Edited by Kate Findley and proofread by Angela Shoemaker, Wondrium Daily
Zinc plays many essential roles in the human body, including wound healing. Although zinc deficiency is rare in the United States, certain populations still need to use caution. Professor Anding explains who is most vulnerable and what to look out for.
The elderly, low-income children, vegetarians, and alcoholics are particularly vulnerable for zinc deficiency. The symptoms of a deficiency are not necessarily unique to zinc but include anemia, delayed growth in children, slow wound healing, glucose intolerance, poor appetite and taste, and skeletal abnormalities if it occurs during adolescence and childhood.
Skin problems can develop around the eyes, nose, mouth, and on the buttocks. Skin problems usually look like the early stages of atopic dermatitis. You can have a greasy dermatitis around your eyes and the opening of your nose and mouth.
However, you should use caution when taking zinc as a supplement, as it can interfere with medications. For example, zinc can reduce the absorption of tetracycline, an antibiotic, and it can bind with warfarin, a blood thinner.
Zinc may actually increase the toxicity of cisplatin, which is used for the treatment of cancer. In general, any time you decide to take a supplement, you get advice from your healthcare provider.
“I also recommend that if you’re taking a lot of dietary supplements, that you actually put them on a 3 x 5 index card and put them in your wallet in case you are unfortunate enough to be in a car accident or ill enough where you couldn’t speak for yourself, so that your healthcare provider would know what you are taking,” Professor Anding said. “I’ve done this for all my children and my family.”
As with most minerals and vitamins, it is best to get zinc from dietary sources rather than supplements. Cooked oysters contain 39 milligrams (mg) of zinc. Ground beef has about 5.5 mg per a 3.5-ounce portion.
Zinc and iron come from many of the same food sources. So, if you’re deficient in iron, you may also be deficient in zinc. Like iron, zinc from meat sources is about four to five times more bioavailable than zinc from plants.
Thus, vegetarians may need up to 50% more zinc, given the issues with bioavailability. Additionally, phytates, found in the hulls of nuts, seeds, and grain and high-fiber foods can decrease the bioavailability of zinc.
That said, some vegetarian sources contain pumpkin seeds, which are a good source of zinc. A quarter of a cup of pumpkin seeds contains 4.2 mg and a quarter of a cup of soy nuts has 2.1 mg. Thus, you can get zinc from a variety of food sources, but keep in mind that animal sources are typically the most plentiful.
In general, the Dietary Reference Intakes (DRI)s for vitamins and minerals assume that you are healthy. With this in mind, males ages 19 to 70 need about 11 mg of zinc and females ages 19 to 70 need 9 mg.
A serving of oysters and some pumpkin seeds, then, would likely provide you with more than enough zinc for the day. Many breakfast cereals are also fortified with zinc and iron.
When it comes to toxicity, the upper level for zinc for adults is 40 mg per day. A dose larger than 40 mg per day is only required to correct a deficiency.
Zinc in excess of 80 mg a day can result in lower levels of HDL cholesterol (also known as “good cholesterol”). It can also lead to immunosuppression, the reduction of white blood cells, an interference with the mineral copper, and defective cholesterol metabolism. As with all mineral excess, too much zinc can cause GI disturbances such as vomiting and diarrhea. This is an example, once again, which shows how too much of a good thing is truly not a good thing.
This article was edited by Kate Findley, Writer for Wondrium Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for Wondrium Daily.
Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.