Vitamin K is rarely dangerous, and this nutrient is vital for proper blood clotting and healthy bones. Despite its relative safety, most healthy individuals are not deficient in this vitamin and are advised against supplementing with it, unless they are under the supervision of a doctor.

The Three Types of Vitamin K

Vitamin K is a fat-soluble vitamin. This vitamin is actually a group of three similar substances: K1, K2 and K3. Your large intestines produce the majority of the vitamin K that is found in your body, and this variety is known as vitamin K2. Vitamin K found in food sources is referred to as K1, and vitamin K3 is a synthetic or man-made version of the vitamin, which is often given as an injection or supplement to individuals for medicinal purposes.

Vitamin K Toxicity

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Elson Haas, N.D., says in his book “Staying Healthy With Nutrition” that vitamin K is rarely dangerous when it is obtained from food or synthesized in the intestines; toxicity can occur, however, from the synthetic variety of vitamin K found in supplements and medical injections 2. Haas explains that K1 and K2 are easily eliminated when there is an excess, whereas K3 can build up in the blood and become toxic.

Vitamin K3 Side Effects

According to Haas, one possible side effect of too much K3 is the destruction of red blood cells, which can lead to a reduction in the number of red blood cells in the body, a condition known as hemolytic anemia. Other possible symptoms of toxicity include flushing, sweating or a sensation of tightness in your chest; however, these side effects are rare. Vitamin K is also contraindicated in individuals who are on blood-thinning, or anticoagulant, drugs because it can interfere with the drugs’ mechanism of action.

Vitamin K's Primary Benefit

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Vitamin K is necessary for normal blood clotting, and its key benefit is the prevention of hemorrhaging and abnormal bleeding. To this end, vitamin K is often given as an injection to people who have a reduced ability for blood clotting and to newborn infants because they do no have vitamin K in their intestines at birth.

Other Benefits of Vitamin K

According to Phyllis Balch in her book "Prescription for Nutritional Healing," vitamin K also promotes healthy liver function and helps the liver in the conversion and storage of glucose into glycogen 1. Additionally, vitamin K may support immune system function in children and help them to resist infections. Balch says that vitamin K may play a role in preventing cancers that target the inner lining of your organs, such as stomach cancer and cervical cancer; however, more research is needed to confirm this theory. Finally, vitamin K may be beneficial to rheumatoid arthritis sufferers because it is thought to reduce inflammation of the synovial lining of the joints, says Haas