Zinc (Z)

Zinc is a trace element that is found in all cells and body fluids. Zinc is essential for normal functioning of around 200 different enzymes that control growth, metabolism, the nervous system, the immune function, and a variety of other functions. Most of our zinc is found in muscle tissue and bone tissue and there is a rather large zinc concentration in the prostate gland and in the choroidal membrane of the eye. Around 11% of our zinc is found in the skin and liver. An adult contains 2-4 grams of zinc. We are only able to absorb 10-30% of the zinc that we get from our diet, and there are several factors that can either increase or decrease zinc absorption.

Functions and importance for

• Carbohydrate, fat, and protein metabolism
• Vision, taste, and hearing
• Memory
• Tissue and organ growth
• Genes and DNA synthesis
• Fertility and pregnancy
• Testosterone (male sex hormone)
• Immune defence
• Regulation of inflammation
• Skin, hair, nails, and bones
• Wound healing
• Vitamin A and folic acid metabolism
• Antioxidant function

Deficiencies and poor utilisation may be caused by

• Unbalanced diets
• Large intake of iron and calcium
• Large intake of phytates (they bind zinc in grain and flour)
• Lack of animal protein from the diet
• Excessive sweating
• Old age
• Alcohol and alcohol-related liver diseases
• Celiac disease (gluten intolerance)
• Chronic pancreatitis
• Poorly managed diabetes
• Diarrhea, especially in infants
• Parenteral nutrition (intravenous)
• Chronic nephropathy (kidney disease)
• Diuretics
• Long-term use of antibiotics (tetracycline)

Absorption is increased by

Animal protein (meat, fish, eggs, dairy products)
Pregnancy and lactation
Breast milk

Deficiency symptoms

An estimated 25% of the world population is zinc deficient. The problem is roughly divided in three categories: minor deficiencies, moderate deficiencies, and severe deficiencies:

• Minor zinc deficiency
• Weight loss
• Elevated ammonia levels
• Reduced levels of S-testosterone (total level of male sex hormone)
• Pregnancy complications

Moderate zinc deficiency

• Apathy
• Rough skin
• Sensitive skin and blemishes
• Impaired wound healing
• Reduced appetite
• Impaired sense of taste
• Changes in the conjunctiva and the cornea of the eye
• Hypogonadism - too little testosterone (male sex hormone) in the blood
• Growth retardation

Severe zinc deficiency

• Mental disturbances
• Neurosensory disorders
• Weight loss
• Hearing loss
• Diarrhea
• Dermatitis - eczema and skin inflammation (dermatitis)
• Infections (viral, bacterial, and fungal)
• Hypogonadism - too little testosterone (male sex hormone) in the blood
• Delayed puberty
• Acrodermatitis - a rare life-threatening genetic disorder (diarrhea, growth retardation, and frequent infections) that is treated with zinc supplements
• Death

Sources

Mainly oysters, liver, meat, shellfish, dairy products, nuts, seeds, kernels, and beans.

Please note: Animal sources are absorbed the easiest

Zinc content in mg per 100 grams

Recommended daily allowance (RDA)

Adults: 11 years of age and older: 10 mg
Children: 1-10 years of age: 5 mg

Increased need

• The above listed deficiency symptoms
• Pregnancy and lactation
• Bedsores and burns
• Vegetarians
• Diarrhea - zinc is effective both for prevention and treatment
• Acute infections
• Alcoholism
• Liver diseases such as hepatitis and liver cirrhosis
• Hepatic encephalopathy (hepatic coma)

Overdosing - side effects

Supplements are rarely the cause of side effects. Possible symptoms include

• Abdominal pain
• Diarrhea
• Nausea and vomiting
• Irritation of the gastric mucosa
• Impaired immune defence
• Long-term consumption of zinc supplements may inhibit the body's iron and copper absorption

Important information

Measuring of zinc plasma levels is an inexpensive analysis that is used increasingly frequent. If a zinc deficiency is detected the health professional prescribes zinc supplements, depending on the severity of the deficiency and the patient's diet in general.

Minor zinc deficiencies are treated with zinc supplements in the range of 15-30 mg daily. Moderate to severe zinc deficiencies are normally treated with larger doses - in some cases up to 45 mg three times daily (but no longer than four months).

When taking zinc supplements to treat a deficiency it is important to continue supplementing for a period of time after zinc levels have normalised, as zinc is mainly concentrated outside the blood.