Zinc is a not often thought of mineral. Most often in the pharmacy, I have customers asking where they can find the zinc-containing Zicam product marketed to reduce the duration of illness caused by a cold virus. Studies do show that zinc is effective at strengthening our immune response, and also that zinc is important for other processes within our body as well. Zinc is an essential trace mineral, which means we need it for the body to function properly, but only a small (trace) amount is usually necessary. Zinc has been shown to be essential not only for human life but for all organisms, and within humans is a part of over 300 enzymes and proteins. This important mineral is needed for the growth, division, and function of our cells and for protein metabolism. Taking a look inside the human body, a majority of zinc would be found in the muscle and bone with some also concentrated in the prostate, liver, kidney, skin, lung, brain, pancreas, and gastrointestinal tract.
With zinc being essential for cells and proteins in the body, the most zinc is needed during times of growth (childhood and pregnancy and lactation). Zinc deficiency is more common in non-industrialized countries, but even within the U.S. with availability to ample food choices and supplementation deficiency still occurs. Certain medications have been shown to decrease zinc within the body including:
- fluoroquinolone antibiotics (ex. ciprofloxacin, levofloxacin, ofloxacin)
- tetracycline antibiotics (ex. tetracycline, minocycline, but NOT doxycycline)
- captopril
- loop diuretics (bumetanide, furosemide, torsemide, ethacrynic acid)
- thiazide diuretics (chlorthalidone, hydrochlorothiazide, indapamide, metolazone)
Zinc deficiency can present in many ways because of the widespread importance for the body. Areas of the body known to be affected when low in zinc include the skin, gastrointestinal tract, the reproductive systems, the immune system, the central nervous system, and the skeletal system. Signs and symptoms of zinc deficiency include:
- weak immune system
- skin problems (dry, cracking, psoriasis, dandruff, acne, eczema, cold sores)
- infertility
- mental slowness and impaired function (shown helpful with ADHD and dementia)
- slow growth of children
- chronic inflammation
- low levels of sex hormones (ex. testosterone, estrogen)
- decreased thyroid function
- lower insulin levels
- poor sense of smell and taste
- slow wound healing
- vision changes
When we eat a food containing zinc, it is absorbed in the small intestine and then delivered to other areas in the body by proteins in the blood. The amount of zinc typically absorbed from food eaten ranges from 15% to 40% depending on the source and current requirement of the body. The intestines regulate both the absorption and elimination of zinc to maintain a balanced amount. During times the body is low in zinc, the intestines will absorb it more quickly and if the body is well-stocked zinc can be eliminated through the intestines and also through sweat. The foods containing the highest amounts of zinc include:
- beef
- lamb
- oysters
- chicken
- spinach
- pumpkin seeds
- squash seeds
- nuts
- dark chocolate
- beans
- grains
- mushrooms
Meat provides a higher amount of zinc, and beans have to be prepared the right way otherwise the zinc will not be absorbed. Beans (legumes) and other plant seeds contain phytic acid which is used to germinate the plant but can interfere with the absorption of zinc in humans. Vegetarians and vegans need to make sure they are eating legumes prepared correctly to reduce the amount of phytic acid present or zinc deficiency may occur. The goal is to promote the degradation of phytic acid before eating. This can be done by soaking the beans overnight prior to eating, by eating sprouted seed and grain bread, or through fermentation (think sourdough bread). Zinc absorption is also limited by iron supplementation when taken at the same time. Separating the supplements will prevent absorption issues, and the same issue does not appear to happen when zinc and iron are combined with a food source such as red meat.
There is no reliable test to determine the level of zinc deficiency. Measuring the amount present within the blood is not an accurate measure of zinc amount within the body. The most reliable way to determine if zinc will help with symptoms you may be experiencing is to start supplementing with zinc and see if your symptoms improve.
The risks of zinc supplementation are low because of the ability of the small intestine to regulate the amount of zinc absorption. It is possible for zinc to reduce the amount of copper absorbed because they are both absorbed by the same process, but is generally only an issue if too high of a zinc dose is used. Zinc deficiency is most often caused by not eating enough zinc containing food, but malabsorption and increased need by the body also play a role in too little zinc. Zinc supplements can cause stomach upset including nausea and diarrhea. My personal experience with testing many zinc supplements led me a great tasting and non-nausea causing lozenge that I highly recommend if you are experiencing signs and symptoms of zinc deficiency. The recommended daily dose of zinc in adults is 11-15 mg, children 5-9 mg, and infants 2-3mg. To prevent toxicity make sure you do not exceed 40mg daily of zinc. Toxicity symptoms include watery diarrhea, irritation of gastrointestinal tract, fatigue, nerve pain, severe vomiting. When choosing a supplement, make sure it includes zinc gluconate or zinc acetate for best absorption.
Zinc is important for many of the processes within the human body and must be either absorbed through the food we eat or through a nutritional supplement. The people who are most at risk for being deficient in zinc include children, pregnant woman, people over age 65, anyone taking a medication show to decrease zinc, and vegetarians/vegans. Be on the lookout for signs you may be low on zinc and ensure you are always in tune with your body and trying to get to the bottom of what is causing your symptoms.
Your Health Matters
Tiffany Herring PharmD
**THIS AUTHOR AND SITE INTENDS ONLY TO SHARE INFORMATION AND NOT TO DIAGNOSE OR TREAT DISEASE.