Zinc Deficiency

What zinc does

Zinc is the second most abundant trace mineral in the body after iron, but the body has no dedicated store, so you need a regular supply from food. Zinc is needed for:

• Immune cells, especially T cells.
• Skin repair and wound healing.
• Growth and sexual development.
• Taste and smell.
• DNA synthesis and cell division.
• More than 300 enzymes.
• Vision in low light, through vitamin A metabolism.

How much zinc you need

Vegetarians may need up to 50 percent more, because phytates in grains and legumes reduce absorption. The upper limit for adults is 40 mg a day from all sources, unless a doctor advises otherwise.

Symptoms of zinc deficiency

Mild to moderate deficiency

• Loss of appetite.
• Changes in taste and smell.
• Frequent colds and infections.
• Slow wound healing.
• Hair loss or thinning.
• Dry, rough skin and brittle nails.
• Poor night vision.
• Low sperm count and low testosterone.
• Poor growth and delayed puberty in children.

Severe deficiency

• A red, scaly, crusted rash, sometimes blistering, around the mouth, eyes, nose, hands, feet, groin and anus. It can look like eczema, psoriasis or a yeast infection.
• Diarrhea.
• Mood changes, irritability and lethargy.
• Mouth sores and a sore tongue.
• Eye inflammation.

Acrodermatitis enteropathica

A rare inherited disorder in which the gut cannot absorb zinc properly. It typically appears when an infant is weaned from breast milk, with the classic triad of rash around the body openings and on the hands and feet, diarrhea and hair loss. It needs lifelong zinc supplements, which are highly effective.

Causes and risk factors

Low intake

• Vegetarian and vegan diets, especially high in phytate-rich grains and legumes.
• Poor diet in older adults.
• Eating disorders such as anorexia nervosa.
• Exclusive breastfeeding beyond about 6 months without zinc-rich complementary foods.
• Long-term IV nutrition without added zinc.

Poor absorption or increased loss

• Crohn's disease and ulcerative colitis.
• Celiac disease.
• Short bowel syndrome and weight-loss surgery.
• Chronic diarrhea.
• Exocrine pancreatic insufficiency and cystic fibrosis.
• Alcohol use disorder, which reduces absorption and increases loss in urine.
• Chronic kidney disease and dialysis.
• Liver cirrhosis.
• Diabetes, through increased urinary loss.
• Sickle cell disease.
• Burns and extensive wounds.
• Medicines: some diuretics, penicillamine, some antibiotics and acid suppressants with long use.

Increased needs

• Pregnancy and breastfeeding.
• Rapid growth in infancy and adolescence.

How zinc deficiency is diagnosed

There is no perfect test. Doctors combine symptoms, risk factors and blood levels:

• Serum or plasma zinc: the usual test. Levels below about 60 to 70 micrograms per deciliter suggest deficiency. Results are lowered by inflammation, infection, low albumin, pregnancy and time of day, so a morning fasting sample is preferred.
• Alkaline phosphatase: a zinc-dependent enzyme that may be low.
• Response to supplements: improvement of rash, appetite or taste within weeks supports the diagnosis.
• Tests for underlying causes: celiac antibodies, inflammatory markers, kidney and liver function.

Treatment

Zinc-rich foods

Soaking, sprouting and fermenting grains and legumes (as in sourdough bread) reduces phytates and improves absorption.

Zinc supplements

Zinc gluconate, sulfate, acetate or citrate are available over the counter. For mild deficiency, follow the label dose or your doctor's advice. Doctors may prescribe a higher dose for a set period for confirmed deficiency. Taking zinc with food reduces nausea, but take it apart from iron and calcium supplements.

The WHO recommends a short course of zinc for children with acute diarrhea in low-income settings, because it shortens the illness and reduces recurrence.

Treating the cause

Managing Crohn's or celiac disease, reducing alcohol, and adjusting IV nutrition all help maintain zinc levels.

Risks of too much zinc

Taking more than 40 mg a day for long periods can cause copper deficiency, leading to anemia, low white blood cell counts and nerve damage with numbness and unsteady walking. High doses also cause nausea, stomach cramps and lower good cholesterol. Zinc nasal sprays have been linked to permanent loss of smell and should be avoided. Long-term high-dose zinc should be monitored by a doctor.

Frequently asked questions

What are the symptoms of zinc deficiency?

Common symptoms include loss of appetite, taste and smell changes, hair loss, slow wound healing, frequent infections, diarrhea and a red, scaly rash around the mouth, hands and feet. Children may grow slowly or have delayed puberty. Mild deficiency may cause only subtle symptoms.

Can zinc deficiency cause hair loss?

Yes. Zinc is needed for the cells that build hair, and deficiency can cause diffuse thinning or patchy hair loss. Supplements help only if you are actually deficient. Taking zinc when your levels are normal does not improve hair growth and can cause copper deficiency.

What causes zinc deficiency?

Causes include low dietary intake (especially vegan and vegetarian diets and poor diets in older adults), malabsorption from Crohn's disease, celiac disease or weight-loss surgery, alcohol use disorder, chronic kidney and liver disease, sickle cell disease, diabetes and increased needs during pregnancy.

How is zinc deficiency treated?

It is treated with zinc-rich foods such as meat, shellfish, seeds and fortified cereals, plus zinc supplements when needed. Your doctor may prescribe a higher dose for a few weeks to months. Treating the underlying cause, such as a gut disorder or alcohol use, is also important.

How long does it take to correct zinc deficiency?

Taste, appetite and skin rashes often improve within 1 to 4 weeks of starting supplements. Hair regrowth and catch-up growth in children take several months. A repeat blood test may be done after a few months, and long-term high-dose zinc should be monitored.