Zinc deficiency is a common condition that can lead to health problems. Many people know that supplementation is then necessary. However, it is less well known that zinc overdose is also possible. Although less common, it is also harmful to health.
In this article we explain how a zinc overdose occurs, the most common symptoms and how you can help yourself. In addition, the usual reference amounts per day are shown and the interactions with other minerals are discussed.
the essentials in brief
- As with all dietary supplements, the dosage of zinc intake is of particular importance. If you don't dose zinc properly, you run the risk of overdose or deficiency.
- Zinc overdose is associated with many side effects such as vomiting, fever, chills, anemia, and others
- The general upper limit is 40 mg per day. It may only be exceeded with medical approval to avoid a possible zinc overdose.
Definition: Is a zinc overdose possible?
Zinc is a mineral involved in over 100 chemical reactions in our body. The mineral plays a role in immune function, wound healing, cell division, and other metabolic processes (1).
In principle, zinc overdose through natural intake rarely occurs. Recent studies indicate that zinc deficiency is more common in the population in developing countries (1).
Food sources high in zinc include red meat, poultry, seafood, whole grains. Additionally, oysters contain the highest amount of zinc, which is up to 493% of the daily value in an 85-gram serving (2). Despite the high zinc content in oysters and other foods, it is almost impossible to get excess amounts of zinc from the diet.
Zinc is also found in almost all multivitamin/mineral supplements. Zinc overdose can most commonly occur from supplements or from accidentally ingesting zinc-containing household products.
More and more people are taking zinc supplements for a variety of reasons, such as treating inflammatory acne, as a remedy for the common cold (zinc lozenges), to promote healing of skin ulcers, and others. However, the scientific evidence for these therapeutic effects is weak. If you decide to take zinc for this or other problems yourself without medical advice, there is a risk that you can overdose on it.
Background: What you should know about zinc overdose
Before we share any self-help tips with you, you need to clear the doubt as to whether your condition is related to a zinc overdose. However, the following information should only serve as initial information. In any case, you must contact a doctor if you think you have overdosed on zinc in any way.
How much zinc do you need to take per day?
In general, the recommended daily dose for adults is around 15 mg of zinc (3).
In the table below you will find the upper limit for the different age categories and genders (2). These values āādo not apply to people taking zinc under medical supervision for medical reasons.
| life stage | Upper limit |
|---|---|
| Babies up to 6 months | 4 mg |
| Children 1-3 years | 7 mg |
| Children 4-8 years | 12 mg |
| Children 9-13 years | 23 mg |
| Teenagers 14-18 years old | 34 mg |
| Adult | 40 mg |
For pregnant and breastfeeding women over the age of 18, the upper limit is 40 mg, as they need more zinc. The upper limit for pregnant and lactating women aged 14 to 18 is 34 mg (4).
These limits should only be exceeded under the supervision of a healthcare professional as it can lead to zinc overdose.
How to overdose with zinc and what are the symptoms?
As already mentioned, it is almost impossible for zinc-containing foods to cause a zinc overdose because they contain only small amounts of zinc. However, there are many other ways that it can happen randomly.
Below are the most common ways to overdose on zinc.
Zinc overdose from zinc tablets
If you take zinc tablets in the wrong dosage, it is possible to cause a zinc overdose. It is therefore important to always pay attention to the amount of zinc in the respective dietary supplement. Symptoms of an overdose can also be felt with long-term therapy with zinc. Below are the most common symptoms:
- nausea
- Diarrhea
- Vomit
- Headache
- fatigue
- Metallic taste in the mouth
Zinc overdose by inhalation
However, a zinc overdose can happen in the workplace through the inhalation of zinc oxide fumes or zinc dust in foundries. This type of zinc overdose is also the most common cause of metal fume fever. The following symptoms occur (3):
- fatigue
- chills
- Fever
- myalgias
- Cough
- shortness of breath
- leukocytosis
- thirst
- metallic taste
- salivation
Zinc overdose from denture adhesive creams
Zinc is also contained in some denture adhesive creams. Using large amounts of these products, far in excess of recommended amounts, could lead to excessive zinc intake and copper deficiency. This can lead to neurological problems such as (2):
- deafness
- weakness in the arms and legs
Consumption of acidic foods in galvanized containers
One cause of zinc overdose that many underestimate or ignore is consuming acidic foods, such as orange juice, from galvanized containers. This can even get into the body 800 milligrams of zinc per day. A toxic reaction occurs when acids come into contact with zinc. Zinc salts form, which can cause gastrointestinal upset (5):
What is the difference between zinc overdose and zinc poisoning?
It should be noted that zinc overdose and zinc poisoning are characterized by different characteristics:
| zinc overdose | zinc poisoning |
|---|---|
| nausea | High fever |
| Vomit | chills |
| loss of appetite | Headache |
| Diarrhea | malaise |
| Stomach cramps | |
| Headache |
Because of this, it's very important to tell the doctor your exact symptoms so they can properly determine what your condition is like.
It is important to note that, to date, there have been no reported cases of zinc poisoning from naturally occurring zinc in foods (6).
What are the consequences of zinc overdose for the body?
Zinc overdose can have both acute and chronic effects. The severity of the symptoms depends largely on the dose and the length of time it is taken. A zinc overdose that is persistent leads to zinc toxicity.
acute ingestion
Gastrointestinal symptoms are the most common when high doses of zinc are taken acutely.
Chronic Effects
In severe cases, such as accidental ingestion of zinc-containing household products, conditions such as:
- Gastrointestinal Corrosion
- bleeding
With long-term use, less immediate but serious side effects can occur, such as:
- Low "good" HDL cholesterol
- copper deficiency
- Suppressed immune system
What effect does a zinc overdose have on the absorption of other trace elements in the body?
copper deficiency
Zinc and copper have a competitive absorption relationship (7). Excess consumption of zinc (more than 50 mg/day) over several weeks can reduce the bioavailability of copper and lead to copper deficiency.
With normal amounts of zinc intake, however, this interaction does not occur. Contrary to all logic, increased copper consumption does not cause a disruption in zinc absorption (8).
iron deficiency
Zinc-induced copper deficiency is associated with various blood disorders, including iron deficiency anemia. There may also be peripheral neuropathy with loss of sensation in extremities.
An oversupply of zinc has a bad effect on iron levels in the body. 450 mg or more of zinc per day can cause problems with blood iron (6). Because of these interactions, it's best to take zinc and iron at different times of the day.
First aid with calcium
Calcium decreases the absorption of zinc, which can be beneficial in the event of an overdose. For example, the person who overdosed on zinc may drink more milk to relieve the symptoms of the overdose.
The calcium and phosphorus found in milk can help bind excess zinc and prevent absorption from the stomach and intestines.
What happens to pregnant women if they overdose on zinc?
Pregnant women in particular need to be careful about their daily intake of supplements, including zinc.
In principle, there are more studies on zinc deficiency during pregnancy, as it is much more common. Mild zinc deficiency in pregnancy can result in increased maternal morbidity, abnormal taste sensation, prolonged gestation, inefficient labor, atonic bleeding, and increased risk to the fetus.
This zinc deficiency in preterm infants could be due to high faecal zinc losses, low levels of zinc in the body at birth, and increased zinc requirements for rapid growth (9).
An excess of zinc in the body of a pregnant woman can cause vomiting, nausea, diarrhea and abdominal pain.
In the case of a zinc overdose during pregnancy, one should also expect that the side effects can be much more severe. For example, copper and iron deficiencies would be exacerbated because the child also uses up these nutrients.
Observational studies have found strong associations between poor maternal zinc status and various indicators of poor pregnancy outcome (10). That's why you should definitely have your zinc levels tested if you're pregnant or planning a pregnancy.
Zinc Overdose: 4 Effective Approaches to Self-Help and Treatment
So that you not only recognize a zinc overdose quickly, but also overcome it as soon as possible, we have summarized the following approaches for you.
Consult a doctor
A large overdose of zinc sulfate tablets will require medical attention (11). Another common zinc overdose that requires medical evaluation is overuse of denture cream. This can lead to the ingestion of an excessive amount of zinc, which in turn can lead to copper deficiency.
Because zinc overdose is a serious condition, it's important to see a doctor immediately if you think you may have overdosed. (Image source: jeshoots.com / unsplash)
Blood zinc levels can be measured to assess the degree of overdose or toxicity.
In general, you should always seek medical attention or contact a poison center if you suspect you may have ingested too much zinc.
To prevent a zinc overdose from happening in the first place, use caution when taking zinc supplements or pills, which are readily available at most drug stores. This means that you should read the labels and package inserts carefully or, at best, discuss zinc intake with your doctor.
Reduce zinc intake for a while
Of course, the first thing to do when overdosing on zinc is to reduce your zinc intake. What is meant by this is that you should stop taking zinc tablets and not completely exclude zinc from your diet. This trace element is essential for the human body and should be maintained in small amounts in your diet.
Nourishment
The bad news is that zinc is not easily removed from the body. Therefore, in the event of an overdose, you can reduce the intake a bit, just wait and treat the symptoms.
Teas such as mint, anise and caraway can help with nausea and vomiting as a result of a zinc overdose. As already mentioned, drinking milk also helps to overcome zinc overdose thanks to the high calcium content. (Image source: David Mao / unsplash)
The good news is that you can relax your stomach with a bland diet. In general, you should avoid spicy or overly strong spices. Soups, rice, or chicken broth should help soothe and relax the stomach lining.
Balance copper levels in the body
One of the underestimated consequences of zinc overdose is copper deficiency. Because of the excess zinc content in the body, copper absorption is impaired. One study states that when there is a lack of copper in the body, the consequences are anemia and nerve damage (12).
If you are concerned that you may have overdosed on zinc, then you should discuss with your doctor whether copper supplementation would be necessary in your case.
Another study indicates that a man who self-treated for acne with very high daily doses (zinc gluconate, 850 to 1000 mg/d) caused an acute copper deficiency in his body. Therefore, he was treated with intravenous copper sulfate, followed by 3 months of oral therapy (7).
Conclusion
In recent years, dietary supplements have gained popularity and, on the other hand, patients' distrust of doctors has increased. It's not uncommon for people to overdose on supplements because they think it's "safe" and "natural."
With most supplements, it can also be said of zinc that the dose makes the poison. For this reason, you should definitely follow the recommendations on the packaging if you want to take zinc without a doctor's prescription.
A doctor's consultation is also recommended before you want to take zinc or other dietary supplements. This way you would be on the safe side that your body would be optimally supplied and that there would be no unexpected side effects or overdose.
References
- Sandstead HH. Understanding zinc: recent observations and interpretations. J Lab Clin Med. 1994;124(3):322-327.
- zinc. Fact Sheet for Health Professionals. National Institutes of Health. Office of Dietary Supplements.
- Donald G Barceloux & Dr. Donald Barceloux (1999) Zinc, Journal of Toxicology: Clinical Toxicology, 37:2, 279-292, DOI: 10.1081/CLT-100102426
- Vitamins & Supplements. zinc.
- trace elements. Deutsches GrĆ¼nes Kreuz eV Information portal for health.
- Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001). Food and Nutrition Board. Institute of Medicine. National Academy Press. Washington D.C
- Igic P, Lee E, Harper W and Roach K 2002. Toxic Effects Associated With Consumption of Zinc. Mayo Clinic Proceedings, 77(7), pp.713-716.
- Interactions of zinc with other micronutrients (vital substances). Eucell. Because health is the most important thing.
- Kaur, K., Gupta, R., Saraf, S. and Saraf, S., 2014. Zinc: The Metal of Life. Comprehensive Reviews in Food Science and Food Safety, 13(4), pp.358-376.
- Caulfield LE, Zavaleta N, Shankar AH, Merialdi M. Potential contribution of maternal zinc supplementation during pregnancy to maternal and child survival. Am J Clin Nutr. 1998;68(2 Suppl):499S-508S. doi:10.1093/ajcn/68.2.499S
- Burkhart KK, Kulig KW, Rumack B. Whole-bowel irrigation as treatment for zinc sulfate overdose. Ann Emerg Med. 1990;19(10):1167-1170. doi:10.1016/s0196-0644(05)81523-9
- Zinc Toxicity. Handbook on the Toxicology of Metals (Fourth Edition), 2015.
