Women's Bone Health: Vitamins D & K

Vitamins D and K work with calcium to keep your bones strong and prevent osteoporosis, a disease that makes bones porous and frail. Getting adequate amounts of these nutrients becomes even more important after menopause, when your body produces less estrogen, a hormone that helps you absorb calcium. No matter how old you are, you can improve your bone health by meeting your daily requirement of calcium and vitamins D and K.

Function

Your body requires vitamin D to absorb calcium, a nutrient that provides most of the mineral material in bone. Vitamin K plays a vital role in bone formation by activating osteocalcin and other proteins that allow calcium to bind to the bone matrix. Inadequate intake of vitamins D and K may increase the risk of osteoporosis-related fractures in women, especially women over the age of 65, according to the Linus Pauling Institute.

Research

In a study of the effects of vitamin K on bone mineral density published in the "American Journal of Clinical Nutrition" in 2004, Sarah L. Booth and colleagues report that women with low vitamin K intake had lower bone mineral density than women who had a high dietary intake of vitamin K. Women who had eaten leafy green vegetables regularly during the 12 months of the study had higher bone mineral density, suggesting that their dietary intake of vitamin K helped prevent bone loss. According to the Harvard School of Public Health, vitamins D, K and calcium are all essential in maintaining bone health, especially after the age of 50.

Sources

Your skin synthesizes vitamin D through exposure to sunlight or ultraviolet radiation. If you spend 10 to 15 minutes in sunlight three times a week, your body may be manufacturing enough vitamin D to promote calcium absorption, according to the University of Maryland Medical Center. Food sources such as saltwater fish, liver, egg yolks and fortified dairy products offer vitamin D, as well. Foods high in vitamin K include dark green vegetables such as kale, broccoli, and spinach, as well as olive oil and canola oil. Fortified dairy products, fish, and vegetables such as spinach, kale and broccoli also provide calcium, adding to their nutritional value for your bones.

Recommendations

The Institute of Medicine's recommended dietary intake of vitamin D is 10 mcg per day for women under 50 and 15 mcg per day for women over 50. The recommended dietary allowance of vitamin K is 90 mcg per day for women over 19. The Linus Pauling Institute recommends eating 1 cup of leafy vegetables per day and replacing butter and hydrogenated oils with soybean or olive oil to fulfill your daily requirement of vitamin K.

Considerations

Although vitamins D and K play vital roles in maintaining healthy bones, getting enough calcium is the most important factor in preventing osteoporosis, according to the NIH. If you're between 19 and 50 years old, you need 1,000 mg of calcium per day. After 50, your calcium requirement increases to 1,200 mg per day. Meeting your recommended dietary allowance of vitamins D and K will help you make the most of your calcium intake and protect your bones against osteoporosis.