| Vitamin :: Vitamin K |
| Other Terms: | Phylloquinone | Menaquinone | Menadione |
| Solubility: | Fat-soluble. It needs fats and bile for absorption and is stored by the body in fatty tissue. |
| On this Page: | What is Vitamin K · Benefits · Deficiency Signs · Foods · Supplements · RDA · Toxicity | Overdose |
What is Vitamin K ?
Vitamin K is a family of fat-soluble vitamins that includes :
- Phylloquinone or vitamin K1: the plant form of vitamin K. This is the main dietary source of the vitamin. It is one of the natural forms used in health supplements.
- Menaquinone or vitamin K2: this is produced in small amounts in our intestines by gut bacteria. It is the other natural form commonly used in nutritional supplements.
- Menadione or vitamin K3: the synthetic form that is water-soluble. This form is not allowed in health supplements as it has been found to cause adverse side effects.
Vitamin K is generally stable to heat and water, but destroyed by light, acids, bases, and oxidizers. Little vitamin K is lost in normal cooking, but food that is processed or frozen would lose a significant part of its vitamin K content.
Vitamin K is needed by the body, specifically the liver, to make proteins (called clotting factors) that are necessary for blood to coagulate properly and shorten bleeding time.
Without it, blood does not clot and we would bleed to death when a blood vessel is damaged, either from an internal or external injury. Blood clotting also isolates the area around a wound and begins its healing process.
Vitamin K is also critical for bone and cartilage formation. It enables bones to use calcium, and anchors calcium inside bones. Vitamin K supplements have been shown to lessen the amount of calcium lost in urine.
Over half of Americans older than 50 have osteoporosis. We can benefit from studies that show that vitamin K helps people maintain bone mineral density in many ways. Those who consume more vitamin K have lower risk of bone fractures.
| :: | Vitamin K Benefits & Functions |
| 1. | regulates normal clotting of blood to prevent excessive blood loss from injuries and begin the healing process |
| 2. | acts as an antioxidant to neutralize harmful free radicals that damage cell membranes, and so prevents oxidative cell damage |
| 3. | needed for formation of cartilage, bone and dentine (part of teeth) |
| 4. | decreases the amount of calcium lost in urine and anchors calcium inside bones to maintain bone density |
| 5. | helps prevent and treat osteoporosis and lowers risk of fractures |
Vitamin K Deficiency Symptoms and Causes
Vitamin K deficiency is rare in adults, mainly because this vitamin is found in many foods and because some of it can be made by intestinal bacteria.
Deficiency can occur, however. Risk factors are chronic malnutrition and alcohol dependency. People with digestive tract problems who have difficulty absorbing fats and nutrients, or liver or gallbladder problems that affect secretion of bile required for vitamin K absorption, are also at risk.
A diet that is extremely low in fats which are needed for the absorption of fat-soluble vitamins, can therefore cause vitamin K deficiency symptoms, as well as deficiency of the other fat-soluble vitamins (A, D and E).
Some drugs may interfere with the absorption of vitamin K or reduce blood levels of it. For example, antibiotics, anti-convulsants, and certain sulfa drugs kill not only harmful bacteria but also beneficial vitamin K-generating bacteria in the intestines. Long term usage can lead to deficiency.
X-rays, radiation, aspirins, certain antacids, and mineral oil laxatives, may also interfere with absorption of vitamin K or raise the level needed.
Vitamin K deficiency appears to be linked to osteoporosis and higher bone fracture rates, as people with these conditions tend to have lower levels of vitamin K. This is aggravated by the fact that vitamin K levels in blood tend to decrease with age.
Supplements have been used in the treatment of osteoporosis, especially for postmenopausal women.
Newborns, especially those born prematurely, are prone to deficiency as they get only a little vitamin K before birth and lack the intestinal bacteria to produce the vitamin the first few days after birth.
This makes them vulnerable to bleeding or hemorrhagic disease. A vitamin K injection is often given to newborns to reduce the risk of bleeding in the brain after delivery.
The main vitamin K deficiency symptoms are summarized here.
| :: | Vitamin K Deficiency Symptoms |
| 1. | The main symptom is bleeding or hemorrhage. This could be in the skin (seen as a bruise), from a wound or the nose, in or around the brain (newborns), and in the stomach, intestine, or urinary tract. Bleeding in the stomach might cause vomiting with blood. Blood may also appear in the stool or urine. The risk is higher for those with liver disease as well, since the clotting proteins are made in the liver. |
| 2. | Blood takes longer to clot than normal, which in severe cases can lead to fatal anemia |
| 3. | Lower bone mineral density that can eventually lead to osteoporosis |
| 4. | Higher risk of bone fracture (such as hip fractures) |
Vitamin K Foods
Rich vitamin K foods
· soybeans · vegetables, especially dark green leafy vegetables, like asparagus, beet greens, broccoli, Brussel sprouts, green cabbage, cauliflower, chard, collard greens, garden cress, kale, lettuce, mustard greens, romaine lettuce, spinach, turnip greens, watercress.
Other foods with vitamin K
· alfalfa · animal liver · carrots · egg yolk · garbanzo beans · green beans and peas · cereals (oats, oatmeal, rye, wheat) · safflower oil.
Vitamin K Supplements
Taking vitamins and minerals in their correct balance is vital to the proper functioning of all vitamins. They work synergistically, which means that the effectiveness of any one nutrient requires or is enhanced, sometimes dramatically, by the presence of certain other nutrients.
For this reason, if you are looking to take supplements for maintenance of optimal health, the recommended approach is to take a multi-vitamin that has the proper balance of all the necessary nutrients your body needs.
For a list of reputable top ranked vitamin and mineral supplements chosen in an independent supplement review, see Best Multivitamin Supplements. Many of these are manufactured to pharmaceutical or nutraceutical GMP compliance, which is the highest multivitamin standard possible.
Keep in mind, however, that while vitamin supplements are useful to plug nutritional gaps that are almost inevitable in modern diets, and to ensure we get optimal doses of nutrients, they are no substitute for a good diet. Instead, use them to complement a healthy diet and lifestyle.
Vitamin K RDA (Recommended Dietary Allowance)
The Food & Nutrition Board of the Institute of Medicine, National Academy of Sciences, in their 1997-2001 collaboration between the US and Canada, set the daily Adequate Intake (AI) of Vitamin K as follows.
| Life Stage | Gender | Vitamin K Dosage | Day |
| Infants 0-6 mths | 2.0* µg |
| Infants 7-12 mths | 2.5* µg |
| Children 1-3 yrs | 30* µg |
| Children 4-8 yrs | 55* µg |
| Girls 9-13 Yrs | 60* µg |
| Boys 9-13 Yrs | 60* µg |
| Females 14-18 Yrs | 75* µg |
| Males 14-18 Yrs | 75* µg |
| Females 19-50 Yrs | 90* µg |
| Males 19-50 Yrs | 120* µg |
| Females older than 50 Yrs | 90* µg |
| Males older than 50 Yrs | 120* µg |
| Pregnant Women 14-18 Yrs | 75* µg |
| Pregnant Women 19-50 Yrs | 90* µg |
| Lactating Mothers 14-18 Yrs | 75* µg |
| Lactating Mothers 19-50 Yrs | 90* µg |
These dosages are the minimum required per day to ward off deficiency. In therapeutic use of this nutrient, dosage is increased as necessary for the ailment, keeping in mind Vitamin K toxicity levels.
Legend
1 µg = 1 mcg = 1 microgram = 1/1,000,000 of a gram
1 mg = 1 milligram = 1/1,000 of a gram
* Indicates AI figures based on Dietary Reference Intake (DRI) figures
Vitamin K Overdose Symptoms, Toxicity Level & Side Effects
There has been no case of vitamin K overdose reported for natural forms of it, even at high dosages. The Food and Nutrition Board of the Institute of Medicine decided not to set a Tolerable Upper Intake Level (UL) for it.
This does not mean that no vitamin K side effects exist. High dosages can accumulate and cause flushing and sweating. Excessive supplementation in pregnancy is also not recommended, especially soon before birth. It is, however, safe for breastfeeding mothers to take vitamin K, as little of it is transmitted in breast milk to infants.
High doses of Menadione or vitamin K3, the synthetic form of vitamin K, can cause serious adverse effects such as jaundice and hemolytic anemia in infants. It can lead to toxic reaction in the baby when taken in the last few weeks of pregnancy.
There have also been a few rare cases of liver damage in infants injected with synthetic vitamin K preparation Menadiol (not available in the US).
High doses of vitamin K3 can also cause adults to lose glutathione, the important antioxidant produced in the body. Vitamin K3 is therefore not allowed for use in nutritional supplements.
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References
| 1. | Institute of Medicine, Food and Nutrition Board. Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. Washington, DC: National Academy Press; 2001. |
| 2. | U.S. National Libary of Medicine [NLM] & National Institutes of Health [NIH]: MedlinePlus. NLM-NIH home page. <http://www.nlm.nih.gov/medlineplus>. Use the built-in search function to find specific data. Accessed 2009 March – June. |
| 3. | The George Mateljan Foundation: The world’s healthiest foods [WHFoods]. WHFoods home page. <http://www.whfoods.com>. Accessed 2009 March – June. |
| 4. | Balch JF, Balch PA. Prescription for nutritional healing: A practical A-Z reference to drug-free remedies using vitamins, minerals, herbs & food supplements. Garden City Park, New York: Avery Publishing; 1990. |
| 5. | Ulene A. Dr. Art Ulene’s complete guide to vitamins, minerals and herbs. New York, NY: Avery Publishing; 2000. |
