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Vitamin K - Benefits, Deficiency Symptoms And Food Sources

Alternative names :- Vitamin K deficiency; Deficiency - vitamin K

Dam and his associates at Copenhagen demonstrated. a hemorrhagic tendency in chicks fed on a fat-free diet. This was later found to be due to deficiency of a specific vitamin, originally called koagulations vitamin and now known as vitamin K.

Vitamin K is found in nature in two forms - K1, also called phylloquinone, is found in plants and vitamin K2, also called menaquinone, which can be synthesized by many bacteria. Vitamin K3, menadione, is a synthetic form of this vitamin which is manmade.

Benefits and functions of Vitamin K

Vitamin K activates the enzyme system in the liver endoplasmic reticulum which promotes gamma-carboxylation of glutamyl residues; this confers upon prothrombin its calcium-binding property, which is essential for conversion of prothrombin to thrombin.

Vitamin K is needed for proper bone formation and blood clotting. In both cases, vitamin K does this by helping the body transport calcium . Vitamin K is used by doctors when treating an overdose of the drug warfarin . Also, doctors prescribe vitamin K to prevent excessive bleeding in people taking warfarin but requiring surgery.

Recommended dosage of Vitamin K

The Recommended Dosage for vitamin K are :-

• Men - 80 micrograms per day .
• Women - 70 micrograms per day.

Deficiency symptoms of Vitamin K

Vitamin K deficiency is very rare and occurs when there is an inability to absorb the vitamin from the intestinal tract. Vitamin K deficiency can also occur after prolonged treatment with oral antibiotics.

A deficiency of this vitamin in newborn babies results in hemorrhagic disease, as well as postoperative bleeding and hematuria while muscle hematomas and inter-cranial hemorrhages have been reported.

A shortage of this vitamin may manifest itself in nosebleeds, internal hemorrhaging.

Food sources of Vitamin K

Vitamin K is found in cabbage, cauliflower, spinach and other green leafy vegetables, cereals, soybeans, and other vegetables.

Bacterial Synthesis

Vitamin K is synthesized by the intestinal bacteria. Newborns have a sterile intestinal tract, and hence have low blood prothrombin level for about a week.

Toxicity

Paradoxically, excessive administration of vitamin K has been reported to produce hypoprothrombinemia and alteration in liver function. For therapy, more than 10 mg daily of vitamin K is best avoided.

Vitamin K analogue should be administed with caution to infants and to mothers in late pregnancy. The dose should not exceed what is recommended, as hyperbilirubinemia and kernicterus in premature infants may result. The infant's liver has limited capacity for glucuronide formation, which is required for bilirubin conjugation as well as vitamin K excretion; hence, with excessive vitamin K, unconjugated bilirubin level may be markedly raised (kernicterus).

In patients with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, a large dose of vitamin K results in hemolysis. The naturally occurring vitamin K1 is less likely to result in hemolysis.

Intramuscular vitamin K in infants was presumed to increase the prevalence of childhood cancer but no such relation was noted on careful study. The serious consequences of withholding vitamin K make it unethical to conduct comparative trials.