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Vitamins: SparkDiet Resource Center

At the turn of the century, the romance and thrill of discovering the first vitamins captured the world’s heart. People loved vitamins! They were the perfect answers for people looking for an easy path to good health. Fascinating stories described how vitamins cured diseases that had mystified doctors for centuries:
  • For years, sailors had suffered at sea with bleeding gums called scurvy. However when the sailors ate lemons, oranges and limes that had been loaded on the ship, the disease was cured. Sailors were fondly called “limeys”. These citrus fruits provided the missing vitamin C that was needed in their diets.

  • In the 19th century, children were given their daily dose of cod liver oil to prevent the bone deforming disease called rickets. But not until 1922 did scientists discover that vitamin D was the substance in cod liver oil that provided the protection.

  • As white, polished rice became more popular than brown rice the risk of developing beriberi also increased. A Dutch scientist observed that chickens in a prison yard showed symptoms similar to those of his patients. The chickens ate the polished-rice scraps of the prisoners. However, when the chickens were accidentally given the part of the rice that was discarded after polishing, their health improved. This discarded part of the rice contained the nutrient thiamin.

With discoveries such as these, it is easy to see why people were so impressed. With the discovery of each vitamin, whole groups of people were miraculously cured.

The term given these substances originally was vitamine (vita meaning life). When it was later realized that most vitamins are not amines, the e on vitamine was dropped. At first, vitamins were named using letters, like vitamin A, vitamin B, and vitamin C. Later, chemical analysis showed that what had been thought to be one chemical was actually two or more. So sub-numerals were used like vitamin B-1, vitamin B-2. Some vitamins are also named based on the diseases they cure.

Why Too Much Can Be Bad

Vitamins are important and good for your health. Many have the notion that if a little is good, then more must be better. This is a myth which can be very dangerous. Vitamins actually function primarily as catalysts, regulating chemical reactions within the body. They are also essential for the release of energy from food. But they do not provide calories or energy themselves. Each vitamin serves one or more special functions in the body that no other nutrient can. Deficiencies also have specific consequences.

To become active in the body, each vitamin must associate with a special protein. Together they form an active enzyme ready to regulate body processes. However, it is important to realize that once the special proteins in the body cells are filled up with a particular vitamin, no further activity can possibly be achieved by adding any more of that vitamin. The excess vitamin serves as a chemical substance that in many cases can do damage to the body. This is why over-dosages of vitamin supplements cannot benefit the body and may in fact be harmful.

Vitamins are sometimes referred to as micronutrients since they are needed in only small amounts. Vitamins are measured in milligrams (one-thousandth of a gram) and in micrograms (one-millionth of a gram), or in International Units. An inadequacy of a minute amount of a vitamin can have far-reaching effects on body processes and health. Too much of certain vitamins, though seemingly a small amount, can produce harmful toxic conditions.

The Vitamin Family

Vitamins belong in two groups: water-soluble and fat-soluble. Each name describes an important quality—how it is carried in food and transported in your body.

Water-soluble vitamins dissolve in water. They include the B-complex vitamins and vitamin C. They are carried in your bloodstream and are not stored in the body in significant amounts. Your body uses the amount that is needed, and then the extra is excreted in the urine. Since your body does not store water-soluble vitamins, regular intake is necessary. Water-soluble vitamins are also destroyed more easily during food storage, processing and preparation.

Fat-soluble vitamins dissolve in fat. To be carried in your bloodstream and throughout your body, they must be attached to body chemicals made of lipids or fat. Four vitamins are fat-soluble: A, D, E, and K. Your body is able to store these fat-soluble vitamins in body fat. Getting a new supply each day is not essential. Harmful, toxic levels of the fat-soluble vitamins can occur when excess amounts are consumed on a regular basis, usually from supplements.  

Nutrition Reference Guide

Check out these other important nutritional items as well.

Introduction   Minerals
Carbohydrates   Vitamins
Proteins   Fiber
Fats   Calorie


  Vitamin A
  Vitamin D
  Vitamin E
  Vitamin K


  Thiamin (vitamin B-1)
  Riboflavin (vitamin B-2)
  Pyridoxine (vitamin B-6)
  Folic Acid
  Vitamin B-12
  Pantothenic Acid
  Vitamin C

Fat-Soluble Vitamins

Vitamin A

Functions Vitamin A is needed for night vision and helps the eyes adjust to lower levels of light. It promotes the growth of skin, bones, and male and female reproductive organs. Vitamin A protects you from infections by keeping the skin and tissues in your mouth, stomach, intestines, respiratory, genital, and urinary tracts healthy. Beta-carotene is converted into vitamin A in the body. Beta-carotene may reduce the risk of certain types of cancer and possibly heart disease.
Deficiencies Lack of vitamin A may lead to night blindness, dry eyes, eye infections, dry scaly skin, reproductive problems, and slow growth.
Excesses Because vitamin A is stored in the body, large quantities can be very harmful. Symptoms of overdosing include headaches, dry scaly skin, liver damage, bone and joint pain, vomiting, appetite loss, nerve damage, and birth defects. The Tolerable Upper Intake Level for vitamin A is 3,000 micrograms for adult males and females.
Amount Needed The recommended intake for adult males is 900 micrograms and 700 micrograms for adult females.
Food Sources Your body can get vitamin A in two forms: retinols and beta-carotene. Retinols are found in foods that come from animals such as meat, milk fortified with A, fish oil and eggs. Bete-carotene is found in red, yellow, and orange vegetables and fruits, and many dark-green leafy vegetables.

Vitamin D

Functions Vitamin D is one member of a large team of nutrients and hormones that promotes the absorption of calcium and phosphorus. Vitamin D helps deposit these minerals in your bones and teeth, thus making them stronger and healthier.
Deficiencies Lack of vitamin D in childhood may lead to a condition called rickets, in which bones and teeth are weak. In older adults a lack of vitamin D can cause a condition called osteomalacia, a softening of the bones. It can also cause bone loss called osteoporosis.
Excesses Because vitamin D is stored in the body, large quantities can be toxic. Kidney stones, kidney damage, weak bones, excessive bleeding, muscle weakness and damage can occur. The Tolerable Upper Intake Level for vitamin D is 4,000 IU for adults.
Amount Needed The recommended daily intake for adults up to age 70 is 600 IU. After age 70, the recommended intake goes up to 800 IU daily.
Food Sources Vitamin D is found naturally in fish and fish-liver oils. However it is also found in vitamin D fortified milk. Vitamin D is known as the “sunshine vitamin” because it is made in your skin when the ultraviolet light hits your skin. If you eat a balanced diet and get outside in the sunshine at least 1 ½ to 2 hours a week, you should be getting all the vitamin D you need. As a precaution, especially during the winter, for people who do not get outdoors much (especially during the winter), and for older people whose skin is less efficient with this conversion, milk is fortified with vitamin D. If you do not drink milk, ask your health care professional about supplementation. Note: most cheese and yogurt products are NOT made with fortified milk.

Vitamin E

Functions Vitamin E is the bodyguard for your body. It works as an antioxidant, preventing a chemical reaction called oxidation, which can sometimes result in harmful effects in your body. For example, vitamin E protects polyunsaturated fats, red blood cells, and vitamin A from the destructive forces of oxygen. The cells of the lungs are continually exposed to the destructive properties of oxygen, but vitamin E protects these tissues. It is important for proper functioning of nerves, blood and muscle tissue.
Deficiencies Because it is abundant in many foods, a deficiency of vitamin E is rare. However, there are two exceptions. Since the transfer of vitamin E from mother to infant occurs during the very last weeks of pregnancy, premature infants may be deficient. Without vitamin E, the red blood cells rupture and the infant becomes anemic. There are also some people who are unable to absorb fat normally and therefore develop a vitamin E deficiency. In this case the nervous system can be affected.
Excesses People who take large doses by mouth do not seem to have major symptoms. However blurred vision, diarrhea, dizziness, headache, nausea, stomach cramps, unusual tiredness, and weakness have been reported. The Tolerable Upper Intake Limit for vitamin E is 1,000 milligrams daily.
Amount Needed Vitamin E is a group of substances call tocopherals with different potencies. The amount is given in alpha-tocopherol equivalents as a standard measure. The recommended daily intake for adults is 15 alpha-tocopherol equivalents.
Food Sources E is found in a variety of foods. The best sources include wheat germ and wheat germ oil, soybean, corn, safflower and cottonseed oil. Good sources include margarine, mayonnaise, salad dressings, nuts, seeds, peanuts, and peanut butter. Fair sources include whole grains, corn, beef liver, leafy-green vegetables, fish and eggs.

Vitamin K

Functions Vitamin K refers to a group of chemically similar fat-soluble compounds. Vitamin K is necessary to make proteins that cause your blood to coagulate and clot. This stops bleeding. Vitamin K also helps your body make other body proteins for your blood, bones, and kidneys.
Deficiencies Vitamin K deficiency is rare. However, a deficiency can lead to defective blood coagulation and increased bleeding and bruising. Certain health problems can cause deficiencies such as malnutrition due to alcohol dependency, celiac disease, ulcerative colitis, cystic fibrosis, and short bowel syndrome. Some drugs may reduce vitamin K levels by altering liver function or destroying the intestinal bacteria that makes vitamin K.
Excesses No symptoms have been observed with excess intake. Moderation is still the best approach. People taking blood-thinning drugs and anticoagulants such as warfarin (coumadin) need to eat foods with vitamin K in moderation. Too much can make blood clot faster. The Tolerable Upper Intake Level for vitamin K has not been determined.
Amount Needed The recommended daily intake for adult males is 120 micrograms and 90 micrograms for adult females.
Food Sources Vitamin K can be made in your digestive tract by the billions of bacteria that are in your intestines. Some of these bacteria synthesize vitamin K that your body can then absorb. Good food sources include green-leafy vegetables such as spinach and broccoli, pork, liver, whole wheat, oats, and bran. Fair sources include fruits, vegetables, seeds, tubers, milk, and eggs.

Water-Soluble Vitamins

Thiamin(vitamin B-1)

Functions In all the cells of the body, thiamin is needed for the breakdown and utilization of carbohydrates
Deficiencies In the United States, a deficiency of thiamin is rare because refined grains are enriched with this nutrient. Before refined grain products were enriched, a thiamin deficiency could result in a disease called beriberi. Signs of beriberi include loss of appetite, constipation, muscle weakness, pain or tingling in the arms and legs, swelling of the feet, mental depression, memory problems, shortness of breath, and fast heartbeat. Thiamin deficiency does occur in alcoholics because of impaired absorption.
Excesses In some people an excessive intake can cause an allergic reaction. For most people, the body excretes the excess consumed. Extra thiamin does not boost your energy level. The Tolerable Upper Intake Level has not been determined due to a lack of data concerning adverse effects.
Amount Needed Adult males need 1.2 milligrams of thiamin each day and adult females need 1.1 milligrams daily.
Food Sources The best food sources of thiamin include pork, peas, liver, and wheat germ. Good sources include whole-grain and enriched grain products, such as bread, rice, pasta, tortillas, and fortified cereals. Fair sources include pineapple, citrus fruits, milk, spinach, tomatoes, bananas, beans, nuts, seeds, and peanuts.

Riboflavin (vitamin B-2)

Functions Riboflavin is involved in several vital metabolic processes in the body. It is necessary for normal cell and tissue function. Riboflavin is needed for normal protein and energy metabolism.
Deficiencies A deficiency of riboflavin rarely occurs except in the severely malnourished. Symptoms can include eye disorders, dry and flaky skin, sores at the corners of the mouth, a sore, red swollen tongue, throat swelling, and anemia.
Excesses There are currently no reports that indicate problems associated with an excessive intake of riboflavin.
Amount Needed Healthy, adult males need 1.3 milligrams of riboflavin daily and females need 1.1 milligrams daily.
Food Sources The best food sources of riboflavin include liver, milk, cottage cheese and other dairy products. Good sources include eggs and meats. Fair sources are whole grains, enriched grains, green leafy vegetables, asparagus, broccoli, beans, and peas. Ultraviolet light, including sunlight, can quickly destroy riboflavin. That’s why milk is stored in opaque plastic or cardboard containers, not clear glass.


Functions Niacin helps the body to metabolize and release the energy in carbohydrates and fats. It is involved with the making of protein and fat. Niacin helps promote healthy cells, gastro-intestinal tract, skin, and nervous system.
Deficiencies Pellagra is a disease that develops due to a deficiency of niacin. Symptoms include skin problems, diarrhea, dementia, and depression.
Excesses An excessive intake of niacin can cause tingling and flushing of the skin, itching, digestive upsets, low blood pressure, abdominal pain, liver problems, and ulcers. Large doses of niacin have been used along with medication to help lower cholesterol levels. Speak with your physician before ever starting such a treatment plan. The Tolerable Upper Intake Level is 35 milligrams daily for both adult males and females.
Amount Needed Niacin recommendations are given in niacin equivalents (NE). This is because niacin comes from two sources: (1) niacin found in food and (2) the amino acid tryptophan which can be converted to niacin in the body. 1 milligram of niacin equals 60 milligrams of tryptophan. The recommended intake of niacin (as NE) is 16 milligrams daily for adult males and 14 milligrams for adult females.
Food Sources The best sources of niacin include meats, poultry, and fish. Good sources include mushrooms, peanuts, legumes, and nuts. Fair sources include enriched grain products. Niacin is also produced in the body from the amino acid tryptophan.

Pyridoxine (vitamin B-6)

Functions Pyridoxine is necessary for the normal breakdown of protein, carbohydrates, and fat. It helps turn the amino acid tryptophan into niacin and serotonin. Serotonin is a messenger in the brain. Niacin also helps produce body chemicals such as insulin, antibodies, and hemoglobin.
Deficiencies A lack of pyridoxine may lead to anemia or weak blood, depression, nerve damage, seizures, greasy, flaky skin problems, and sores in the mouth.
Excesses At extremely high doses, nervous system damage can occur. The Tolerable Upper Intake Level is 100 milligrams for both adult males and females.
Amount Needed The recommended intake for adult males is 1.3 milligrams during the ages of 19-50. From age 51 and above, the amount is 1.7 milligrams. The recommended intake for adult females is 1.3 milligrams during the ages of 19-50. From age 51 and above, the amount is 1.5 milligrams each day.
Food Sources The best food sources of pyridoxine are blackstrap molasses, wheat bran and germ, soybeans, and brown rice. Good sources include organ meats, veal, lamb, chicken, fish, and pork. Fair sources include bananas, lima beans, cabbage, corn, oats, carrots, potatoes, and legumes.

Folic Acid (folacin or folate)

Functions Folic acid is necessary for strong, healthy blood by helping to form hemoglobin. It plays a role in making new cells. By synthesizing the essential nucleic acids, DNA and RNA, normal cell division and replication occurs.
Deficiencies A lack of folic acid produces poorly formed blood cells that cannot carry as much oxygen. A deficiency can affect normal cell division and impair growth. Pregnant women who do not get enough folic acid prior to conception and during the first trimester have a greater risk of having a baby with neural tube defects such as spina bifida.
Excesses Consuming too much folic acid can mask a vitamin B-12 deficiency. An excess can also interfere with some medications. Sleep disturbances are possible as well as irritability. The Tolerable Upper Limit Level is 1,000 micrograms daily for both adult males and females.
Amount Needed The recommended intake of folic acid for adult males and females is 400 micrograms daily.
Food Sources The best food sources of folic acid include liver, and green leafy vegetables. Good sources include lima beans, asparagus, broccoli, nuts, whole grains, fortified bread, rice, macaroni, noodles, cereals, oranges and orange juice, and lentils.

Vitamin B-12 (cobalamin)

Functions Vitamin B-12 works closely with folic acid to make red blood cells. Vitamin B-12 is necessary for a healthy nervous system. It helps the body to use fat acids and some amino acids.
Deficiencies A lack of vitamin B-12 may lead to anemia, fatigue, nerve damage, stomach problems, a smooth tongue, or very sensitive skin. A vitamin B-12 deficiency can be masked by taking extra folic acid. Some people have a medical problem called pernicious anemia in which vitamin B-12 is not absorbed from the intestines properly. They are missing a body chemical called intrinsic factor that comes from the stomach lining. Others have a diseased intestine or have had a large part of their stomachs or intestines removed. These conditions require treatment with vitamin B-12 injections. Strict vegetarians, who eat no animal products, are at risk for developing a vitamin B-12 deficiency. The elderly are also at risk for vitamin B-12 deficiency since 10-30% absorb food-bound vitamin B-12 poorly. If not managed, this could cause severe anemia and irreversible nerve damage. It is important to include a variety of vitamin B-12 fortified foods or a dietary supplement to prevent these problems.
Excesses There are no known symptoms of taking excessive amounts of vitamin B-12. Extra vitamin B-12 does not boost energy levels. A Tolerable Upper Intake Level has not yet been determined due to a lack of data of adverse effects.
Amount Needed Adult males and females need 2.4 micrograms of vitamin B-12 daily.
Food Sources The best sources of vitamin B-12 include animal products, such as organ meats, beef, pork, fish, poultry, eggs, milk, and other dairy foods. Some foods are fortified with vitamin B-12 and are fair sources.


Functions Biotin helps produce energy in your cells. It helps metabolize protein, fat and carbohydrates. Biotin is required by the body in order for four specific enzymes to function properly in metabolism.
Deficiencies A biotin deficiency is extremely rare in people who eat a healthy diet. In rare cases, these symptoms may appear: heart abnormalities, appetite loss, fatigue, depression, dry skin, low blood sugar between meals, acidic blood, and high blood ammonia. A chemical in raw egg whites prevents the body from absorbing biotin. This problem is prevented by cooking eggs, which destroys avidins ability to bind the biotin.
Excesses There are currently no reported effects of consuming excess amounts of biotin. Therefore the Tolerable Upper Intake Level has not been determined.
Amount Needed The recommended intake for both adult males and females is 30 micrograms daily.
Food Sources Biotin is found in a variety of foods. Good sources include eggs, liver, yeast breads, cereals, chocolate, peanuts, cauliflower, nuts, peas, and mushrooms. Fair food sources include milk. Biotin is also produced by the bacteria naturally found in the intestines.

Pantothenic Acid

Functions Pantothenic acid helps with the breakdown and utilization of carbohydrates, proteins, and fats. It also helps the body produce energy in the cells. Pantothenic acid is involved in antibody production, adrenal activity, growth and metabolism.
Deficiencies A deficiency of pantothenic acid is rarely a problem for those who eat a healthy diet.
Excesses The only symptoms of excessive intake are occasional diarrhea and water retention. An excess may trigger a thiamine deficiency. No Tolerable Upper Intake Level has been determined for pantothenic acid due to a lack of data on adverse effects.
Amount Needed The amount needed by both adult males and females is 5 milligrams daily.
Food Sources Pantothenic acid is found widespread in plant and animal foods. Meat, poultry, fish, whole-grain products, legumes, and eggs are considered the best sources. Good sources include broccoli, cauliflower, mushrooms, bran, sweet potatoes, potatoes, lima beans, soybeans, peanuts, peas, oatmeal, and cheese.

Vitamin C

Functions Vitamin C forms collagen, a connective tissue, which gives strength and structure by holding together muscles, bones, and other tissues. It helps to build, repair, and maintain red blood cells, bones, and other tissues. It gives strength and flexibility to blood vessels and capillary walls. This helps to prevent bruising. It helps the body to absorb iron found in plant foods. Vitamin C is necessary for cuts and wounds to heal. It keeps the gums healthy and protects you from infection by keeping the immune system strong and healthy.
Deficiencies A lack of vitamin C can lead to a disease called scurvy. Scurvy causes muscle weakness, swollen and bleeding gums, loss of teeth, bleeding under the skin, bruising, poor wound healing, tiredness, and depression.
Excesses Vitamin C is water-soluble, so the body excretes any excess consumed. However, very large doses may cause kidney stones and diarrhea. The Tolerable Upper Intake Level is 2,000 milligrams for both adult males and females.
Amount Needed Adult males need 90 milligrams of vitamin C daily and adult females need 75 milligrams daily. People who smoke need about twice as much vitamin C daily.
Food Sources The best sources of vitamin C include citrus fruits (oranges, grapefruits, tangerines), strawberries, peppers, kiwi, and cantaloupe. Good sources include some green-leafy vegetables, cauliflower, tomatoes, potatoes, and pineapple.

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