Bluish-silver zinc is a workhorse element, crucial to many industrial processes that often go unseen. Humans have used zinc for many centuries now, with archaeologists finding a handful of zinc artifacts that date back to 300 B.C. Today, the metal is used mostly as coating for steel and iron to prevent rusting. But even more importantly, zinc is essential to healthy nutrition. In fact, it is one of the most complex and versatile trace elements in our diet, and not getting enough of it can lead to many severe health problems.
While zinc usage may be firmly rooted in ancient history, its importance to life sciences was, for a long time, overlooked. As scientists point out, only in 1961 was zinc recognised as essential for human health, and we are still learning what exact roles this nutrient plays in our bodies.
Here, we’ll discuss what science says about zinc and its potential health benefits, as well as the best sources of zinc and signs of potential deficiency.
Why do we need zinc?
Zinc was discovered before it was officially discovered. In 1746, German chemist Andreas Marggraf (also the inventor of a process to extract sugar from beets) figured out how to isolate zinc by heating carbon and calamine (the stuff in calamine lotion). Marggraf reported the finding in great detail, which earned him credit for the discovery, even though several European researchers had already completed the same feat. An English metallurgist, William Champion, had even patented the process years earlier.
Zinc is crucial to the proper functioning of our immune system. According to the journal Advances in Nutrition, this trace mineral is essential to fighting off viruses, and zinc-deficient populations are often most at risk of acquiring infections like HIV or hepatitis C virus.
Zinc supplementation is also used as a complementary treatment for several infectious diseases, including malaria. According to the Molecules and Cells journal, that is because this nutrient helps with passing on the information within the immune system and regulating the activity of immune-boosting white blood cells.
More recently, zinc has been shown to play a role in obesity, insulin resistance and fat metabolism. According to a review published in the Nutrients journal, researchers are particularly interested in the newly discovered zinc-related adipokine, zinc-α2-glycoprotein (ZAG). Adipokines are a type of cell signaling proteins released by fat tissue, many of which contribute to inflammation and chronic diseases. Studies suggest that excess body fat lowers blood concentrations of zinc and ZAG, leading not only to the development of obesity, but also to other components of the metabolic syndrome. Zinc itself appears to regulate ZAG levels in the body.
Researchers have found that zinc supplementation in overweight individuals significantly reduced blood cholesterol and triglyceride levels. In addition, in vitro studies have shown that ZAG may inhibit the production of leptin, a hunger-regulating hormone.
According to a review published in the Cardiology in Review journal, zinc deficiency has been linked to heart failure, hardening of the veins, and heart attacks. It has been suggested that these effects are due to zinc involvement in regulating inflammation and blood pressure levels.
What’s more, according to the Journal of Cardiac Failure, zinc supplementation may improve heart function in patients with heart failure. Increasing the intake of this micronutrient can also help significantly reduce systolic blood pressure, but not the diastolic blood pressure, as reported in the European Journal of Nutrition.
Zinc is important for proper brain function. According to the Neuroscience journal, it is abundant in many regions of the brain, and is heavily involved in neurotransmission and sensory processing. And as stated in the International Journal of Molecular Sciences, zinc deficiency has been linked to a host of pathological conditions with both acute and chronic effects on brain function, including age-related cognitive decline, depression and Alzheimer's disease.
Zinc may be essential to gut health. According to the International Journal of Molecular Sciences, zinc may increase gut bacteria biodiversity and improve gut wall integrity. Moreover, alterations of gut microbiota caused by distubed zinc metabolism have been linked to systemic inflammation, acute pancreatitis, autism spectrum disorder, attention deficit hyperactivity disorder, fetal alcohol syndrome and obesity.
As reported in the Nutrients journal, zinc-fortified foods may help increase the populations of beneficial Lactobacillus and Ruminococcus bacteria strains, while decreasing the potentially pathogenic Streptococcus, Escherichia, and Enterobacter strains.
According to the Nutrients journal, the skin is the third most zinc-abundant tissue in the body, and contains multiple zinc transporters. Mutations or dysregulation of these zinc transporters have been linked to skin diseases like acrodermatitis enteropathica (skin inflammation around mouth and/ or anus), Ehlers-Danlos syndrome (condition characterized by hypermobile joints and overstretched skin), and epidermodysplasia verruciformis (skin lesions).
Zinc levels appear to be related to exercise. According to a review published in the Sports Medicine journal, serum zinc levels increase immediately after exercise and decrease during exercise recovery. Scientists suggest that this trace mineral is linked to muscle repair mechanisms.
The zinc fireworks could have real-world applications for women dealing with infertility, Woodruff told Live Science.
Maintaining a good zinc status may be critical for healthy pregnancy. According to a review published in the Journal of Trace Elements in Medicine and Biology, zinc deficiency has been linked to numerous adverse effects on maternal health and pregnancy outcomes. That is because this trace mineral ensures proper expression of genetic material, and as such, healthy fetal development.
How much zinc do you need?
The Daily Value (DV) for adults aged 19 and over is 11 mg per day for men and 8 mg per day for women.
The Recommended Dietary Allowance (RDA) for pregnant and breastfeeding women is 11 mg per day and 12 mg per day, respectively.
The Tolerable Upper Intake Level (UL) for all adults aged 19 and over is 40 mg per day. Higher intakes may lead to harmful health effects, particularly in the case of zinc supplements.
As listed by the Harvard School of Public Health, signs of zinc toxicity include:
- Nausea and vomiting
- Poor appetite
- Abdominal pain or cramping
What are the best sources of zinc?
Zinc is mostly found in animal-based foods. Some plant foods are also good sources of this micronutrient, but they may also contain compounds called phytates. Phytates may bind to zinc and lower its absorption in the digestive tract.
The best sources of zinc included:
- Oysters: 52mg (472% DV) per 6 oysters / 61mg (555% DV) per 100g
- Beef steak: 15mg (140% DV) per 5oz serving / 11mg (99% DV) per 100g
- Chicken leg: 5mg (49% DV) per leg / 2mg (19% DV) per 100g
- Firm tofu: 4mg (36% DV) per cup / 2mg (14% DV) per 100g
- Lean pork chops: 4mg (32% DV) per 6oz serving / 2mg (19% DV) per 100g
- Squash and pumpkin seeds: 3mg (27% DV) per 1oz handful / 10mg (94% DV) per 100g
- Lentils: 3mg (23% DV) per cup / 1mg (12% DV) per 100g
- Low-fat yoghurt: 2mg (22% DV) per cup / 1mg (9% DV) per 100g
- Oatmeal: 2mg (21% DV) per cup / 1mg (9% DV) per 100g
- Cooked Shiitake mushrooms: 2mg (18% DV) per cup / 1mg (12% DV) per 100g
Can you be deficient in zinc?
Zinc deficiency is relatively rare. It is mostly seen in people who do not absorb zinc properly due to digestive disorders, gastrointestinal surgery, or prolonged diarrhea. Severe conditions that increase zinc requirements, such as burns and sepsis, can also increase the risk of developing deficiency.
According to the Harvard School of Public Health, the main symptoms of zinc deficiency include:
- Loss of taste and/or smell
- Poor appetite
- Depressed mood
- Decreased immunity
- Delayed wound healing
- Hair loss
This article is for informational purposes only and is not meant to offer medical advice.
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Anna Gora is a health writer at Live Science, having previously worked across Coach, Fit&Well, T3, TechRadar and Tom's Guide. She is a certified personal trainer, nutritionist and health coach with nearly 10 years of professional experience. Anna holds a Bachelor's degree in Nutrition from the Warsaw University of Life Sciences, a Master’s degree in Nutrition, Physical Activity & Public Health from the University of Bristol, as well as various health coaching certificates. She is passionate about empowering people to live a healthy lifestyle and promoting the benefits of a plant-based diet.