Zinc Supplements: What is Zinc Good For + How It Works
Did you know zinc wasn’t discovered to be essential for humans until 1961? 1 Now, of course, most of us realize it is an essential mineral (i.e., it is necessary, but the body can’t produce or store it), and as a result, we must consume sufficient amounts from food and/or supplements. What is zinc good for? It’s required for numerous processes within the body, including immune function, growth and development, protein synthesis, and wound healing.
Fortunately, it’s found in a number of plant- and animal-based foods, and zinc supplements are also easy to find. In addition, many processed foods—particularly cereals, snacks, and flour—are fortified with zinc. Zinc supplements tend to be marketed for their significant impact on immune function. You can find zinc supplements as lozenges, nasal sprays, capsules, and more.
In today’s Zinc Supplement article, we will cover:
- Zinc in the Body
- Zinc Bioavailability and Absorption
- What is Zinc Good For?
- How to Get Enough Zinc
- Can You Have Too Much Zinc?
- Are Zinc Supplements Good For You?
After iron, zinc is the second most abundant trace mineral in the body. 2 It’s found in every cell and is required for metabolism, digestion, nerve function, etc. In fact, it’s needed for the function of over 300 enzymes and over 1,000 transcription factors, which span a wide variety of classes. 3,4 Practically speaking, what that means is that zinc is involved in many, many cellular processes and reactions that help keep us young, vibrant, and healthy.
The reason many people are interested in zinc (and why it’s found in immune support supplements) is because of its critical role in the development and function of the immune system. That’s how it was discovered in the Middle East just 40 years ago: zinc-deficient individuals were found to have severe immune dysfunctions, which led to early death due to infections. 5
A zinc deficiency can also lead to decreased testosterone levels in the blood as well as negatively affecting T helper cells and decreased lean body mass. These deficiencies can lead not only to immune impairment but to impaired growth and cognitive function. 5 Zinc supplements have also been found in recent research to help decrease markers of oxidative stress and inflammatory cytokines, which are important components of the immune system that, when unchecked, can contribute to unhealthy levels of inflammation and an imbalanced immune system that doesn’t properly respond to threats. 5
Zinc is also required for healthy skin as well as DNA and protein synthesis. So, if infants, children, or adolescents are deficient, it can lead to growth failure, and the skin, gut, central nervous system, immune system, skeletal system, and reproductive system can all be negatively affected. 1,6
Both your senses of taste and smell are dependent on sufficient zinc, and in fact, a deficiency can reduce these senses, which are important for appetite, nutritional well-being, and quality of life. 7
Because zinc is added to many foods in addition to being found in many supplements, you’d expect deficiencies to be much lower. However, the body’s ability to absorb zinc can also be an issue. 1 This is especially true when zinc is consumed with foods that contain phytic acid (which is often called an “anti-nutrient”), which can bind to zinc and inhibit its absorption in the body.
Foods high in phytic acid (aka inositol-6-phosphate, or phytate) include grains, seeds, legumes, beans, and nuts. That said, phytic acid only inhibits absorption of zinc (or iron or calcium) when it is consumed at the same time, within the same meal. As long as zinc is consumed separately, the issue becomes moot.
Zinc is vital for so many processes in the body, and it has been shown by research to have several key health benefits, including providing:
• Immune System Support. Quite simply, the immune system needs zinc for cell function and signaling as well as to reduce oxidative stress. It’s important for both innate and adaptive immunity. 8 When the body is deficient, the immune response is weaker. Zinc supplements have been shown to support a healthy, balanced immune response. Some research has even found that supplementing with zinc lozenges providing less than 75 mg per day of zinc acetate or zinc gluconate may reduce the length of a common cold by up to 33%. 9
• Support Against Disease. By helping the body fight against oxidative stress and promoting the activity of T-cells and natural killer cells, zinc may help protect against infections. It appears to be especially beneficial for older adults. 10 For example, zinc supplementation has been found to be a potential low-cost intervention to reduce death due to pneumonia in the elderly who have low zinc status. 11 Because of its effects on oxidative stress and inflammatory chemicals, healthy levels of zinc may also help support the body’s ability to fight off chronic diseases like heart disease. 12,13
• Support for Wound Healing. Zinc is found in high concentrations within the skin, and it’s important for collagen synthesis, immune system function, and a healthy inflammatory response. What this all means is zinc is a key player in the healing process from burns and skin wounds. 14 In one 12-week study, participants who used 200 mg per day of zinc saw reductions in the size of wounds compared to those using a placebo. 15
• Support for Acne. Speaking of skin health, acne affects millions of people worldwide and is the eighth most prevalent disease. 16 Topical washes, gels, lotions, and creams often come with unpleasant side effects, so zinc products appear to be a promising, effective alternative or adjunct option. 17 Zinc supplements have also shown promise for other dermatological conditions, such as dandruff and diaper rash. 18
• Support for Psychological and Cognitive Functioning. Zinc has a critical role in the function of the brain and central nervous system 19 and has been shown to significantly reduce stress, especially in aging populations. 20 Zinc is also involved in how memories are formed and how we learn. 21
• Protection Against Macular Degeneration. When combined with vitamins C and E, beta-carotene, and other nutrients, zinc has been shown to potentially help slow progression of age-related macular degeneration. 22
Up to two billion people in the world are likely deficient in zinc because they aren’t getting enough from their diets. 23 Although deficiency rates appear to be much lower in the United States, 20 – 30% of Americans fall short of the bare-bones minimum recommendation, and suboptimal zinc intake decreases immune function, increasing the risk for infection. 24
People at greater risk include those with GI diseases (like Crohn’s disease or inflammatory bowel disease), vegetarians and vegans, pregnant and breastfeeding moms, older breastfeeding infants (those over six months old), people who are malnourished (including those with anorexia or bulimia), and people who abuse alcohol. 25 Even a mild zinc deficiency can result in side effects 26 like:
- Diarrhea 27
- Hair loss/thinning
- Decreased immunity
- Upper respiratory tract infections
- Slowed wound healing 28,29
- Dry skin
- Mood disturbances
- Mental lethargy
- Depression 30
- Fertility issues and hypogonadism in men 31
- Delayed child development 32,33
- Poor appetite
- Insulin resistance
Most people get “enough” zinc, as it is found in both plant- and animal-based food sources, including shellfish, meat, poultry, fish, beans and legumes, nuts and seeds, dairy products, eggs, whole grains, and some vegetables (such as kale, peas, asparagus, and mushrooms). It’s also added to some staple foods (e.g., fortified breakfast cereals) to improve zinc status, and therefore, improve health outcomes in numerous countries. 34 Oysters, interestingly, are the best source of zinc from food. 35 Still, up to 25% of people likely have an inadequate zinc intake. 36,37
It’s easier for the body to absorb the zinc from meat, poultry, and shellfish, though, as plant-based sources may contain phytic acid and other compounds that can inhibit absorption. If you are deficient, supplements may help. Experts recommend choosing from zinc acetate, zinc citrate, or zinc gluconate over zinc oxide, however, as they’re more absorbable. 38
While there are serious issues with a zinc deficiency, too much zinc can also lead to negative effects, such as nausea, vomiting, abdominal cramps, and diarrhea, as well as decreased appetite, headaches, and impaired immune system function. 39 Too much zinc can also make it more likely to be deficient in other nutrients, as zinc can interfere with the absorption of other minerals, such as iron and copper. 37 Zinc supplementation can also interfere with the effectiveness of certain drugs.
So, while zinc supplementation can have many benefits, it’s important to avoid high-doses of zinc supplements, especially long-term, unless specifically recommended by your doctor or healthcare practitioner. The recommended daily intake is 11 mg for men and 8 mg for women (up to 12 mg per day if pregnant or breastfeeding). 40 Forty milligrams per day is the tolerable upper intake level (UL) for adults. 40
Long-term, high-dosage zinc supplementation is typically not recommended—especially at dosages of 25 – 45 mg. A lower dosage range of 5 – 10 mg, however, may be helpful to avoid a deficiency. 41 And zinc nasal sprays aren’t recommended as they may lead to a loss of smell (which can be permanent). Having said that, there is evidence that short-term (< 7 days), high-dose (> 75mg) zinc supplementation may be particularly beneficial to reduce the duration and severity of upper respiratory tract infections.
Even if you get enough zinc from food, short-term use of low-dose zinc supplements may be beneficial as you prepare your body to face cold and flu season and especially at the first sign of a cold. 42,43,44 To avoid any stomach upset, it’s best to supplement zinc with food. Back off (i.e., stop supplementing and decrease the amount of zinc-containing foods) if you find it causes nausea or if you have a metallic taste in your mouth.
As with almost everything in nutrition, the key is finding the right balance for your body to optimize your health and immune system function.