Vitamin K Intake by Age: How Much You Need

Vitamin K needs change with age. In U.S. guidance, infants need 2 to 2.5 micrograms (mcg) a day, children need 30 to 60 mcg depending on age, and teens need 75 mcg. Adults generally need 90 mcg daily for women and 120 mcg for men; pregnancy and breastfeeding do not change these amounts for adults. Newborns also need the recommended vitamin K shot at birth.

Vitamin K is an essential nutrient that helps blood clot normally and supports healthy bones. Most people can get enough from a varied diet, but the amount used as a daily intake target depends on age and, for adults, sex and certain life stages. Knowing these recommendations can help you plan meals, understand supplement labels, and recognize when individualized advice may be necessary.

How much vitamin K do you need at each age?

The following table uses U.S. dietary reference values published by the National Academies and presented by the National Institutes of Health (NIH). These values are known as adequate intakes for vitamin K because the available evidence is insufficient to establish a Recommended Dietary Allowance (RDA) for every age group.

These values come from the NIH Office of Dietary Supplements. They are U.S. reference values, and recommendations can differ between countries. One microgram is written as mcg or μg and is one-thousandth of a milligram.

What do the recommended vitamin K amounts mean?

An adequate intake (AI) is an estimated daily amount considered sufficient for healthy people when there is not enough scientific evidence to establish an RDA. It is a planning target rather than a precise amount that everyone must consume each day. Your usual diet, food variety, health circumstances, and ability to absorb nutrients all matter when considering nutritional needs.

The National Academies' dietary reference intake guidance explains the basis for these age-specific values. The estimates for infants, children, teenagers, and adults were established using the evidence available for each life stage. An AI should not be interpreted as a diagnostic threshold or as proof that someone has a deficiency when their intake is lower on a particular day.

How does vitamin K intake differ for babies and young children?

Infants have much smaller daily dietary intake targets than older children because their nutritional needs are considered separately by life stage. From birth through six months, the AI is 2 mcg per day. Between seven and twelve months, it increases to 2.5 mcg. The target rises to 30 mcg per day for children aged one to three years and to 55 mcg for those aged four to eight.

These food-intake figures must not be confused with the preventive vitamin K injection recommended for newborns. Babies are born with low vitamin K stores, and breast milk contains relatively little of the vitamin. According to the Centers for Disease Control and Prevention (CDC), the American Academy of Pediatrics recommends a one-time vitamin K injection shortly after birth, whether a baby is breastfed or formula-fed. Parents should discuss the injection with their newborn's healthcare team rather than trying to replace it with dietary changes or oral supplements.

Do teenagers and adults need different amounts?

For children and adolescents, the AI increases from 60 mcg at ages nine to thirteen to 75 mcg at ages fourteen to eighteen. The amount is the same for boys and girls within these age groups. From age nineteen onward, the U.S. reference values differ by sex: adult men need 120 mcg daily, while adult women need 90 mcg.

Pregnancy and breastfeeding do not increase these U.S. reference amounts above the usual value for the corresponding age group and sex. Pregnant or breastfeeding teenagers have an AI of 75 mcg per day, while pregnant or breastfeeding adults have an AI of 90 mcg. People with particular medical or nutritional needs may require advice tailored to their circumstances.

Which foods provide vitamin K?

Many everyday foods contain vitamin K, so a varied diet can often provide the amount adults and children need. Green vegetables are particularly useful sources, and other foods contribute smaller or varying amounts. The NIH Office of Dietary Supplements identifies the following food groups as sources of vitamin K in its Vitamin K fact sheet for health professionals.

• Green leafy vegetables: Spinach, kale, lettuce, and other leafy greens.
• Other vegetables: Broccoli and similar green vegetables.
• Vegetable oils: Certain oils contribute vitamin K to the diet.
• Some fruits: Blueberries and figs contain vitamin K.
• Animal and soy foods: Eggs, meat, cheese, and soybeans can also provide it.

You do not need to eat every food on this list or calculate every microgram to build a balanced diet. Including a variety of vegetables and other nutrient-rich foods can help you obtain vitamin K alongside other essential nutrients. The amount in a particular serving varies with the food, preparation, and portion size.

Should you take a vitamin K supplement?

Not everyone needs a vitamin K supplement. Many people can obtain enough from food, and the daily intake table does not mean you must take a pill to reach the target. Supplements are available alone or in multivitamin products, but their doses can vary substantially. Ask a healthcare professional whether supplementation is appropriate before starting a separate vitamin K product, particularly if you take medicines or have a condition that affects nutrient absorption.

Individual advice may be important for people with conditions that interfere with fat or nutrient absorption, including some intestinal disorders, or for those who have undergone bariatric surgery. Certain medicines can also affect vitamin K absorption or availability. Your healthcare professional can review your diet, medical history, and medicines when deciding whether further assessment or supplementation is appropriate.

What if you take warfarin?

Vitamin K has an important interaction with warfarin, a medicine used to help prevent harmful blood clots. Changes in vitamin K intake can alter how warfarin works. The MedlinePlus medical encyclopedia advises people taking warfarin to keep their vitamin K intake consistent and discuss dietary changes with their healthcare team.

This does not usually mean avoiding spinach, broccoli, or other vitamin K-rich foods. Instead, aim for a reasonably consistent eating pattern and tell your prescriber if you plan to make a substantial change to your diet or begin taking supplements. Do not change your warfarin dose or stop the medicine on your own. Your clinician can determine whether your treatment needs adjustment based on the relevant monitoring results and your medical circumstances.

Can you get too much vitamin K from food?

Vitamin K from ordinary foods is not known to cause harm in healthy people. However, high-dose supplements are different from food sources and may be inappropriate for some individuals, especially those taking medicines that interact with vitamin K. More is not necessarily better, and the intake values in the table are not instructions to exceed normal dietary needs.

If you are considering a supplement, check its dose and ingredients and discuss its use with a healthcare professional or pharmacist. This is especially important during pregnancy, while breastfeeding, when managing a long-term medical condition, or when taking prescription medicines.