Zinc is an essential metallic trace mineral that has the symbol Zn and atomic number 30 on the periodic table. It is vital for various physiological functions in the human body. It plays crucial roles in numerous biochemical processes, including enzyme function, immune system regulation, DNA synthesis, wound healing and cell division.
Food Sources of Zinc
Zinc is an essential nutrient that plays a critical role in maintaining health and well-being. Consuming a varied and balanced diet that includes zinc-rich foods is the best way to ensure adequate intake of this important mineral.
Zinc is found naturally in a variety of foods, including meats such as beef, pork and poultry.
Many foods have zinc that is available for immediate use to satisfy the steady state requirement of the body. (Institute of Medicine, Food and Nutrition Board, 2001) (U.S. Department of Agriculture, 2011).
These foods include:
- Oysters have more zinc than any other food. Also crab and lobster.
- Due to dietary preferences, poultry and red meat such as beef and pork, are the major sources of zinc in the U.S. diet.
- Legumes such as chickpeas, lentils and beans.
- Nuts and seeds such as almonds, pumpkin seeds and cashews.
- Whole grains such as wheat, rice and oats.
- Fortified breakfast cereals.
- Dairy products such as milk, cheese and yoghurt.
Health Benefits of Zinc
Zinc is one of several naturally occurring minerals needed to promote optimum health. Many people, particularly vegetarians, pay particular attention to maintaining their levels of this mineral. Zinc naturally occurs in some foods, is added to others, and available as a single or combination dietary supplements.
The body uses zinc in many parts of cellular metabolism, including the following:
- It is needed to cause or accelerate chemical changes in about 100 enzymes. (HH., 1994) (Institute of Medicine, Food and Nutrition Board, 2001).
- It contributes to immune function. (NW, 1998), (AS, 1995)
- It aids in protein synthesis. (AS, 1995)
- It is known to aid in wound healing. (CA, 1996)
- DNA synthesis is aided by zinc. (Institute of Medicine, Food and Nutrition Board, 2001) (AS, 1995)
- Zinc also helps the body’s cells divide properly. (AS, 1995)
- Without zinc, normal growth and development of the human body during pregnancy, childhood and adolescence would be impossible. (Simmer K, 1985) (Maret W, 2006)
- It helps people smell and taste properly. (Prasad AS, 1997)
People need to take zinc every day, in either food or supplements, to maintain a steady state since the body has no ability to store the mineral. (Rink L, 2000) Zinc is also sold as a help to counteract cold symptoms in some over-the-counter drugs.
Zinc Binding Factors & Bioavailability
The absorption of zinc from food sources can be influenced by factors such as dietary composition, the presence of certain substances (such as phytates and fiber) that can inhibit absorption, and individual differences in zinc status and metabolism.
Animal-based sources of zinc are generally more bioavailable than plant-based sources.
Phytates, found in certain whole-grain breads, cereals and other foods, bind with zinc and inhibit its absorption (Institute of Medicine, Food and Nutrition Board, 2001). This means that the zinc that is available from plants is less usable than that from meats.
Zinc Deficiency
Zinc deficiency can occur due to inadequate dietary intake, impaired absorption or increased losses (e.g., due to diarrhea or certain medical conditions). Symptoms of zinc deficiency may include; impaired immune function, delayed wound healing, skin problems, loss of appetite, growth retardation (in children) and changes in taste or smell.
Recommended Daily Intake of Zinc
The recommended dietary allowance (RDA) for zinc varies depending on age, sex and life stage. The recommended daily intake of zinc has been provided in the Dietary Reference Intakes, which were determined, by the Food and Nutrition Board at the Institute of Medicine of the National Academies.
The Recommended Daily Allowance (RDA) is determined to be the average daily level of intake that is enough to meet the requirements of from 97 to 98 percent of healthy persons.
Pregnant and lactating women may have higher zinc requirements. The current RDA ranges from 2 mg for infants of less than six months to 12 mg for lactating adult women. (Institute of Medicine, Food and Nutrition Board, 2001)
Tolerable Upper Intake Level (UL) is the maximum daily intake that will probably not have adverse effects. (Institute of Medicine, Food and Nutrition Board, 2001). For adults, the RDA for zinc is typically around 11 mg per day for men and 8 mg per day for women.
It’s important to try to obtain zinc from dietary sources to meet daily needs before turning to supplementation.
Who Needs Zinc Supplements?
In some cases, zinc supplementation may be recommended to address deficiency or certain health conditions. However, excessive zinc intake can lead to adverse effects, such as gastrointestinal upset, nausea, vomiting and impaired copper absorption.
Zinc supplements are usually taken by populations that are demonstrated to need extra zinc outside their daily diets.
These populations include:
Babies older than 6 months who are exclusively breast-fed
Alcoholics Sickle Cell disease patients Vegetarians Pregnant and lactating women
Those wishing to boost their immune system, especially to fight off colds and flu.
Where to Buy Zinc
Always take care when taking supplements and Read Our Disclaimer.
Zinc Notes / Side Effects
Dangers of Overuse of Zinc Supplements
Even though zinc is not stored in the body, toxicity from long-term use of large zinc supplements can have the following significant effects:
Low copper status altered iron function, reduced immune function and reduced levels of high-density lipoproteins (Hooper PL, 1980).
Interactions Between Zinc & Medications
Zinc can have powerful interactions with some medications.
Persons who take the following pharmaceuticals on a regular basis should consult their physicians about their zinc status:
Certain antibiotics such as quinolone (Cipro®) and tetracycline (Achromycin® and Sumycin®) Absorption of the drug penicillamine, used for rheumatoid arthritis, can be reduced by zinc. Thiazide diuretics have been shown to increase urinary excretion of zinc by as much as 60 percent. (PO, 1980)
It’s important to consult with a healthcare professional before starting any supplement regimen, especially for long-term use or in high doses.
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