Zinc is a trace element that has several important functions. For example:
Good food sources of zinc include meat, shellfish, dairy foods – such as cheese, bread, cereal products – such as wheat germ.
The amount of zinc you need is about: 5.5-9.5mg a day for men 4.0-7.0mg a day for women
Health benefits of zinc:
The human body needs zinc to activate T lymphocytes (T cells).
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 Clinical Nutrition, "zinc-deficient persons experience increased susceptibility to a variety of pathogens."
Zinc for treating diarrhea
Diarrhea kills an astonishing 1.6 million children under 5 every year. Zinc pills may help reduce diarrhea.
Zinc effects on learning and memory
Research suggests that zinc has a crucial role in affecting how memories are formed and how we learn.
Zinc to treat the common cold
Zinc lozenges have been found to shorten the duration of common cold episodes by up to 40 percent 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."
Zinc's role in wound healing
Zinc plays a role in maintaining skin health. People with chronic wounds or ulcers are often deficient in zinc. Zinc is often used in skin creams for treating diaper rash or other skin irritations. 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 healing rate.
Zinc and decreased risk of age-related chronic disease
A study has found that improving zinc status through diet and supplementation may reduce the risk of inflammatory diseases. Zinc deficiency has been linked to increased inflammation in chronic disease and may trigger new inflammation.
Zinc for preventing age-related macular degeneration (AMD)
Zinc prevents cellular damage in the retina and so helps delay the progression of vision loss, according to a study.
Zinc and fertility
Poor zinc status may result in low sperm quality. One study found that subjects had a higher sperm count after zinc sulphate and folic acid supplementation. Another study concluded that poor zinc intake may also risk low quality of sperm and male infertility.
Other possible zinc benefits
- acne - one study showed promising results of zinc sulphate for the treatment of acne
- attention deficit hyperactivity disorder (ADHD)
- preventing and treating pneumonia
Recommended Zinc intake
Enough zinc 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 is 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.
Foods purporting to contain good levels of zinc.
The best sources of zinc are:
- animal meats
- fish and other seafood
- whole grain cereals
- dairy products.
Zinc is also added to some breakfast cereals and other fortified foods.
Vegetarians may need up to 50 percent 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 ounces: 14.1 milligrams
- beef, lean chuck roast, braised, 3 ounces: 7.0 milligrams
- baked beans, canned, ½ cup: 6.9 milligrams
- crab, King Alaskan, cooked, 3 ounces: 6.5 milligrams
- ground beef, lean, 3 ounces: 5.3 milligrams
- lobster, cooked, 3 ounces: 3.4 milligrams
- pork loin, lean, cooked, 3 ounces: 2.9 milligrams
- wild rice, cooked, ½ cup: 2.2 milligrams
- peas, green, cooked, 1 cup: 1.2 milligrams
- yogurt, plain, 8 ounces: 1.3 milligrams
- pecans, 1 ounces: 1.3 milligrams
- peanuts, dry roasted, 1 ounces: 0.9 milligrams
Zinc supplements are also available in the form of zinc supplements. However, beware the tolerable upper limit for zinc is 40 milligrams for males and females over 18 years.
First focus on obtaining your daily zinc requirement from foods, then use zinc supplements as a backup if necessary.
Normally, 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, and sickle cell disease.
Zinc deficiency signs include:
- loss of appetite
- slow wound healing
- skin conditions such as acne or eczema
- abnormal taste and smell
- depressed growth
- altered cognition
- depression (more research needed)
- hair loss
Zinc deficiency during pregnancy may increase the chances of a difficult or prolonged birth.
Precautions against excessive zinc intake
Excessive zinc intake can be harmful. Adverse effects of severely high zinc intake may include:
- loss of appetite
- stomach pains
Excess zinc may suppress copper absorption, according to a study published in Biological Trace Element Research.
There is also some evidence that increased levels of zinc in the body might play a role in the development of kidney stones. Research into this and other health benefits of zinc are happening now, but we have known for decades that zinc is important to good health.