Many people turn to zinc supplements for an immunity boost. But the recent case of a 42-year-old shared by lifestyle coach Luke Coutinho has raised questions about its safe dosage.
The man exercised regularly, ate home-cooked meals, slept well, and rarely missed a workout. Despite these healthy habits, he experienced fatigue, brain fog, bloating, constipation, low energy, and frequent cold infections for more than six months.
Reason? He had been consuming zinc from multiple sources. What began as a zinc supplement during the pandemic had gradually expanded to include an immunity formula, a multivitamin, and other products that also contained zinc.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
Excess zinc is usually seen in people taking high-dose supplements for long periods, not from food alone (Ai generated image)
But can zinc supplements lead to such extreme side effects? How much and for how long do you have to consume it for it to backfire? We decided to find out.
“While zinc is an essential mineral that supports immunity and overall health, excessive intake can have the opposite effect,” confirms Dr Vineeta Singh Tandon, Senior Consultant– Internal Medicine at ISIC Multispeciality Hospital.
However, zinc toxicity is uncommon from food alone. The problem is more likely to arise when people take high-dose supplements for prolonged periods or combine multiple products containing zinc without realising it—just like the patient from Coutinho’s case study.
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According to Dr Tandon, the risk has also increased in recent years due to the growing popularity of self-prescribed nutritional supplements.
How much zinc is too much?
“Adults generally require about 8-11 mg of zinc per day, depending on age and gender, while the tolerable upper intake level is 40 mg per day for most adults,” notes Dr Manjusha Agarwal, Consultant—Internal Medicine, Gleneagles Hospital, Mumbai.
However, many people unknowingly exceed this amount because zinc is commonly found in multivitamins, immunity boosters, mineral supplements, and over-the-counter products marketed for colds and infections.
“When combined, these products can push zinc intake above safe limits,” says Dr Tandon.
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The early signs of excess zinc may include nausea, vomiting, stomach cramps, diarrhoea, abdominal discomfort, and a metallic taste in the mouth. With prolonged overuse, symptoms may become less obvious.
How does excess zinc affect the body?
“With prolonged overuse, high zinc levels can interfere with copper absorption, potentially leading to fatigue, brain fog, anaemia, and a weakened immune response that may increase susceptibility to infections,” Dr Agarwal cautions.
“Zinc and copper are both important minerals, but they compete for absorption in the intestine. When a person takes too much zinc for a prolonged period, the body produces a protein that binds copper and prevents it from being absorbed properly,” Dr Tandon further explains.
Copper plays an important role in energy production, immune function, red blood cell formation, and nervous system health. Over time, low copper levels can contribute to fatigue, weakness, poor concentration, brain fog, anaemia, nerve-related symptoms, reduced immunity, and more frequent infections.
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Prolonged overuse can potentially lead to fatigue, brain fog, anemia, and a weakened immune response (Freepik)
Who needs to be extra cautious?
People who regularly take high-dose zinc supplements, immunity boosters, or multiple dietary supplements containing zinc face the greatest risk. Those who self-medicate for long periods without professional guidance may also unknowingly consume excessive amounts.
“If someone has been taking zinc supplements daily for many months or years, it may be sensible to discuss testing with their doctor, especially if they have symptoms such as fatigue, weakness, frequent infections, or unexplained health issues,” Dr Tandon advises.
Depending on symptoms, tests such as serum zinc, serum copper, and a complete blood count (CBC) may be advised. Zinc toxicity is usually diagnosed through a person’s symptoms, supplement history, medical evaluation, and blood tests. Treatment generally involves reducing or stopping excess zinc intake and correcting any nutritional deficiencies, particularly copper deficiency.
“In most cases, symptoms improve gradually once excessive zinc intake is discontinued. The earlier the problem is identified, the better the recovery,” says Dr Tandon.
At 42, he exercised regularly, ate home-cooked meals, slept well, and rarely missed a workout.
Yet for more than 6 months, he struggled with:• Constant fatigue
• Brain fog
• Frequent cold infections
• Gut issues like bloating, constipation
• Low energy throughout the day…— Luke Coutinho (@LukeCoutinho17) June 17, 2026
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DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
