Zinc: Benefits, Dosage, and Safety

What zinc is

Zinc is an essential trace mineral that is naturally present in some foods, added to others, and available as a dietary supplement. It is also found in some cold lozenges, over-the-counter cold remedies, and some denture adhesive creams. The total amount of zinc in the body is approximately 1.5 grams in women and 2.5 grams in men, most of it stored in skeletal muscle and bone. Zinc homeostasis is maintained through absorption from the diet, excretion into the gastrointestinal tract, and reabsorption in the gastrointestinal lumen.

What it does

• Required for the catalytic activity of hundreds of enzymes
• Plays a role in immune function
• Supports protein and DNA synthesis
• Involved in wound healing
• Involved in cell signaling and division
• Supports healthy growth and development during pregnancy, infancy, childhood, and adolescence
• Involved in the sense of taste

How much zinc per day

These are population reference values from the NIH and the Dietary Reference Intakes. They are targets for healthy people, not personal prescriptions. The last column is the Tolerable Upper Intake Level, the most you should get from all sources combined.

Deficiency and who is at risk

Because zinc has many functions throughout the body, deficiency affects many tissues and organs, and signs vary by age. In infants and children, diarrhea is a common sign; in older children, alopecia, delayed growth, and frequent infections become more prevalent. In both infants and children, deficiency can impair growth and lead to loss of appetite and later reproductive problems. Deficiency can also interfere with the senses of taste and smell. In older adults it can cause delays in wound healing and changes in cognitive and psychological function. Serum zinc concentrations below 70 mcg/dL in women and 74 mcg/dL in men indicate inadequate zinc status.

Who may need more

• People with inflammatory bowel disease, celiac disease, or who have had gastrointestinal bariatric surgery
• People who follow vegetarian or vegan diets
• Women who are pregnant or lactating
• Older infants exclusively breastfed beyond 6 months (who need age-appropriate zinc-containing foods or formula)
• Children with sickle cell disease
• People with alcohol use disorder

Food sources

Oysters contain more zinc per serving than any other food (Eastern farmed, raw, 3 oz: 32 mg; Pacific, cooked, 3 oz: 28.2 mg). Other good sources are beef (roasted, 3 oz: 3.8 mg), blue crab (3.2 mg), fortified breakfast cereals (about 2.8 mg per serving), pumpkin seeds (2.2 mg/oz), pork, turkey, cheddar cheese (1.5 mg), shrimp, and lentils. Zinc from beans, nuts, and whole grains is less bioavailable because phytates inhibit absorption, and fruits and vegetables contain very little zinc.

Forms and absorption

Forms commonly found in dietary supplements include zinc sulfate, zinc acetate, and zinc gluconate. Supplement Facts labels declare the amount of elemental zinc, not the weight of the whole zinc-containing compound. Absorption from supplements containing zinc citrate or zinc gluconate is similar, at approximately 61% in young adults; absorption from zinc oxide is about 50%. Taking supplements with 25 mg or more of elemental iron at the same time as zinc can reduce zinc absorption and plasma zinc concentrations.

Safety, excess and interactions

Too much

High zinc intakes can cause nausea, dizziness, headaches, gastric distress, vomiting, and loss of appetite. Doses of 50 mg zinc or more taken over weeks (typically from supplements or excessive use of zinc-containing denture adhesive creams) can interfere with copper absorption and cause low copper status, reduce immune function, and lower HDL cholesterol. Very high supplemental doses (about 142 mg/day) might also interfere with magnesium absorption. Chronic overuse of denture creams containing up to 34 mg zinc per gram has led to neurological symptoms including sensory ataxia and myelopathy, and anemia. Zinc in food alone is rarely as high as 50 mg and is unlikely to cause toxicity.

Interactions to know

• Quinolone antibiotics (such as ciprofloxacin) and tetracycline antibiotics can interact with zinc in the gastrointestinal tract, inhibiting absorption of both the zinc and the antibiotic; take the antibiotic at least 2 hours before or 4 to 6 hours after the zinc supplement
• Penicillamine (used for rheumatoid arthritis and Wilson disease): zinc can reduce its absorption and action; take zinc and penicillamine at least 1 hour apart
• Thiazide diuretics such as chlorthalidone and hydrochlorothiazide increase urinary zinc excretion, decreasing serum zinc concentrations
• Supplements containing 25 mg or more of elemental iron taken at the same time as zinc can reduce zinc absorption and plasma zinc concentrations

How status is measured

Serum or plasma zinc concentrations are typically used in clinical practice; in healthy people these range from 80 to 120 mcg/dL (12 to 18 mcmol/L). Concentrations below 70 mcg/dL in women and 74 mcg/dL in men indicate inadequate status. These measures have important limitations: serum zinc is affected by age, sex, and time of blood draw, fluctuates with infection, steroid hormone changes, and muscle catabolism, and does not always correlate with dietary or supplemental intake.

Regulated as a dietary supplement ingredient by the U.S. FDA under DSHEA, not as a drug; supplements are not reviewed for safety and effectiveness before marketing. The FDA Daily Value (DV) for zinc is 11 mg for adults and children age 4 years and older. FDA does not require food labels to list zinc content unless zinc has been added to the food.

What the evidence supports

We grade the strength of evidence behind each common reason people take zinc, mirroring how the NIH describes it.