VITAMIN INFORMATION

Vitamin A (Beta-Carotene) is a fat-soluble vitamin with four major functions in the body: (1) It helps cells reproduce normally—a process called differentiation (cells that have not properly differentiated are more likely to undergo pre-cancerous changes). (2) It is required for vision; vitamin A maintains healthy cells in various structures of the eye and is required for the transduction of light into nerve signals in the retina. (3) It is required for normal growth and development of the embryo and fetus, influencing genes that determine the sequential development of organs in embryonic development. (4) It may be required for normal reproductive function, with influences on the function and development of sperm, ovaries and placenta.

Vitamin B-complex refers to all of the known essential water-soluble vitamins except for vitamin C. These include thiamine (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), pantothenic acid (vitamin B5), pyridoxine (vitamin B6), biotin, folic acid and the cobalamins (vitamin B12).

"Vitamin B" was once thought to be a single nutrient that existed in extracts of rice, liver, or yeast. Researchers later discovered these extracts contained several vitamins, which were given distinguishing numbers. Unfortunately, this has led to an erroneous belief among non-scientists that these vitamins have a special relationship to each other. Further adding to confusion has been the "unofficial" designation of other substances as members of the B-complex, such as choline, inositol, and para-aminobenzoic acid (PABA), even though they are not essential vitamins.

Each member of the B-complex has a unique structure and performs unique functions in the human body. Vitamins B1, B2, B3, and biotin participate in different aspects of energy production, vitamin B6 is essential for amino acid metabolism, and vitamin B12 and folic acid facilitate steps required for cell division. Each of these vitamins has many additional functions. However, contrary to popular belief, no functions require all B-complex vitamins simultaneously.

Human requirements for members of the B-complex vary considerably—from 3 mcg per day for vitamin B12 to 18 mg per day for vitamin B3 in adult males, for example. Therefore, taking equal amounts of each one—as provided in many B-complex supplements—makes little sense. Furthermore, there is little evidence supporting the use of megadoses of B-complex vitamins to combat everyday stress, boost energy, or control food cravings, unless a person has a deficiency of one or more of them. Again, contrary to popular belief, there is no evidence indicating people should take all B vitamins to avoid an imbalance when one or more individual B vitamin is taken for a specific health condition.

Most multivitamin-mineral products contain the B-complex along with the rest of the essential vitamins and minerals. Since they are more complete than B-complex vitamins alone, multiple vitamin-mineral supplements are recommended to improve overall micro nutrient intake and prevent deficiencies.

Vitamin B1 (Thiamine) is is a water-soluble vitamin needed to process carbohydrates, fat, and protein. Every cell of the body requires vitamin B1 to form the fuel the body runs on—adenosine triphosphate (ATP). Nerve cells require vitamin B1 in order to function normally.

Vitamin B12 (Cobalamin) is is a water-soluble vitamin needed for normal nerve cell activity, DNA replication, and production of the mood-affecting substance SAMe (S-adenosyl-L-methionine). Vitamin B12 acts with folic acid and vitamin B6 to control homocysteine levels. An excess of homocysteine is associated with an increased risk of heart disease, stroke, and potentially other diseases such as osteoporosis and Alzheimer’s disease.

Vitamin B2 (Riboflavin) is a water-soluble vitamin needed to process amino acids and fats, activate vitamin B6 and folic acid, and help convert carbohydrates into the fuel the body runs on—adenosine triphosphate (ATP). Under some conditions, vitamin B2 can act as an antioxidant

Vitamin B5 (Pantothenic acid) is a water-soluble vitamin involved in the Kreb’s cycle of energy production and is needed to make the neurotransmitter acetylcholine. It is also essential in producing, transporting, and releasing energy from fats. Synthesis of cholesterol (needed to manufacture vitamin D and steroid hormones) depends on pantothenic acid. Pantothenic acid also activates the adrenal glands.  Pantethine—a byproduct of pantothenic acid—has been reported to lower blood levels of cholesterol and triglycerides.

Vitamin B6 (Pyridoxine) is the master vitamin for processing amino acids—the building blocks of all proteins and some hormones. Vitamin B6 helps to make and take apart many amino acids and is also needed to make the hormones, serotonin, melatonin, and dopamine. Vitamin B6 aids in the formation of several neurotransmitters and is therefore an essential nutrient in the regulation of mental processes and possibly mood. In combination with folic acid and vitamin B12, vitamin B6 lowers homocysteine levels—an amino acid linked to heart disease and stroke, and possibly other diseases as well, such as osteoporosis, and Alzheimer’s disease. A rare, but severe, form of childhood epilepsy results from an inborn error in the metabolism of vitamin B6. Children with this form of epilepsy have an abnormal dependence on vitamin B6 and are usually mentally retarded. Seizure activity is reversible with intravenous injections of vitamin B6, which must be administered by a doctor.  In some, but not all, studies, vitamin B6 supplements improved glucose tolerance in women with diabetes caused by pregnancy.

Vitamin B9 (Folic acid) is needed for cell replication and growth. Folic acid helps form building blocks of DNA, the body’s genetic information, and building blocks of RNA, needed for protein synthesis in all cells. Therefore, rapidly growing tissues, such as those of a fetus, and rapidly regenerating cells, like red blood cells and immune cells, have a high need for folic acid. Folic acid deficiency results in a form of anemia that responds quickly to folic acid supplementation.

The requirement for folic acid increases considerably during pregnancy.  Deficiencies of folic acid during pregnancy are associated with low birth weight and an increased incidence of neural tube defects in infants.  In one study, women who were at high risk of giving birth to babies with neural tube defects were able to lower their risk by 72% by taking folic acid supplements prior to and during pregnancy.  Most doctors, many other healthcare professionals, and the March of Dimes recommend that all women of childbearing age supplement with 400 mcg per day of folic acid. Such supplementation would protect against the formation of neural tube defects during the time between conception and when pregnancy is discovered. If a woman waits until after pregnancy has been discovered to begin taking folic acid supplements, it will probably be too late to prevent a neural tube defect.

Other birth defects may be prevented with folic acid supplementation as well. Women who take folic acid-containing multivitamin supplements around the time they conceive may also reduce the risk of other congenital malformations, such as heart defects, defects of the upper lip and mouth, urinary tract defects, and limb-reduction defects. Rates of prevention of cleft lip and cleft palate may be improved by using very large amounts of folic acid (6 mg per day).  A doctor should supervise anyone wishing to take this much folic acid.

Folic acid is needed to keep homocysteine (an amino acid by-product) levels in blood from rising. A growing body of evidence suggests that an elevated homocysteine level is a risk factor for heart disease and may also be linked to several other diseases. Folic acid and certain other B vitamins function as cofactors for enzymes that can lower homocysteine levels. Research has shown that supplementing with folic acid reduces homocysteine levels.  Of the B vitamins with a role in homocysteine metabolism, folic acid appears to be the most important in lowering homocysteine levels for the average person.  A deficiency of folic acid has also been associated with peripheral vascular disease and coronary artery disease even in people with normal homocysteine levels, suggesting that the vitamin may have protective effects that extend beyond its role in maintaining normal homocysteine levels.

In 1996, the FDA began to require that all enriched flour, rice, pasta, cornmeal, and other grain products contain 140 mcg of folic acid per 100 grams.  Among people who do not take vitamin supplements, this amount of food fortification has been associated with increased folic acid levels in the blood and decreased blood levels of homocysteine.  Nevertheless, evidence is mounting that the FDA-mandated level of folic acid fortification in food is inadequate to fully prevent neural tube defects.  Until fortification rates are quadrupled, women who can possibly become pregnant are advised to take a folic acid supplement of 400 mcg per day.

A diet low in folic acid has been associated with a high incidence of pre-cancerous polyps in the colon, suggesting that folic acid may prevent the development of colon cancer.  Two studies have shown that reduced folic acid levels are associated with an increase in the incidence of cancer in people with ulcerative colitis and a third study showed the degree of abnormal cell growth decreases as folic acid intake increases.  Three large population studies showed that low folic acid intake is associated with an increased risk of colorectal cancer.

 In addition, decreased blood levels of folic acid are associated with an increased risk of colon cancer in women.  Long-term supplementation with folic acid from a multivitamin has been found in one large population study to be associated with a reduced risk of colon cancer. However, 15 years of supplementation was necessary before a significant reduction in colon-cancer risk became apparent. In that study, folic acid from dietary sources alone was associated with a modest reduction in the risk of colon cancer.  

Total folic acid intake was not associated with overall risk of breast cancer in preliminary studies.  However, among women who consume at least one alcoholic beverage per day, the risk of breast cancer appears to be highest among those with low folic acid intake. Current use of a multivitamin supplement has also been associated with lower breast cancer risk among women who consume at least 1.5 alcoholic beverages per day, compared with those who never use a multivitamin supplement.

Vitamin C is a water-soluble vitamin that has a number of biological functions.

Acting as an antioxidant, one of vitamin C’s important functions is to protect LDL cholesterol from oxidative damage. (Only when LDL is damaged does cholesterol appear to lead to heart disease, and vitamin C may be one of the most important antioxidant protectors of LDL.) Vitamin C may also protect against heart disease by reducing the stiffness of arteries and the tendency of platelets to clump together.

  The antioxidant properties of vitamin C are thought to protect smokers, as well as people exposed to secondhand smoke, from the harmful effects of free radicals. A controlled trial demonstrated the ability of 3 grams of vitamin C, taken by nonsmokers two hours prior to being exposed to cigarette smoke, to reduce the free radical damage and LDL cholesterol oxidation associated with exposure to cigarette smoke.  The smoke-induced decline in total antioxidant defense was also diminished. These beneficial effects were not observed in nonsmokers under normal conditions (no free radical exposure).

Vitamin C is needed to make collagen, the "glue" that strengthens many parts of the body, such as muscles and blood vessels. Vitamin C also plays important roles in wound healing and as a natural antihistamine. This vitamin also aids in the formation of liver bile and helps to fight viruses and to detoxify alcohol and other substances.

Recently, researchers have shown that vitamin C improves nitric oxide activity.  Nitric oxide is needed for the dilation of blood vessels, potentially important in lowering blood pressure and preventing spasms of arteries in the heart that might otherwise lead to heart attacks. Vitamin C has reversed dysfunction of cells lining blood vessels.  The normalization of the functioning of these cells may be linked to prevention of heart disease.

Evidence indicates that vitamin C levels in the eye decrease with age and that supplementing with vitamin C prevents this decrease, possibly leading to a lower risk of developing cataracts.  Healthy people have been reported in some, but not all, studies to be more likely to take vitamin C and vitamin E supplements than are people with cataracts.

Vitamin C has been reported to reduce activity of the enzyme, aldose reductase, in people.  Aldose reductase is the enzyme responsible for accumulation of sorbitol in eyes, nerves, and kidneys of people with diabetes. This accumulation is believed to be responsible for deterioration of these parts of the body associated with diabetes. Therefore, interference with the activity of aldose reductase theoretically helps protect people with diabetes.

Vitamin C may help protect the body against accumulation or retention of the toxic mineral, lead. In one preliminary study, people with higher blood levels of vitamin C had much lower risk of having excessive blood levels of lead.  In a controlled trial, male smokers with moderate to high levels of lead received supplements of 1,000 mg per day of vitamin C, 200 mg per day of vitamin C, or a placebo.  Only those people taking 1,000 mg per day of vitamin C experienced a drop in the blood lead levels, but the reduction in this group was dramatic.

People with recurrent boils (furunculosis) may have defects in white blood cell function that are correctable with vitamin C supplementation. A preliminary study of people with recurrent boils and defective white blood cell function, found that 1 gram of vitamin C taken daily for four to six weeks, resulted in normalization of white blood cell function.  Ten of twelve people receiving vitamin C became symptom-free within one month and remained so for periods of one to three years without additional supplementation. The other two people required long-term vitamin C supplementation to prevent recurrences.

A double-blind trial found that 500 mg of vitamin C per day for one year reduced the risk of developing reflex sympathetic dystrophy (a painful nerve condition of the extremities), after a wrist fracture. 

In a small, preliminary trial, vitamin C (500 mg twice daily) combined with rutoside (500 mg twice daily), a derivative of the flavonoid, rutin, produced marked improvement in three women with progressive pigmented purpura (PPP), a mild skin condition.  Alhough not a serious medical condition, cosmetic concerns lead people with PPP to seek treatment with a variety of drugs. The vitamin C/rutoside combination represents a promising, non-toxic alternative to these drug treatments, but larger, controlled trials are needed to confirm these preliminary results.

Vitamin D, the fat-soluble vitamin D’s most important role is maintaining blood levels of calcium, which it accomplishes by increasing absorption of calcium from food and reducing urinary calcium loss. Both effects keep calcium in the body and therefore spare the calcium that is stored in bones. When necessary, vitamin D transfers calcium from the bone into the bloodstream, which does not benefit bones. Although the overall effect of vitamin D on the bones is complicated, some vitamin D is necessary for healthy bones and teeth.

Vitamin D plays a role in immunity and blood cell formation and also helps cells "differentiate"—a process that may reduce the risk of cancer. From animal and human studies, researchers have hypothesized that vitamin D may protect people from multiple sclerosis, autoimmune arthritis, and juvenile diabetes.  Vitamin D is also needed for adequate blood levels of insulin.  Vitamin D receptors have been found in the pancreas where insulin is made, and preliminary evidence suggests that supplementation may increase insulin secretion for some people with adult-onset (type 2) diabetes.

Vitamin E is an antioxidant that protects cell membranes and other fat-soluble parts of the body, such as low-density lipoprotein (LDL; “bad” cholesterol) cholesterol, from damage. Only when LDL is damaged does cholesterol appear to lead to heart disease, and vitamin E is an important antioxidant protector of LDL.1 Several studies, including two double-blind trials, have reported that 400 to 800 IU of natural vitamin E per day reduces the risk of heart attacks. Other recent double-blind trials have found either limited benefit or no benefit at all from supplementation with synthetic vitamin E.  One of the negative trials used 400 IU of natural vitamin E —a similar amount and form to previous successful trials. In attempting to make sense of these apparently inconsistent findings, the following is clear: less than 400 IU of synthetic vitamin E, even when taken for years, does not protect against heart disease. Whether 400 to 800 IU of natural vitamin E is, or is not, protective remains unclear.

Vitamin E also plays some role in the body’s ability to process glucose. Some, but not all, trials suggest that vitamin E supplementation may eventually prove to be helpful in the prevention and treatment of diabetes.

In the last ten years, the functions of vitamin E in the cell have been further clarified. In addition to its antioxidant functions, vitamin E is now known to act through other mechanisms, including direct effects on inflammation, blood cell regulation, connective tissue growth, and genetic control of cell division.

Vitamin K is needed for proper bone formation and blood clotting. In both cases, vitamin K does this by helping the body transport calcium. Vitamin K is used by doctors when treating an overdose of the drug warfarin.  Also, doctors prescribe vitamin K to prevent excessive bleeding in people taking warfarin but requiring surgery.

There is preliminary evidence that vitamin K2 (menadione), not vitamin K1 (phylloquinone; phytonadione), may improve a group of blood disorders known as myelodysplastic syndromes (MDS).  These syndromes carry a significantly increased risk of progression to acute myeloid leukemia. Large-scale trials of vitamin K2 for MDS are needed to confirm these promising early results.

MINERAL INformATION

Calcium is the most abundant, essential mineral in the human body. Of the two to three pounds of calcium contained in the average body, 99% is located in the bones and teeth. Calcium is needed to form bones and teeth and is also required for blood clotting, transmission of signals in nerve cells, and muscle contraction. The importance of calcium for preventing osteoporosis is probably its most well-known role.

Although calcium plays at least some minor role in lowering blood pressure, the mechanisms involved appear complex and somewhat unclear.  The level of calcium in the blood is tightly regulated by parathyroid hormone (PTH), and low intake of calcium causes elevations in PTH, which in turn have been implicated in the development of hypertension.  High calcium intake has also been associated with a reduced risk of cardiovascular disease in postmenopausal women.

By reducing absorption of oxalate, a substance found in many foods, calcium may be able to indirectly reduce the risk of kidney stones.   However, people with a history of kidney stones must talk with a doctor before supplementing with calcium because such supplementation might actually increase the risk of forming stones for the small number of people who absorb too much calcium.

Calcium also appears to partially bind some fats and cholesterol in the gastrointestinal tract. Perhaps as a result, some research suggests that calcium supplementation may help lower cholesterol levels.

Animal studies have established a role of calcium in the development of female egg cells (oocytes). Although the precise role of calcium is unclear, some researchers speculate that future studies may identify important uses for calcium in conditions of the human ovary, such as polycystic ovary syndrome (PCOS).

Through a variety of mechanisms, calcium may have anticancer actions within the colon. Most preliminary studies have shown high calcium diets are associated with reduced colon cancer risk. Most, but not all, preliminary studies have found taking calcium supplements to also be associated with a reduced risk of colon cancer or precancerous conditions in the colon. One preliminary study reported that high dietary, but not supplemental, calcium intake was associated with a decreased risk of precancerous changes in the colon.   In double-blind studies, calcium supplementation has significantly protected against precancerous changes in the colon in some, but not all, studies.

Warning: Calcium supplements should be avoided by prostate cancer patients.

Chromium is an essential trace mineral that helps the body maintain normal blood sugar levels.

In addition to its well-studied effects in diabetes, preliminary research has found that chromium supplementation also improves glucose tolerance in people with Turner’s syndrome—a disease linked with glucose intolerance.

Chromium may also play a role in increasing HDL ("good") cholesterol, while lowering total cholesterol levels.

Chromium, in a form called chromium picolinate, has been studied for its potential role in altering body composition. Preliminary research in animals and humans suggested that chromium picolinate increases fat loss and promotes a gain in lean muscle tissue. Double-blind research has also reported a reduction in body fat and body weight in people given 400 mcg of chromium (as chromium picolinate) per day for three months. However, other studies have failed to show a significant effect of chromium picolinate on body composition.

Copper is an essential trace element present in the diet and in the human body. It is needed to absorb and utilize iron. It is also part of the antioxidantenzyme, superoxide dismutase (SOD). Copper is needed to make adenosine triphosphate (ATP), the energy the body runs on. Synthesis of some hormones requires copper, as does the synthesis of collagen (the "glue" that holds connective tissue together). In addition, the enzyme, tyrosinase, which plays a role in the production of skin pigment, requires copper to function.

Copper supplementation has been shown to increase SOD levels in humans.

Iodine is a trace mineral needed to make thyroid hormones, which are necessary for maintaining normal metabolism in all cells of the body.

Reports suggest that iodine may have a number of other important functions in the body unrelated to thyroid function that might help people with a wide variety of conditions. These other uses for iodine are only supported by minimal research.

Iron is an essential mineral. It is part of hemoglobin, the oxygen-carrying component of the blood. Iron-deficient people tire easily in part because their bodies are starved for oxygen. Iron is also part of myoglobin, which helps muscle cells store oxygen. Without enough iron, adenosine triphosphate (ATP; the fuel the body runs on) cannot be properly synthesized. As a result, some iron-deficient people become fatigued even when their hemoglobin levels are normal (i.e., when they are not anemic).

Although iron is part of the antioxidant enzyme catalase, iron is not generally considered an antioxidant, because too much iron can cause oxidative damage.

Magnesium is an essential mineral to the human body. It is needed for bone, protein, and fatty acid formation, making new cells, activating B vitamins, relaxing muscles, clotting blood, and forming adenosine triphosphate (ATP; the energy the body runs on). The secretion and action of insulin also require magnesium.

Magnesium also acts in a way related to calcium channel blocker drugs. This effect may be responsible for the fact that under certain circumstances magnesium has been found to potentially improve vision in people with glaucoma.  Similarly, this action might account for magnesium’s ability to lower blood pressure.

Since magnesium has so many different actions in the body, the exact reasons for some of its clinical effects are difficult to determine. For example, magnesium has reduced hyperactivity in children in preliminary research.  Other research suggests that some children with attention deficit-hyperactivity disorder (ADHD) have lowered levels of magnesium. In a preliminary but controlled trial, 50 ADHD children with low magnesium (as determined by red blood cell, hair, and serum levels of magnesium) were given 200 mg of magnesium per day for six months.  Compared with 25 other magnesium-deficient ADHD children, those given magnesium supplementation had a significant decrease in hyperactive behavior.

Magnesium levels have been reported to be low in those with chronic fatigue syndrome (CFS), and magnesium injections have been reported to improve symptoms.  Oral magnesium supplementation has also improved symptoms in those people with CFS who had low magnesium levels in another report, although magnesium injections were sometimes necessary.  However, other research reports no evidence of magnesium deficiency in people with CFS.  The reason for this discrepancy remains unclear. People with CFS considering magnesium supplementation should have their magnesium status checked beforehand by a doctor. Only people with magnesium deficiency appear to benefit from this therapy.

People with diabetes tend to have lower magnesium levels compared with those who have normal glucose tolerance.  Supplementation with magnesium overcomes this problem and may help some diabetics improve glucose tolerance.

Magnesium may be beneficial for bladder problems in women, especially common disturbances in bladder control and the sense of "urgency." A double-blind trial found that women who took 350 mg of magnesium hydroxide (providing 147 mg elemental magnesium) twice daily for four weeks had better bladder control and fewer symptoms than women who took a placebo.

Magnesium supplementation may reduce dehydration of red blood cells in sickle cell anemia patients. Administration of 540 mg per day of magnesium pidolate to sickle cell anemia patients was seen after six months, to reverse some of the characteristic red blood cell abnormalities and to dramatically reduce the number of painful days for these patients.  This preliminary trial was not blinded, so placebo effect could not be ruled out. Magnesium pidolate is also an unusual form of magnesium. It is unknown whether other forms of magnesium would produce similar results.

Manganese is an essential trace mineral needed for healthy skin, bone, and cartilage formation, as well as glucose tolerance. It also helps activate superoxide dismutase (SOD)—an important antioxidant enzyme.

Molybdenum is an essential trace mineral needed for the proper function of certain enzyme-dependent processes, including the metabolism of iron.

Preliminary evidence indicates that molybdenum, through its involvement in detoxifying sulfites, might reduce the risk of sulfite-reactive asthma attacks.  However, a physician should be involved in the evaluation and treatment of sulfite sensitivity.

Phosphorus is an essential mineral that is usually found in nature combined with oxygen as phosphate. Most of the phosphate in the human body is in bone, but phosphate-containing molecules (phospholipids) are also important components of cell membranes and lipoprotein particles, such as HDL and LDL (“good” and “bad” cholesterols, respectively). Small amounts of phosphate play important roles in numerous biochemical reactions throughout the body.

The role of phosphate-containing molecules in aerobic exercise reactions has suggested that phosphate loading might enhance athletic performance, though controlled research has produced inconsistent results.

Potassium is an essential mineral needed to regulate water balance, levels of acidity, blood pressure, and neuromuscular function. This mineral also plays a critical role in the transmission of electrical impulses in the heart.

People with low blood levels of potassium who are undergoing heart surgery are at an increased risk of developing heart arrhythmias and an increased need for cardiopulmonary resuscitation.  Potassium is also required for carbohydrate and protein metabolism.

Selenium is an essential trace mineral.

Selenium activates an antioxidant enzyme called glutathione peroxidase, which may help protect the body from cancer. Yeast-derived forms of selenium have induced “apoptosis” (programmed cell death) in cancer cells in test tubes and in animals.  A double-blind trial that included over 1,300 people found those given 200 mcg of yeast-based selenium per day for 4.5 years had a 50% drop in the cancer death rate compared with the placebo group.  In that same study, however, selenium supplementation was associated with a significant increase in the risk of developing one type of skin cancer (squamous cell carcinoma).  Another study found that men consuming the most dietary selenium (assessed indirectly by measuring toenail selenium levels) developed 65% fewer cases of advanced prostate cancer than did men with the lowest levels of selenium intake.

Selenium is also essential for healthy immune functioning. Selenium supplementation has reduced the incidence of viral hepatitis in selenium-deficient populations, presumably by enhancing immune function.  Even in a non-deficient population of elderly people, selenium supplementation has been found to stimulate the activity of white blood cells—primary components of the immune system.  Selenium is also needed to activate thyroid hormones.

In a placebo-controlled study, supplementation with 200 mcg per day of selenium for three months reduced anti-thyroid antibody levels (indicating a reduction in disease activity) in people with autoimmune thyroiditis (inflammation of the thyroid gland).

In a double-blind trial, selenium supplementation of infertile men improved the motility of sperm cells and increased the chance of conception.

Zinc is an essential mineral that is a component of more than 300 enzymes needed to repair wounds, maintain fertility in adults and growth in children, synthesize protein, help cells reproduce, preserve vision, boost immunity, and protect against free radicals, among other functions.

In double-blind trials, zinc lozenges have reduced the duration of colds in adults, but have been ineffective in children.  The ability of zinc to shorten colds may be due to a direct, localized anti-viral action in the throat. For the alleviation of cold symptoms, lozenges providing 13–25 mg of zinc, in the form of zinc gluconate, zinc gluconate-glycine, or zinc acetate, are used, typically every two hours while awake, but only for several days. The best effect is obtained when lozenges are used at the first sign of a cold.

Lozenges containing zinc gluconate, zinc gluconate-glycine, or zinc acetate have been effective, whereas most other forms of zinc and lozenges flavored with citric acid, tartaric acid, sorbitol, or mannitol, have been ineffective.  Trials using forms other than zinc gluconate, zinc gluconate-glycine, or zinc acetate have failed, as have trials that use insufficient amounts of zinc.  Therefore, until more is known, people should only use zinc gluconate, zinc gluconate-glycine, or zinc acetate.

Zinc reduces the body’s ability to utilize the essential mineral copper. (For healthy people, this interference is circumvented by supplementing with copper, along with zinc.) The ability to interfere with copper makes zinc an important therapeutic tool for people with Wilson’s disease—a genetic condition that causes copper overload.

Zinc supplementation in children in developing countries is associated with improvements in stunted growth, increased weight gain in underweight children, and substantial reductions in the rates of diarrhea and pneumonia, the two leading causes of death in these settings.  Whether such supplementation would help people in better nourished populations remains unclear.

A small, preliminary trial has found zinc sulfate to be effective for contact dermatitis (a skin rash caused by contact with an allergen or irritant).  Participants with active skin rashes took approximately 23 mg of zinc (in the form of zinc sulfate) three times daily, for one month. 73% of those taking the zinc sulfate had complete resolution of their skin rashes, while the remaining participants had a 50–75% improvement. Further trials are needed to confirm these preliminary findings, however.