Medical Nutrition Therapy Nutrient: Vitamin K

1. What is the nutrient?

Vitamin K is a fat-soluble vitamin that is required for blood coagulation and also has a crucial role in the calcium absorption into bones and tissues. There are three different types of Vitamin K. Vitamin K₁ is synthesized in plants and is considered the “plant” form of Vitamin K. Vitamin K₂ occurs when Vitamin K₁ is absorbed in animals and is considered the “animal” form of Vitamin K. There are also three synthetic forms of vitamin K not typically seen in human consumption but are used in others ways. For example, Vitamin K₃ is used in the production of pet food and Vitamin K₅ is used to inhibit fungal growth.

1. What is the RDA/DRI for the nutrient?

The RDA increases across the lifespan, and varies based on gender as well. Infants aged 0-6 months have an RDA of 2.0 μg/d and this increases to 2.5 μg/d between the ages of 7-12 months. Children 1-3 years of age have an RDA of 30 μg/d which increases to 55 μg/d from age 4-8. From there, RDA is gender based:

Males	RDA (μg/d)	Females	RDA (μg/d)
9−13 years	60	9−13 years	60
14−18 years	75	14−18 years	75
19+ years	120	19+ years	90

There is an exception to these RDAs in women pregnant or lactating. For women aged 18 and younger who are pregnant of lactating, the RDA is 75 μg/d. For women over the age of 19, the RDA is 90 μg/d.

1. How is the nutrient metabolized?

Vitamin K follows a well-established pathway along with most other dietary lipids and fat-soluble vitamins. This pathways consists of bile salts and pancreatic-dependent solubilization, the uptake of mixed micelles into the entereocytes, the packaging of dietary lipids, and their exocytosis into the lymphatic system. From here it is used to carry out the bodily processes mentioned earlier.

1. What are food sources of the nutrient?

Dietary sources of Vitamin K_1, or plant sources, include green vegetables (collards, spinach, salad greens, and broccoli), brussel sprouts, cabbage, and asparagus. Vitamin K₂ is found in fermented or aged cheese (gouda and brie), butter, egg yolks, and certain meats. Meat sources high in Vitamin K include goose liver, chicken liver and breast, and meat franks.

1. What disease states alter the nutrients metabolism?

Taking broad-spectrum antibiotics can reduce Vitamin K production in the gut and result in Vitamin K deficiency. The elderly also are at risk as the gut produces less Vitamin K with age. Those with chronic kidney disease or other kidney damage (alcoholics), cystic fibrosis, or inflammatory bowel disease are also at increased risk for deficiency. Secondary Vitamin K deficiency can occur in bulimics, those on stringent diets, and those taking anticoagulants.

1. What are the tests or procedures to assess the nutrient level in the body?

Vitamin K status is assessed by prothrombin time (PT) test which measures the time required for the blood to clot. Blood samples are mixed with citric acid and but in a firbometer – a delayed clot formation is the mark of a deficiency.

1.  What is the drug –nutrient interactions?

The most important thing to note when looking at Vitamin K is the ability of the blood to clot. Blood thinning drugs like Warfarin slow the blood clotting process while vitamin K can helps the blood thicken and speeds the clotting process. Changes in Vitamin K intake can impact those who are on blood thinners, and decrease the overall effect.

1.  How is the nutrient measured?

Vitamin K is measured in mcg.

1. What is the Upper Tolerable Limits?

There is no known toxicity level, and no tolerable upper intake level has been set. The only exception is to those taking Warfarin as there is an increased risk of the drug not working when vitamin K consumption is inconsistent. In order for physicians to prescribe the accurate amount of blood thinner, Vitamin K consumption must remain consistent.

10. What are the physical signs of deficiency?

Average diets are not usually lacking in Vitamin K and is rare in adults. Newborn infants are at risk and in most countries, Vitamin K shots are given at birth to prevent this. Deficiency usually results I coagulopathy, a bleeding disorder. Symptoms include anemia, bruising, bleeding of the gums or nose, and heavy menstrual bleeding in women.

11. What are physical signs of toxicity?

Toxicity has not been noticed in vitamin K, although allergic reaction to supplementation is possible.