NUTRIENT LIBRARY

Nutrient Library - Vitamin K

Vitamin K

What does it do?
How much do you need?
What are the best food sources?
What happens if you don’t get enough?
What happens if you get too much?
What are some recipes that are good sources of vitamin K?
Back to Nutrient Library

What does it do?

Vitamin K is a fat-soluble vitamin that plays an important role in blood clotting. In fact, without it our blood would not clot. Its name is derived from the German word “koagulation.” Vitamin K also contributes to skeletal health because it plays a role in bone mineralization. Like vitamin D, vitamin K is one that your body can produce on its own, but usually not in quantities that meet the body’s needs. Bacteria of the lower bowel produce vitamin K and then store it in the liver. However, it has been difficult to determine the contribution of this form of vitamin K to body stores.

How much do you need?

The following table lists the recommended intake for healthy people based on current scientific information.

Life Stage Group	Recommended Dietary Allowance / Adequate Intake (see note below)	Tolerable Upper Intake Level (UL)
Infants	(micrograms/day)
0-6 mo. 7-12 mo.	2.0* 2.5*	Not determinable due to lack of data on adverse effects and concern about inability to handle excess amounts. Source should be from food only to prevent high levels of intake.
Children
1-3 yr. 4-8 yr.	30* 55*
Males
9-13 yr. 14-18 yr. 19-30 yr. 31-50 yr. 51-70 yr. > 70 yr.	60* 75* 120* 120* 120* 120*
Females
9-13 yr. 14-18 yr. 19-30 yr. 31-50 yr. 51-70 yr. > 70 yr.	60* 75* 90* 90* 90* 90*
Pregnancy
< 18 yr. 19-30 yr. 31-50 yr.	75* 90* 90*
Lactation
< 18 yr. 19-30 yr. 31-50 yr.	75* 90* 90*

NOTE: The table is adapted from the Dietary Reference Intakes reports. Recommended Dietary Allowances (RDAs), when available, are in bold type; Adequate Intakes (AIs) are followed by an asterisk(*). RDAs and AIs may both be used as goals for individual intake. RDAs are set to meet the needs of almost all individuals (97 to 98 percent) in a group. For healthy breastfed infants, the AI is the mean intake. The AI for other life stage and gender groups is believed to cover the needs of all individuals in the group, but lack of data means the percentage of individuals covered by this intake cannot be specified with confidence.
UL = The maximum level of daily nutrient intake that is likely to pose no risk of adverse effects. Unless otherwise specified, the UL represents total intake from food, water and supplements.

What are the best food sources?

The best food sources of vitamin K are leafy green vegetables like spinach, broccoli, eggs, wheat bran, and olive, soy and canola oils. Because vitamin K is a fat-soluble vitamin, its absorption from vegetables is enhanced by the presence of dietary fat: so sauté your spinach in a little olive oil. See more food sources and calculate your daily intake.

What happens if you don’t get enough?

Vitamin K deficiency is extremely rare in healthy adults. Cases of deficiency usually only occur in individuals with malabsorption problems, severe liver damage or disease, or those being treated with drugs that interfere with the vitamin’s metabolism. Your health care professional will let you know if you fall into one of these categories. The main symptoms in these cases are that blood doesn’t coagulate normally and you can experience increased bruising.

Infants born in the United States and Canada routinely receive a dose of vitamin K at birth (usually 0.5-1 mg intramuscularly or 2.0 mg orally within 6 hours of birth). This is because infants are usually born with poor vitamin K status and low amounts of clotting factors, thus increasing the risk of bleeding during the first few weeks. In addition, their immature intestines cannot produce vitamin K. Exclusively breastfed infants receive low amounts of vitamin K from human milk.

What happens if you get too much?

It’s not likely that you will experience adverse effects from consuming too much vitamin K—but moderation is still the best approach. However, individuals on warfarin therapy—an anticoagulant, or blood-thinning drug—are advised to monitor intake closely and they need to maintain steady vitamin K intake levels. Vitamin K may reduce the effectiveness of this drug. These individuals should maintain their normal dietary and supplementation patterns once an effective dose of the drug has been established. It is generally recommended that these individuals try to consume the recommended intake but avoid large fluctuations in intake.