What Are the Benefits & Sources of Vitamin K?

Green tea is high in vitamin K.

Vitamin K plays a key role in blood clotting and bone health, according to the University of Maryland Medical Center. Most people do not experience a vitamin K deficiency or require supplementation, as vitamin K is found in several common foods and produced naturally in the intestine.

Benefits

UMMC points out that upon birth in the U.S., newborns receive a vitamin K shot to prevent hemorrhage after delivery. This serves as a testament to vitamin K's efficacy as a blood coagulator. Babies receive the injection because it takes time for them to receive adequate amounts of vitamin K naturally and through diet. Individuals with liver problems and malabsorption syndromes, as well as persons using antibiotics over the long-term, typically receive extra vitamin K to reduce the risk of bleeding. The Harvard School of Public Health explains that individuals who take blood thinners must ensure they receive the necessary daily intake of vitamin K.

UMMC also reports that high vitamin K levels are associated with greater bone density, while researchers have linked low levels to osteoporosis. Vitamin K lowers the risk of bone fractures in high-risk groups, particularly post-menopausal women.

Food Sources

Foods high in vitamin K content include green leafy vegetables, broccoli, cabbage, asparagus, beef liver and green tea. While UMMC claims a deficiency is rare because our intestines naturally produce vitamin K, the Harvard School of Public Health contends that only 1 in 4 Americans receive the recommended daily allowance of vitamin K through diet alone. The contention is that people who do not regularly eat salads or leafy vegetables run a risk of falling short. Freezing foods can destroy vitamin K content, but regular cooking does not decrease the vitamin's presence.

Dosing

Adults males require 120 mcg of vitamin K daily, while women should consume 90 mcg. Adolescents from 14 to 18 years of age should take in 75 mcg of vitamin K per day. UMMC states that 9- to 13-year-olds need 60 mcg a day, 4- to 8-year-olds require 55 mcg, 1- to 3-year-olds should get 30 mcg a day and infants between 7 and 12 months old should take in 2.5 mcg of vitamin K each day. In addition to receiving a vitamin K injection at birth, newborns should receive 2 mcg daily.

Vitamin K-1 and K-3 are included in multivitamin supplements. They are also sold on their own in 5 mg tablets, says UMMC.

References

• University of Maryland Medical Center (UMMC): Vitamin K
• Harvard School of Public Health (HSPH): Vitamin K