Vitamins (Encyclopedia of Cancer)
Vitamins are compounds that are essential in small amounts for proper body function and growth. Vitamins are either fat soluble: A, D, E, and K; or water soluble: vitamin B and C. The B vitamins include vitamins B1 (thiamine), B2 (riboflavin), and B 6 (pyridoxine), pantothenic acid, niacin, biotin, folic acid (folate), and vitamin B 12 (cobalamin). Vitamins may also be referred to as micronutrients.
A guide to the amount an average person needs each day to remain healthy has been determined for each vita-min. In the United States, this guide is called the recommended daily allowance (RDA). Consumption of too little or too much of certain vitamins may lead to a nutrient deficiency or a nutrient toxicity respectively.
Consumption of a wide variety of foods, with adequate vitamin and mineral intake is the basis of a healthy diet. Good nutrition may assist in the prevention of cancer, or for those with existing malignancies, may help cancer patients to feel better and fight infection during treatments. Obtaining nutrients through food remains the best method for obtaining vitamins, however, requirements may be higher because of the tumor or...
(The entire section is 1169 words.)
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Vitamins (Encyclopedia of Medicine)
Vitamins are organic components in food that are needed in very small amounts for growth and for maintaining good health. The vitamins include vitamin D, vitamin E, vitamin A, and vitamin K, or the fat-soluble vitamins, and folate (folic acid), vitamin B12, biotin, vitamin B6, niacin, thiamin, riboflavin, pantothenic acid, and vitamin C (ascorbic acid), or the water-soluble vitamins. Vitamins are required in the diet in only tiny amounts, in contrast to the energy components of the diet. The energy components of the diet are sugars, starches, fats, and oils, and these occur in relatively large amounts in the diet.
Most of the vitamins are closely associated with a corresponding vitamin deficiency disease. Vitamin D deficiency causes rickets, a disease of the bones. Vitamin E deficiency occurs only very rarely, and causes nerve damage. Vitamin A deficiency is common throughout the poorer parts of the world, and causes night blindness. Severe vitamin A deficiency can result in xerophthalamia, a disease which, if left untreated, results in total blindness. Vitamin K deficiency results in spontaneous bleeding. Mild or moderate folate deficiency is common throughout the world, and can result from the failure to eat green, leafy vegetables or fruits and fruit juices. Folate deficiency causes megaloblastic...
(The entire section is 1698 words.)
Vitamin (Encyclopedia of Science)
Vitamins are complex organic compounds that occur naturally in plants and animals. People and other animals need these compounds in order to maintain life functions and prevent diseases. About 15 different vitamins are necessary for the nutritional needs of humans. Only minute amounts are required to achieve their purpose, yet without them life cannot be maintained. Some vitamins, including vitamins A, D, E, and K, are fat soluble and are found in the fatty parts of food and body tissue. As such they can be stored in the body. Others, the most notable of which are vitamin C and all the B-complex vitamins, are water soluble. These vitamins are found in the watery parts of food and body tissue and cannot be stored by the body. They are excreted in urine and must be consumed on a daily basis.
Vitamins were not discovered until early in the twentieth century. Yet it was common knowledge long before that time that substances in certain foods were necessary for good health. Information about which foods were necessary developed by trial and errorith no understanding of why they promoted health. Scurvy, for example, had long been a dreaded disease of sailors. They often spent months at sea and, due to limited ways of preserving food without refrigeration, their diet consisted of dried foods and salted meats. In 1746, English naval captain and surgeon James Lind...
(The entire section is 3154 words.)
Vitamins (Encyclopedia of Children's Health)
Vitamins are organic components in food that are needed in very small amounts for growth and for maintaining good health. The vitamins include vitamins D, E, A, and K (fat-soluble vitamins), and folate (folic acid), vitamin B12, biotin, vitamin B6, niacin, thiamin, riboflavin, pantothenic acid, and vitamin C (ascorbic acid) (water-soluble vitamins). Vitamins are required in the diet in only tiny amounts, in contrast to the energy components of the diet. The energy components of the diet are sugars, starches, fats, and oils, and these occur in relatively large amounts in the diet.
Most of the vitamins are closely associated with a corresponding vitamin deficiency disease. Vitamin D deficiency causes rickets, a disease of the bones. Vitamin E deficiency occurs only very rarely and causes nerve damage. Vitamin A deficiency, common throughout the poorer parts of the world, causes night blindness. Severe vitamin A deficiency can result in xerophthalmia, a disease that, if left untreated, results in total blindness. Vitamin K deficiency results in spontaneous bleeding. Mild or moderate folate deficiency, common throughout the world, can result from the failure to eat green, leafy vegetables or fruits and fruit juices. Folate deficiency causes megaloblastic anemia, which is characterized...
(The entire section is 1780 words.)
Vitamins (Encyclopedia of Nursing & Allied Health)
Vitamins are organic components in food that are needed for growth and for maintaining good health. They include the fat-soluble vitamins, such as vitamin D, vitamin E, vitamin A, and vitamin K; and the water-soluble vitamins, such as folate (folic acid), vitamin B12, biotin, vitamin B6, niacin, thiamin, riboflavin, pantothenic acid, and vitamin C (ascorbic acid). Vitamins are required in the diet in only tiny amounts, in contrast to the energy components (sugars, starches, fats, and oils).
All of the vitamins serve several important functions in the body and provide many health benefits. Therefore, a lack of a particular vitamin in the diet can cause a corresponding vitamin-deficiency disease.
Vitamin D, which helps to fight infection, is available from butter, cream, salmon, egg yolks, and adequate sun exposure. Vitamin D deficiency in children is called rickets, which is a disease of the bones. Symptoms include knocked knees, bowed legs, and protruding chests. Osteomalacia is the adult form of vitamin D deficiency; it is a result of low calcium intakes or lack of sun exposure during childhood and the adult years. Vitamin E acts as an antioxidant in the body for cells that are highly exposed to oxygen, and it resists hemolysis of red blood cells. Vitamin E is very widespread in food, so a deficiency is rare. However, when vitamin E deficiency does occur, it can cause serious nerve damage. Hemolytic anemia results if there is a vitamin E deficiency. A deficiency in vitamin E usually occurs only in premature babies due to the fact that they are born before the vitamin can be transferred to the developing baby during the last few weeks of pregnancy.
Vitamin A functions in maintaining vision, immune defense, bone development, cell growth, and reproduction. Food sources of vitamin A include fortified milk, spinach, carrots, and sweet potatoes. Vitamin A deficiency is common throughout the poorer parts of the world, and causes night blindness (nyctalopia). Severe vitamin A deficiency can result in xerophthalamia, a disease that, if left untreated, results in total blindness. Dry, scaly skin (hyperkeratosis) also results from vitamin A deficiency. Vitamin K is a nutrient that is essential for blood clotting; it can be obtained from intestinal bacteria. It is also present in dark-green leafy vegetables, cabbage, liver, eggs, cereals, and fruit. Vitamin K deficiency results in spontaneous bleeding. It can be affected by mineral oil, antibiotics, and anticoagulants.
Folate, also known as folic acid, is required for the synthesis of new cells in the body. Mild or moderate folate deficiency is common throughout the world, and can result from the failure to eat green leafy vegetables or fruits and fruit juices. Folate deficiency causes megaloblastic anemia, which is characterized by the presence of large abnormal cells, called megaloblasts, in the circulating blood. The symptoms of megaloblastic anemia are tiredness and weakness. Folic-acid deficiency is also associated with neural-tube birth defects such as spina bifida and anencephaly. These serious congenital malformations are the result of inadequate folate intake during pregnancy. Neural-tube defects occur early in pregnancy before most women even know they are pregnant, so it is essential that women of childbearing age receive adequate amounts of folate before they become pregnant, as well as during pregnancy. For this reason, folate fortification of enriched flour, breads, rice, and other grain products was approved by the U.S. Food and Drug Administration (FDA) in 1996. Vitamin B12 helps make red blood cells in the body and protect nerve fibers. A deficiency occurs with the failure to consume sufficient meat or milk or other dairy products. Vitamin B12 deficiency causes pernicious anemia, which is the result of a lack of the intrinsic factor needed for the absorption of vitamin B12. A deficiency of vitamin B12 can be masked by folate deficiency.
The B vitamins niacin, thiamine, and riboflavin each play a role in the energy metabolism of cells. Niacin can be found in such foods as tuna, chicken, mushrooms, and baked potatoes. A deficiency of niacin results in the disease known as pellagra, which involves skin rashes, scabs, diarrhea, and mental depression. Thiamin is found in pork, ham, green leafy vegetables, legumes, and whole-grain cereals. Thiamine deficiency results in beriberi, a disease resulting in atrophy, weakness of the legs, nerve damage, and heart failure. Vitamin C helps protect against infection and enhances the absorption of iron. Orange juice, grapefruit, broccoli, green peppers, and brussels sprouts are significant sources of vitamin C. A deficiency results in scurvy, a disease that contributes to the breakdown of collagen, which causes loose teeth, bleeding gums, and swollen wrists and ankles. Specific diseases uniquely associated with deficiencies in vitamin B6, riboflavin, or pantothenic acid have not been found in humans, though people who have been starving, or consuming poor diets for several months, might be expected to be deficient in most of the nutrients, including vitamin B6, riboflavin, and pantothenic acid. Homocystinurias, a group of autosomal recessive disorders, are associated with low levels of folate and vitamins B6 and B12.
|Vitamin||What It Does For The Body|
|Vitamin A (Beta Carotene)||Promotes growth and repair of body tissues; reduces susceptibility to infections; aids in bone and teeth formation; maintains smooth skin|
|Vitamin B-1 (Thiamin)||Promotes growth and muscle tone; aids in the proper functioning of the muscles, heart, and nervous system; assists in digestion of carbohydrates|
|Vitamin B-2 (Riboflavin)||Maintains good vision and healthy skin, hair, and nails; assists in formation of antibodies and red blood cells; aids in carbohydrate, fat, and protein metabolism|
|Vitamin B-3 (Niacinamide)||Reduces cholesterol levels in the blood; maintains healthy skin, tongue, and digestive system; improves blood circulation; increases energy|
|Vitamin B-5||Fortifies white blood cells; helps the body's resistance to stress; builds cells|
|Vitamin B-6 (Pyridoxine)||Aids in the synthesis and breakdown of amino acids and the metabolism of fats and carbohydrates; supports the central nervous system; maintains healthy skin|
|Vitamin B-12 (Cobalamin)||Promotes growth in children; prevents anemia by regenerating red blood cells; aids in the metabolism of carbohydrates, fats, and proteins; maintains healthy nervous system|
|Biotin||Aids in the metabolism of proteins and fats; promotes healthy skin|
|Choline||Helps the liver eliminate toxins|
|Folic Acid (Folate, Folacin)||Promotes the growth and reproduction of body cells; aids in the formation of red blood cells and bone marrow|
|Vitamin C (Ascorbic Acid)||One of the major antioxidants; essential for healthy teeth, gums, and bones; helps to heal wounds, fractures, and scar tissue; builds resistance to infections; assists in the prevention and treatment of the common cold; prevents scurvy|
|Vitamin D||Improves the absorption of calcium and phosphorous (essential in the formation of healthy bones and teeth) maintains nervous system|
|Vitamin E||A major antioxidant; supplies oxygen to blood; provides nourishment to cells; prevents blood clots; slows cellular aging|
|Vitamin K (Menadione)||Prevents internal bleeding; reduces heavy menstrual flow|
Some of the vitamins serve only one function in the body, while other vitamins serve a variety of unrelated functions. Hence, some vitamin deficiencies tend to result in one type of defect, while other deficiencies result in a variety of problems.
People are treated with vitamins for three reasons. The primary reason is to relieve a vitamin deficiency when one has been detected. Chemical tests suitable for the detection of all vitamin deficiencies are available. The diagnosis of vitamin deficiency is often aided by visual tests, such as the examination of blood cells with a microscope, the x-ray examination of bones, or a visual examination of the eyes or skin.
A second reason for vitamin treatment is to prevent the development of an expected deficiency. In this case, vitamins are administered even with no test for possible deficiency. One example is vitamin K treatment of newborn infants to prevent bleeding. Food supplementation is another form of vitamin treatment. The vitamin D added to foods serves the purpose of preventing the deficiency from occurring in people who may not be exposed much to sunlight and who fail to consume foods that are fortified with vitamin D, such as milk. Niacin supplementation prevents pellagra among people who rely on corn as the main source of food and who do not eat much meat or milk. In general, the U.S. food supply is fortified with niacin.
A third reason for vitamin treatment is to reduce the risk for diseases that may occur even when vitamin deficiency cannot be detected by chemical tests. One example is folate deficiency. The risk for cardiovascular disease can be slightly reduced for a large fraction of the population by folic-acid supplements. These supplements can also sharply reduce the risk for certain birth defects.
Vitamin treatment is important during specific diseases where the body's normal processing of a vitamin is impaired. In these cases, high doses of the needed vitamin can force the body to process or utilize it in the normal manner. One example is pernicious anemia, a disease that tends to occur in middle age or old age; it impairs the absorption of vitamin B12. Surveys have revealed that about 0.1% of the general population, and 2% to 3% of the elderly, may have the disease. If left untreated, pernicious anemia leads to nervous-system damage. The disease can easily be treated with large daily oral doses of vitamin B12 (hydroxocobalamin) or with monthly injections of the vitamin.
Vitamin supplements are widely available as over-the-counter products. But whether they work to prevent or curtail certain illnesses, particularly in people with a balanced diet, is a matter of debate and ongoing research. For example, vitamin C is not proven to prevent the common cold, yet millions of people take it for that reason.
Vitamin A and vitamin D can be toxic in high doses; side effects range from dizziness to kidney failure. High doses of niacin can be toxic to the liver, while excessive intake may occur with vitamin C, especially among the elder. Doses of vitamin K can have toxic effects in infants. A physician or pharmacist should be consulted about the correct use of a multivitamin supplement that contains these vitamins.
Vitamin treatment is usually done in three ways: by replacing a poor diet with one that supplies the recommended dietary allowance (RDA), by consuming oral supplements, or by injections. Injections are useful for persons with diseases that prevent absorption of fat-soluble vitamins. Oral vitamin supplements are especially useful for people who otherwise cannot or will not consume food that is a good vitamin source, such as meat and dairy products. For example, a vegetarian who will not consume meat may be encouraged to consume oral supplements of vitamin B12.
Treatment of genetic diseases that impair the absorption or utilization of specific vitamins may require megadoses of the vitamin throughout one's lifetime. Megadose means a level of about 10 to 1,000 times greater than the RDA for a particular vitamin. Pernicious anemia, homo-cystinuria, and biotinidase deficiency are three examples of genetic diseases that are treated with megadoses of vitamins.
The diagnosis of a vitamin deficiency usually involves a blood test. An overnight fast is usually recommended as preparation prior to the blood test so that vitamin-fortified foods do not affect the test results.
The response to vitamin treatment can be monitored by chemical tests, by an examination of red or white blood cells, or by physiological tests, depending on the exact vitamin deficiency.
Although there are few complications associated with vitamin treatment, possible risks depend on the vitamin and the reason why it was prescribed. In general, the higher the dose that is taken, the higher the risk of toxicity. It is also important to remember that vitamins are better absorbed from food rather than in concentrated pill form. Physicians or pharmacists should be consulted about how and when to take vitamin supplements, particularly those that have not been prescribed by a physician.
Health care team roles
Dietitians can provide a wide range of information concerning the well-balanced diet that is necessary to receive adequate amounts of all the vitamins. Dietitians also play an important role in educating people about the dangers of consuming too much or too little of a particular vitamin. When a particular vitamin deficiency is present, consulting a dietitian, pharmacist, or physician about how and when to take vitamin supplements is advised.
Anencephaly neural-tube defect that causes lack of brain formation and results in death shortly after birth.
Antioxidant compound that prevents other compounds from being damaged by oxygen by reacting with oxygen itself.
Genetic disease disease that is passed from one generation to the next but does not necessarily appear in each generation. An example of genetic disease is Down syndrome.
Neural tube defects group of birth defects that affect the brain and spinal cord.
Recommended dietary allowance (RDA)he recommended dietary allowances (RDAs) are quantities of nutrients of the diet that are required to maintain human health. RDAs are established by the Food and Nutrition Board of the National Academy of Sciences and may be revised every few years. A separate RDA value exists for each nutrient. The RDA values refer to the amount of nutrient expected to maintain health in the greatest number of people.
Vitamin statushe state of vitamin sufficiency or deficiency of any person. For example, a test may reveal that a patient's folate status is sufficient, borderline, or severely inadequate.
Brody, T. Nutritional Biochemistry. San Diego: Academic Press, 1998.
Food and Nutrition Board. Recommended Dietary Allowances, 10th Edition. Washington, DC: National Academy Press, 1989.
Sizer, F., and E. Whitney. Nutrition: Concepts and Controversies, 7th Edition. Belmont, CA: Wadsworth, 1997.
Worthington-Roberts, B. S., and S. Rodwell Williams. Nutrition Throughout the Life Cycle, 4th Edition. Boston: McGraw-Hill, 2000.
Vitamins: Overview (Encyclopedia of Food & Culture)
The word "vitamin" came from the term vita mines (vital amines), which was introduced by Casimir Funk, who, in 1912, isolated a growth factor from rice polishings that contained an amine (a compound incorporating a nitrogen atom with two hydrogen atoms) and could cure the disease beriberi. Several other growth factors were identified early in the twentieth century as well, and these substances were also called vitamins even though they did not contain an amine. Vitamins are classified into two major groups: fat-soluble and water-soluble. (See the Appendix for a complete chart of vitamins.)
Vitamin A. In the early 1900s, Sir Frederick Hopkins demonstrated that animals would not grow if lard was provided as a sole dietary lipid. When a small quantity of milk containing fat was added to the diet, the animals thrived. The fat-soluble factor was isolated and designated as vitamin A, later called retinol or retinal; these and similar compounds are referred to as retinoids. Carotenoids, which are essentially two retinoids joined tail to tail, are inactive forms of vitamin A and are called provitamin A. They are converted to vitamin A in the intestine and liver. Vitamin A and carotenoids are absorbed in the chylomicron (a lipoprotein particle that transports lipids from the intestine) fraction and stored in the liver. Some foods such as milk are fortified with vitamin A. Rich sources of carotenoids include carrots, leafy green vegetables, and pink grapefruit.
Vitamin A is, chemically, a subgroup of retinoids, which are defined as a class of compounds that consist of a six-membered ring and a side chain with four conjugated double bonds (four isoprenoid units). The term vitamin A is used to describe retinoids exhibiting qualitatively the biologic activity of the retinoid, retinol.
Vitamin A binds to a retinol-binding protein that transports the light-sensitive vitamin to various target tissues, including the eyes, skin, and gastrointestinal track. The major functions of vitamin A include vision and regulation of cellular proliferation and differentiation. Vitamin A functions on vision by interacting with the rod and cone cells in the retina. It is responsible for absorbing light. The 11-cis form of vitamin A (retinal) combines with the protein opsin to form rhodopsin in the rod cells and iodopsins in the cone cells. The rhodopsin and iodopsins absorb light at various wavelengths and trigger a nerve impulse to the visual cortex in the brain that is ultimately perceived as black-and-white and color vision, respectively.
Vitamin A's other major physiologic function is to maintain the health of skin and mucous-secreting cells by regulating their cellular activity and maturation. The dietary requirements depend on age.
The major consequence of vitamin A deficiency, which continues to be a serious nutritional problem among millions of schoolchildren in southern and southeastern Asia and parts of Africa and South America, is night blindness. Vitamin A deficiency can lead to complete blindness and severe damage to the outer covering of the eye (the cornea), often causing it to perforate, with loss of the fluid from inside the eye (keratomalacia). Vitamin A deficiency also produces changes in the skin that are related to the inability of the skin cells to mature and produce keratin properly. This leads to follicular hyperkeratosis and phrynoderma (a condition characterized by rough, dry skin). Vitamin A deficiency has also been linked to increased mortality in early childhood.
Acute and chronic ingestion of excessive amounts of vitamin A can cause a multitude of symptoms and consequences. The most serious is that it can cause severe birth defects, spontaneous abortions and learning defects, and skin and epithelial-cell exfoliation. Inexperienced white explorers of the Arctic who ate polar-bear liver in excess developed severe vitamin A intoxication that caused a total sloughing of their skin and mucoussecreting cells in the upper airway and esophagus, bringing on painful death. (This is in contrast to the indigenous Inuit, who specifically avoid eating polar-bear liver.)
Vitamin D. One of the consequences of the industrial revolution was the high incidence of the bone-deforming disease rickets. It was estimated, at the turn of the twentieth century, that more than ninety percent of children living in the industrialized cities of northern Europe and the northeastern United States had rickets. It had been known that cod-liver oil possessed a factor that had antirachitic activity. Originally, it was thought that the antirachitic factor was vitamin A. However, Hopkins heated cod-liver oil to destroy the vitamin A activity and demonstrated that it still possessed antirachitic activity. This new fat-soluble vitamin was labeled vitamin D. It was also recognized that exposure of food, animals, and humans to ultraviolet radiation also prevented and cured rickets.
There are two principal forms of vitamin D: Vitamin D 2 comes from the precursor ergosterol found in yeast and plants, and vitamin D 3 comes from the cholesterol precursor 7-dehydrocholesterol that is found in the skin of reptiles, birds, mammals, and humans. Vitamin D 2 and vitamin D 3 are essentially equally active in most birds and in most mammals, including humans. Chickens and New World monkeys, however, cannot utilize vitamin D 2. There are very few foods that naturally contain vitamin D. Fatty fish, such as salmon and mackerel, and fish-liver oils, such as cod-liver oil are good sources of vitamin D. Cow's milk and human milk have very little vitamin D. However, in the United States and Canada, milk and some breads and cereals are fortified with vitamin D. In Europe, fortification of foods with vitamin D was outlawed when sporadic cases of vitamin D intoxication were observed in children in the 1950s. Today some margarine and cereals are fortified with vitamin D in Europe, but milk is not.
Vitamin D 3 is made by the action of sunlight on the skin. Provitamin D 3 (7-Dehydrocholesterol) absorbs solar ultraviolet B radiation (wavelengths 29015 nm) and is transformed into previtamin D 3. Previtamin D 3 is unstable at body temperature and isomerizes (rotates its double bonds) to vitamin D 3. Once formed, vitamin D 3 leaves the skin and enters the circulation, bound to the vitamin D binding protein. It travels to the liver where it is activated to 25-hydroxyvitamin D [25(OH)D]. This form, however, is biologically inert at physiologic concentrations and is the major circulating form of vitamin D. It is, nevertheless, the form that is measured to determine the vitamin D status of an individual, because it represents a summation of dietary and skin sources of vitamin D. 25(OH)D is transported on the vitamin D binding protein to the kidney, where it undergoes its final activation on carbon 1 to form 1,25-dihydroxyvitamin D [1,25(OH) 2D], the biologically active form of vitamin D.
The principal function of vitamin D is to maintain blood calcium and phosphorus in the normal range in order to promote neuromuscular function and to maintain metabolic activities. It accomplishes this by enhancing the efficiency of intestinal calcium transport in the small intestine and by stimulating precursor cells of osteoclasts to become mature osteoclasts. Among the functions of osteoclasts is to remove calcium from bone. Serum calcium and phosphorus are in the form of Ca x(PO 4). When these compounds are in the normal range, they are in a supersaturated state that can thus be deposited in the skeletal matrix as calcium hydroxyapatite.
1,25(OH) 2D interacts with a receptor in the nucleus of cells, known as the VDR (vitamin D receptor). It also complexes with the "retinoic acid x" receptor in that cellular structure. These receptor-activated vitamin D complexes find their way to genes that have responsive elements known as the vitamin D-responsive element. These elements in turn unlock genetic information that is responsible for various biologic functions in intestine and bone. It is recognized that a wide variety of tissues including the brain, parathyroid glands, breast, pro state, stomach, and skin also have VDR. Although the exact physiologic function of 1,25(OH) 2D in these non-calcium-regulating tissues is not well understood, 1,25(OH) 2D inhibits cellular proliferation and induces terminal differentiation of a wide variety of cells, including bone, skin, skeletal muscle, breast, and prostate. The dietary requirement depends on age.
Vitamin D deficiency results in a decrease in the efficiency of intestinal calcium absorption that in turn leads to a decrease in unbound or free calcium concentrations in the circulation. This is recognized by the parathyroid gland and results in an increase in the production and secretion of parathyroid hormone (PTH). PTH enhances calcium reabsorption by the kidney and causes increased output of phosphate in the urine. PTH also stimulates the kidney to produce more 1,25(OH) 2D. The net effect of vitamin D deficiency is a low-normal serum calcium and a low serum phosphorus (due to the PTH-induced phosphate wasting in the kidney). Thus calcium and phosphorus concentrations fall below supersaturating levels, thereby resulting in poorly mineralized bone. In children, this causes rickets and, in adults, osteomalacia. In addition, vitamin D deficiency in adults can precipitate and exacerbate osteoporosis. In winter, little if any vitamin D can be made in the skin of people who live above 40° north or below 40° south of the equator. An increase in the zenith angle of the sun due to latitude, time of day, and season of the year will dramatically reduce the production of vitamin D 3 in the skin. Moreover, aging and sunscreen use can markedly reduce the production of vitamin D by more than 60 percent and 99 percent, respectively. Rickets due to vitamin D deficiency in children may include bowlegs or knock-knees, widening of the ends of the long bones, growth retardation, and muscle weakness. In adults, in addition to osteomalacia and increased risk of osteoporosis, it causes bone pain, muscle weakness, and fractures.
The safe upper limit for Vitamin D is 2,000 units a day. Although it is difficult to ingest enough to cause vitamin D intoxication, it can occur. Usually, oral ingestion of 10,000 units a day and greater will cause vitamin D intoxication. This intoxication causes an elevation in the blood levels of calcium and phosphorus, which results in the calcification of soft tissues, including the kidney and major blood vessels, and may also cause the formation of kidney stones.
Vitamin E. The discovery of vitamin E (tocopherolsrom toc- meaning 'childbirth', phero- meaning 'bringing forth', and -ol representing the alcohol portion of the molecule) was due to the observation that supplementation of the diet with vitamin E prevented fetal death in animals that were fed a diet containing rancid lard. There are eight naturally occurring vitamin E compounds. Four of them are known as tocopherols and four are known as tocotrienols. The most abundant form of vitamin E is alpha-tocopherol. One of the major functions of vitamin E is to act as a biologic antioxidant to protect the sensitive cellular membranes from oxidative destruction. The major sources of vitamin E consumed by Americans are vegetables and seed oils, such as corn oil, soybean oil, and safflower oil. Wheat germ is a rich source of vitamin E. Although butter contains very little vitamin E, American margarine contains a significant amount of this antioxidant vitamin.
Vitamin E, like the other fat-soluble vitamins, is absorbed in the chylomicron fraction into the lymphatic system and is transported into the venous blood. The dietary requirements depend on age.
There have been difficulties in defining a clinical syndrome that correlates with vitamin E deficiency in humans. Vitamin E deficiency is associated with anemia in newborns.
Toxicity from excess vitamin E has been associated with increased bleeding tendency in adults and impaired immune function, decreased levels of vitamin K-dependent clotting factors, and impairment of leukocyte function.
Vitamin K. Vitamin K was discovered by Henrik Dam in Copenhagen in 1929. He observed that chicks fed a fat-free diet developed severe bleeding under the skin and in the muscle and other tissues. He named this new fatsoluble vitamin, vitamin K (for "Koagulation vitamin"). Vitamin K is distributed widely in both animal and vegetable foods as well as in milk. It comes in several forms: vitamin K 1 comes from plants and is known as phylloquinone, and vitamin K 2, first isolated from fish meal and in animal foods, comprises a group of compounds known as menaquinones. In addition, bacterial flora in the intestine synthesize menaquinones that are bioavailable.
Vitamin K, like other fat-soluble vitamins, is absorbed in the chylomicron fraction and then appears in the lymph and subsequently in the venous circulation. The major physiologic function of vitamin K is to activate blood-clotting proteins. This is accomplished by the modification of a substance, glutamate, found in several precoagulant factors, including factors II, VII, VIIII, and X, that are produced in the liver. Vitamin K is also re sponsible for the modification of other proteins, including the major noncollagenous protein in bone. The dietary requirements depend on age.
Vitamin K deficiency is rare because of the widespread distribution of the vitamin in plant and animal foods and because microbiotic flora in the normal gut synthesize menaquinones. However, vitamin K deficiency in breast-fed newborns remains a major worldwide cause of infant morbidity and mortality. Infants have very little stored vitamin K at birth, and the gut is nearly sterile during the first few days of life. As a result, infants can develop a severe bleeding condition known as hemorrhagic disease of the newborn if they do not obtain vitamin K during the first few days of life from an exogenous source, particularly since mother's milk contains little vitamin K and few bacteria other than those it picks up from maternal skin as an infant suckles. Adults who have intestinal malabsorption syndrome and who are taking antibiotics can become severely vitamin K-deficient. This can lead to generalized bleeding from all orifices.
There are no reported cases of intoxication due to excessive ingestion of phylloquinone. Ingestion of excessive amounts of menadione, a vitamin K precursor, can cause anemia secondary to the destruction of red blood cells, and an alteration in bilirubin metabolism causing hyperbilirubinemia in infants (kernicterus).
Thiamine (vitamin B 1). Beriberi is a disease with a constellation of systems affecting the nervous and cardiovascular systems. It was first described by the Chinese in 2697 B.C.E. In 1926, B. C. P. Jansen and W. F. Donath identified a factor from rice-bran extracts that prevented beriberi. The antiberiberi factor was identified chemically and called thiamine (vitamin B1). Thiamine is found in yeast, lean pork, and legumes. It serves as a receptor for high-energy pyrophosphate. It is this form of the vitamin that provides its chemical function. Pyrophosphate is extremely important for the generation of energy in the cell. However, it cannot enter the cell unless it is attached to thiamine. Thiamine is absorbed by the small intestine and transported to the liver. The major biochemical function of thiamine is to act as a coenzyme (that is, to provide a transfer site) in the alpha-keto acid carboxylation pathway. The dietary requirements depend on age.
Thiamine deficiency causes beriberi. Anorexia, neuritis, gastrointestinal dysfunction, cardiac irregularities, and muscle atrophy are present. There are three types of this disorder: wet, dry, and infantile. Wet beriberi is associated with body fluid retention (edema). Dry beriberi is related to neurologic abnormalities. It is recognized that alcoholics who have poor nutrition and thiamine deficiency, when receiving intravenous fluids, for example in the emergency room of a hospital, can develop severe altered mental states known Wernicke's and Korsakoff's syndromes. Wet beriberi is associated with heart abnormalities; dry beriberi is associated with neurological abnormalities that can cause permanent confusion if not treated in a timely manner.
Excessive ingestion of thiamine is cleared by the kidneys. There is no evidence that ingesting excessive amounts causes toxicity.
Riboflavin. In the 1920s, another water-soluble vitamin was discovered; it exhibited antipellagra activity and was termed vitamin B2. The substance was found to be yellow in color and was identified as a coenzyme, riboflavin 5'-phosphate (flavin mononucleotide or FMN).
The more abundant form of this vitamin is a complex flavin-adenine dinucleotide (FAD) that also participates as a coenzyme. Usually, the FMN and FAD are associated loosely with proteins and are released in the acidic gastrointestinal juices. The vitamin is absorbed by the proximal small intestine. Sources of riboflavin include eggs, lean meats, milk, broccoli, and enriched breads and cereals.
The physiologic function of riboflavin is to participate in oxidation-reduction reactions in numerous metabolic pathways and in energy production via the respiratory chain in the mitochondria. The dietary requirements depend on age.
Riboflavin is distributed widely in foodstuffs, and therefore deficiency is not common. However, there are reported cases of deficiency that are characterized by sore throat, hyperemia and edema of the pharyngeal and oral mucosal membranes, cheilosis (abnormal scaling and fissuring of the lips), angular stomatitis (surface inflammation of the mouth), glossitis (inflammation of the tongue), seborrheic dermatitis (an inflammation of the skin involving oversecretion by the oil-producing cutaneous glands), and anemia. Severe riboflavin deficiency can affect the conversion of vitamin B6 to its coenzyme and reduce the conversion of tryptophan, an amino acid found in proteins of animal and plant origin, to niacin (see next section). Deficiency is principally due to abnormal digestion, abnormal absorption, or both. People who are lactose-intolerant condition that is most common among blacks and Asiansften limit consumption of milk (as noted above, an excellent source of riboflavin); they may therefore be at increased risk for riboflavin deficiency. Intestinal malabsorption syndromes, including tropical sprue celiac disease, small bowel resection, and gastrointestinal and biliary obstruction can lead to riboflavin deficiency.
There is no evidence that toxicity can occur as a result of excessive ingestion of riboflavin. The most likely reason for this is that riboflavin is cleared rapidly by the kidney and is not stored in the body.
Niacin. In the mid-1700s, a Spanish physician, Gaspar Casal, recognized a disease known as pellagra that caused diarrhea, dementia, and dermatitis in maize-eating (corneating) populations throughout the world. In 1937, Conrad Elvehjem and his colleagues observed that nicotinic acid was an effective treatment for pellagra. Nicotinic acid is synonymous with both niacin and nicotinamide. It is associated with ribose lyphosphate to form nicotinamide adenine dinucleotide (NAD) and NAD phosphate. Most niacin in food is present as a component of NAD or NADP and is relatively stable to cooking and storage. Good sources of niacin include meats (especially liver), fish, legumes such as peanuts, some nuts, and some cereals. Both coffee and tea also contain reasonable amounts of this vitamin. Niacin is unique among the B vitamins because its precursor amino acid, tryptophan, can help meet the daily niacin requirement.
Niacin has a multitude of physiologic functions in a wide variety of metabolic pathways that are related to energy production and biosynthetic processes. At least two hundred enzymes are dependent on NAD and NADP. Both of these substances act as electron acceptors or hydrogen donors. Most NAD-dependent enzymes are involved in catabolic reactions, whereas NADP is used more commonly for reductive biosyntheses of fatty acids and steroids, for example. The dietary requirements depend on age.
Niacin deficiency causes pellagra. This condition is associated with diarrhea, dementia, and dermatitis. It is endemic in India and in parts of China and Africa. The classic appearance of pellagra is a pigmented rash that develops symmetrically in areas of the skin exposed to sunlight. The tongue can become bright red and there is often vomiting and diarrhea. Patients can also exhibit anxiety or sleeplessness, and can become disoriented and delusional.
Nicotinic acid is now used to treat hypercholesterolemia. Side effects of large amounts of nicotinic acid include flushing of the skin, abnormalities in liver function, and hyperglycemia. At extremely high ingestion levels, nicotinamide causes death in rats.
Pyridoxine (vitamin B 6). Vitamin B6 was identified in the 1930s. Like many of the water-soluble B vitamins, vitamin B6 includes a group of compounds that act as a coenzyme phosphate donor. These include pyridoxal 5>-phosphate (PLP), and pyridoxamine 5>-phosphate (PMP). Plants foods contain predominantly pyridoxine, whereas animal products contain primarily pyridoxal and pyridoxamine. Vitamin B6 is absorbed mainly by the lower small intestine (jejunum).
Like many of the other coenzyme B vitamins, vitamin B6 has numerous biologic functions that are related to metabolism. B6 is critically important for the production of glucose. PLP is also necessary for the conversion of tryptophan to niacin, which is why the two are often associated. The dietary requirements depend on age.
As with many of the other B vitamins, there are a wide variety of clinical symptoms associated with vitamin B6 deficiency including an abnormal electroencephalogram, convulsions, stomatitis, cheilosis, glossitis, irritability, depression, and confusion.
High doses of pyridoxine have been used to treat premenstrual syndrome and other neurological diseases. Such uses have resulted in neurotoxicity and photosensitivity.
Pantothenic acid. Pantothenic acid was one of the more difficult vitamins to isolate and separate from the other water-soluble B vitamins. Finally in the 1940s, it was synthesized and was found to be associated with coenzyme A (CoA). CoA is an essential cofactor for biologic acetylation reactions and participates in the respiratory tricarboxcylic acid cycle, fatty-acid synthesis and degradation, and a wide variety of other metabolic and regulatory processes. The dietary requirements depend on age.
Pantothenic acid deficiency affects the adrenal gland, nervous system, skin, and hair adversely. Pantothenic acid deficiency in humans is rare, but has been associated with fatigue and depression.
High doses of calcium pantothenate have not been found to be toxic in humans.
Folic acid and cobalamin (vitamin B12). In the mid-1800s, several physicians recognized that a severe form of anemia was associated with disorders of the digestive system. In 1934, William Castle and his associates observed that normal human gastric juice contained an intrinsic factor (IF) that combines with an extrinsic factor in animalprotein food, resulting in the absorption of a vitamin that prevents anemia. Vitamin B12 was isolated in 1948 and was shown to be the extrinsic antianemia factor.
Vitamin B12 absorption is unique among the B vitamins, in requiring an IF to help its absorption. Folate, on the other hand, is absorbed directly by the upper (proximal) small intestine.
Whereas vitamin B12 is found only in animal protein, folates are common in nature and present in nearly all natural foods. The dietary requirements depend on age.
Vitamin B12 deficiency can occur either because of inadequate vitamin B12 ingestion or because of the loss or inadequacy of production of intrinsic factor in the stomach. The two most notable clinical signs of vitamin B12 deficiency include megaloblastic anemia and neurological deficits. Vitamin B12 deficiency can cause paresthesia (especially numbness and tingling in the hands and feet); the diminution of vibration and position sense; unsteadiness; poor muscular coordination with ataxia (loss of muscular coordination); moodiness; mental slowness; poor memory; confusion; agitation; depression; and central visual loss. Delusions, overt psychosis, and paranoid ideas may occur in severe deficiency.
Folate deficiency also causes megaloblastic anemia and can cause neurological abnormalities as well, including irritability, forgetfulness, and hostile and paranoid behavior. For adults, ingestion of ten thousand times the minimum requirement for B12 and several hundred times that for folic acid has not been associated with toxicity.
Biotin. Biotin was identified in the 1940s. It, like many of the other B vitamins, acts as a coenzyme. Biotin is plentiful in foods such as liver, egg yolk, soybeans, yeast, cereals, legumes, and nuts. With the exception of cauliflower and mushrooms, vegetables, fruits, and meats, however, are poor sources of biotin. Biotin is also present in human and cow's milk. The major physiologic functions of biotin are related to carbohydrate and lipid metabolism. The dietary requirements depend on age.
Biotin deficiency causes mental-status changes, myalgia (muscle pain), hyperesthesia (abnormal sensitivity to pain, touch, cold, etc.), localized paresthesia, and anorexia with nausea. Dermatitis can also be associated with deficiency. The immune system is impaired in biotin-deficient animals. Neurological disorders including seizures and developmental delays have been reported in children. There have been no reports of intoxication due to excessive biotin ingestion.
Vitamin C. Scurvy is recognized as a deficiency disease that has taken a high toll in human suffering and death. The disease, which is caused by vitamin C deficiency, was recognized in ancient times by the Egyptians, Greeks, and Romans. It was especially prevalent among sea explorers of the sixteenth to eighteenth centuries. Typically, sailors developed bleeding and rotting gums, swollen and inflamed joints, dark blotches on the skin, and muscle weakness that occurred within months when at sea. It was the loss of 1,051 sailors in 1774 that prompted the British Admiralty to seek a cure for this devastating disease. They found that lemon or lime juice could prevent the disease. In the late 1920s, Albert Szent-Györgyi and Glenn King isolated vitamin C and identified it as hexuronic acid. Vitamin C is water-soluble and is absorbed efficiently by the small intestine. Its major physiologic function is to provide reducing activity for a wide variety of metabolic steps. It is important for the modification of lysine and prolinewo amino acids that are common components of collagen. These modifications result in the cross-linking of collagen strands providing structural support for this essential component of bone and fibrous tissues. The dietary requirements depend on age.
As noted, vitamin C deficiency causes scurvy, which is associated with a wide variety of abnormalities, including hemorrhages under the skin, black-and-blue marks, hyperkeratosis, joint discomfort, edema, weakness, fatigue, lassitude, depression, and hysteria.
It was suggested by the Nobel Prize Laureate Linus Pauling that extremely high doses of vitamin C could prevent cancer. With the exception of excessive amounts of vitamin C causing bowel impaction via a large number of vitamin C tablets ingested, there are very few serious consequences from an overingestion of vitamin C, though it can increase the risk of kidney stones and other renal diseases.
Other nutrients. Other nutrients that are essential could be considered vitamins. These include choline, carnitine, inositol, and taurine.
See also Beriberi; Choline, Inositol, and Related Nutrients; Inuit; Maize; Niacin Deficiency (Pellagra); Nutrients; Vitamin C; Vitamins: Water-soluble and Fat-soluble Vitamins; Appendix: Dietary Reference Intakes.
Frisell, W. R., ed. Human Biochemistry. New York: Macmillan, 1982.
Holick, Michael F. "Vitamin D: New Horizons for the 21st Century" (McCollum Award Lecture, 1994). The American Journal of Clinical Nutrition 60 (1994): 61930.
Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, D.C.: National Academy Press, 2001.
Institute of Medicine. "Vitamin D." In Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride, pp. 25087. Washington, D.C.: National Academy Press, 1997.
Shils, M. E., J. A. Olson, and M. Shike, eds. Modern Nutrition in Health and Diseases. 8th ed. Philadelphia: Lea and Febiger, 1994.
Vitamin (How Products are Made)
Vitamins are organic compounds that are necessary in small amounts in animal and human diets to sustain life and health. The absence of certain vitamins can cause disease, poor growth, and a variety of syndromes. Thirteen vitamins have been identified as necessary for human health, and there are several more vitamin-like substances that may also contribute to good nutrition. Originally, it was thought that vitamins were particular chemical compounds called amines, but now it is known that the vitamins are unrelated chemically. Their actions are different, and though exhaustively studied, not everything is understood about how they work and what they do. The vitamins are named by lettersitamin A, vitamin C, D, E, K, and the group of B vitamins. The eight B vitamins were originally thought to be one vitamin, and as more was learned about them, they were given numeral subscripts: vitamin B,, B2, etc. The B vitamins are now commonly called more aptly by chemically descriptive names: B, is thiamine, B2 is riboflavin, B6 and B12 retain their numeral names, and the other B vitamins are niacin, pantothenic acid, biotin, and folic acid. The vitamins are found in plant and animal food sources. They have also been chemically synthesized and so can be ingested in their pure form as nutritional supplements. It is not known precisely how much of each vitamin each person needs, but there are recommended daily allowances for 10 vitamins.
Some researchers have made extravagant claims about the benefits of large doses of specific vitamins as either preventatives or cures for diseases from acne to cancer. As new discoveries are made and old claims are either debunked or reinforced often, it is safest to say that more is understood about the consequences of lack of vitamins than what particular vitamins may do. For example, deficiency of vitamin A leads to break-down of the photosensitive cells in the retina of the eye, causing night blindness. Absence of vitamin C in the diet leads to scurvy, a disease formerly the bane of sailors. Absence of vitamin D may lead to rickets, a bone disease.
Many researchers were responsible for piecing together the existence of vitamins as necessary components of the human and animal diets. One of the first people to study nutrition from a chemical standpoint was English physician William Prout. In 1827, he defined the three essentials of the human diet as the oily, the saccharin, and the albuminous, which in modern-day terms are fats and oils, carbohydrates, and proteins. In 1906, an English biochemist, Frederick Hopkins, discovered that mice fed on a pure diet of the three essentials could not survive unless they were given supplementary small amounts of milk and vegetables. A Polish scientist, Casimir Funk, coined the term vitamines in 1912 to describe the chemicals he believed were found in the supplementary food that helped the mice survive. Funk first believed that the vitamines were chemically related amines, thus vita (life) plus amines. As other vitamins were isolated that were not amines, the spelling of the word changed. Other researchers working on diseases such as scurvy and beriberi, which are caused by vitamin deficiency, contributed to the isolation of the different vitamins. Still, little was generally understood about vitamins at the beginning of the twentieth century. For instance, though the use of lime juice to prevent scurvy in sailors dates back to at least 1795, the physician who accompanied Scott's voyage to the South Pole in 1910 believed scurvy was caused by bacteria, and inadequate nutritional measures were taken to prevent the disease among the explorers. Between 1925 and 1955, the known vitamins were all isolated and synthesized. Research continues today on the function of the various vitamins.
Vitamins can be derived from plant or animal products, or produced synthetically in a laboratory. Vitamin A, for example, can be derived from fish liver oil, and vitamin C from citrus fruits or rose hips. Most commercial vitamins are made from synthetic vitamins, which are cheaper and easier to produce than natural derivatives. So vitamin A may be synthesized from acetone, and vitamin C from keto acid. There is no chemical difference between the purified vitamins derived from plant or animal sources and those produced synthetically. Different laboratories may use different techniques to produce synthetic vitamins, as many can be derived from various chemical reactions.
Vitamin tablets or capsules usually contain additives that aid in the manufacturing process or in how the vitamin pill is accepted by the body. Microcrystalline cellulose, lactose, calcium, or malto-dextrin are added to many vitamins as a filler, to give the vitamin the proper bulk. Magnesium stearate or stearic acid is usually added to vitamin tablets as a lubricant, and silicon dioxide as a flow agent. These additives help the vitamin powder run smoothly through the tablet-making or encapsulating machine. Modified cellulose gum or starch is often added to vitamins as a disintegration agent. That is, it helps the vitamin compound break up once it is ingested. Vitamin tablets are also usually coated, to give the tablets a particular color or flavor, or to determine how the tablet is absorbed (in the stomach versus in the intestine, slowly versus all at once, etc.). Many coatings are made from a cellulose base. An additional coating of carnauba wax is often put on as well, to give the tablet a polished appearance.
Herbs of various kinds may be added to vitamin compounds, as well as minerals such as calcium, iron, and zinc. Typically, specialized laboratories produce purified vitamins and minerals. A distributor buys these from the laboratories and sells them to manufacturers, who put them together in different compounds such as multivitamin tablets or B-complex capsules.
The Manufacturing Process
- 1 A vitamin manufacturer purchases raw vitamins and other ingredients from distributors. Raw vitamins from a reputable distributor arrive with a Certificate of Analysis, stating what the vitamins are and how potent they are. In many cases, the manufacturer will nevertheless test the raw materials or send samples to an independent laboratory for analysis. If herbs are to be an ingredient in the vitamin capsule, these must be tested for identity and potency, and for possible bacterial contamination as well.
- 2 Often, the raw vitamins arrive at the manufacturer in a fine powder, and they need no preliminary processing. However, if the ingredients are not finely granulated, they will be run through a mill and ground. Some vitamins may be preblended with a filler ingredient such as microcrystalline cellulose or malto-dextrin, because this produces a more even granule which aids further processing steps. Laboratory technicians may run test batches when working with new ingredients and determine if preblending is necessary.
- 3 For vitamin tablets, particle size is extremely important in determining how well the formula will run through the tabletting machine. In some cases, the raw vitamins arrive from the distributor milled to the appropriate size for tabletting. In other cases, a wet granulation step is necessary. In wet granulation, the fine vitamin powder is mixed with a variety of cellulose particles,
Weighing and mixing
- 4 When all the vitamin ingredients are ready, a worker takes them to the weigh station and weighs them out on a scale. The required weights for each ingredient in the batch are listed on a formula batch record. After weighing, the worker dumps all the ingredients into a mixer. The volume of a typical mixer may be from 15-30 cu ft (0.42-0.84 cu m), though in a large manufacturing facility, it may be many times that large. The ingredients spend from 15 to 30 minutes in the mixer. At this point, samples are taken from different sides of the mixer and checked in the laboratory. The lab technicians verify that all the ingredients are distributed in the same proportion throughout the mix. If the manufacturer is making a large batch, workers may check the first three or four lots in the mixer, and then only re-check periodically. After mixing is complete, workers take the vitamin formula to either an encapsulating or a tablet-making machine.
- 5 If the lot in the mixer has been approved, workers tote the mixture to the encapsulating machine and dump it in a hopper. At the beginning of a batch, workers
Polishing and inspection
- 6 The filled vitamin capsules are next run through a polishing machine. The vitamins are circulated on a belt through a series of soft brushes. Any excess dust or vitamin powder is removed from the exterior of the capsules by the brushes. The polished capsules are then poured onto an inspection table. The inspection table has a belt of rotating rods. The vitamins fall in the grooves between the rods, and the vitamins rotate as the rods turn. Thus, all sides of the vitamin are visible for the inspector to see. The inspector removes any capsules that are too long, split, dimpled, or otherwise imperfect. The vitamins that pass inspection are then taken over to the packaging area.
- 7 Vitamin tablets are made in a tableting machine. After the vitamin blend has been mixed in the mixer, workers dump it into a hopper above the machine. The vitamin powder then flows through the hopper to a filling station beneath, and flows from there to a rotating table. The rotating table may be 2-4 ft (0.6-1.2m) in diameter, or even bigger, and is fitted with holes on its outside edge that hold dies in the shape of the desired tablet (oval, round, animal, etc.). The dies are interchangeable, so the same table can produce whatever shape the manufacturer wishes, as long as the proper dies are installed. The vitamin powder flows from the filling station to fill the die. When the table rotates, the filled die moves into a punch press. When the upper and lower halves of the punch meet, 4-10 tons (3.6-9 metric tons) of pressure is exerted on the vitamin powder. The pressure compresses the vitamin powder into a compact tablet. The punch releases, and the lower punch lifts to eject the tablet. Some tableting machines may have two punches, one on each side, so two tablets are made simultaneously. The speed of the rotation of the table determines how many tablets are made per minute. The tablets eject onto a vibrating belt which vibrates any loose dust off the tablets. The tablets then are moved to the coating area.
8 Vitamin tablets are usually coated for a variety of reasons. The coating may make the tablet easier to swallow. It may mask an unpleasant taste, and it may give the tablet a pleasant color. A manufacturer may coat in two different colors tablets that are the same size and shape, for identification. Tablets may also be given an enteric coating pH sensitive chemical coating that resists gastric acid. Tablets with an enteric coating will not break open in the stomach, but move to the intestine before dissolving. Other coatings determine the timing of the tablet's dissolution, so the vitamins can be absorbed slowly, or all at once, depending on what is appropriate to that tablet.
Once the tablets are taken from the tableting area, they are placed in the coating pan. The coating pan is a large rotating pan surrounded by one to six spray guns operated by pumps. As the tablets revolve in the pan, the pumps spray coating over them. Many tablets also receive a second coating of carnauba wax. After air drying, the tablets are ready for packaging. The packaging step is the same for tablets as for capsules.
- 9 Packaging the vitamins takes several steps, and different machines carry out these steps. So in the packaging area, the vitamins pass through a row of machines. Once the vitamins are dumped in the hopper of the first machine, no human touches them. The worker sets the machine to count out the required number of capsules or tablets per bottle, and the rest is done automatically. The capsules or tablets fall into a bottle, and the bottle is passed to the next machine to be sealed, capped, labelled, and shrink-wrapped. The finished bottles are then set in boxes and are ready for distribution.
Checks for quality are taken at many stages of vitamin manufacturing. All the ingredients of vitamin tablets or capsules are checked for identity and potency before they are used. Often this is tested both by the raw vitamin distributor and by the manufacturer. The mixed vitamin powder is checked before it is tableted or encapsulated, and the finished product is also thoroughly inspected. Federal regulations govern what substances can be used in vitamins and what claims manufacturers can make for their products. Vitamin ingredients must be proven safe before they can be made available to consumers.
Vitamin research is a volatile field, with new studies constantly suggesting new roles for vitamins in health and prevention of disease. Certain vitamins or vitamin-like substances go through fads of consumer popularity as some of this research surfaces. Nevertheless, the manufacturing process remains the same for new substances. The future of vitamins will likely change most conceptually, in how much we understand about how vitamins work.
Where to Learn More
Bender, David A. Nutritional Biochemistry of the Vitamins. Cambridge University Press, 1992.
Hendler, Sheldon Saul. The Doctor's Vitamin and Mineral Encyclopedia. Simon and Schuster, 1991.
Lieberman, Shari and Nancy Bruning. The Real Vitamin & Mineral Book. Avery Publishing Group, 1990.
Vitamins (Encyclopedia of Drugs, Alcohol, and Addictive Behavior)
Vitamins are organic substances that are required in small amounts for normal functioning of the body. Lack of adequate quantities of vitamins results in well-known deficiency diseases, such as scurvy from Vitamin C deficiency and rickets from Vitamin D deficiency in childhood. For the most part, vitamins are not synthesized by the body but are found in a variety of foods, hence the need for a well-balanced diet or supplementation by taking the vitamins separately.
In the United States, daily minimum requirements for vitamins are recommended, and periodically reassessed, by the Food and Nutrition Board of the National Academy of Scienceational Research Council. Some professionals advocate taking larger amounts of certain vitamins is for better health or for disease prevention or therapy. The question of whether vitamins are drugs is, in one sense, a semantic issue. Sometimes, very high doses of a vitamin can actually be used as a medication. For example, in very high doseswenty or more times higher than needed to prevent the vitamin deficiency disease pellagraiacin, a member of the B vitamin complex, lowers blood levels of cholesterol and triglycerides and niacin is commonly prescribed for this purpose.
It is possible to OVERDOSE and have serious side effects from large quantities of certain vitamins, such as vitamins A and D. Therefore, taking larger than needed amounts of vitamins should be done only with the advice of a physician. Deficiencies in vitamin intake can occur under a variety of situations including poverty, dieting, or certain disease states where antibiotics or other factors reduce vitamin absorption. Individuals who drink large quantities of ALCOHOL, for example, without adequate attention to diet often become deficient in some vitamins, such as B 1 (thiamine), and may require their administration to avoid serious and permanent toxicity. Prolonged serious shortages of Vitamin B 1 can cause the death of certain NEURONS in the brain, a situation that leads to confusion and severe impairment of short-term memory (the Wernicke-Korsakoff syndrome).
(SEE ALSO: Complications)
MARCUS, R., & COULSTON, A. M. (1990). The vitamins. In A. G. Gilman et al. (Eds.), Goodman and Gilman's the pharmacological basis of therapeutics, 8th ed. New York: Pergamon.
MICHAEL J. KUHAR