Zinc (Zn) Benefits, Deficiency, Side Effects, Absorption, RDA


Zinc (ZN) belongs to the micronutrients, as it is an essential mineral, which the human body needs in very small quantities. It has the second highest concentration in the human body after iron, and plays an important role in many of the body’s basic functions.

What is Zinc

Zinc is an essential component for more than 100 enzymes involved in the digestion and utilization of fat, protein and carbohydrates by the body, and is closely linked to the energy production process.

It is essential for the proper functioning of the immune system and protection of the body from infections and viruses, and helps in the wound healing process.

Its role in DNA synthesis and in the reproduction and development of the body’s cells makes it a vital element for normal development during pregnancy, childhood and adolescence. Finally, zinc is essential for the sense of taste and smell.

Bohr model of zinc. Source: Signal Garden

Zinc is present everywhere in the human body. It is the most abundant metal in the intracellular space.

It is absorbed from food through the small intestine and then transported into the blood with the help of albumin and alpha-macroglobulin, but only 0.1% of the total zinc content in the body is found in the blood.

95% of the zinc is in the cells. An adult male has about 2 grams of zinc in his body, of which 57% is found in skeletal muscle, 30% in bone and 4-6% in skin.

Zinc Benefits

Zinc has three different types of function in the human body: catalytic, structural and regulatory. Here are some of the most important zinc health benefits.

  • Enzymes – Most of its biochemical roles reflect its involvement in a large number of enzymes. Over 100 different zinc-containing enzymes have been identified, which include polymerase I and II, RNA nucleotide, alkaline phosphatase and carbonic anhydrases.
  • Protein Kinases – Zinc is also essential for the action of protein kinases involved in the signal transduction process and as a stimulator of the interacting factors responsible for the regulation of gene expression.
  • T-Lymphocytes – Zinc is required for the creation of T-lymphocytes, the white cells in the body that attack viruses and pathogenic bacteria. It is thought to reduce the symptoms of colds.
  • Prevents growth of cancer cells – There is evidence that zinc prevents the growth of cancer cells.
  • Aphrodisiac – Finally, zinc is considered an aphrodisiac in the sense that it raises testosterone, but this only happens when there is a deficiency in the body. It may also provide prostate benefits.

Zinc Deficiency

Zinc is necessary to be taken daily through the diet, as the body has no specialized system for its storage. Zinc deficiency is manifested by the following symptoms:

  • Low growth rate
  • Hair loss
  • Diarrhoea
  • Skin problems
  • Dark vision weakness
  • Loss of appetite
  • weight loss
  • Delay in wound healing
  • Disorders of smell and taste
  • Frequent infections
  • Delay in sexual maturation
  • Pogonadism in men

Vegetarians may be at increased risk for zinc deficiency, people on crash diets, anorexics, people who use soy as a meat substitute, pregnant and breastfeeding women, people with gastrointestinal disorders, alcoholics and the elderly.

The Global Zinc Shortage

Research conducted over the past few years shows that zinc deficiency is affecting the health and well-being of populations around the world. The International Zinc Advisory Group (IZiNCG) has estimated that the prevalence of zinc deficiency is 31% worldwide, ranging from 4% to 73%, with the highest rates of deficiency and the most severe effects of zinc deficiency occurring mainly in African, Eastern Mediterranean and South-East Asian countries.

It has been estimated that 1/3 of the world’s population resides in countries at high risk of deficiency, with infants, young children, pregnant and lactating mothers being the most vulnerable groups due to their increased zinc needs.

Zinc supplementation programs, which have been implemented in developing countries, have been shown to result in reduced incidence and severity of diarrhea, pneumonia and possibly malaria, and lower mortality rates in children.

In addition, zinc supplements have helped improve growth and weight gain in malnourished and underweight children, and there is evidence that zinc supplementation in pregnant women can prevent adverse pregnancy outcomes, contribute to postpartum weight gain and reduce infections.

Read Also: Manganese Health Benefits, Sources, Deficiency, RDA

Zinc Food Sources

Zinc is found in a wide range of foods. The richest sources are high-protein foods.

  • Red meat (beef, pork, lamb) contains more zinc than fish and seafood, with the exception of oysters, which provide more zinc per serving than any other food.
  • Chicken is also a good source, but its darker-colored parts contain more zinc than the lighter-colored parts.
  • Other important sources of zinc are peanuts, peanut butter, pulses, wholegrains and their products and dairy products.

The phytic acids found in foods of plant origin bind zinc and prevent its absorption. Thus, people who exclude meat from their diet should include dairy products, eggs, whole grains, nuts and pulses in order to obtain adequate amounts of zinc.

Best Zinc Food Sources

FoodsDescriptionZinc (mg/100 g)
OystersRaw55 – 136
Pumpkin seeds10,3
Sesame seeds10,2
LiverRaw, Calf7,8
Black Chocolate6,8
BeefWithout fat4,3
LampWithout fat4,0
PorkWithout fat2,4
Wheat flourWhole meal2,9
Sunflower seeds2
RiceRaw, White.1,8
CrabsBoiled1,3 – 5
EggsChicken, whole, raw0,5 – 3,3
Cheese0,2 – 5,0
YoghurtFrom full fat milk0,5 – 0,7
CodRw0,3 – 0,5
Green leafy vegetables0,2 – 0,6
Cow’s milk0,4
Fruits(On average)0,4
PotatoesRaw0,2 – 0,3
Source: Holland et al 1995, Dietitians of Canada.

Zinc Toxicity

Severe acute toxicosis from excessive zinc intake has been described after ingestion of water stored in galvanised containers or after the use of such water during dialysis.

Side effects include nausea, vomiting and fever and occur after an acute intake of 2 grams or more of zinc.

Prolonged intakes of zinc in amounts well above normal (e.g. 75-300 mg per day) have been associated with a reduction in copper utilisation (causing microcytic anaemia and neutropenia), a reduction in immune responses and a drop in high-density lipoprotein levels.

However, some scientists argue that even a short-term intake of about 25-50 mg of zinc per day from dietary supplements can interfere with the metabolism of both iron and copper.

Oysters on a plate
– Oysters have high quantities of Zinc

Recommended Daily Intake

The American Food and Nutrition Council has reported that there is no evidence of side effects from the intake of zinc contained in food.

However, it has settled on a maximum limit of 40 mg per day for adults over 19 years of age. This amount represents the total intake of zinc from food, water and dietary supplements including fortified foods.

The European Union has set a maximum limit of 25 mg per day.

The (American) recommendations for daily zinc intake are:

  • 12 mg (sufficient intake for the first 6 months),
  • 3 mg (7-12 months),
  • 3 and 5 mg (1-3 years and 4-8 years, respectively),
  • for adolescent boys 8 and 11 mg (9-13 years and 14-18 years, respectively) and for adult males 11 mg (over 19 years),
  • for adolescent girls 8 and 9 mg (9-13 years and 14-18 years, respectively) and for adult females 8 mg (over 19 years),
  • for pregnant women 13 and 11 mg (younger than 18 years and 19-50 years, respectively) and for lactating women 14 and 12 mg (younger than 18 years and 19-50 years, respectively).

Zinc is lost through sweat and therefore athletes should obtain adequate amounts from their diet. Note that some studies have found low testosterone in athletes and it may be that the cause is the loss of zinc. Diabetics also lose zinc through urine.

Recommended Zinc Supplements

While there are hundreds of different zinc supplements on the market we recommend the following zinc supplements for their proven consistency in delivering quality zinc products.

1️⃣ Microingredients Zinc Picolinate with Vitamin C, 365 Capsules

2️⃣ Microingredients, Zinc Complex, 200 Capsules

3️⃣ Pure Encapsulations Zinc 30 – 60 Capsules

4️⃣ Garden of Life Vitamin Code® – Raw Zinc – 60 Vegan Capsules

5️⃣ Integrative Therapeutics Zinc-Carnosine – 60 Vegetable Capsules

Final Take

Zinc is an essential mineral involved in the regulation of many enzymes in the human body. It also has antioxidant activity and is used in dietary supplements that help the immune system.

It is present in dozens of proteins called metalloproteins including the enzyme superoxide dismutase, an endogenous antioxidant that includes both zinc and copper. It is also needed for the conversion of cholesterol to testosterone.

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