vitamin K - essential to human health

Vitamin K Dosage and Daily Intake Recommendations

Vitamin K dosage and daily intake recommendations.

How much vitamin K should you take? You might be surprised to learn that experts say there's no easy answer.

Recommendations for oral dosages of vitamin K depend on the condition and can also be controversial. For example, 100-200 µg/day has been suggested as a dose to stabilize clotting times in patients for people taking anticoagulant drugs as a result of some studies. However, other researchers have challenged these results.(16)

Experts also caution that too much vitamin K could interfere with anticoagulant drug activity. In fact, 1-5 mg of vitamin K is typically given to counteract the effects of too much warfarin — a common anticoagulant drug. People taking anticoagulant drugs should not take vitamin K at any dosage level without talking to their doctor.(16)

Dosage for Osteoporosis

Even dosages for one of the most common uses for vitamin K - osteoporosis - aren't set in stone (or bone!) Up to 10 mg/day of vitamin K or 45 mg/day of vitamin K2 has been used in clinical trials involving patients with osteoporosis. However, results have been mixed for vitamin K in terms of increasing bone mass density (BMD). Some studies showed no increase in BMD linked to vitamin K, so some experts are reluctant to recommend vitamin K at all.(13)

Despite this, decades of dietary studies suggest eating foods high in vitamin K may help limit fractures. Clinical results also indicate vitamin K2 does help increase bone density in postmenopausal women with osteoporosis.(1311)

Daily Adequate Intake

There is not enough information for recommended dietary allowances (RDAs) for vitamin K. The daily adequate intake (AI) recommendations are as follows:(1)

Table 2: Vitamin K AI Recommendations by Age & Gender
Age AI
0-6 months 2 µg/day
6-12 months 2.5 µg/day
1-3 years 30 µg/day
4-8 years 55 µg/day
9-13 years 60 µg/day
14-18 years 75 µg/day
19+ Men 120 µg/day

19+ Women

(including pregnant and lactating)

90 µg/day
Also known as vitamin K1.(1)
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