|
Other common
name(s): zinc gluconate, zinc sulfate, zinc acetate, zinc
carbonate, zinc picolinate
Scientific/medical
name(s): Zn, Zn++
Description
Zinc is an essential trace mineral that plays a key role in
many important body processes such as building DNA and RNA, producing
energy, regulating the immune system, and cell metabolism. It is
required for wound healing, tasting, and smelling. Zinc is found in
seafood, meats, nuts, eggs, cheese, grains, and other foods.
Overview
Some studies have found that zinc supplements may help reduce
cancer risk in animals, but research in humans has not been as
promising. A few early studies have suggested that zinc might help
fight some side effects of radiation therapy, such as loss of taste and
mouth sores for people being treated for cancer of the head or neck.
Zinc supplements can help fight infections in those with zinc
deficiency and may be useful in people with sickle cell disease.
Although zinc is very popular as a cold remedy, studies are mixed on
whether it actually helps cold symptoms. Zinc nasal spray has been
blamed by some people for the loss of their ability to smell and taste.
Too much zinc can lead to serious side effects.
How is it promoted for use?
Some people claim zinc protects against certain types of
cancer, shrinks enlarged prostate glands, decreases asthma and allergy
symptoms, and fortifies the skin. Marketers claim it helps everything
from anthrax and gout to menopause and varicose veins.
Some supporters claim that zinc reduces the severity and
duration of the common cold. It is also promoted as an antioxidant, a
compound that blocks the action of free radicals, activated oxygen
molecules that can damage cells.
What does it involve?
Zinc is in a number of foods, such as enriched breakfast
cereal, lean beef and pork, oysters, poultry, soybeans, nuts, pumpkin
and sunflower seeds, eggs, cheese, and wheat bran. The recommended
dietary allowance, or RDA, of zinc is 11 milligrams per day for men, 8
milligrams per day for women, 11 milligrams per day for pregnant women,
and 12 milligrams per day for breast-feeding women. Zinc capsules,
tablets, lozenges, and liquid "ionic zinc" are available in most drug
stores and pharmacies. Zinc spray or ointment is sometimes applied to
wounds, burns, or injuries to speed healing.
What is the history behind it?
Zinc has been found in metals that date back to 1400 BC. In
the thirteenth century, metallic zinc was produced in India. In 1500,
zinc was recognized as an element by Andreas Marggraf in Germany. In
the 1700s, zinc factories were built in Europe. Medical researchers
began serious investigations of zinc in the body in the early 1970s.
What is the evidence?
There have been a number of studies looking at the possible
roles of zinc in the body. Some researchers have focused on zinc levels
in the body in people with cancer and other diseases. A few studies
found that zinc levels in serum and/or inside white blood cells were
often lower in patients with head and neck cancer or childhood
leukemia. Low zinc levels were also linked to larger head or neck
tumors, more advanced stage of disease, and a greater number of
unplanned hospitalizations. However, it is impossible to know whether
the low zinc level was due to the effects of the cancer, to lower
dietary intake of zinc, or to some other unknown factor.
Another study found a connection between zinc intake from food
and supplements and a lower risk of melanoma (the most serious form of
skin cancer) and pre-cancerous lesions of the mouth. More recent
studies in humans do not show a consistent link between zinc
supplements and lower cancer risk.
A study published in 2004 (called SU.VI.MAX) reported on more
than 13,000 French adults who had taken either a combination of low
doses of vitamin E, vitamin C, beta carotene, selenium, and zinc, or a
placebo. After a median of more than 7 years of follow-up, there were
no major differences in cancer rates between the people who took real
supplements and those who received placebo supplements. However, when
researchers looked at men and women separately, the men who took
antioxidants had a lower risk of cancer and death from all causes than
the men who had not. This was not true for the women in the study.
However, the men began the study with lower levels of antioxidants,
especially beta carotene and vitamins C and E, in their bodies. This
may partly explain why they benefited more. It is unclear whether or
how much zinc contributed to this effect.
A subgroup of more than 5,000 men from the SU.VI.MAX study was
looked at specifically for prostate cancer. After about 8 years, there
appeared to be a slightly lower risk of prostate cancer in the men who
had taken the antioxidant supplements than in those who had taken a
placebo. However, the difference was not statistically significant
(that is, the result could have occurred by chance). Of more interest,
in the men who started the study with a normal level of
prostate-specific antigen (a protein made by the prostate gland), the
risk of getting prostate cancer was significantly lower for those who
took the supplement than for those who took the placebo. In contrast,
for the men who started with a higher PSA (3 or greater), the prostate
cancer risk tended to be higher for those who got the supplements than
for those who took the placebo. This increased risk was not considered
statistically significant.
A very small randomized clinical trial in Italy involving
patients with head and neck cancer found that zinc sulfate tablets
helped reverse the loss of taste caused by radiation therapy. However,
a large randomized clinical trial from the Mayo Clinic reported that
loss of taste was the same in patients who received the placebo and
those who were treated with zinc supplements. Another small study in
Turkey looked at patients receiving radiation therapy for head and neck
cancers to find out whether zinc helped with mouth sores. Those who
took zinc had milder mouth sores, and the sores developed later in the
course of radiation, than they did in the people who took a placebo.
In an analysis of the SU.VI.MAX study that focused on heart
disease risk, those who took antioxidants ended up with no difference
in risk factors such as cholesterol than those on placebo. In fact, the
women who had received the supplement had slightly worse risk factors
than those who did not. Since this study looked at several antioxidants
all together, it is difficult to say what zinc’s role might
have been.
It is known that the immune system does not work as well when
a person does not take in enough zinc. In people with zinc deficiency,
supplements may help immune function. For example, studies that were
done in malnourished children from developing countries found that zinc
helped prevent pneumonia and diarrhea. It also helped to slow down and
shorten the duration of diarrhea that was caused by infection. However,
zinc supplements do not help people with normal zinc levels and may
cause harm if too much is taken.
Zinc has also proven useful in helping people with sickle cell
disease, apparently because the illness causes zinc deficiency. Studies
in those with sickle cell disease report that children often grow
faster if given zinc supplements. Studies also report that adults with
sickle cell disease tend to have fewer serious infections and
hospitalizations if they take zinc supplements.
Zinc has been proven to reduce the body’s absorption
of copper. This has been proven useful for one rare health problem. The
U.S. Food and Drug Administration (FDA) has approved a form of zinc
known as zinc acetate for people with Wilson’s disease, an
inborn condition in which copper builds up in the body. Unlike zinc
supplements sold over the counter, the prescription drug is regulated
by the FDA. This means that it must meet strict quality standards,
including containing the labeled amount of zinc in each tablet.
Results of studies on zinc and its effects on cold symptoms
have been mixed. Two randomized, double-blind placebo studies found
that zinc gluconate in a glycine base reduced the length of cold
symptoms. In a review of 8 clinical trials, researchers concluded that
zinc reduced the duration and severity of the common cold. A later
study found that zinc gluconate lozenges were not effective in treating
cold symptoms in children and adolescents. Later studies were mixed.
The type of lozenge or spray, dose, timing, and other factors may
affect zinc’s effectiveness. Generally, zinc seemed to work
best when used as soon as symptoms started and then every couple of
hours for a few days. Further study is needed to determine what, if
any, role zinc plays in affecting cold symptoms.
There is some evidence that zinc, with other antioxidants, may
delay age-related macular degeneration in older people and the loss of
vision that goes with it. One study of the effect of zinc supplements
on macular degeneration observed that men taking high doses of zinc
were more likely to be admitted to the hospital with urinary problems,
including enlarged prostate, kidney stones, and infections than those
not taking zinc. Women taking high doses of zinc had more urinary tract
infections than those who were not taking zinc supplements. However,
those who took zinc also seemed live longer than those who did not.
These findings deserve careful study to see whether they hold true in
other groups and settings.
At this time, it is hard to say how each nutrient or nutrient
combination affects a person’s risk of cancer. On the other
hand, studies of large groups of people have shown that those whose
diets are high in vegetables and low in animal fat, meat, and/or
calories have lower risks for some of the most common types of cancer.
Until more is known about this, the American Cancer Society recommends
eating a variety of healthful foods--with most of them coming from
plant sources--rather than relying on supplements.
Although it is best to get vitamins and minerals from foods,
supplements may be helpful for some people, such as pregnant women,
women of childbearing age, and people with restricted food intakes. If
a supplement is taken, the best choice for most people is a balanced
multivitamin/mineral supplement that contains no more than 100% of the
"Daily Value" of most nutrients.
Are there any possible problems or
complications?
This product is sold as a
dietary supplement in the United States. Unlike companies that produce
drugs (which must provide the FDA with results of detailed testing
showing their product is safe and effective before the drug is approved
for sale), the companies that make supplements do not have to show
evidence of safety or health benefits to the FDA before selling their
products. Supplement products without any reliable scientific evidence
of health benefits may still be sold as long as the companies selling
them do not claim the supplements can prevent, treat, or cure any
specific disease. Some such products may not contain the amount of the
herb or substance that is written on the label, and some may include
other substances (contaminants). Though the FDA has written new rules
to improve the quality of manufacturing processes for dietary
supplements and the accurate listing of supplement ingredients, these
rules do not take full effect until 2010. And, the new rules do not
address the safety of supplement ingredients or their effects on health
when proper manufacturing techniques are used.
Most such
supplements have not been tested to find out if they interact with
medicines, foods, or other herbs and supplements. Even though some
reports of interactions and harmful effects may be published, full
studies of interactions and effects are not often available. Because of
these limitations, any information on ill effects and interactions
below should be considered incomplete.
An overdose of zinc can lead to a weakened immune system,
vomiting, headache, and fatigue. Very high exposure to zinc, which
occurs in some industries, may contribute to the development of
prostate cancer. High zinc doses over long periods may increase the
risk of urinary tract problems, including infections.
Taking 150 milligrams to 450 milligrams of zinc per day is
linked to low copper levels, anemia, poor immune function, low levels
of "good" cholesterol, and changes in the way iron works in the body.
Zinc can reduce the body’s ability to absorb antibiotics,
copper, and iron. Other potential interactions between zinc and other
drugs and herbs should be considered. Always tell your doctor and
pharmacist about any supplements or herbs you are taking
The National Institutes of Health say that an adult should not
take in more than 40 milligrams of zinc per day from foods and
supplements. Zinc overdose can occur with a single overdose or by
taking too much zinc over a longer period of time. A zinc overdose can
cause severe nausea and vomiting within half an hour, and at least one
death has been reported due to kidney failure.
Manufacturers of zinc nasal spray have been sued by several
hundred people who reported that they lost some or all of their ability
to smell and taste because of zinc nasal spray, and most have not
gotten it back. Typically, these users noted severe burning in their
noses when using the spray and right away found their sense of smell
and taste was lost or greatly reduced. Some companies have stopped
making zinc nasal sprays.
Women who are pregnant or breast-feeding should take zinc
supplements only if advised to do so by their doctors. If the mother
has high zinc levels, it can be passed to the baby and cause copper
deficiency. However, low zinc levels in the mother can also be harmful
to the infant during pregnancy, and getting enough zinc is important.
Pregnant women should speak to their doctor before taking any zinc
supplement. Relying on this type of treatment alone and avoiding or
delaying conventional medical care for cancer may have serious health
consequences
Additional Resources
More information from your American Cancer
Society
The following information on complementary and alternative
therapies may also be helpful to you. These materials may be found on
our Web site (www.cancer.org)
or ordered from our toll-free number (1-800-ACS-2345).
References
Age-Related Eye Disease Study Research Group. A randomized,
placebo-controlled, clinical trial of high-dose supplementation with
vitamins C and E, beta carotene, and zinc for age-related macular
degeneration and vision loss: AREDS report no. 8. Arch Ophthalmol.
2001;119:1417-1436.
Clemons TE, Kurinij N, Sperduto RD; AREDS Research Group.
Associations of mortality with ocular disorders and an intervention of
high-dose antioxidants and zinc in the Age-Related Eye Disease Study:
AREDS Report No. 13.
Arch Ophthalmol. 2004;122:716-726.
Ertekin MV, Koç M, Karslioglu I, Sezen O. Zinc
sulfate in the prevention of radiation-induced oropharyngeal mucositis:
a prospective, placebo-controlled, randomized study. Int J Radiat Oncol Biol Phys.
2004;58:167-174.
Galan P, Briançon S, Favier A, Bertrais S, Preziosi
P, Faure H, Arnaud J, Arnault N, Czernichow S, Mennen L, Hercberg S.
Antioxidant status and risk of cancer in the SU.VI.MAX study: is the
effect of supplementation dependent on baseline levels? Br J Nutr.
2005;94:125-132.
Godfrey JC, Godfrey NJ, Novick SG. Zinc for treating the
common cold: review of all clinical trials since 1984. Altern Ther Health Med.
1996;2:63-72.
Gruenwald J. PDR
for Herbal Medicines. 3rd ed. Montvale, NJ: Thomson PDR;
2004.
Gupta PC, Hebert JR, Bhonsle RB, Mutri PR, Mehta H, Mehta FS.
Influence of dietary factors on oral precancerous lesions in a
population-basedcase-control study in Kerala, India. Cancer.
1999;85:1885-1893.
Halyard MY, Jatoi A, Sloan JA, Bearden JD 3rd, Vora SA,
Atherton PJ, Perez EA, Soori G, Zalduendo AC, Zhu A, Stella PJ,
Loprinzi CL. Does zinc sulfate prevent therapy-induced taste
alterations in head and neck cancer patients? Results of phase III
double-blind, placebo-controlled trial from the North Central Cancer
Treatment Group (N01C4). Int
J Radiat Oncol Biol Phys. 2007;67:1318-1322.
Hercberg S, Bertrais S, Czernichow S, Noisette N, Galan P,
Jaouen A, Tichet J, Briançon S, Favier A, Mennen L, Roussel
AM. Alterations of the lipid profile after 7.5 years of low-dose
antioxidant supplementation in the SU.VI.MAX Study. Lipids.
2005;40:335-342.
Hercberg S, Galan P, Preziosi P, Bertrais S, Mennen L, Malvy
D, Roussel AM, Favier A, Briançon S. The SU.VI.MAX Study: a
randomized, placebo-controlled trial of the health effects of
antioxidant vitamins and minerals. Arch
Intern Med. 2004;164:2335-2342.
Jackson JL, Lesho E, Peterson C. Zinc and the common cold: a
meta-analysis revisited. J
Nutr. 2000;130(5S Suppl):1512S-1515S.
Jafek BW, Linschoten MR, Murrow BW. Anosmia after intranasal
zinc gluconate use. Am
J Rhinol. 2004;18:137-141.
Johnson AR, Munoz A, Gottlieb JL, Jarrard DF. High dose zinc
increases hospital admissions due to genitourinary complications. J Urol.
2007;177:639-643.
Kirkpatrick CS, White E, Lee JA. Case-control study of
malignant melanoma in Washington State. II. Diet, alcohol, and obesity.
Am J Epidemiol.
1994;139:869-880.
Kristal AR, Stanford JL, Cohen JH, Wicklund K, Patterson RE.
Vitamin and mineral supplement use is associated with reduced risk of
prostate cancer. Cancer
Epidemiol Biomarkers Prev. 1999;8:887-892.
Leitzmann MF, Stampfer MJ, Wu K, Colditz GA, Willett WC,
Giovannucci EL. Zinc supplement use and risk of prostate cancer. J Natl Cancer Inst.
2003;95:1004-1007.
Macknin ML, Piedmonte M, Calendine C, Janosky J, Wald E. Zinc
gluconate lozenges for treating the common cold in children: a
randomized controlled trial. JAMA.
1998;279:1962-1967.
Meyer F, Galan P, Douville P, Bairati I, Kegle P, Bertrais S,
Estaquio C, Hercberg S. Antioxidant vitamin and mineral supplementation
and prostate cancer prevention in the SU.VI.MAX trial. Int J Cancer.
2005;116:182-186.
Mossad SB, Macknin ML, Medendorp SV, Mason P. Zinc gluconate
lozenges for treating the common cold. A randomized, double-blind,
placebo-controlled study. Ann
Intern Med. 1996;125:81-88.
Mossad SB. Treatment of the common cold. BMJ.
1998;317:33-36.
Facts about dietary supplements: zinc. Office of Dietary
Supplements Web site. http://ods.od.nih.gov/factsheets/cc/zinc.html.
Updated December 9, 2002. Accessed June 9, 2008.
Phillips MJ, Ackerley CA, Superina RA, Roberts EA, Filler RM,
Levy GA. Excess zinc associated with severe progressive cholestasis in
Cree and Ojibwa-Cree children. Lancet.
1996;347(9005):866-868.
Erratum in:
Lancet.
1996;347(9017):1776
Prasad AS, Beck FW, Doerr TD, Shamsa FH, Penny HS, Marks SC,
Kaplan J, Kucuk O, Mathog RH. Nutritional and zinc status of head and
neck cancer patients: An interpretive review. J Amer Coll Nutr.
1998;17:409-418.
Prasad AS, Beck FW, Kaplan J, Chandrasekar PH, Ortega J,
Fitzgerald JT, Swerdlow P. Effect of zinc supplementation on incidence
of infections and hospital admissions in sickle cell disease (SCD). Am J Hematol.
1999;61:194-202.
Ripamonti C, Zecca E, Brunelli C, Fulfaro F, Villa S,
Balzarini A, Bombardieri E, De Conno F. A randomized, controlled
clinical trial to evaluate the effects of zinc sulfate on cancer
patients with taste alterations caused by head and neck irradiation. Cancer.
1998;15:1938-1945.
Zemel BS, Kawchak DA, Fung EB, Ohene-Frempong K, Stallings VA.
Effect of zinc supplementation on growth and body composition in
children with sickle cell disease. Am
J Clin Nutr. 2002;75:300-307.
Zicam maker settles lawsuit over users' loss of smell. 7 News
Denver Channel Web site.
http://www.thedenverchannel.com/7newsinvestigates/6279576/detail.html.
Accessed June 9, 2008.
Zinc. Memorial Sloan-Kettering Cancer Center Web site.
http://www.mskcc.org/mskcc/html/69427.cfm. Updated February 18, 2008.
Accessed June 9, 2008.
Zinc. PDRhealth.com.
http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/zin_0281.shtml.
Accessed June 9, 2008.
Note: This information may not cover
all possible claims, uses, actions, precautions, side effects or
interactions. It is not intended as medical advice, and should not be
relied upon as a substitute for consultation with your doctor, who is
familiar with your medical situation.
Last Medical Review: 11/01/2008
Last Revised: 11/01/2008
|
