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Bacteria in the body’s intestines can produce vitamin K on their own. This vitamin K is stored in the liver. However, newborn infants are born with a sterile intestinal tract that does not begin to produce these bacteria for several weeks. As a result, newborns typically receive a shot of vitamin K to ensure that they are not deficient in this vitamin. In the past, there were some concerns that these shots might cause cancer. However, research has not found this to be true.  

The amount of vitamin K produced by bacteria in the body accounts for about one-half of a person’s needs. The rest must come from dietary sources. The best sources include green, leafy vegetables (e.g., spinach), liver, and members of the cabbage (e.g., broccoli, cauliflower) family.

Other dietary sources of vitamin K include:

• Cereal
• Eggs
• Fruits
• Meat
• Milk and other dairy products
• Other vegetables
• Some unsaturated oils, especially from fish

Examples of certain foods and the amount of vitamin K (in micrograms) they contain include:

Freezing foods may destroy vitamin K; however, heating does not affect it.

Vitamin K is also available in supplement form. People who have bruising and bleeding disorders may benefit from taking supplements. Supplements also may be recommended for women who are at risk of osteoporosis. Studies have shown that women who take vitamin K supplements are less at risk for hip fractures, a major complication associated with osteoporosis.

People should not take vitamin K supplements without first consulting a physician. These supplements can cause health problems when used by certain populations. For example, women who are pregnant and take these supplements may cause jaundice in their children. People with certain health conditions also may be poor candidates for using supplements. Such conditions include:

• Chronic diarrhea
• Gallbladder disease
• Intestinal problems
• Glucose-6-phosphate dehydrogenase (G6PD) deficiency
• liver disease
  Cystic fibrosis or other diseases affecting the pancreas