Vitamin K Excess

Vitamin K toxicity is rare but is most common in formula-fed infants. 

Vitamin K has two forms:

• Phylloquinone: This form occurs in plants and is consumed in the diet. It is absorbed better when it is consumed with fat. Phylloquinone is not toxic, even in large amounts.

• Menaquinone: This form is produced by bacteria in the intestine, but only small amounts of it are produced. In some countries, this form is used for supplementation.

Vitamin K is necessary for normal blood clotting. It is also needed for healthy bones and other tissues.

The effects of vitamin K toxicity can include anemia due to rupture of red blood cells and jaundice. Jaundice in newborns can cause kernicterus (a type of brain damage). 

(See also Overview of Vitamins.)