Zinc is an essential trace element. The body cannot form zinc itself, so it must be consumed regularly in the diet.
Zinc is also sometimes called the “immune system mineral.”
Serious zinc deficiency is rare in Western populations. However, subclinical deficiency is somewhat more common, and its importance is often underestimated.
Why Do We Need Zinc?
Zinc acts as a cofactor in > 300 enzyme reactions in the body and is of central importance because it participates in numerous metabolic processes. It influences the synthesis and breakdown of carbohydrates, proteins, fats, and nucleic acids (DNA, RNA).
Zinc is important for:
Growth and regeneration, e.g. wound healing, collagen synthesis, cell division, DNA synthesis
A strong immune system
- Brain function, e.g. mood, behavior, and cognition
- It influences hormone metabolism in various ways and is therefore important for
– Insulin and glucagon effectiveness
– Male fertility (spermatogenesis, testosterone synthesis)
– Thyroid function
- Sensory organs (sight, smell, taste)
- Antioxidant function
- Genetic and epigenetic processes
Possible Causes of Deficiency
- Diet contains few foods rich in zinc (see below)
- Heavy alcohol consumption, smoking
- Athletes (lose ~ 1 mg zinc/liter)
- High-fiber or phytate-rich diet [Phytic acid (phytate) can reduce zinc absorption in the intestine by up to 45%]
- Excessive intake of calcium, iron, copper phosphate, selenium, vitamin C
- Oral heavy metal exposure, e.g. cadmium, lead
- Intestinal diseases, e.g. ulcerative colitis, Crohn’s disease, chronic diarrhea
- Liver diseases, e.g. cirrhosis of the liver, hepatitis
- In case of inflammation, physical exertion, or stress, zinc is redistributed to the tissue
- Increased excretion via the kidneys during higher-grade renal failure
Interaction with medication:
- For example: antacids, captopril, ciclosporin, corticoids, diuretics, enalapril, laxatives, MTX, oral contraceptives etc.
Symptoms of Deficiency
- General symptoms: decreased appetite, adynamia, chronic fatigue
- Weakened immune system, tendency to develop infections
- Disorders of the intestinal barrier function, diarrhea
- Metabolism: weight loss, insulin resistance, growth disorders, collagen and bone metabolism disorders
- Skin: impaired wound healing, susceptibility to fungal infection
- Hair: hair loss
- Sensory organs: visual and hearing disorders, night blindness
- CNS: difficulty concentrating, learning disabilities, hyperactivity, depression
Zinc absorption can be severely reduced by a substance called phytic acid. Phytic acid is found in many plant-based foods, especially whole grains and legumes, and can reduce zinc absorption in the intestine by up to 45%. The recommendations for daily zinc intake are therefore dependent on the diet.
For those eating a whole food, plant-based diet (with generous quantities of fiber and vegetables), the diet probably contains a moderate amount of phytate; in this case, zinc intake of 8 mg/day for women and 14 mg/day for men is recommended.
It’s good to know, however, that certain common food preparation methods can greatly reduce the proportion of phytic acid in foods, thereby significantly improving the bioavailability of zinc. These methods include soaking before cooking (e.g., pulses) and sprouting (e.g., grains) or fermentation (e.g., sourdough bread).
The Best Plant Sources (per 100 g)
Whole grain cereals, legumes, nuts, and seeds are good sources of zinc:
- Hemp seeds, peeled – 9 mg
- Wheat bran – 9 mg
- Sesame – 7.7 mg
- Pumpkin seeds – 7.0 mg
- Sunflower seeds – 6 mg
- Flax seeds – 5.5 mg
- Oatmeal – 4.4 mg
- Brazil nuts – 4.0 mg
- Lentils, dried – 3.8 mg
- Tempeh – 3.3 mg
- Peanuts – 2.8 mg
- Walnuts – 2.7 mg
- Almonds – 2.2 mg
- Cashews – 2 mg
Sanna A., Firinu D., Zavattari P., Valera P. Zinc Status and Autoimmunity: A Systematic Review and Meta-Analysis. Nutrients 2018, 10 (1), 68.
Gröber, U. (2011): Micronutrients. Metabolic tuning – prevention – therapy. 3rd ed. Wissenschaftliche Verlagsgesellschaft mbH Stuttgart