Zinc is responsible for a number of different functions in the human body and it helps stimulate the activity of 100 different enzymes.
This Medical News Today information article highlights the potential health benefits of zinc and provides details on good sources of the nutrient, symptoms of zinc deficiency, and precautions to consider – associated with excessive zinc intake.
Only a very small intake of zinc is necessary to reap the benefits. Currently, the “Recommended Dietary Allowance” (RDA) for zinc in the US is: 8 mg/day for women and 11 mg/day for men.
Having a low level of zinc makes a person more susceptible to disease and illness. It has been reported that zinc deficiency is responsible for over 800,000 childhood deaths in the world every year.
The element is naturally found in a number of different foods, but it is also available as a dietary supplement.
What are the possible health benefits of zinc?
Zinc is important for a healthy immune system, properly synthesizing DNA, promoting healthy growth during childhood, and healing wounds. Let’s look at each of these in turn.
1) Regulating immune function
T cells help the body in two ways:
- Controlling and regulating immune responses
- Attacking infected or cancerous cells.
Zinc deficiency can severely impair immune system function.
According to a study published in the American Journal of American Journal of Clinical Nutrition, “zinc-deficient persons experience increased susceptibility to a variety of pathogens.”
2) Treating diarrhea
According to the World Health Organization, diarrhea “kills an astonishing 1.6 million children under 5 every year. An article in TIME magazine said that “zinc pills appear to halt diarrhea in its tracks.”
In addition, a PLoS Medicine study, which “followed a nationwide public health campaign to increase zinc use for childhood diarrhea in Bangladesh,” confirmed that a 10-day course of zinc tablets is effective at treating diarrhea and also helps prevent future bouts of the condition.
3) Affecting learning and memory
Research conducted at the University of Toronto and published in the journal Neuron suggested that zinc has a crucial role in regulating how neurons communicate with one another, affecting how memories are formed and how we learn.
4) Helping treat the common cold
Zinc lozenges were found to shorten the duration of common cold episodes by up to 40% in a study published in the Open Respiratory Medicine Journal.
In addition, a Cochrane review concluded that taking “zinc (lozenges or syrup) is beneficial in reducing the duration and severity of the common cold in healthy people, when taken within 24 hours of onset of symptoms.”
5) Wound healing
Zinc plays a role in maintaining skin integrity and structure. Patients experiencing chronic wound or ulcers often have deficient zinc metabolism and lower serum zinc levels. Those with low levels should be treated with increased zinc.
A Swedish study that analyzed zinc in wound healing, concluded that “topical zinc may stimulate leg ulcer healing by enhancing re-epithelialization, decreasing inflammation and bacterial growth. When zinc is applied on wounds, it not only corrects a local zinc deficit, but also acts pharmacologically.”
However, research has not consistently shown that use of zinc sulfate in patients with chronic wounds or ulcers is effective at improving the healing rate.
6) Proper growth
Zinc deficiency was first discovered in adolescent boys suffering from mild anemia, short stature and delayed sexual maturation. Their diets were high in unrefined cereals and unleavened breads, both high in phytate, which competes with zinc for absorption.
Once zinc deficiencies were corrected, the boys grew as much as 5 inches per year. Infant and children’s foods such as ready to eat cereals are now fortified with zinc.
7) Decreased risk of age-related chronic disease
A study from researchers at Oregon State University have found that improving zinc status through diet and supplementation may reduce the risk of inflammatory diseases.
Using cell cultures, and a mouse model, researchers were able to show that age-related reductions in zinc status may lead to impaired immune system function and systemic inflammation, both contributing factors to chronic diseases.
Adults 60 years of age and older from food-insufficient households have a significantly higher risk of zinc deficiency, reporting an intake of less than 50% of the Recommended Daily Intake for zinc compared with adults from food-sufficient households.
8) Preventing age-related macular degeneration (AMD)
Zinc prevents cellular damage in the retina, which helps in delaying the progression of AMD and vision loss, according to a study published in the Archives of Ophthalmology.
Several studies and trials have linked poor zinc status with low sperm quality. For example, one study in the Netherlands found that subjects had a higher sperm count after zinc sulfate and folic acid supplementation.
In another study, researchers concluded that poor zinc intake may be a risk factor for low quality of sperm and male infertility.
Other possible health benefits of zinc
Zinc may also be effective for the treatment of:
- Acne – one study, published in JAMA, showed promising results of zinc sulfate for the treatment of acne
- Attention deficit-hyperactivity disorder (ADHD)
- Preventing and treating pneumonia.
Recommended zinc intake
The Recommended Daily Allowance (RDA) for zinc is 8 milligrams per day for adult females and 11 milligrams per day for adult males.
Adequate zinc intake is especially important for children because even mild zinc deficiency can impede growth, increase risk of infection and increase risk of diarrhea and respiratory disease.
The recommended intake for children 1-8 years old ranges from 3-5 milligrams, increasing as the child gets older.
Males 9-13 years old require 8 milligrams of zinc per day. After the age of 14, the requirement increases to the 11 milligrams per day that is required for all adult males.
For females over the age of 8, the requirement stays stable at 8 milligrams per day, except for ages 14-18, where the recommendation increases to 9 milligrams per day.
Pregnant and lactating women have an increased need for zinc at 11-13 milligrams per day, depending on age.
Along with growth retardation, zinc deficiency can cause delayed wound healing, decreased taste perception, skin lesions, night blindness and hair loss. Zinc deficiency has also been linked with neuronal plasticity defects and impact behavior in children with ADHD.10
Zinc supplements are available, but it is best to obtain any vitamin or mineral through food. It is not the individual vitamin or mineral alone that make certain foods an important part of our diet, but the synergy of nutrients in that food working together.
It has been proven time and again that isolating certain nutrients in supplement form will not provide the same health benefits as consuming the nutrient from a whole food. First focus on obtaining your daily zinc requirement from foods, then use supplements as a backup if necessary.
Sources of zinc
The best sources of zinc are beans, animal meats, nuts, fish and other seafood, whole grain cereals and dairy products. Zinc is also added to some breakfast cereals and other fortified foods.
The typical western diet allows for adequate zinc intake, at an average range of between 10-15 milligrams per day.
Several dietary factors can decrease zinc absorption. Phytates (found in whole-grain breads, cereals and legumes), copper, calcium and folic acid may all reduce zinc absorption. Zinc absorption is increased when consumed with red wine, glucose, lactose or soy protein.
Vegetarians may require up to 50% more than the recommended intake of zinc because of low bioavailability of zinc from plant-based foods.
Foods with the highest reported zinc content are:
- Raw oysters (Pacific), 3 oz: 14.1 mg
- Beef, lean chuck roast, braised, 3 oz: 7.0 mg
- Baked beans, canned, ½ cup: 6.9 mg
- Crab, King Alaskan, cooked, 3 oz: 6.5 mg
- Ground beef, lean, 3 oz: 5.3 mg
- Lobster, cooked, 3 oz: 3.4 mg
- Pork loin, lean, cooked, 3 oz: 2.9 mg
- Wild rice, cooked, ½ cup: 2.2 mg
- Peas, green, cooked, 1 cup: 1.2 mg
- Yogurt, plain, 8 oz: 1.3 mg
- Pecans, 1 oz: 1.3 mg
- Peanuts, dry roasted, 1 oz: 0.9 mg.
Zinc supplements are also available in the form of capsules and tablets. However, the tolerable upper limit for zinc is 40mg for males and females over 18 years.11
Usually zinc deficiency is due to insufficient dietary intake.
However, it may also be due to malabsorption and chronic illnesses such as diabetes, malignancy (cancer), liver disease, sickle cell disease.
Signs of zinc deficiency include:
- Loss of appetite
- Slow wound healing
- Abnormal taste
- Depressed growth
- Altered cognition
- Hair loss.
Experts believe that around 40 percent of elderly Americans and up to two billion people around the world have diets that are deficient in zinc.
Excessive zinc intake can be harmful as it suppresses copper absorption, according to a study published in Biological Trace Element Research.12
Adverse effects of severely high zinc intake may include:
- Loss of appetite
- Stomach pains