Vitamin & Mineral Guide: Vitamin K

Aids blood clotting and activates osteocalcin, a protein that builds and strengthens bones.

How Much: RDA for vitamin K = 90 micrograms (mcg) for women;120 mcg for men.

Too Much:  No UL set.

Too Little: increases blood-clotting time, and can cause bruises and bleeding gums.

Foods: Leafy greens and fermented soybeans.

Interactions:  Antibiotics, blood-thinning drugs.

Research Note:  Three studies show vitamin K reduces the incidence of vertebral fractures, but only modestly improves bone density in postmenopausal women with osteoporosis.  But a study of more than 72,000 women found a link between low dietary vitamin K intake and an increased risk of hip fracture.  Women who ate iceberg or romaine lettuce one or more times daily were 45 percent less likely to break a hip than those who ate lettuce once a week or less.