What Is Zinc Deficiency

Overview

Zinc is an essential micronutrient that has a significant role in the human body’s growth, reproduction, immunity, and wound repair.¹ It is also an antioxidant that helps prevent cell damage that contributes to heart disease, cancer, and other serious health conditions. Zinc deficiency occurs when the body does not have enough zinc to carry out the body’s essential functions. Zinc deficiency is uncommon worldwide but is more encountered in developing countries due to malnutrition and high phytate intake. It can be either inherited or acquired. It is estimated that up to 17% of the global population is at risk of developing zinc deficiency.^1,2

If not treated, zinc deficiency can result in impaired growth, neuronal abnormalities, decreased iron absorption and hence iron deficiency anaemia, and even cardiovascular diseases.³ The human body cannot store zinc in large amounts, and hence, regular intake and supplementation of zinc are required.1 Zinc is mostly stored in the body’s skeletal muscles with an approximate amount of 2-3 g in an adult body.3 The dietary intake of zinc depends on the age, sex assigned at birth, and whether the person is pregnant or breastfeeding assigned females at birth.¹

Roles of zinc in the human body

Zinc plays multiple vital roles within the human body and is involved in several metabolic processes, including:

• It is involved in the molecular synthesis of DNA, RNA, and proteins.
• It is involved in the stabilisation of ribosomes and cell membranes,
• Decrease lipid peroxidation and hence free radical production.
• It is needed for spermatogenesis, embryogenesis, and foetal growth.
• Zinc is found in high concentrations in the skin due to its important role in normal keratinocyte proliferation and inflammation suppression. It keeps the skin viable as an initial barrier to pathogens as well as mediates the innate and acquired immune function. Furthermore, it is used by
• Macrophages for phagocytosis, intracellular killing, and cytokine production. It also potentiates programmed cell death by apoptosis.¹

Causes of zinc deficiency

• Inadequate supply due to malnutrition,
• Decreased intake, as in the case of strict vegetarian diets, anorexia nervosa, or exclusive parenteral nutrition.
• Malabsorption, which occurs in the case of co-ingestion of phytates, calcium, or phosphate. Other causes of inadequate absorption include Crohn’s disease, subsequent small bowel malabsorption, short bowel syndrome, hookworm infestation, and pancreatic insufficiency. Moreover, some medications, including penicillamine, certain antibiotics, various diuretics, and sodium valproate, can inhibit absorption.
• Regional and geographic risk factors,
• Excess loss (such as during burns, haemodialysis, haemolysis diarrhoea, or urinary loss by alcohol use or diuretics), or
• Increased metabolic demand (in case of pregnancy or preterm infants).¹

Signs and symptoms

Severe zinc deficiency is associated with the following clinical features:

• Growth retardation
• Delayed sexual and bone maturation
• Dermatitis
• Loss of hair
• Diarrhoea
• Defects in the immune system
• Impairment of taste acuity
• Behavioural changes⁴

Symptoms of mild zinc deficiency are similar but much less dramatic and with a milder cutaneous involvement.¹

Diagnosis of zinc deficiency

The clinical diagnosis of zinc deficiency in humans faces major limitations. Currently, it is based on the clinical features and blood serum levels. The most commonly used method for diagnosing zinc deficiency is measuring the zinc concentrations in blood plasma or serum. However, this method is not 100% accurate simply because a single blood drawing has low validity since serum zinc concentrations may fluctuate by as much as 20% per day. ²

Serum concentrations of zinc between 70 to 250 µg/dl in adults are considered normal. Serum concentrations of 40 to 60 µg/dl indicate a mild deficiency, whereas serum concentrations less than 40 µg/dl indicate severe deficiency. ¹

Diagnosis of zinc deficiency can be based on the described risk factors, geographical prevalence, and age of presentation. Taking an appropriate and detailed history enables us to differentiate between inherited or acquired deficiencies. ¹

Patients with acquired forms of zinc deficiency usually present with a combination of various nutritional factors and/ or the presence of chronic illnesses.

Nutritional factors include lack of meat intake, excess phytates or oxalates

Chronic illnesses include chronic gastrointestinal diseases, diabetes, liver disease, sickle cell disease, kidney disease, excess alcohol consumption, and HIV infection. ¹

Inherited form presents earlier in life. An example of inherited zinc deficiency is a condition called Acrodermatitis enteropathica, which is a rare inherited form of zinc malabsorption which becomes symptomatic 4-6 weeks after an infant has stopped breastfeeding. The diagnosis of Acrodermatitis enteropathica is based on clinical presentation supported by laboratory findings (low plasma zinc concentrations and low serum alkaline phosphatase). Clinical symptoms include:

• Irritability
• Withdrawn disposition
• Growth impairment
• Anorexia
• Night blindness
• Pica
• Photophobia
• Various psoriasiform lesions
• Nail dystrophy, paronychia, and alopecia.¹

Health benefits of zinc

Zinc has many health benefits including:

• Shortens the duration of a cold, helping in the production of immune system cells. Zinc does not stop people from catching colds, nor does it lessen the severity of cold symptoms. However, it does help to get over colds and feel better faster. 
• Protects eyesight, where 80mg of a zinc supplement, along with other vitamins for eye health, lowers the risk of advanced age-related macular degeneration and vision loss by 25%. Moreover, it protects the retinas from harmful free radicals that cause cell damage.
• Lowers blood sugar and cholesterol in Type 2 diabetes.
• Promotes wound healing. Topical zinc oxide is a proven diaper rash treatment. It acts as a barrier to moisture, helping protect the baby’s sore bottom from additional irritation.
• Improves sperm quality, where those with infertility have seen an improvement in sperm quality after taking zinc supplements.

Complications of zinc deficiency

 Untreated and prolonged deficiency of zinc can lead to:

• Growth failure that results in permanently stunted growth and development.
• Hypogonadism and oligospermia (only for people who are assigned male at birth)
• Recurrent infections, where zinc deficiency can aggravate both acute and chronic infections, exacerbating zinc deficiency themselves.
• Diarrhoea
• Skin manifestations include conditions like acrodermatitis enteropathica, cheilitis, and dermatitis.
• Delayed wound healing.¹ 

Treatment of zinc deficiency

The most common method of zinc deficiency treatment is taking a zinc supplement, usually in the form of an oral tablet or capsule.

Your doctor should decide upon the exact dose of zinc to be taken, depending on your symptoms. For adults, a daily dose of 20-40 mg or 2 to 3 mg/kg often cures all clinical manifestations within 1 to 2 weeks.¹

In patients with inherited zinc deficiency (Acrodermatitis enteropathica), the standard therapy is daily oral zinc replacement with 1 to 2 mg/kg with life-long supplementation. The recommended daily elemental intake of zinc is as follows (Table 1):

             Table 1. Daily recommendations for zinc intake¹

It is important to follow the doctor’s recommendations, as taking too much zinc can lead to side effects, including nausea, diarrhoea, abdominal discomfort, and impairing the absorption of iron and copper. The recommended formulations of zinc supplements include:

• Zinc sulphate
• Zinc acetate
• Zinc aspartate
• Zinc orotate
• Zinc gluconate¹

To check if the patient is responding to therapy, the patient’s symptoms should be monitored closely, and the serum levels should be checked after 3 to 6 months of supplementation. Usually, there is a rapid improvement of symptoms, where diarrhoea resolves within 24 hours, and skin lesions heal within 1 to 2 weeks. In case of inadequate response, the zinc dose may be increased but with care so as not to reach the toxic level. Furthermore, copper levels will need to be monitored since zinc intake competes with copper absorption and hence, copper supplementation may be considered. ¹

Prevention of zinc deficiency

The best way to avoid zinc deficiency is to eat foods with high zinc content such as:

• Red meat (beef),
• Poultry (chicken and turkey),
• Dairy foods,
• Seafood (like oysters, crab, and lobster)
• Eggs
• Pasta, bread,
• Whole-grain cereal,
• Nuts (like cashews and almonds),
• Seeds,
• Legumes (like lentils, beans, and peas)

Another way to prevent zinc deficiency is by promoting the fortification of foods with zinc. However, ways of implementing this fortification are limited and not well established. Most of the food fortification experience comes from industrialised countries. Whereas, in developing countries, food fortification with micronutrients is largely limited to iodine and some to iron.⁵

Conclusion

Clearly, zinc deficiency is not something that is worth underestimating. Early stages of zinc deficiency can be managed and treated by primary care providers. However, if the deficiency is severe and the underlying cause is unclear, consultations with other specialists, such as gastroenterologists, dermatologists, endocrinologists, and nutritionists, may be required. More accurate biomarkers of zinc deficiency should be established to make the process of diagnosis more straightforward. Innovative approaches for food fortification with zinc should be researched and implemented in developing countries with the highest mortalities.

FAQs

Can I take zinc supplements without consulting a doctor?

If it is part of a multivitamin, then yes, but if you want to take it as a separate supplement, then it is better to do it through a doctor to avoid taking too much and developing side effects.

Which other supplements should you avoid while taking zinc?

Copper, iron, or phosphorus should not be taken at the same time as zinc supplements. To get the full benefit of these supplements, it is best to space the doses 2 hours apart.

With which medications does zinc interact?

• Antibiotics (Tetracyclines and quinolones): Take the antibiotic 2 hours before or 4-6 hours after taking zinc supplements.
• Blood pressure medications like amiloride and ACE inhibitors.
• Thiazide Diuretics (water pills)