Vitamin Benefits, Side Effects, Deficiency Symptoms and Sources

Vitamins are essential nutrients your body needs in small amounts for various roles in the human body such as the maintenance of good health and the prevention of a number of diseases. Vitamins are substances that your body needs to grow and develop normally.

You can usually get all your vitamins from the foods you eat. Your body can also make vitamins D and K. People who eat a vegetarian diet may need to take a vitamin B12 supplement.

Each vitamin has specific jobs. If you have low levels of certain vitamins, you may develop a deficiency disease. For example, if you don't get enough vitamin D, you could develop rickets. Some vitamins may help prevent medical problems. Vitamin A prevents night blindness.

In this article, we look at the properties of vitamins A, B, C, D, E, K, and common food sources.

Types of Vitamins

Unlike water-soluble vitamins that need regular replacement in the body, fat-soluble vitamins are stored in the liver and fatty tissues, and are eliminated much more slowly than water-soluble vitamins.

Water-soluble vitamins dissolve in water. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of such vitamins in your diet.

Vitamin A (Retinol)

Vitamin A, also known as retinol, is a fat-soluble vitamin that is essential to our health. It promotes good vision, especially in low light. Vitamin A helps you see in color, from the brightest yellow to the darkest purple. Studies have indicated that it may be very important for reproduction and breast-feeding mothers as well. Vitamin A promotes normal growth and health of body cells and keeps skin and hair healthy and is needed for the proper development of an embryo and fetus. It also helps keep skin and mucous membranes that line the nose, sinuses, and mouth healthy. It is a powerful antioxidant that plays a key role in the body's immune system, growth, bone formation, reproduction, and wound healing.

Another source of vitamin A is a substance called beta-carotene. This is converted by the body into vitamin A. It is found in orange, yellow and green vegetables and fruits.

Vitamin B Complex

All B vitamins help the body convert food (carbohydrates) into fuel (glucose), which is used to produce energy. These B vitamins, often referred to as B complex vitamins, also help the body use fats and protein. B complex vitamins are needed for healthy skin, hair, eyes, and liver. They also help the nervous system function properly and guards against heart disease, mental disorders, and anemia, and keeps your immune system strong. This group of vitamins is also involved in making red blood cells, which carry oxygen throughout your body. Every part of your body needs oxygen to work properly, so these B vitamins have a really important job.

Thiamine (Vitamin B1)

Thiamine, also called vitamin B1 or thiamin, is one of 8 B vitamins. It is found in many foods including yeast, cereal grains, beans, nuts, and meat. Thiamin helps the body's cells convert carbohydrates into energy. It is also essential for the functioning of the heart, muscles, and nervous system. Like other B complex vitamins, thiamine is sometimes called an "anti-stress" vitamin because it may strengthen the immune system and improve the body's ability to withstand stressful conditions. In fact, thiamine is so important to a healthy mental state, it has been called the "morale vitamin". It is named B1 because it was the first B vitamin discovered.

A lack or deficiency of thiamin can cause weakness, fatigue, psychosis, and nerve damage. It's rare to be deficient in thiamine, although alcoholics, people with Crohn's disease, anorexia, and those undergoing kidney dialysis may be deficient. Symptoms of thiamine deficiency are fatigue, irritability, depression and abdominal discomfort. People with thiamine deficiency also have trouble digesting carbohydrates. That allows a substance called pyruvic acid to build up in their bloodstream, causing a loss of mental alertness, difficulty breathing, and heart damage, a disease known as beriberi.

In severe thiamin deficiency, brain damage can occur. One type is called Korsakoff syndrome. The other is Wernicke's disease. Either or both of these conditions can occur in the same person.

Riboflavin (Vitamin B2)

Riboflavin, also known as vitamin B2, is one of 8 B vitamins. It can be found in certain foods such as milk, meat, eggs, nuts, enriched flour, and green vegetables. Riboflavin is important for body growth and red blood cell production and helps maintain a strong immune system by protecting the body from free-radical damage. Free radicals can damage cells and DNA, and may contribute to the aging process, as well as the development of a number of health conditions, such as heart disease and cancer. Antioxidants such as riboflavin can fight free radicals and may reduce or help prevent some of the damage they cause. Without riboflavin, the other B vitamins, especially niacin (vitamin B3) and pyridoxine (vitamin B6), cannot do their job, and a host of chemical processes necessary to keep the body alive would come to a grinding halt.

Most healthy people who eat a well-balanced diet get enough riboflavin. However, elderly people and alcoholics may be at risk for riboflavin deficiency because of poor diet. Symptoms of riboflavin deficiency include fatigue; slowed growth; digestive problems; cracks and sores around the corners of the mouth; swollen magenta-colored tongue; eye fatigue; swelling and soreness of the throat; and sensitivity to light.

Niacin (Vitamin B3)

Niacin and niacinamide are forms of vitamin B3. It is one of 8 B vitamins. It is also known as nicotinic acid and has 2 other forms, niacinamide (nicotinamide) and inositol hexanicotinate, which have different effects from niacin. Niacin is an important part of metabolism. It helps the body to convert food (carbohydrates) into fuel (glucose), which is used to produce energy. It also helps with the conversion of fats and proteins, although to a lesser extent. Niacin is also necessary for a healthy digestive system, circulatory system, and nervous system, along with healthy hair, eyes, and nails. Niacin also is essential in reducing cholesterol in the blood thus preventing atherosclerosis and thrombosis.

Vitamin B3 is found in many foods including yeast, meat, fish, milk, eggs, green vegetables, beans, and cereal grains. Niacin and niacinamide are also found in many vitamin B complex supplements with other B vitamins.

You can meet all of your body's needs for B3 through diet. It is rare for anyone in the developed world to have a B3 deficiency. In the United States, alcoholism is the main cause of vitamin B3 deficiency. Symptoms of mild deficiency include indigestion, fatigue, canker sores, vomiting, and depression. Severe deficiency can cause a condition known as pellagra. Pellagra is characterized by cracked, scaly skin, dementia, and diarrhea. It is generally treated with a nutritionally balanced diet and niacin supplements. Niacin deficiency also causes burning in the mouth and a swollen, bright red tongue.

Pantothenic Acid (Vitamin B5)

Pantothenic Acid, also called vitamin B5 or pantothenate, is one of 8 B vitamins. It is widely found in both plants and animals including meat, vegetables, cereal grains, legumes, eggs, and milk. It is an anti-stress vitamin supporting the adrenal glands to produce cortisone to neutralize stress, prevent aging, wrinkles and keeps your skin healthy, and is used in a number of cosmetics. It helps metabolism of carbohydrates as well, which is used to produce energy. It also help the body use fats and protein, helping to repair tissues in the body, and os needed need to synthesize cholesterol.

This B vitamin is found in the plasma of the blood. Vitamin B5 is essential to maintain the body's balance of sodium and potassium. Without vitamin B5 your body would not be able to regulate its fluids neither would it be able to properly regulate your blood pressure. In addition to playing a role in the breakdown of fats and carbohydrates for energy, vitamin B5 is critical to the manufacture of red blood cells, as well as sex and stress-related hormones produced in the adrenal glands, small glands that sit atop the kidneys. Vitamin B5 is also important in maintaining a healthy digestive tract, and it helps the body use other vitamins, particularly B2 or riboflavin.

It is rare for anyone to be deficient in vitamin B5. Symptoms of a vitamin B5 deficiency may include fatigue, insomnia, depression, irritability, vomiting, stomach pains, burning feet, and recurring upper respiratory infections.

Since this vitamin supports the function of the adrenal glands a deficiency of this vitamin can lead to adrenal exhaustion. The brain is another organ in the body that utilizes a significant amount of pantothenic acid. The brain is the only part of the body that uses the highest form of vitamin B5, therefore individuals resulting in a decreased amount of vitamin B5 can notice mood changes, such as fluctuations, and trouble with depression.

Pyridoxine (Vitamin B6)

Pyridoxine, also called vitamin B6, is one of 8 B vitamins. Vitamin B6 is abundant in meats, fish, poultry, shellfish, leafy green vegetables, legumes, fruits, and whole grains. Pyridoxine is required for the proper function of sugars, fats, and proteins in the body. It is also required for the proper growth and development of the brain, nerves, skin, and many other parts of the body. It is needed for normal brain development and function, and helps the body make the hormones serotonin and norepinephrine, which influence mood, and melatonin, which helps regulate the body clock.

Vitamin B6 is necessary for the production of over 100 different enzymes the body uses to metabolize proteins. It improves the immune system and helps to alleviate symptoms of depression. In addition, it helps the body convert the amino acid known as tryptophan into niacin, another B vitamin.

Along with vitamins B12 and B9 (folic acid), B6 helps control levels of homocysteine in the blood. Homocysteine is an amino acid that may be associated with heart disease. Your body needs B6 in order to absorb vitamin B12 and to make red blood cells and cells of the immune system.

It is rare to have a significant deficiency of B6, although studies indicate many people may be mildly deficient, especially children and the elderly. Certain medications can also cause low levels of B6 in the body. Symptoms of serious deficiency include muscle weakness, nervousness, irritability, depression, difficulty concentrating, and short-term memory loss.

Biotin (Vitamin H, Vitamin B7)

Biotin, also known as Vitamin B7, Vitamin H, Coenzyme R or Biopeiderm, plays a key role in the body, and is one of 8 B vitamins. It supports the health of the skin, nerves, digestive tract, metabolism, and cells. Biotin may also help to treat some types of nerve pathology, such as the peripheral neuropathy that can result from kidney failure or diabetes. Biotin is also important for normal embryonic growth, making it a critical nutrient during pregnancy. Your body needs biotin to metabolize carbohydrates, fats, and amino acids, the building blocks of protein. Biotin is often recommended for strengthening hair and nails and it's found in many cosmetic products for hair and skin.

Biotin has had a number of different names since it was first discovered. Scientists weren't sure what it did, couldn't decide if it was an enzyme or a vitamin, and had trouble naming it. Biotin is still sometimes referred to as vitamin H, although it is now known that biotin is a B-complex vitamin.

Biotin is consumed from a wide range of food sources in the diet, however there are few particularly rich sources. Foods with a relatively high biotin content include Swiss chard, raw egg yolk (however, the consumption of egg whites with egg yolks minimizes the effectiveness of egg yolk's biotin in one's body), liver, some vegetables, and peanuts.

It' s rare to be deficient in biotin. Symptoms include hair loss, dry scaly skin, cracking in the corners of the mouth (called cheilitis), swollen and painful tongue that is magenta in color (glossitis), dry eyes, loss of appetite, fatigue, insomnia, and depression. People who have been on parenteral nutrition -- nutrition given through an IV -- for a long period of time, those taking antiseizure medication or antibiotics long-term, and people with conditions like Crohn' s disease that make it hard to absorb nutrients are more likely to be deficient in biotin.

Folic Acid (Vitamin B9)

Folic acid, also known as vitamin B9 or folate, is a very important nutrient for the body, and is one of 8 B vitamins. This vitamin works to accelerate the metabolic activity and assist the function of other essential nutrients. Without folic acid, the body will be easily attacked by various diseases, ranging from depression, anxiety, fatigue, insomnia, difficulty remembering, red tongue and wound up indigestion.

Folic acid is crucial for proper brain function and plays an important role in mental and emotional health. It aids in the production of DNA and RNA, the body's genetic material, and is especially important when cells and tissues are growing rapidly, such as in infancy, adolescence, and pregnancy. Folic acid also works closely with vitamin B12 to help make red blood cells and help iron work properly in the body.

It's fairly common to have low levels of folic acid. Alcoholism, inflammatory bowel disease, and celiac disease can cause folic acid deficiency. Also, certain medications may lower levels of folic acid in the body. Folic acid deficiency can cause poor growth, tongue inflammation, gingivitis, loss of appetite, shortness of breath, diarrhea, irritability, forgetfulness, and mental sluggishness.

Since 1998, folic acid has been added to cold cereals, flour, breads, pasta, bakery items, cookies, and crackers, as required by federal law. Foods that are naturally high in folic acid include leafy vegetables (such as spinach, broccoli, and lettuce), okra, asparagus, fruits (such as bananas, melons, and lemons) beans, yeast, mushrooms, meat (such as beef liver and kidney), orange juice, and tomato juice.

Pregnant women need more folic acid to lower the risk of neural tube birth defects, including cleft palate, spina bifida, and brain damage. Neural tube defects are birth defects caused by abnormal development of the neural tube, a structure that eventually gives rise to the brain and spinal cord. Since folic acid has been added to many grain foods in the U.S., such as bread and cereal, neural tube defects have decreased dramatically.

Food	Serving size	Amount of folate
Asparagus	115g	132mcg
Black beans	115g	128mcg
Breakfast cereal	30-40g	80-120mcg
Brussels sprouts	115g	47mcg
Chicken liver	100g	770mcg
Chick peas	115g	180mcg
Cooked broccoli	115g	47mcg
Cooked spinach	115g	131mcg
Cooked white rice	170g	60mcg
Kidney beans	115g	115mcg
Oranges	1 medium	47mcg
Pasta	55g	100-120mcg
Tomato juice	1 cup (225ml)	48mcg
Wheat germ	2 tbsp	38mcg

Cobalamin (Vitamin B12)

Cobalamin, also called vitamin B12 and cyanocobalamin, is one of 8 B vitamins. Vitamin B12 is needed to form healthy blood cells; red blood cells to supply the body with oxygen, and white blood cells to fight against infection. It is also needed to make myelin, a protective fatty layer that coats nerve cells and keeps electrical impulses moving through the body.

Vitamin B12 works closely with folic acid (vitamin B9) and pyridoxine (vitamin B6) to convert food into energy. It also works with these B vitamins to protect your heart by removing homocysteine from the blood. Homocysteine is an amino acid found in meats that causes blood cells to clump together and cling to arterial walls. Too much homocysteine in the system can damage arterial walls and contribute to the development of atherosclerosis, a condition that often leads to early heart attack.

Without enough vitamin B12 the nervous system can "short out" and cause interruptions in mental function--symptoms of B12 deficiency can be so severe that they actually mimic senility. Vitamin B12 helps prevent nerve damage and maintain fertility, and is needed for production of acetylcholine, a neurotransmitter that enhances memory and learning.

Vitamin B12 is found in animal products such as meat, shellfish, milk, cheese, and eggs. Most people who eat animal products are not likely to develop vitamin B12 deficiency anemia unless their bodies can't absorb it from food. Strict vegetarians (vegans) who do not eat animal products and babies of mothers who are strict vegetarians are at increased risk for developing anemia and should take a supplement containing vitamin B12. Vitamin B12 is stored in the liver for a year or more, which reduces a person's risk of anemia.

Vitamin C (Ascorbic Acid)

Vitamin C, also called ascorbic acid, is a water-soluble vitamin that is necessary for normal growth and development. It helps to maintain healthy collagen in the skin, repair damaged tissue, promote healthy teeth and bones, and boost the immune system. Vitamin C is also one of the commonly used dietary supplements for immune stimulation, for wound healing, as an antioxidant, and for cancer prevention. In addition, it also helps with the normal function of blood vessels and helps you absorb iron from plant sources as opposed to the iron in red meat.

Water-soluble vitamins, including vitamin C, dissolve in water. Leftover amounts of the vitamin leave the body through the urine. That means you need a continuous supply of such vitamins in your diet. Some animals can make their own vitamin C, but people must get this vitamin from food and other sources. Good sources of vitamin C are fresh fruits and vegetables, especially citrus fruits. Vitamin C can also be made in a laboratory (ascorbic acid).

Vitamin C functions as an anti-inflammatory, and helps the body fight inflammatory diseases, including arthritis, fibromyalgia, and chronic fatigue. A multitude of other conditions may be improved by vitamin C, including angina, bronchitis, bruises, canker sores, constipation, diabetes, eyestrain, gingivitis, glaucoma, infertility, joint pain, rashes, rosacea, shingles, sore throat, sprains, sunburn, and yeast infections, urinary tract infections, and scurvy (a disease caused by vitamin C deficiency). Because vitamin C helps the body absorb iron, it is also useful in treating iron deficiency and anemia.

However, vitamin C may yield its greatest benefits in fighting cancer, heart disease, and in boosting the immune system. One analysis of the dietary consumption of eleven thousand individuals found that getting 300 milligrams daily of Vitamin C could add as much as six years to the life of a man and as much as two years to the life of a woman.

Supplemental doses of vitamin C have been found to reduce the risk of certain cancers (including esophageal, pancreatic, and cervical cancer), provide protection against heart disease (studies have shown that vitamin C supplementation can not only lower systolic blood pressure, but also drive up good HDL cholesterol while lowering bad LDL cholesterol), and boost the immune system. Supplemental doses of vitamin C can increase the body's production of lymphocyes and glutathione.

Too little vitamin C can lead to signs and symptoms of deficiency, including anemia, bleeding gums, decreased ability to fight infection, decreased wound-healing rate, dry and splitting hair, easy bruising, gingivitis (inflammation of the gums), nosebleeds, possible weight gain because of slowed metabolism, rough, dry, scaly skin, swollen and painful joints, and weakened tooth enamel. A severe form of vitamin C deficiency is known as scurvy, which mainly affects older, malnourished adults.

Vitamin D (Calciferol)

Vitamin D, also known as calciferol, is a steroid vitamin, and is needed for normal absorption of calcium and phosphorus. It helps put these minerals into bones and teeth. This makes bones stronger and reduces your risk for bone fractures. Vitamin D also helps keep the immune system functioning helping the body resist disease.

Vitamin D is found in many dietary sources, such as fish, eggs, fortified milk, and cod liver oil. The sun also contributes significantly to the daily production of vitamin D, and as little as 10 minutes of exposure is thought to be enough to prevent deficiencies. People who are exposed to normal quantities of sunlight do not need vitamin D supplements because sunlight promotes sufficient vitamin D synthesis in the skin.

The term "vitamin D" refers to several different forms of this vitamin. Two forms are important in humans: ergocalciferol (vitamin D2), which is found in such foods; and cholecalciferol (vitamin D3), which is manufactured when the body is exposed to sun. Vitamin D2 is synthesized by plants. Vitamin D3 is synthesized by humans in the skin when it is exposed to ultraviolet B (UVB) rays from sunlight. Foods may be fortified with vitamin D2 or D3.

You can get vitamin D in three ways: through your skin, from your diet, and from supplements. Your body forms Vitamin D naturally after exposure to sunlight. However, too much sun exposure can lead to skin aging and skin cancer. So many people try to get their vitamin D from other sources.

Vitamin D is one of those vitamins for which a deficiency can cause severe effects. Children that do not get enough vitamin D in their diets are at increased risk of developing rickets, a disease that causes malformations of bones and teeth in children. Adults with low levels of vitamin D are more likely to develop osteomalacia (similar to rickets) and to suffer from osteoporosis, a bone-weakening disease. Vitamin D also regulates the nervous system, aiding in the treatment of insomnia. A glass of warm milk before bed may indeed help you sleep soundly! Vitamin D deficiency has also been linked to the development of other illnesses, including type 1 diabetes, muscle and bone pain, and cancer.

Vitamin D is fat-soluble. This means that excess amounts of it are stored in the body tissues. Long-term high doses may be deposited in the soft tissues, irreversibly damage the kidneys and cardiovascular system. Like other fat-soluble vitamins, vitamin D can be toxic. Symptoms of too much vitamin D include nausea, weakness, constipation, irregular heartbeat, weight loss, seizures, and irritability.

Sunlight is the best source of vitamin D, because sunlight exposure does not cause vitamin D toxicity, and 10 minutes of sun on your hands and face provides enough vitamin D to reach the daily value. However, getting the necessary amount of vitamin D from the sun is not as simple as it sounds. For one thing, people in northern hemisphere may have difficulty getting vitamin D from sun in the winter due to infrequent exposure to direct sunlight (light coming through a glass window of a car or building doesn't count, because it filters out vitamin D). Also, the recent explosion in the number of skin cancer cases has caused the public to use more and stronger sunscreen, which inhibits the body's ability to manufacture its own vitamin D from sunlight. However, if you have a history of skin cancer, it is probably best to try to get the vitamin D needed from your diet instead rather than the sun.

The major source of vitamin D in our diet is fortified milk, but it would take one quart of fortified milk to provide the Daily Value. Because there are relatively few foods that contain vitamin D, you may wish to rely on a vitamin supplement to meet your daily needs.

The Recommended Dietary Allowance (RDA) of vitamin D is 800 International Units (IU) for children 18 and under, 600 IU for adults 19-22, and 400 IU for anyone over 23 years. Healthy infants are born with enough vitamin D to last them three months.

However, vitamin D supplements should be taken with caution. Doses of 1,800 IU units a day can cause stunted growth in infants and young children. Too much vitamin D can lead to birth defects, coma, or even death. No one should take more than 600 IU of vitamin D daily without doctor supervision.

Vitamin E

Vitamin E, also known as tocopherol and alpha-tocopherol, is a fat soluble nutrient that dissolves in fat. Vitamin E is key for strong immunity and healthy skin and eyes. Vitamin E is an antioxidant that helps protect the body from the effects of free radicals. Free radicals are harmful compounds in the body that damage DNA (genetic material) and even cause cell death. Free radicals are believed to contribute to aging as well as the development of a number of health problems, including heart disease and cancer.

Vitamin E works to neutralize free radicals, which are naturally occurring unstable molecules that can damage the body's healthy molecules by taking electrons to balance themselves. When enough vitamin E is present in the body, unstable free radicals get their electrons from the vitamin E molecules and leave the healthy molecules alone, thus causing less damage to tissues.

Vitamin E also helps ease respiratory problems, and may also prevent some of the damage that diabetes does to the body, particularly to the eyes. It also boosts the immune system's ability to fight off infectious diseases by increasing levels of interferon and interleukin, the biochemicals that are produced by the immune system to fight infection. Vitamin E is also important in the formation of red blood cells and it helps the body to use vitamin K.

Vitamin E is being tested as a treatment for many chronic diseases for the elderly, including Alzheimer's, macular degeneration, osteoarthritis, and prostate enlargement. And it is thought that this powerful antioxidant may help keep some types of cancer from developing.

Vitamin E is also an effective anti-inflammatory, and may help to prevent sun damage. Vitamin E oil containing at least 5 percent vitamin E can help prevent inflammation and skin damage if applied within eight hours after sun exposure. Do not apply the cream before going into the sun, as vitamin E reacts to UV rays in a way that will speed up rather than slow down the oxidation process.

Vitamin E is found in many foods including vegetable oils, nuts, cereals, meat, poultry, eggs, fruits, vegetables, wheat germ and wheat germ oil, whole-wheat flour, spinach, lettuce, onions, blackberries, apples, and pears. It is also available as a supplement. However, because it can be difficult to get the amount of vitamin E needed from food, you may wish to take a vitamin E supplement. There are eight different forms of the vitamin E, but look for the bottle labeled d-alpha-tocopherol, as it is this form that makes the most vitamin E available to your body.

Vitamin E is a fat-soluble substance, and excess amounts of this nutrient are stored in the body. However, unlike vitamin A and vitamin D, extra vitamin E stored in the body has not proven to be toxic. Infants with low birth weight, people with cystic fibrosis, and anorexics, or anyone with a condition that interferes with the proper absorption of fat, may need more than the Recommended Dietary Allowance (RDA) of this vitamin.

The RDA for adult males is 30 IU, and 24 IU for adult females. Women need an additional 6 IU each day during pregnancy, and an extra 9 IU per day if breastfeeding. People over the age of 55, smokers, and those who abuse alcohol may need to take vitamin E supplements.

However, most healthy individuals could benefit from taking this vitamin supplement. Some studies show that as much as 200 to 800 IU is needed to prevent disease and obtaining vitamin E in such amounts through dietary sources alone would be difficult.

There are some serious risks associated with taking too much vitamin E. More than 2,400 IU per day may cause bleeding problems due to its clot-preventing ability. People who are already taking anticoagulants (blood thinner) for a heart condition should not take vitamin E supplements.

Vitamin E can also interfere with the body's absorption of vitamin K, which is involved in blood coagulation. Too much vitamin E may also reduce your body's supply of vitamin A and alter the immune system.

Vitamin K

Vitamin K, also known as vitamin K1, vitamin K2 and vitamin K3, is a group fat-soluble vitamins that are needed for the synthesis of the proteins that help control bleeding (clotting factors) and thus for the normal clotting of blood. Vitamin K also helps your body by making proteins needed for healthy bones and other tissues. If you don't have enough vitamin K, you may bleed too much. Vitamin K is a vitamin found in leafy green vegetables, broccoli, and Brussels sprouts.

Vitamin K was identified in 1929 by Danish scientist Henrik Dam when he investigated the role of cholesterol by feeding chickens a cholesterol-depleted diet. After several weeks, the animals developed hemorrhages and started bleeding. These defects could not be restored by adding purified cholesterol to the diet. It appeared that—together with the cholesterol—a second compound had been extracted from the food, and this compound was called the coagulation vitamin. The new vitamin received the letter K because the initial discoveries were reported in a German journal, in which it was designated as Koagulationsvitamin.

Vitamin K comes in three forms: phylloquinone, menaquinone, and menadione. Phylloquinone, or vitamin K1, is found in green leafy vegetables, and helps bones absorb and store calcium. One recent study showed that increased amounts of vitamin K in the diet might lower the risk of hip fracture; over time, a shortage of vitamin K could lead to osteoporosis. Menaquinone, or vitamin K2, is manufactured in the body by naturally occurring intestinal bacteria. People that regularly take antibiotics or have a medical condition that upsets the balance of bacteria in the intestine are at risk of developing a vitamin K deficiency. Menadione, or vitamin vitamin K3, is an artificial form of vitamin K, which is water-soluble and more easily absorbed by people who have problems with fat absorption.

It is rare to have a vitamin K deficiency. That's because in addition to being found in leafy green foods, the bacteria in your intestines can make vitamin K. Sometimes taking antibiotics can kill the bacteria and lead to a mild deficiency, mostly in people with low levels to begin with.

Persons deficient in vitamin K are first and foremost likely to have symptoms related to problematic blood clotting or bleeding. These symptoms can include heavy menstrual bleeding, gum bleeding, bleeding within the digestive tract, nose bleeding, easy bruising, blood in the urine, prolonged clotting times, hemorrhaging, and anemia. A second set of vitamin K deficiency-related symptoms involves bone problems. These symptoms can include loss of bone (osteopenia), decrease in bone mineral density (osteoporosis), and fractures -- including common age-related fractures like that of the hips. Yet another set of vitamin K deficiency-related symptoms involves excess deposition of calcium in soft tissues. These calcification-based problems include hardening of the arteries or calcium-related problems with heart valve function.

Food	Serving size	Amount of vitamin C
Strawberries	1 bowl	70-120mg
Kiwi fruit	1 fruit	50mg
Steamed broccoli	1 serving (80g)	50mg
Orange	1 large	70mg
Mango and passion fruit smoothie	250ml glass/bottle	48mg
Frozen peas, cooked	1 serving (85g)	17mg

Facts about Vitamins and Vitamin Benefits, Deficiencies and Sources