Zinc

What Is Zinc?

Zinc is a trace mineral — meaning your body only needs small amounts of it — but its impact is anything but small. It is involved in more than 300 enzymes and plays a role in immune function, wound healing, cell growth, taste and smell, and even how your DNA is built and repaired. Your body cannot store zinc the way it stores some other minerals, so you need a steady supply from food or supplements every day.

You will find zinc throughout your body — in your muscles, bones, skin, liver, kidneys, and brain. It is especially concentrated in your eyes and prostate gland. Despite being needed in tiny amounts (think milligrams, not grams), running low on zinc can affect nearly every system in your body.

What Does It Measure?

A serum zinc test measures the concentration of zinc circulating in your bloodstream. This is the most commonly ordered test for assessing zinc status, though it has some limitations — zinc levels in the blood can fluctuate based on the time of day you are tested, whether you have eaten recently, and whether your body is fighting an infection or dealing with inflammation.

Because blood zinc represents only about 0.1 percent of your total body zinc, a single test can sometimes miss a mild deficiency. Your doctor may consider your symptoms, dietary history, and other lab results alongside this number to get the full picture.

Normal Ranges

| Group | Range | Unit | |---|---|---| | Adults (morning, fasting) | 60 – 120 mcg/dL | mcg/dL | | Adults (afternoon) | 60 – 110 mcg/dL | mcg/dL | | Children (1–18 years) | 65 – 120 mcg/dL | mcg/dL | | Pregnant individuals | 50 – 100 mcg/dL | mcg/dL | | Deficient | Below 60 mcg/dL | mcg/dL |

Note: Some labs report results in micromol/L. To convert mcg/dL to micromol/L, multiply by 0.153. For example, 80 mcg/dL equals roughly 12.2 micromol/L. Zinc levels are best measured in the morning while fasting, as levels naturally dip after meals and later in the day.

What Does a High Level Mean?

Zinc toxicity from food alone is essentially unheard of. High zinc levels almost always come from supplements, occupational exposure, or accidental ingestion of zinc-containing products.

Possible causes of high zinc:

• Excessive zinc supplementation (the most common cause by far)
• Occupational exposure — welders, miners, and metalworkers can inhale zinc fumes
• Accidental ingestion of zinc-containing products (certain denture adhesives, coins, or industrial materials)
• Contamination of food or water stored in galvanized containers

Common symptoms of zinc toxicity:

• Nausea, vomiting, and diarrhea
• Stomach cramps and abdominal pain
• Headaches
• A metallic taste in the mouth
• Loss of appetite
• Copper deficiency (chronic excess zinc interferes with copper absorption, which can eventually lead to anemia and neurological problems)

Recommended next steps:

• Stop taking zinc supplements or remove the source of excess zinc
• Your doctor may check your copper level, since prolonged high zinc intake depletes copper
• Symptoms of acute zinc toxicity usually resolve once exposure stops
• If copper deficiency has developed, copper supplementation may be needed
• Follow up with blood work in a few weeks to confirm levels have normalized

What Does a Low Level Mean?

Zinc deficiency affects an estimated 2 billion people worldwide, making it one of the most common nutritional deficiencies on the planet. In developed countries, it tends to affect specific groups rather than the general population — but it is still more common than many people realize.

Possible causes of low zinc:

• A diet low in zinc-rich foods (vegetarians and vegans are at higher risk because plant-based zinc is harder for the body to absorb)
• Digestive conditions like Crohn's disease, ulcerative colitis, celiac disease, or short bowel syndrome
• Chronic diarrhea
• Chronic liver disease, including alcoholic liver disease
• Chronic kidney disease
• Diabetes
• Sickle cell disease
• Pregnancy and breastfeeding (zinc needs increase)
• Heavy alcohol use
• Certain medications, including some diuretics and penicillamine

Common symptoms of low zinc:

• Frequent colds and infections (weakened immune system)
• Slow wound healing
• Loss of taste or smell
• Loss of appetite
• Hair loss
• Skin rashes or dermatitis, especially around the mouth, eyes, and hands
• Diarrhea
• Delayed growth in children
• Night blindness
• In men, low testosterone and fertility issues

Recommended next steps:

• Your doctor may recommend zinc supplements — typical doses for deficiency range from 15 to 45 mg of elemental zinc daily
• Zinc gluconate, zinc picolinate, and zinc citrate are well-absorbed supplement forms
• If you have a digestive condition, treating it can improve zinc absorption
• Recheck your zinc level after 3 months of supplementation
• Avoid taking zinc supplements at the same time as iron or calcium supplements, as they compete for absorption

When Should You Get Tested?

Consider talking to your doctor about a zinc test if you:

• Have wounds that are healing unusually slowly
• Get sick frequently or have recurrent infections
• Have lost your sense of taste or smell (and it is not related to a recent cold or COVID-19)
• Are experiencing unexplained hair loss
• Follow a vegetarian or vegan diet
• Have a digestive condition that affects nutrient absorption
• Drink alcohol heavily
• Are pregnant or breastfeeding
• Have skin rashes that have not responded to typical treatments
• Have diabetes and are wondering whether micronutrient deficiencies could be contributing to your symptoms

How to Improve Your Levels

Food sources: The richest dietary sources of zinc are oysters (a single serving provides several times the daily requirement), red meat, crab, lobster, pork, chicken, and fortified breakfast cereals. Plant-based sources include baked beans, chickpeas, cashews, pumpkin seeds, oatmeal, and yogurt. However, plant-based zinc comes packaged with phytates, which bind to zinc and reduce absorption by as much as 50 percent.

Boost absorption from plant foods: Soaking, sprouting, or fermenting grains, beans, and seeds breaks down phytates and significantly improves zinc absorption. Pairing zinc-rich plant foods with a source of acid (like lemon juice or vinegar) can also help.

Supplements: If you cannot get enough from food, zinc supplements are widely available. Look for forms like zinc picolinate or zinc citrate, which are absorbed better than zinc oxide. Take them on an empty stomach for best absorption, but if they upset your stomach, take them with a small meal. Stick to 40 mg per day or less unless your doctor advises otherwise — that is the tolerable upper intake level for adults.

Space out your minerals: If you also take iron or calcium supplements, take them at a different time of day from your zinc supplement. These minerals use the same absorption pathways and can interfere with each other.

Frequently Asked Questions

Q: Do zinc lozenges really help with colds?

There is evidence that zinc lozenges or syrup, started within the first 24 hours of cold symptoms, can shorten the duration of a cold by roughly one to two days. The zinc appears to interfere with the virus's ability to replicate in the throat and nasal passages. However, zinc nasal sprays should be avoided — they have been linked to a permanent loss of smell in some people.

Q: Why are vegetarians at higher risk for zinc deficiency?

Two reasons. First, the best dietary sources of zinc are animal-based foods like meat, shellfish, and poultry. Second, plant foods that contain zinc also tend to be high in phytates — natural compounds that bind to zinc in the gut and reduce how much your body can absorb. A vegetarian eating the same total milligrams of zinc as a meat-eater may absorb significantly less of it. Vegetarians may need up to 50 percent more dietary zinc than the general recommendation to compensate.

Q: Can zinc supplements interact with medications?

Yes. Zinc can reduce the absorption of certain antibiotics (tetracyclines and quinolones) and penicillamine (used for rheumatoid arthritis and Wilson's disease). If you take any of these medications, space your zinc supplement at least 2 hours before or 4 to 6 hours after the medication. Always let your doctor and pharmacist know about any supplements you take.

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This content is for educational purposes only and is not medical advice. Always consult your healthcare provider about your lab results.