What do oysters, potatoes and soy all have in common?
These are all dietary foods rich in zinc.
The primary role of zinc is to activate hundreds of enzymes involved in cell regulation, immune function, DNA and protein synthesis, fat metabolism and digestion. Zinc is needed for good vision, hearing, taste sensation, sexual development and wound healing.
Zinc also functions as an antioxidant, anti-inflammatory and anti-viral against some viruses such as those responsible for cold symptoms and the herpes virus.
Other uses of zinc include:
Treating acne, diarrhea, gastric ulcers, muscle cramps, osteoporosis, sickle cell disease, ADHD, macular degeneration, cirrhosis, anorexia nervosa, depression, taste disorders, tinnitus, fatigue, hair loss, poor wound healing, white spots on the fingernails, and many, many more.
So who’s at risk for developing zinc deficiency?
Anyone with malabsorption (Crohn’s disease or celiac disease) or who is malnourished (anorexics, dieters). The risk is also high in those who are alcoholics, have chronic kidney disease, pregnant women, sickle-cell disease and the elderly.
There are many different salt forms of zinc. All of these forms have different amounts of elemental zinc. For instance, zinc sulfate contains 23% of elemental zinc. So when you look at a bottle of zinc, and it says 220 mg of zinc sulfate, you are actually getting 50 mg of elemental or active absorbable zinc. Zinc gluconate only contains 14.3% of elemental zinc. And then there’s zinc acetate and zinc oxide, which are primarily used topically.
If you want to treat a cold or are recovering from surgery, zinc picolinate or zinc citrates are preferable because they are better tolerated. The main side effect of zinc is nausea.
Other reported side effects include vomiting, diarrhea, headache, abdominal cramps, a metallic taste in mouth and decreased appetite. Doses up to 50 mg are safe, but the usual dose is 25-30 mg of elemental zinc 1-3 times per day with meals. Zinc dosages are lower for children, but increase during periods of growth.
Absorption is a big deal even if you have the right dose. For instance, taking zinc with coffee reduces zinc absorption by 50%!! Dairy and calcium can also decrease zinc absorption so don’t take your zinc with milk.
Certain medications block zinc absorption such as antacids, ACE inhibitor drugs used for lowering high blood pressure, aspirin, diuretics (like hydrochlorothiazide) and some antibiotics such as Cipro.
On the other hand, zinc absorption increases with animal proteins. It’s tougher for vegetarians because soy proteins as well as unrefined grains, legumes and seeds lower zinc absorption due to the high phytate content in these foods (fancy name for a phosphate molecule found in these foods).
How do you know if you are zinc deficient?
Laboratory measurements are not very reliable. I will usually run an RBC (intracellular) zinc level, but even though that may be normal, it does not rule out zinc deficiency. I base it on each persons symptoms, how much zinc they are taking, evidence of malabsorption, and conditions that are associated with zinc deficiency such as short stature, immunodeficiency, night blindness and any of the other above findings.
Be aware that large amounts of zinc interfere with copper absorption. Large doses of zinc would be 100-200 mg /day for 1-2 years. Copper deficiency can cause anemia, immune deficiency, neurological problems related to the spinal cord and cholesterol abnormalities. Supplementing with 2-3 mg daily (usually found in a multivitamin) is enough to prevent this deficiency. If people respond well with zinc supplementation, then that’s a good sign and reason to keep them on zinc and make sure they are on a small amount of copper.
Talk to your practitioner if you have symptoms that are associated with zinc deficiency.
References: Natural Medicines Comprehensive Database 2013, 13th edition. Published by Therapeutic Research Faculty, Stockton, CA. pp. 1709-1721.
Nutritional Medicine, Gaby, A. Fritz Perlberg Publishing, Concord NH, 2011.