•Kale, cooked. Serving: 1/2 cup, 531 micrograms

•Spinach, cooked. Serving: 1/2 cup, 444 mcg

•Collards, cooked. Serving: 1/2 cup, 418 mcg

•Swiss chard, raw. Serving: 1 cup, 299 mcg

•Swiss chard, cooked. Serving: 1/2 cup, 287 mcg

•Mustard greens, raw. Serving: 1 cup. 279 mcg

•Turnip greens, cooked. Serving: 1/2 cup, 265 mcg

•Parsley, raw. Serving: 1/4 cup, 265 mcg

•Broccoli, cooked. Serving: 1 cup, 220 mcg

•Brussels sprouts, cooked. Serving: 1 cup, 219 mcg

•Mustard greens, cooked. Serving: 1/2 cup, 210 mcg

•Spinach, raw. Serving: 1 cup, 145 mcg

•Turnip greens, raw. Serving: 1 cup, 138 mcg

•Endive, raw. Serving: 1 cup, 116 mcg

•Cabbage, cooked. Serving: 1/2 cup, 82 mcg

•Green leaf lettuce. Serving: 1 cup, 71 mcg

•Prunes, stewed. Serving: 1 cup, 65 mcg

•Avocado. Serving: 1 cup, 30 to 48 mcg

•Tuna, canned in oil. Serving: 3 oz., 37 mcg

•Blueberries, blackberries, raw. Serving: 1 cup, 9 mcg

Source: National Institutes of Health