Zinc Deficiency Syndrome: Causes, Symptoms & Treatment

What is Zinc Deficiency Syndrome?

Zinc deficiency syndrome refers to a clinically significant lack of zinc in the human body. Zinc is an essential trace element involved in more than 300 enzymatic reactions and is indispensable for numerous bodily functions. A deficiency can affect the immune system, wound healing, growth, reproduction, and the nervous system.

Causes

Zinc deficiency syndrome can have various causes:

• Insufficient intake: Unbalanced diets, vegan or vegetarian diets high in phytates (which inhibit zinc absorption)
• Impaired absorption: Chronic inflammatory bowel diseases such as Crohn's disease or celiac disease, short bowel syndrome
• Increased requirements: Pregnancy, breastfeeding, rapid growth during childhood and adolescence
• Increased losses: Chronic diarrhea, excessive sweating, burns, chronic kidney disease requiring dialysis
• Genetic causes: Acrodermatitis enteropathica, a rare inherited disorder with impaired intestinal zinc absorption
• Alcohol misuse: Reduced absorption and increased renal excretion of zinc
• Certain medications: Diuretics, proton pump inhibitors, and ACE inhibitors can increase zinc excretion

Symptoms

The symptoms of zinc deficiency are diverse and affect multiple organ systems:

Skin and Mucous Membranes

• Scaly, inflammatory skin rashes (especially around the mouth, nose, and genital area)
• Delayed wound healing
• Brittle nails, white spots on nails
• Hair loss (alopecia)
• Cracks at the corners of the mouth (angular cheilitis)

Immune System and Susceptibility to Infections

• Frequent infections, weakened immune defense
• Prolonged duration of colds

Growth and Development

• Growth retardation in children
• Delayed sexual maturation
• Hypogonadism (reduced function of the gonads)

Neurology and Psyche

• Impaired sense of smell and taste (hyposmia, dysgeusia)
• Difficulty concentrating, irritability, depressive moods
• Visual disturbances, night blindness

Further Symptoms

• Loss of appetite
• Reduced fertility (in men: reduced sperm quality)
• Weakening of bone structure

Risk Groups

Certain population groups are particularly susceptible to zinc deficiency:

• Infants and toddlers (especially with exclusive breastfeeding without zinc supplementation after 6 months)
• Pregnant and breastfeeding women
• Older adults (over 65 years)
• Vegans and vegetarians
• People with chronic intestinal diseases
• Patients with alcohol dependence
• People in developing countries with zinc-poor diets

Diagnosis

Diagnosing zinc deficiency can be challenging, as no single marker is sufficiently sensitive. The following diagnostic methods are used:

• Serum zinc level: Most common method; normal values are 70-120 µg/dl. A value below 70 µg/dl is indicative of deficiency.
• Zinc in erythrocytes or leukocytes: A better indicator of intracellular zinc status
• Alkaline phosphatase: A zinc-dependent enzyme; reduced levels may indicate deficiency
• Clinical assessment: Symptoms, dietary history, and risk group membership are considered
• Therapeutic trial: Clinical improvement following zinc supplementation can confirm the diagnosis

Treatment

Dietary Adjustment

In cases of mild zinc deficiency, dietary adjustments may be sufficient. Good dietary sources of zinc include:

• Meat (especially beef and lamb)
• Seafood (especially oysters)
• Legumes (lentils, chickpeas)
• Nuts and seeds (pumpkin seeds, sesame)
• Dairy products and eggs
• Whole grains (with reduction of phytates through soaking or sprouting)

Supplementation

In clinically relevant deficiency, zinc supplementation is recommended. Common preparations include:

• Zinc sulfate (widely used, readily available)
• Zinc gluconate (well tolerated)
• Zinc bisglycinate (chelated zinc, high bioavailability)
• Zinc oxide (lower bioavailability, often used in topical preparations)

The recommended daily allowance (RDA) according to the World Health Organization (WHO) for adults is approximately 8-11 mg/day (8 mg for women, 11 mg for men). Therapeutic doses for confirmed deficiency are often 25-50 mg of elemental zinc per day, in consultation with a physician.

Treatment of the Underlying Condition

If the zinc deficiency is caused by an underlying condition (e.g., Crohn's disease, celiac disease), this must be treated to achieve a lasting improvement in zinc status.

Interactions and Safety

Excessive zinc intake can also be harmful. Long-term intake of high zinc doses (above 40 mg/day) can lead to copper deficiency, as zinc and copper compete for the same absorption pathways. The European Food Safety Authority (EFSA) has set the tolerable upper intake level (UL) for zinc in adults at 25 mg/day. Furthermore, high zinc doses can inhibit the absorption of iron and certain antibiotics (e.g., tetracyclines, fluoroquinolones).

References

1. World Health Organization (WHO): Zinc supplementation in infants and young children. Geneva, 2021. Available at: https://www.who.int
2. National Institutes of Health (NIH), Office of Dietary Supplements: Zinc - Fact Sheet for Health Professionals. 2022. Available at: https://ods.od.nih.gov
3. Prasad AS: Zinc in human health: effect of zinc on immune cells. Molecular Medicine, 14(5-6):353-357, 2008. PubMed PMID: 18385818.