Vitamin K Deficiency In Children

  • Zaynab Karim BS Biochemistry, Queen Mary University of London, UK
  • Stephanie Leadbitter MSc Cancer Biology & Radiotherapy Physics, BSc (Hons) Biomedical Science, University of Manchester, UK
  • Ellen Rogers MSc in Advanced Biological Sciences, University of Exeter


Vitamin K is a fat-soluble compound involved in blood clotting, cardiovascular health, and bone development.1 Lots of foods contain vitamin K, making dietary vitamin K deficiency rare in adults. It is more common in infants and often leads to a bleeding disorder known as Vitamin K deficiency (VKDB). There are three types of VKDB: early VKDB is apparent within 24 hours of birth, classic VKDB appears in the first week of life, and late VKDB appears within the first 1 to 12 weeks of life. After birth, the levels of vitamin K in a baby’s blood are very low. Combined with the fact that breast milk lacks this vitamin, babies are much more likely to develop VKDB than adults.2 This can be very dangerous as without vitamin K, babies can bleed internally from the intestines or brain.3 

Functions of vitamin K

Vitamin K is primarily needed for blood clotting, which is done through a series of events known as the ‘coagulation cascade’.4 Vitamin K needs to be available to bind to calcium ions in order for clotting factors, such as proteins, to help with coagulation. Prothrombin, a vitamin K-dependent protein, plays a pivotal role in the coagulation cascade. Along with this, there are proteins such as protein C and protein S, which are anticoagulants that maintain a balance within the cascade, as uncontrolled clotting can be equally life-threatening. These coagulation proteins are processed in the liver. Therefore,  severe liver diseases can lead to low levels of clotting factors, increasing the risk of uncontrolled bleeding. 

Vitamin K also plays an important role in bone health. It is able to regulate calcium, which helps with bone strength and structure, in two ways:

  • Vitamin K activates a protein called osteocalcin, which allows calcium to gather in the bones and teeth.5
  • Vitamin K uses a protein to prevent calcium from gathering in soft tissues, such as blood vessels.6

Studies show that high levels of vitamin K are linked to an increase in bone mineral and a decrease in fracture risk.7 

Vitamin K is also known for its anti-inflammatory properties.8 Many chronic inflammatory diseases have been linked with a deficiency in this vitamin, and it is the key nutrient in many anti-ageing products. 

Sources of vitamin K

Vitamin K is divided into two groups:9

  • Vitamin K1 (phylloquinone): This is the most common form of Vitamin K. It's mainly found in leafy greens such as spinach and kale, but it is also found in fruits such as avocado and grapes. Your body can absorb the Vitamin K in these foods more quickly when they are cooked or served with butter or oil.
  • Vitamin K2 (menaquinone): This is mainly found in meat, fermented food, and dairy products. There are several subclasses of vitamin K2. The two major subclasses are menaquinone-4 (MK-4), which is found in meat, liver, and eggs, and menaquinone-7 (MK-7), which is formed by bacterial fermentation and found in fermented foods.10

The function of intestinal microflora (the good bacteria living in our gut and intestines) is to make energy for nutrient uptake (including our uptake of vitamin K) and protect the body from pathogens.11 If we do not have gut bacteria, it can cause health problems such as:12 

  • Immune problems
  • Thyroid issues
  • Arthritis
  • Type 1 diabetes
  • Digestive issues
  • Sleep issues
  • Skin rashes
  • Sugar craving
  • Fatigue
  • Mood swings
  • Weight gain or weight loss

Symptoms of vitamin K deficiency 

Symptoms of vitamin K deficiency include:

  • Excessive bleeding, which can lead to death or brain damage if left untreated
  • Poor bone development
  • Osteoporosis (a condition that makes the bones fragile and more susceptible to breakage)
  • Cardiovascular disease
  • Vitamin K deficiency bleeding

Symptoms of VKDB include:

  • Bruises
  • Bleeding from the nose or umbilical cord
  • Pale skin 
  • The sclera (white area of the eyes) becomes yellow
  • Blood present within stool or vomit
  • Seizures, irritability, and extreme fatigue (all signs of internal bleeding)

Risk factors for vitamin K deficiency in children

Babies are at a higher risk of VKDB until they are able to eat solid food and their intestinal microflora are able to make vitamin K. Whilst a small amount of vitamin K can pass through the placenta whilst the baby is in the womb and provide babies with a limited store of vitamin K, breast milk does not contain enough vitamin K to support a baby’s development. As such, babies will need to obtain vitamin K via injections or other food sources. 

Some babies are at higher risk of VKDB. These infants are those who:

  • Do not receive a vitamin K injection when born and are only breastfed.
  • Have mothers who take medication to treat seizures, as these drugs disturb the body's absorption and usage of vitamin K
  • Those who suffer from liver diseases, as the proteins in their body, are not able to use the vitamin K stored.
  • Those who suffer from diarrhoea, cystic fibrosis, or coeliac disease, which all affect the absorption of vitamins

The recommended amount of vitamin K for infants is:13

  • 2.0 μg/day for children between 0-6 months
  • 2.5 μg/day for children between 7-12 months

As children grow and become accustomed to regular food (typically from 6 months onward), their dietary habits will impact their vitamin K uptake. Although the bacteria in the gut are able to produce enough vitamin K for your body from the age of 4-6 months, the body still needs to obtain some vitamin K from the diet - such as from the foods listed above. In addition to this, a diet with a very low-fat content reduces the uptake of vitamin K, so it is important to consume high-fat foods (such as oil and butter) in moderation. This balance of fat and food with vitamin K works to reduce your risk of vitamin K deficiency. 

The recommended amount of vitamin K for children is:

  • 30 μg/day – 1-3 years
  • 55 μg/day – 4-8 years
  • 60 μg/day – 9-13 years
  • 75 μg/day – 14-18 years 

Diagnosis and monitoring

If you suspect your child has vitamin K deficiency, your doctor might make take a blood sample for testing. They might test the levels of vitamin K in your child’s blood directly or assess how well their blood clots. Generally, if your child’s blood clotting is slow or inefficient and injecting vitamin K improves it, they have a vitamin K deficiency. 

Another blood test that can be done is the prothrombin time (PT), which measures the rate of blood clotting.14 This is what to expect:

  • The test involves taking a blood sample (usually from the crook of your elbow), which can take a few minutes.
  • Results: blood clotting normally takes 10-13 seconds, with anything above or below this range being considered abnormal. However, any blood-thinning medications you take will be taken into account.
  • You may experience pain, discomfort and/or bruising in the area from which the blood is drawn.

Besides using blood tests, the extent and effect of vitamin K deficiency on the body can be shown using bone density scans.15 These scans are known as DEXA (dual energy x-ray absorptiometry) scans, and are able to measure calcium levels in the bones, as well as their thickness and strength. 

Treatment and prevention

There are both oral and injectable forms of treatment for vitamin K deficiency. Infants can receive an injection of 1 mg of vitamin K1 within 1 hour of birth, with a further 1-2 mg dose of vitamin K1 being offered to babies suffering from VKDB. Children with malabsorption issues may need a daily oral dose of 0.3 to 15 mg of vitamin K1. Ideally, this vitamin should be accessible through the diet. Consuming a wide variety of leafy vegetables and fruit could help combat this deficiency. 

Normally, a single injection of vitamin K at birth is able to prevent vitamin K deficiency and VKDB in newborns. However, if your child suffers from malabsorption, you should consult their doctor about taking supplements and closer monitoring.


Vitamin K deficiency is a nutrient deficiency more commonly seen in infants and new-borns, but it can be easily treated with an injection. Vitamin K is known for its role in blood clotting and bone development and its anti-inflammatory properties. As such, a deficiency in this vitamin can lead to severe complications if left untreated. Children acquire intestinal bacteria which make vitamin K at around sixth months of age, and vitamin K can be easily obtained through diet. The early detection of vitamin K deficiency is important, as it can lead to excessive internal bleeding and other significant symptoms. Monitoring and (if possible) preventing this deficiency through collaboration with your doctor is essential.


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  14. Mayo Clinic. Prothrombin time test [Internet]. [cited 2023 Oct 12]. Available from: 
  15. MedlinePlus. Bone density scan [Internet]. [cited 2023 Oct 12]. Available from: 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Zaynab Karim

BS Biochemistry, Queen Mary University of London, UK

Zaynab, a biochemistry graduate, possesses a robust background in writing and presenting information for the lay audience. With previous experience in crafting articles, she enthusiastically explores the captivating realm of medical writing. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
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