• Zinc Sulfate, Zinc Gluconate, Zinc Citrate, Zinc Picolinate, Chelated Zinc
Zinc is an important element that is found in every cell in the body. More than 300 enzymes in the body need zinc in order to function properly. Although the amount of zinc we need in our daily diet is tiny, it's very important that we get it. However, the evidence suggests that many of us do not get enough. Mild zinc deficiency seems to be fairly common, and for this reason taking a zinc supplement at nutritional doses may be a good idea.
However, taking too much zinc isn’t a good idea—it can cause toxicity. In this article, we discuss the possible uses of zinc at various doses.
The official US recommendations for daily intake of zinc are as follows:
- 0-6 months: 2 mg
- 7-12 months: 3 mg
- 1-3 years: 3 mg
- 4-8 years: 5 mg
- 9-13 years: 8 mg
- 14 years and older: 11 mg
- 9-13 years: 8 mg
- 14-18 years: 9 mg
- 19 years and older: 8 mg
- Pregnant Women
- 18 years and younger: 13 mg
- 19 years and older: 11 mg
- Nursing Women
- 18 years and younger: 14 mg
- 19 years and older: 12 mg
The average diet in the developed world may provide insufficient zinc, especially in women, adolescents, infants, and the elderly. 1-5,163
Various drugs may tend to reduce levels zinc in the body by inhibiting its absorption or increasing its excretion. These include
Oysters have a very high zinc content—one oyster provides at least the full daily dose of zinc (about 8 mg to15 mg zinc). Besides oysters, other types of shellfish, along with poultry and meat (especially organ meats), are high in zinc, providing 1 mg to 8 mg of zinc per serving. Whole grains, nuts, and seeds provide smaller amounts of zinc, ranging from 0.2 mg to about 3 mg per serving, and the zinc from them is not as absorbable. Breakfast cereals and nutrition bars are often fortified with substantial amounts of zinc.
Zinc can also be taken as a nutritional supplement, in one of many forms. Zinc citrate, zinc acetate, or zinc picolinate may be the best absorbed, although zinc sulfate is less expensive. When you purchase a supplement, you should be aware of the difference between the milligrams of actual zinc that the product contains (so-called elemental zinc) and the total milligrams of the zinc product, which includes the weight of the sulfate, picolinate, and so forth. All dosages given in this article refer to elemental zinc (unless otherwise stated).
For most purposes, zinc should simply be taken at the recommended daily requirements listed previously.
Some evidence suggests that 30 mg of zinc daily may be helpful for acne. This is a safe dose for most people. However, in most studies of zinc for acne, a much higher dose was used: 90 mg daily or more. Doses this high should only be used under physician supervision (see Safety Issues
For best absorption, zinc supplements should not be taken at the same time as high-fiber foods.
Zinc gluconate may be slightly better absorbed than zinc oxide.
When taking zinc long-term it is advisable to take 1 mg to 3 mg of
Zinc is used topically in lozenge or nasal gel form for the treatment of colds. When using zinc this way, the purpose is not to increase zinc levels in your body, but to interfere with the action of viruses in the back of your throat or in the nose. It appears that of the common forms of zinc, only zinc gluconate and zinc acetate have the required antiviral properties.
Note : When using zinc nasal gel products, do not deeply inhale, as this may cause severe pain. Rather, simply squeeze the gel into the nose, according to the directions.
Use of zinc nasal spray or zinc lozenges at the beginning of a cold
Zinc can also be taken long-term at nutritional doses orally to
A significant body of evidence suggests that oral zinc can reduce symptoms of
Growing evidence suggests that oral zinc, especially in combination with antioxidants, can help slow the progression of
Zinc has shown some promise for treating dysgeusia (impaired taste sensation). In a study of 50 people with idiopathic dysgeusia (impaired taste sensation of no known cause), use of zinc at a rather high dose of 140 mg daily improved taste ability.
study, use of zinc appeared to modestly decrease inflammation of the mucous membranes and skin caused by radiation therapy.
Weak and/or contradictory results have been seen in studies of zinc for
Some, but not all, studies have found that
Although the evidence that zinc works is not yet meaningful, the supplement is sometimes recommended for the following conditions as well:
What Is the Scientific Evidence for Zinc?
Use of lozenges containing zinc gluconate or zinc acetate have shown somewhat inconsistent but generally positive results for reducing the severity and duration of the common cold. For example, in a double-blind trial, 100 people who were experiencing the early symptoms of a cold were given a lozenge that either contained 13.3 mg of zinc from zinc gluconate or was just a placebo. 116 Participants took the lozenges several times daily until their cold symptoms subsided. The results were impressive. Coughing disappeared within 2.2 days in the treated group versus 4 days in the placebo group. Sore throat disappeared after 1 day versus 3 days in the placebo group, nasal drainage in 4 days (versus 7 days), and headache in 2 days (versus 3 days).
Positive results have also been seen in double-blind studies of zinc acetate.
It has been suggested that the exact formulation of the zinc lozenge plays a significant role in its effectiveness.
Use of zinc in the nose is somewhat more controversial.
For example, in a double-blind, placebo-controlled trial of a widely available zinc nasal gel product , 213 people with a newly starting cold used one squirt of zinc gluconate gel or placebo gel in each nostril every 4 hours while awake.
Besides using zinc to directly interfere with viruses, supplementation at nutritional dosages may also help reduce the frequency of colds by generally
Chronic zinc deficiency is known to weaken the immune system,
Cold sores are infections caused by the herpes virus. One study suggests that topical zinc may be helpful. In this trial, 46 individuals with cold sores were treated with a zinc oxide cream or placebo every 2 hours until cold sores resolved.
Zinc is thought to interfere with the ability of the herpes virus to reproduce itself. As with colds, the formulation of zinc must be properly designed to release active zinc ions. This study used a special zinc oxide and glycine formulation.
Some participants in this study experienced burning and inflammation caused by the zinc itself, but this seldom caused a serious problem.
A double-blind, placebo-controlled trial evaluated the effects of zinc with or without antioxidants on the progression of macular degeneration in 3,640 individuals in the early stage of the disease.
The results suggest that zinc (alone or, even better, with antioxidants) significantly slowed the progression of the disease.
Previous studies of zinc for macular degeneration found mixed results, but they were much smaller.
There is also some evidence that making sure to get your dietary requirement of zinc on a daily basis over many years might reduce the risk of developing macular degeneration later in life.
Keep in mind that the dosages of zinc used in most of these studies are rather high, and should be used only under a physician's supervision.
Attention Deficit Hyperactivity Disorder
Zinc has shown some promise for treatment of
Another, much smaller double-blind, placebo-controlled study evaluated whether zinc at 15 mg per day could enhance the effect of Ritalin.
Studies suggest that people with acne have lower-than-normal levels of zinc in their bodies.
In one of these studies, 54 people were given either placebo or 135 mg of zinc (as zinc sulfate) daily. Zinc produced slight, but measurable benefits.
Two studies have compared zinc against a standard treatment for acne, the antibiotic tetracycline. One study found that zinc was as effective as tetracycline taken at 250 mg daily,
Keep in mind that the dosages of zinc used in most of these studies are rather high; case reports indicate that people have made themselves extremely ill by taking zinc in hopes of treating their acne symptoms.
Zinc is thought to have a stabilizing effect on the cell membrane of red blood cells in people with sickle cell disease. For this reason, it has been tried as an aid for preventing sickle cell crisis. In a double-blind, placebo-controlled study of 145 people with sickle cell disease conducted in India, participants received either placebo or about 50 mg of zinc 3 times daily.
Sickle cell disease can also cause skin ulcers (nonhealing sores). In a 12-week, placebo-controlled trial, use of zinc at 88 mg 3 times per day for 12 weeks enhanced the rate of ulcer healing.
: The high dosages of zinc used in the last two studies can cause dangerous toxicity and should be taken (if at all) only under the supervision of a doctor.
The nutritional dose described in the first study, however, is safe. (See
Zinc taken orally seldom causes any immediate side effects other than occasional stomach upset, usually when it's taken on an empty stomach. Some forms do have an unpleasant metallic taste. Use of zinc nasal gel, however, has been associated with anosmia (loss of sense of smell). 191
Long-term use of oral zinc at dosages of 100 mg or more daily can cause a number of toxic effects, including severe copper deficiency, impaired immunity, heart problems, and anemia.
The US government has issued recommendations regarding "tolerable upper intake levels" (ULs) for zinc. The UL can be thought of as the highest daily intake over a prolonged time known to pose no risks to most members of a healthy population. The ULs for zinc are as follows:
- 0-6 months: 4 mg
- 7-12 months: 5 mg
- 1-3 years: 7 mg
- 4-8 years: 12 mg
- 9-13 years: 23 mg
- Males and Females
- 14-18 years: 34 mg
- 19 years and older: 40 mg
- Pregnant Women and Nursing Women
- 18 years or younger: 34 mg
- 19 years and older: 40 mg
There are also some interactions between zinc and certain medications to consider:
Use of zinc can interfere with the absorption of the drug penicillamine and also antibiotics in the tetracycline or fluoroquinolone (Cipro, Floxin) families.
The potassium-sparing diuretic amiloride was found to significantly reduce zinc excretion from the body.
Interactions You Should Know About
If you are taking:
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Last reviewed April 2009 by EBSCO CAM Medical Review Board
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