Zinc

What is zinc?

Zinc is an essential trace element required for hundreds of enzymes and many regulatory proteins. The body cannot produce zinc and has only limited storage capacity, so regular dietary intake is necessary.

Where does zinc occur naturally?

Good sources include:

• Oysters and other seafood
• Meat
• Cheese and dairy products
• Eggs
• Legumes
• Nuts and seeds
• Whole grains

Zinc from animal foods is generally absorbed more efficiently than zinc from plant foods. Phytate in grains and legumes can bind zinc and reduce absorption.

What functions does zinc have?

Zinc contributes to:

• Normal immune function
• Protection of cells from oxidative stress
• Normal DNA synthesis
• Normal fertility and reproduction
• Maintenance of normal skin, hair, nails and bones
• Normal cognitive function
• Normal acid-base and carbohydrate metabolism
• Normal testosterone levels in the blood
• Normal vision

Zinc also plays a central role in wound healing, cell division and gene regulation.

Zinc deficiency

Possible symptoms include:

• Impaired immune function
• Delayed wound healing
• Hair loss
• Skin changes
• Reduced taste or smell
• Loss of appetite
• Growth impairment
• Reduced fertility

Risk is increased in people with malabsorption, chronic diarrhea, inflammatory bowel disease, bariatric surgery, very restrictive diets or high alcohol intake.

Zinc and infections

Zinc is important for normal immune-cell function. Lozenges have been studied for the common cold, with some studies reporting a shorter duration when appropriate formulations are started early.

Results vary according to zinc compound, dose and timing. Nasal zinc products have been associated with loss of smell and should be avoided.

Zinc and skin health

Zinc is involved in tissue repair and inflammatory regulation. It is used medically in selected dermatological products and may be relevant in documented deficiency.

High-dose supplementation is not automatically beneficial for acne, eczema or hair loss unless zinc status is inadequate.

Can too much zinc be harmful?

Yes. Chronic excessive intake can reduce copper absorption and may cause copper deficiency, anemia, neurological symptoms and altered immune function.

Acute high doses may cause nausea, vomiting, abdominal pain or diarrhea.

People using zinc for longer periods should consider total intake from food and all supplements. Copper status may require monitoring when high doses are medically prescribed.

Interactions

Zinc can reduce the absorption of certain antibiotics and medicines. It may also compete with iron, calcium and copper when taken at the same time.

Spacing zinc and medication by several hours may be necessary. The exact interval should be discussed with a pharmacist or physician.

Conclusion

Zinc is essential for immunity, DNA synthesis, wound healing and numerous metabolic processes. Adequate intake is important, but more is not necessarily better. Long-term high-dose use can cause clinically significant copper deficiency.