Vitamins and Minerals
Objectives
1. Identify the actions and indications for vitamins and minerals.
2. List at least six products used to treat vitamin or mineral deficiencies.
3. Present a teaching plan for patients who require vitamin or mineral supplements.
Key Terms
ascorbic acid (ăs-KŎR-bĭk, p. 430)
minerals (MĬN-ĕr-ălz, p. 432)
niacin (NĪ-ă-sĭn, p. 427)
riboflavin (RĪ-bō-flā-vĭn, p. 427)
thiamine (THĪ-ă-mĭn, p. 426)
vitamin A (VĪ-tă-mĭn, p. 426)
vitamins (VĪ-tă-minz, p. 425)
Overview
http://evolve.elsevier.com/Edmunds/LPN/
This chapter discusses the uses of vitamins and minerals. An overview of their actions, indications for use, and common adverse effects and drug interactions is presented. Vitamins are taken by people to maintain health and also by those who use medications to correct nutritional deficiencies. There may be drug interactions between vitamins and medications that affect both nutrient and drug absorption. Brief comments of importance for the nurse are included. Summaries of a sample of vitamin and mineral supplements available on the market are included in tables at the end of each major discussion. These over-the-counter (OTC) products change quickly, and the latest information should always be obtained for specific products. See Chapter 15 for additional related information about fluid and electrolyte products.
Vitamins
Overview
Vitamins are chemical compounds found naturally in plant and animal tissues but most are not made in the human body. Some are available in their active form; others come from food as a “precursor” or “provitamin” that then is converted to the active form. Two vitamins, Vitamin K and biotin, are not from food at all but are synthesized by bacteria inside the intestinal tract. They are necessary for life and essential to normal metabolism. They can act as coenzymes to regulate the creation of compounds in the body. Vitamins are classified into two types. Fat soluble vitamins are found primarily in various plant and animal oils or fats and can be stored in the body so daily intake is not essential. These vitamins are transported through the body by the bloodstream and remain dissolved because of unique-carrier proteins. Deficiencies are slow to develop. Water soluble vitamins are readily excreted in the urine and not stored in the body. The vitamins are destroyed by heat and deficiencies are quickly seen in patients. Usually patients get enough vitamins from a well-balanced, nutritious diet, except when certain conditions prevent them from eating food (such as intravenous therapy when a patient is taking nothing by mouth) or when the vitamins are not absorbed or their action is blocked (as in disorders that block fat metabolism) or the metabolism is accelerated (with some types of thyroid disease or pregnancy). Such conditions may require a vitamin supplement until a normal diet can be resumed or the underlying problem corrected.
Although controversy exists over natural versus synthetic vitamin preparations, current research confirms that vitamins are still vitamins, and the least expensive vitamin preparation is most likely as good therapeutically as a more expensive version. There are still many mysteries about the action of various vitamins in the body, but research has consistently demonstrated that taking large amounts of vitamins is unnecessary, may be harmful, and should be avoided.
There is a lot of literature about antioxidant vitamins and nutritional supplements. The major antioxidants are vitamin E (alpha-tocopherol), beta-carotene (a precursor, or forerunner, to vitamin A), vitamin C (ascorbic acid), and the mineral selenium. All of these are found in fruits and vegetables. Many research studies are looking at the mechanism of action of antioxidants. Current research suggests that when low-density lipoprotein (LDL) cholesterol is oxidized, sometimes incomplete oxidation takes place, producing free radicals that lead to atherosclerotic plaques. (An analogy has been made to wood that burns incompletely in a fireplace and “pops,” sending sparks against the screen.) It is thought that antioxidants retard or prevent LDL oxidation because they are oxidized in preference to LDL. This slows or eliminates the progression of atherosclerosis. It is also believed that antioxidants may slow the process that may cause cancer in cells. This has resulted in a large market for antioxidants to reduce the risk of cardiovascular disease and cancer.
Although many major research studies have looked at antioxidants after the fact and have suggested major benefits from increased use for many disease states, there are at present no intervention studies that support the role of antioxidants in cancer prevention. Epidemiologic evidence does indicate that those who eat fruits and vegetables regularly have a lower risk of cancer, although there is no conclusive evidence that this is the result of antioxidants. Therefore supplementation with vitamin antioxidants may be beneficial; however, in certain populations, such as smokers, research has found that it may actually be harmful. Nonetheless, the U.S. Department of Agriculture and the U.S. Department of Health and Human Services released new food guidelines in early 2011 based on what should be on a plate rather than the food pyramid. Today there is more emphasis than ever on eating fruits, vegetables, and whole-grain products, and on taking in fewer calories and getting more exercise to reverse widespread obesity in all age groups.
Vitamin A
Action And Uses
Vitamin A is a fat-soluble, long-chain alcohol that comes in several isometric forms: retinol, retinene, carotene, and retinoic acid. Its best understood action is helping the eye adjust to changes from light to darkness. Less understood actions include: (1) helping to stabilize and maintain the cell membrane structure, especially epithelial cell membranes, thereby helping the body resist infection; (2) affecting the synthesis of protein, which affects growth of skeletal and soft tissue; and (3) playing an essential role in reproduction.
Vitamin A supplementation is used to treat deficiency that may be provoked by sprue, colitis, regional enteritis, biliary tract or pancreatic disease, or partial gastrectomy. It is also used for the treatment of specific eye diseases and night blindness.
Adverse Reactions
If vitamin A is given in high doses for a long time, the treatment should be stopped at times to avoid hypervitaminosis. Any patient receiving 25,000 International Units or more should be closely supervised. Pregnant women should not receive more than 6000 International Units daily, or they may risk fetal abnormalities.
Drug Interactions
Women taking oral contraceptives often show elevated plasma vitamin A levels and should be closely monitored for hypervitaminosis. Mineral oil interferes with the absorption of fat-soluble vitamins. Certain antihyperlipidemic agents may also affect absorption of this product.
Nursing Implications and Patient Teaching
One International Unit of vitamin A is equivalent to 0.6 mcg of beta-carotene or 0.3 mcg of retinol. This medication may be given orally, intravenously, or intramuscularly, depending on the rapidity of needed replacement.
Recommended daily allowances (RDAs) are as follows:
Children 0 to 9 years: 300 to 450 mcg/day
Children 9 to 18 years: 575 to 750 mcg/day
Adults 18 to 75 years and older: 750 mcg/day
Some foods rich in vitamin A are animal products such as dairy products; eggs; and organ meats (all contain preformed vitamin A); and deep orange, yellow, and green fruits and vegetables (these contain carotene). In addition, some fortified sources of vitamin A are infant formula, skim milk, margarine, and some cereals.
Vitamin B1 (Thiamine)
Action And Uses
Vitamin B1, or thiamine, is water soluble and functions as a coenzyme that is closely involved with carbohydrate metabolism. Thiamine is involved in 24 different reactions, including the citric acid cycle. It also has been thought to have a role in neurophysiologic function. Thiamine is excreted in the urine.
Vitamin B1 is used to treat beriberi, which is rare but not unknown in the United States. Vitamin B deficiency is usually found in patients with alcoholism, gastric lesions, or hyperemesis of pregnancy. Symptoms include anorexia (lack of appetite), vomiting, fatigability, aching muscles, ataxia (poor coordination) of gait, and emotional disturbances such as moodiness, depression, or excess alcohol use.
Adverse Reactions
Adverse reactions to thiamine include sensitivity (allergy) reactions, particularly after parenteral administration, which can be severe, including anaphylaxis (shock). Fatalities may occur. Sensitivity tests should be done before the therapeutic dose is given. Intravenous (IV) doses should be given very slowly. Feelings of warmth, pruritus (itching), urticaria (hives), nausea, angioneurotic edema (abnormal collection of fluid in deep layers of skin, often with lip swelling and hives), pulmonary edema, sweating, tightness of the throat, malaise (weakness), and cyanosis (blue color to the skin) are also seen.
Drug Interactions
Products that have neutral or alkaline solutions will produce poor stability of thiamine preparations.
Nursing Implications and Patient Teaching
Thiamine is easily leached (lost) out of food and is destroyed when food is heated to more than 100° C, fried in hot pans, or cooked for a long time under pressure. There is some loss of thiamine during dehydration of vegetables. Thiamine is also sensitive to ultraviolet light. Foods rich in thiamine include pork, whole grains, enriched breads, cereals, and legumes. Satisfactory sources include green vegetables, fish, meats, fruits, and milk.
Vitamin B2 (Riboflavin)
Action And Uses
Vitamin B2, or riboflavin, is water soluble and acts as a precursor of two essential enzymes that deal with metabolism of proteins, fats, and carbohydrates. It is related to the release of energy to the cells and is active in tissue respiratory systems. It is used for the prophylaxis or treatment of riboflavin deficiency with symptoms which include soreness and burning of the tongue, lips, and mouth; discomfort in eating and swallowing; and photophobia (sensitivity to light), lacrimation (excess tear production), burning and itching of the eyes, visual fatigue, and the loss of visual acuity.
Drug Interactions
Riboflavin is only slightly soluble in water. Riboflavin levels in the body can be decreased by oral contraceptives, even in low doses. This loss has been shown through studies to be greater when patients have been taking oral contraceptives for at least 3 years.
Nursing Implications and Patient Teaching
B2 or riboflavin supplements should be protected from light by keeping it in a tightly closed, light-resistant container. The medication turns urine a yellow color. Food sources naturally rich in riboflavin include milk; eggs; liver; kidney; heart; green, leafy vegetables; and enriched breads and cereals.
Niacin
Action And Uses
Niacin, previously called vitamin B3, is water soluble and an essential part of two coenzymes involved with intracellular respiration. These coenzymes convert lactic acid to pyruvic acid and function in energy release and in amino acid metabolism.
Niacin is used to prevent or treat deficiency states caused by a limited dietary intake of niacin, excessive dietary intake of leucine (which increases the daily need for niacin), general anorexia related to disease or other problems, or malabsorption syndrome. The deficiency state known as pellagra is rare but may be more prevalent in geographic regions where corn is the major staple food. Pellagra is usually found along with other vitamin deficiencies.
Pellagra symptoms are seen as changes in mucous membranes, skin, the gastrointestinal (GI) tract, and the central nervous system (CNS). Anorexia, irritability, anxiety, and mental changes such as hallucinations, lassitude (weariness), apprehension, and depression may be noticed.
GI symptoms include glossitis (swollen, beefy, red tongue), stomatitis (inflammation of the mouth), and diarrhea. Dermatitis of different body parts exposed to sun or trauma may develop, as well as lesions on the skin that result from sun, fire, or heat. Mental changes that are mild early in deficiency may progress to disorientation, loss of memory, confusion, hysteria, and, sometimes, manic outbursts.
Adverse Reactions
Adverse reactions to niacin include dry skin, pruritus, skin rash, GI disorders, allergies, feelings of warmth, headache, tingling of the skin, and transient flushing (red color in the face and neck).
Drug Interactions
Sympathetic blocking agents (antihypertensives) may increase the vasodilatory effect of niacin, leading to postural hypotension (low blood pressure when a person suddenly stands up).
Nursing Implications and Patient Teaching
Flushing is a frequent side effect of niacin. If patients feel weak or dizzy, they should lie down until they feel better. Usually this reaction does not require stopping the drug. The usual dose is 8 mg/1000 kcal for infants and 6.6 mg/1000 kcal for children and adolescents. Less than 8 mg/day should not be given. The recommended intake for adults is 13 mg/day for women and 18 mg/day for men.
Foods rich in niacin are lean meats, peanuts, yeast, and cereal (especially bran and wheat germ). Other good sources include eggs, liver, red meat, whole grains, and enriched bread.
Pantothenic Acid
Action And Uses
Pantothenic acid, previously known as vitamin B5, is essential for the synthesis of coenzyme A, which has a role in the release of energy in fats, proteins, and carbohydrates. This vitamin has been used to treat paralytic ileus after surgery, possibly acting to stimulate GI motility. Deficiency states are produced only in the laboratory.
Nursing Implications and Patient Teaching
When food is cooked to more than the boiling point, considerable loss of pantothenic acid occurs. The loss is smaller when food is moderately cooked or baked.
This vitamin is available naturally in all plant and animal tissues. Much of the original vitamin content is lost from frozen meat in the liquid that drips off during thawing. Rich sources include yeast, liver, kidney, egg yolk, wheat bran, and fresh vegetables. Human milk contains 2.2 mg/L and cow’s milk contains 3.4 mg/L.
Vitamin B6
Action And Uses
Vitamin B6, or pyridoxine hydrochloride, is water soluble and functions as a coenzyme in the metabolism of protein, carbohydrates, and fat.
Pyridoxine is used to treat pyridoxine deficiency seen in patients with inborn errors of metabolism, such as vitamin B6 dependency; vitamin B6-responsive chronic anemia; and other rare vitamin problems.
Pyridoxine deficiency is most likely to develop in the older adult population and in women of childbearing age, especially those who are pregnant or breastfeeding. Women taking oral contraceptives, alcoholics, and those whose diets are of poor quality and quantity or are high in refined foods are also at risk.
Symptoms of deficiency include malaise, nervousness, irritability, and difficulty in walking. There may also be personality changes in adults, such as depression and a loss of sense of responsibility. High doses of pyridoxine may produce neurotoxicity—ataxia, numb feet, and clumsiness.
Adverse Reactions
Adverse effects are not commonly seen in patients taking pyridoxine. Pyridoxine dependency (a state of conditioned need) may develop in adults taking doses exceeding 200 mg/day for a month.
Drug Interactions
Oral contraceptives may induce pyridoxine deficiency. Concurrent use with levodopa will neutralize CNS effects. Pyridoxine may prevent chloramphenicol-induced optic neuritis. Some drugs interfere with vitamin activity enough to block action and produce symptoms of deficiency.
Nursing Implications and Patient Teaching
Pyridoxine should be kept in a tightly sealed, light-resistant container. Good food sources of vitamin B6 include yeast, wheat, corn, egg yolk, liver, kidney, and muscle meats; limited amounts are available from milk and vegetables. It is also found in liver, whole-grain breads and cereals, and soybeans.
Appropriate food preparation is important in preserving this vitamin. Freezing of vegetables results in a 20% loss of pyridoxine, and the milling of wheat results in a 90% loss.
Folic Acid
Action And Uses
Folic acid (also known as vitamin B9) is required for normal erythropoiesis, or red blood cell formation, and nucleoprotein synthesis. It is metabolized in the liver, where it is changed to its more active form. Folic acid is used to treat anemias caused by folic acid deficiency; it is also used in alcoholism, hepatic disease, hemolytic anemia, infancy (especially for infants receiving artificial formulas), lactation, oral contraceptive use, and pregnancy. Folic acid supplements may be needed in low-birth-weight infants, infants nursed by mothers deficient in folic acid, or infants with infections or prolonged diarrhea.
Recent guidelines have emphasized the importance of increased folic acid intake by all women of childbearing age, especially in those women intending to get pregnant and in early pregnancy to help prevent spinal cord malformations in the fetus (neural tube defects). The folic acid additives in commercial bread and grain products have been increased in an attempt to provide more adequate supplies of this important vitamin.
Research has suggested that concentrations of the amino acid homocysteine increases in the body with age and low levels of folate and vitamins B6 and B12. High homocysteine levels may be involved in the development of occlusive vascular disease (atherosclerosis), which may increase the risk of myocardial infarction. Therefore the level of folate in persons younger than 65 years of age should be measured.
Adverse Reactions
Folic acid is not toxic. An allergic reaction may produce bronchospasm, erythema (redness or irritation), malaise, pruritus, and rash; large amounts may discolor the urine.
Drug Interactions
Chloramphenicol and methotrexate are folate antagonists, and they may cause decreased folic acid activity. Para-aminosalicylic acid and sulfasalazine may cause symptoms of folic acid deficiency. Use with many anticonvulsants may decrease the anticonvulsant effect, leading to increased seizure activity. Use of oral contraceptives may lead to folic acid deficiency.
Nursing Implications and Patent Teaching
The RDAs of folic acid are as follows:
These RDAs are usually provided by an adequate diet.
Folic acid for parenteral use must be protected from light.
Proper nutrition is essential, and dietary measures are preferable to drug therapy. The patient should be counseled to eat foods high in folic acid to prevent a deficiency problem in the future.
Blood for hematologic laboratory tests should be drawn before beginning therapy. Drug therapy should improve the blood test results within 2 to 5 days.
Patient education should include the importance of remaining under medical supervision while receiving therapy. The patient may need to have the dose increased or decreased. Patients often fail to return for follow-up visits when they begin to feel better.
Diet is important in restoring proper folic acid levels and preventing deficiencies in the future. The patient should eat foods high in folate, including fresh, leafy green vegetables; other vegetables and fruits; yeast; and organ meats.
Vitamin B12
Action And Uses
Vitamin B12 is water soluble and contains cobalt. It is produced by the bacterium Streptomyces griseus. It functions in many metabolic processes in protein, fat, and carbohydrate metabolism. The coenzymes of B12 are also part of the erythrocyte-maturing factor of the liver and are required in the synthesis of deoxyribonucleic acid (DNA). Vitamin B12 has a hemopoietic activity identical to the antianemia factor of the liver, and it is essential for growth, cell reproduction, and nucleoprotein and myelin synthesis. Intrinsic factor must be present in the stomach and small intestine to absorb B12. Vitamin B12 interacts with folate in metabolic functions, and a deficiency in B12 makes folate useless in the body.
Vitamin B12 is used to treat all B12 deficiency conditions, including pernicious anemia (with or without neurologic symptoms), certain other anemias, malabsorption syndromes, hemorrhage, blind loop syndrome, chronic liver disease complicated by deficiency of vitamin B12, malignancy, and pregnancy and thyrotoxicosis (in which deficiency is seen because of increased metabolic rate), and renal disorders. Vitamin B12 is also used as the flushing dose in Schilling test (a specific test used for pernicious anemia). Symptoms of deficiency are rare, occurring mainly in people on strict vegetarian diets, because although vitamin B12 is water soluble, it is found only in animal products. Symptoms include dyspepsia, sore tongue, breathlessness, and a characteristic stiff back, often dubbed a “poker” or “vegan” back. Most patients with Vitamin B12 deficiency have a malabsorption problem in the GI tract, and the vitamin replacement is injected which bypasses the GI tract. Parenteral, nasal, or oral therapy may be used to maintain normal B12 levels.
Nascobal is a vitamin B12 nasal spray used as a maintenance drug for persons in remission after undergoing intramuscular (IM) therapy for pernicious anemia. The dose is usually 500 mcg intranasally once weekly. If the patient develops adverse effects such as infection, headache, glossitis, nausea, and rhinitis after taking the nasal spray, it is often necessary to start IM vitamin B12 again.
Adverse Reactions
Allergy to vitamin B12 is rare. The patient may report pruritus, a feeling of swelling of the entire body, or a severe anaphylactic reaction. A few patients may experience mild pain, localized skin irritation, or mild transient diarrhea after an injection of cyanocobalamin.
Drug Interactions
Alcohol, colchicine, and para-aminosalicylic acid lower the absorption of vitamin B12. Some antibiotics lower the response to vitamin B12 therapy.
Nursing Implications and Patient Teaching
Irreparable neurologic damage may occur if a deficiency state continues longer than 3 months or when treatment for pernicious anemia includes only folic acid. If colchicine, para-aminosalicylic acid, or excessive alcohol intake occurs for more than 2 weeks, malabsorption of vitamin B12 may occur.
The recommended daily intake of cyanocobalamin for adults is 3 mcg. The best food sources of B12 include organ meats; bivalves such as clams and oysters; nonfat dry milk; fermented cheese such as Camembert and Limburger; and seafood such as lobster, scallops, flounder, haddock, swordfish, and tuna.
Vitamin C
Action And Uses
Vitamin C, or ascorbic acid, has multiple functions, some of which are understood better than others. Vitamin C functions in a number of enzyme systems and is involved in intracellular oxidation-reduction potentials. It aids in the change of folic acid and the metabolism of certain amino acids, assists the absorption of iron and calcium, and blocks the absorption of copper in the GI tract. Ascorbic acid protects vitamins A and E and polyunsaturated fatty acids. It is also necessary for the formation of the ground substance of bones, teeth, connective tissue, and capillaries and for the synthesis of collagen. Ascorbic acid aids in wound healing and may be involved in blood clotting.
Ascorbic acid is used to treat debilitated (weak) patients, especially after surgery in older adult patients with fractures, and as a supplement for burn victims or patients undergoing severe stress. Infection, smoking, chronic illness, and febrile states may increase the need for vitamin C. It is used along with iron therapy and in patients on prolonged IV therapy. Premature infants require relatively large doses. It is also used for the prophylaxis and treatment of scurvy, the deficiency state.
With modern refrigeration and processing methods of citrus fruits, scurvy is rarely seen in the United States, but it may be found when other vitamin deficiencies are present. Symptoms include tender, painful muscles, joints, and bones; muscle cramps; anorexia; fatigue; malaise; and sore gums. Wound healing is impaired, and hemorrhagic manifestations are demonstrated by subperiosteal bleeding and petechial hemorrhages. Vasomotor instability, bruising, faulty bone and tooth development, loosened teeth, and gingivitis also may develop.
Adverse Reactions
The patient may experience mild, brief soreness at injection sites if the medication is given intramuscularly or subcutaneously. Patients may also experience brief episodes of faintness or dizziness when IV injections are given too rapidly. Excessive doses are usually rapidly excreted into the urine. Doses in excess of 1 to 3 g daily may result in GI complaints, glycosuria, oxaluria, and development of renal stones, especially in patients prone to these problems. Patients who chronically overuse vitamins may develop dependency.
