Vitamin K

Vitamin K is not just one substance but is actually a group of substances identified as naphthoquinones. Most of the human’s sources of vitamin K come from plant sources, particularly the green leafy vegetables.

Food	Serving Size	Vitamin K (mcg)	Food	Serving Size	Vitamin K (mcg)
Kale, cooked	1/2 cup	531	Parsley, raw	1/4 cup	246
Spinach, cooked	1/2 cup	444	Spinach, raw	1 cup	145
Collards, cooked	1/2 cup	418	Collards, raw	1 cup	184
Swiss chard, cooked	1/2 cup	287	Swiss chard, raw	1 cup	299
Mustard greens, cooked	1/2 cup	210	Mustard greens, raw	1 cup	279
Turnip greens, cooked	1/2 cup	265	Turnip greens, raw	1 cup	138
Broccoli, cooked	1 cup	220	Broccoli, raw	1 cup	89
Brussels sprouts, cooked	1 cup	219	Endive, raw	1 cup	116
Cabbage, cooked	1/2 cup	82	Green leaf lettuce	1 cup	71
Asparagus	4 spears	48	Romaine lettuce, raw	1 cup	57
Table from "Important information to know when you are taking: Warfarin (Coumadin) and Vitamin K", Clinical Center, National Institutes of Health Drug Nutrient Interaction Task Force.[1]

Vitamin K₁ is found chiefly in leafy green vegetables such as spinach, swiss chard, and Brassica (e.g. cabbage, kale, cauliflower, broccoli, and brussels sprouts); some fruits such as avocado, kiwifruit and grapes are also high in vitamin K. By way of reference, two tablespoons of parsley contain 153% of the recommended daily amount of vitamin K. Some vegetable oils, notably soybean, contain vitamin K, but at levels that would require relatively large calorific consumption to meet the USDA recommended levels. Colonic bacteria synthesize a significant portion of humans' vitamin K needs; this is one of the reasons why newborns often receive a vitamin K shot at birth - in order to tide them over until day 5-7 when their colon becomes colonized.

It is believed that phylloquinone's tight binding to the thylakoid membranes in the chloroplasts is the reason behind the poor bioavailability of vitamin K in green plants. For example, cooked spinach has a 5% bioavailability of phylloquinone. However when one adds fat to the spinach, the bioavailability increases to 13% due to the increased solubility of vitamin K in fat.

Vitamin K₂ (Menaquinone-4) is synthesized by animal tissues and is found in meat, eggs, and dairy products. Menaquinone-7 is synthesized by bacteria during fermentation and is found in fermented soybeans (natto).

Special Precautions of Vitamin K

• a SYNTHETIC form of vitamin K, vitamin K3 (menadione), is demonstrably toxic. In fact, the FDA has banned this synthetic form of the vitamin from over-the-counter supplements because large doses have been shown to cause allergic reactions, hemolytic anemia, cytotoxicity in liver cells, formation of radicals from enzymes of leukocytes, weakens the immune system, mutagenic effects, damage to the natural vitamin K cycle, hemolytic anemia and hyperbilirubinemia, disturbing levels of calcium ions, vomiting, albuminuria, irritation of skin and mucous membranes, allergic reactions, eczema and unlike natural vitamin K - it builds up in tissue.
• Drug Interactions : Phylloquinone (K1)or menaquinone (K2) are capable of blocking the blood thinning action of anticoagulants like warfarin, which work by interfering with the action of vitamin K. They also reverse the tendency of these drugs to cause arterial calcification in the long term.
• Vitamin K2 is considered safe for most people. However, taking high amounts of any form of vitamin K may be harmful to pregnant and breastfeeding women, patients receiving dialysis treatments due to kidney disease, and people with clotting problems caused by severe liver disease. In addition, vitamin K may interact with certain supplements (including coenzyme Q10 and vitamin E).

The benefits of Vitamin K are

• Vitamin K1—phylloquinone, also known as phytonadione : Vitamin K1 makes up 90% of the vitamin K found in the Western diet. According to the National Institutes of Health, vitamin K1 is faster-acting, stronger, and more effective for some conditions than other forms of vitamin K. Consuming leafy green vegetables will provide an ample amount of this life-giving mineral and ensure optimal health.
  • Vitamin K1 is a necessary and important contributor to bone growth and overall bone health.
  • Vitamin K1 is best known in its ability to promote blood clotting. In fact, the letter “K” comes from the German term, koagulation.
  • Vitamin K1 is also an integral mineral for reducing prostate cancer risk. Regarding prostate cancer, it can reduce blood clotting, increase circulation, and in effect, support the healthy flow of urine and blood to the prostate.
  • Having high levels of Vitamin K1 may also reduce one’s risk for Alzheimer’s disease, reduce bruising, strengthen bones, improve skin, and reduce risk of developing heart disease (because it prevents hardening of the arteries).
• vitamin K2, also known as menaquinone, is very different. Vitamin K2 is essential for your cardiovascular health because of its amazing ability to utilize calcium : Calcium belongs in our bones, not in our blood. When our vitamin K2 levels are low, calcium collects in our blood and can lead to calcification in our arteries. Vitamin K is associated with a significantly lower risk of coronary heart disease and atherosclerosis. There's also some evidence that K2 may boost bone health and reduce risk of osteoporosis. (See also : Vitamin D) Preliminary research indicates that vitamin K2 may aid in the treatment of some forms of cancer. For example, in a 2003 test-tube study from the International Journal of Oncology, researchers found that vitamin K2 may help promote the death of lung cancer cells.
• Vitamin K3—menadione synthetic variant : This synthetic form of vitamin K is NOT for human consumption. It offers no benefits and comes with possibly risky side effects. Unfortunately, many vitamin manufacturers offer vitamin K3 as a supplement, so it is advisable to steer clear of these supplements!
• Vitamin K is also beneficial in protecting the bones from fractures and in helping women in their menopausal stage from having unhealthy bones. The link between bone health and vitamin K has been researched extensively. Primary to this is the ability of vitamin K, in its menaquinone form, to impede the formation of osteoclasts. Osteoclasts are responsible for removing the minerals in the bone for proper body functioning. While these minerals are important in the body, we do not want too much of the osteoclastic activity as it can result to bone demineralization. Therefore, if vitamin K is increased, there will be less demineralization of bones, less chances of getting fractures.
• vitamin K intake helps prevent diabetes.

Males require 120 micrograms of vitamin K, while females only need 90 micrograms daily. The excellent source of vitamin K is boiled kale and boiled spinach, which can provide over 1000 percent of the nutrients daily value per 1 cup of the vegetable.