It takes just 11 milligrams of zinc to maintain its optimal role in your cellular metabolism, according to the National Institutes of Health Office of Dietary Supplements. Although severe zinc deficiency is uncommon in the U.S. and other developed countries, the World Health Organization (WHO) estimates that mild to moderate deficiency is common worldwide.
However, exceeding maximum zinc doses can do as much or more harm to a body than being a little low on the nutrient.
The maximum recommended dosage for adults is 40 mg of zinc per day; however, during times of illness or other zinc-zapping life events, you could ingest several times that amount for up to a year.
Zinc's Role in the Body
Zinc interacts with up to 100 enzymes in the human body to maintain many aspects of cell metabolism. Present in virtually every cell in the human body, zinc helps protect and mobilize sperm so it can fertilize an egg, and is vital in healthy growth and development during every stage of pregnancy. A deficiency of zinc in childhood results in stunted growth, and puberty is delayed in adolescents short on the substance.
Although it's called a "trace element," it is one of the most essential. Zinc is vital in the role of the immune system and is crucial to the proper functioning of smell, taste and sight. Most of the body's zinc gets stored in muscles and bones, as well as sex organs, teeth and vital organs, but it's essential to consume it in your daily diet, because the body doesn't make more.
Recommended Daily Allowances
Depending on your age, sex and life stage, 12 mg or less of zinc is required as the recommended daily allowance, according to the National Institutes of Health Office of Dietary Supplements. Men 19 years or older need 11 mg, as do pregnant women. Lactating mothers need a little extra too, topping the RDA at 12 mg. When not pregnant or lactating, women should take 8 mg of zinc daily.
Zinc is crucial for children, especially babies born prematurely or those growing up in impoverished conditions where nutrition is less than optimal. Babies should have 2 mg daily in their diet for the first six months of life, increasing to 3 mg for the first three years of life.
The dosage rises to 5 mg at 4 years of life and 8 mg during the preteen years. Beginning in adolescence, the full adult dosage is appropriate — with the exception that adolescent girls take 9 mg instead of 8 to support the development of the reproductive system.
Upper Intake for Healthy Adults
No matter your age or life stage, the National Institutes of Health (NIH) doesn't recommend exceeding daily intake levels above 40 mg for healthy adults. Lactating, pregnant or nonpregnant women, as well as men, shouldn't exceed the daily dosage as a general rule.
Exceptions for the Zinc Deficient
Although most people in the U.S. have either no or minor zinc deficiency, zinc is so essential to human metabolism that even a small shortage can make a dramatic difference.
Zinc deficiency is a significant factor in reproductive issues and infertility, and supplementing with a diet rich in zinc or zinc supplements can set the stage for successful conception. WebMD recommends taking two to three times the RDA for your age group and life stage for up to six months to correct zinc deficiencies.
Men are the most impacted. A lack of zinc can negatively affect sperm motility, sperm quantity and structure. Taking three times the RDA for men over age 19 would amount to a maximum dosage of 33 mg daily.
Feel Icky? Think "Zinc"
Having a difficult time conceiving probably won't be your only worry if you're zinc deficient. You might not even feel like hopping into the sack and giving it a try.
Symptoms of zinc deficiency include diarrhea, insomnia, and frequent colds and flu. You might feel itchy, mentally foggy or moody. Food might start to taste bland, and you might start spending more time on the couch binging Netflix, due to low energy.
You could experience a total lack of sex drive, and your poor memory might make you forget things like your Friday night date. As things progress, you could develop unsightly skin disorders or have your hair start to fall out.
Determining Zinc Deficiency
Because blood levels of zinc are no indicator of whether your body is deficient in the micronutrient, blood tests are mostly useless in determining whether you need to supplement your diet with more zinc. Although your doctor can test a strand of your hair, easy tests you can do at home will clue you in.
Look at your fingernails. Do they have odd white spots on the nail bed? This can be a sign of zinc deficiency, according to DTK Nail Supply. Other telltale signs include inflamed cuticles and slow nail growth.
You can also buy a bottle of zinc sulfate to do your own home test. Oddly, people who are deficient in zinc can't taste the metallic flavor of zinc sulfate. The more deficient you are, the less metal you'll taste. If you're good on zinc, the flavor will hit you with an immediate strong taste. If it takes you a few seconds to a few minutes to notice the metallic flavor, you're mildly to moderately zinc deficient.
Even if you test zinc deficiency at home, you should always check with your doctor before drastically changing your diet or vitamin supplementation.
What Causes Zinc Deficiency?
Beside just not getting enough zinc in your diet, several life circumstances can predispose you to low zinc levels. Medications, for example, that inhibit the production of stomach acids — such as antacids, over-the-counter pain relievers and many prescription meds — are top culprits. If your doctor prescribes ACE inhibitors, antibiotics, estrogen, birth control pills or vasodilators, it's wise to watch for signs of deficiency.
Chronic stress is another culprit that causes your body to burn through its zinc supply more quickly than usual. Exposure to toxins like heavy metals in vehicle emissions, pesticides or even zinc-leaching copper in city water supplies can drain your body and trigger it to need even more.
Digestive issues can also cause zinc to be malabsorbed by the body. Leaky gut, low stomach acidity and other stomach woes can cause zinc to pass through your system with less-than-optimal uptake into your system.
Diet Is Key
There's more to getting enough zinc than just popping a daily supplement. What you do and don't put in your body is crucial to assisting your body in fulfilling its need for the nutrient.
If you have trouble maintaining proper blood sugar levels, such as in hypoglycemia, insulin resistance or diabetes, you're probably not absorbing zinc as well as you should. Making sure you have adequate zinc intake can help clear glucose from the blood according to a 2013 study. Zinc binds to insulin receptors and activates pathways that stimulate insulin.
Vegans and vegetarians are at particular risk for zinc deficiency. Not only does turkey and lean red meat deliver lots of natural zinc, but the grain and legume-rich plant-based diet of non-meat eaters also leaches the body's zinc stores due to phytic acids. Reduce the harmful acid by soaking and sprouting grains and legumes before cooking, using leavening that will reduce phytic acid leaching, or eat grain products fortified with zinc.
Exceeding the Zinc Dosage
In some studies, amounts of zinc more than 40 mg per day have been administered under medical supervision to treat specific conditions. Should you get tempted to take more than 40 mg per day of zinc, check with your doctor first.
Side effects of taking too much zinc can make you feel as miserable as when you have a deficiency. Diarrhea, lethargy, moodiness, gastric pain and brain fog were symptoms you probably wanted to get rid of by taking zinc — but they return if you take too much. You can also put yourself at higher risk of Alzheimer's disease, prostate cancer, diabetes and other diseases.
Zinc Helps Acne
Slightly less than 10 percent of the global population suffers from acne, a common skin disorder fueled by blockage of oil-producing glands that then become inflamed from bacteria. Both oral zinc supplementation and topical zinc treatments can help reduce the inflammation and keep the P. acnes bacteria from reproducing. Zinc can also suppress overactive oil glands.
As little as a 30 mg zinc dosage has shown positive effects for treating acne according to WebMD. Maximum dosages tested are up to 150 mg daily; however, don't exceed 40 mg daily unless you're directly under medical supervision.
Zinc for Wellness
Zinc isn't a stranger to the medical world. Hospitals often use zinc to accelerate healing for burns, skin ulcers and other skin conditions. Your skin holds about 6 percent of your body's zinc.
The mineral also helps reduce oxidative stress that can lead to conditions brought on by chronic inflammation such as cancer, heart disease and mental decline. Adults older than 40 showed significantly reduced inflammatory markers when taking 45 mg of zinc per day, according to one recent study.
Zinc can even help treat the common cold. A 2017 review of recent studies on the effect of taking zinc gluconate or zinc acetate lozenges revealed a lessened cold duration of 25 to 43 percent. Lozenges range from 4.5 to 24 mg. For best results, dissolve lozenges of a lower dosage in your mouth every two hours while you're awake.
Getting Zinc From Food
If you're worried about taking too much zinc, tweak your diet to get as much as possible from natural foods high in zinc.
- Oysters contain more zinc benefits than any other food, at 74 mg in a 3-ounce serving.
- Meat is a great way to add zinc to your diet. A 3-ounce serving of beef chuck roast or a quarter pound hamburger patty each has a zinc dosage of 7 mg, and an equal amount of Alaskan king crab delivers 6.5 mg.
- Legumes such as chickpeas and kidney beans contain 1.3 and 0.9 mg of zinc per 1/2 cup. Soak them and let them sprout to prevent malabsorption of zinc from the action of phytates. Better yet, eat baked beans to get 2.9 mg per 1/2 cup.
- Cashews and almonds make zinc-rich snacks. One ounce of cashews has 1.6 mg of zinc, while almonds have 0.9 per ounce.
- Dairy products are notable sources of zinc. Get 1.7 mg in 8 ounces of yogurt, 1.2 in one ounce of Swiss cheese and 1 mg in a cup of low-fat milk.
- Dark chocolate packs a surprising 3.3 mg of zinc into a 3.5-ounce bar of 70 to 85 percent cacao.
- Mayo Clinic: Zinc
- National Institutes of Health Office of Dietary Supplements: Zinc
- World Health Organization: The World Report Chapter 4
- Our World in Data: Micronutrient Deficiency
- US National Library of Medicine National Institutes of Health
- DTK Nail Supply: The Best Vitamins and Minerals for Nail Growth Reviews 2019
- Dr. Jockers: How to Test Zinc Levels at Home
- University Health News: Zinc Benefits for Diabetes
- US National Library of Medicine National Institutes of Health: Zinc as a potential Coadjuvant in Therapy for Type 2 Diabetes.
- US National Library of Medicine National Institutes of Health
- WebMD: Zinc
- Oregon State University: Minerals and Skin Health