Zinc is a nutrient that your body uses to boost your immune system, heal wounds, and help your metabolism—the process by which you convert food into energy. If you have low levels of zinc, which your doctor can confirm with a blood test, they may recommend taking a zinc supplement in addition to eating foods that are rich in the essential mineral, such as oysters, chicken, red meat, fortified cereals, and more.
Jennifer Bourgeois, PharmD, SingleCare's pharmacy and health expert, explains that one way zinc supplementation can play a vital role in the immune system is by aiding in the development and functioning of immune cells like T-lymphocytes and neutrophils.
"This enhances the body's ability to fight infections, reducing the severity and duration of illnesses like the common cold," she explains. "Zinc also acts as an antioxidant, protecting cells from damage caused by free radicals, which further supports a healthy immune response."
That said, there are a few possible zinc side effects that you may be unaware of—and it's important to discuss these hidden dangers with your doctor before you begin a new supplement regimen.
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1 | Gastrointestinal Issues
ShutterstockYou're most likely to experience the side effects of zinc if you take supplements in high doses above the Recommended Daily Allowance (RDA). According to Harvard Health Publishing, current guidelines suggest that among adults over the age of 19, men should consume 11 mg of zinc per day and women should consume 8 mg per day. "Pregnancy and lactation require slightly more at 11 mg and 12 mg, respectively," their experts write.
Bourgeois says that gastrointestinal issues such as nausea, vomiting, and loss of appetite are some of the most common side effects of taking more zinc than you need. "It is best to supplement zinc with meals to avoid stomach upset," she suggests.
2 | Poor Immune Function
iStock / Moyo StudioPerhaps somewhat counterintuitively, taking too much zinc can also harm your immune system.
"While zinc is essential for a good immune system, too much zinc can negatively impact immune function. This can disrupt how immune cells work and may harm the balance of immune responses in your body," says Chris Mohr, PhD, RD, fitness and nutrition advisor at Fortune Recommends Health. "It's a reminder that more isn't better."
This can ultimately make your body more prone to infections and illnesses, agrees Raj Dasgupta, MD, a medical reviewer for NCOA and an ABIM quadruple board-certified physician specializing in internal medicine, pulmonology, critical care, and sleep medicine.
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3 | Reduced Copper Absorption
:Goodboy Picture Company / iStockGetting too much zinc can inhibit your body's absorption of copper, another essential mineral. Though you need only a small amount of copper to carry out essential functions, your health can suffer if your levels are low.
"Taking high doses of zinc over a long period can lead to a copper deficiency, or insufficiency, which has its own range of health issues, including anemia and potentially weakened bones," cautions Mohr.
In some cases, copper deficiencies can lead to neurological problems, irregular heartbeat, and numbness and weakness in the arms and legs.
4 | Reduced Iron Absorption
ShutterstockCopper isn't the only essential nutrient that too much zinc can disrupt. "Zinc can compete with iron for absorption in the gut, potentially leading to iron deficiency anemia over time. This is especially concerning for people who already have low iron levels, as it can make this even worse," says Dasgupta.
5 | Medication Interactions
iStockIt's always important to share a full list of medications and supplements you plan to take with your doctor or pharmacist—before you begin taking them.
"Zinc supplements can interact with various medications, including certain antibiotics and diuretics, potentially making them work improperly," says Mohr.
The National Institutes of Health (NIH) adds that some of these medications can also lower the amount of zinc in your body—another good reason you should consult your doctor to help find the right balance.
6 | Hormonal Imbalance
iStockMinerals, including zinc, play an important role in maintaining hormonal balance and enhancing the functions of the endocrine system. They do this by enabling hormone production, secretion, and synthesis, as well as promoting receptor binding and the transmission of hormone signals.
"High levels of zinc can interfere with hormones, which may impact natural hormonal functions, like reproduction in both men and women," notes Mohr.
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7 | Kidney Problems
ShutterstockFinally, zinc supplements can cause kidney problems, especially when a person takes more than the daily upper limit (UL). In most adults, this is 40 mg per day.
"When taken in high doses over time, zinc can potentially lead to kidney damage due to the body's attempts to excrete the excess mineral. The kidneys play an important role in filtering and removing waste, and overwhelming them can lead to problems," explains Mohr.
