Zinc in a nutshell:
Zinc is an essential part of the structure of hundreds of different enzymes and has been implicated in male fertility. It is a vital nutrient in our diets. However, in high doses, zinc is toxic (and can cause copper deficiency), so do consult your doctor if you are taking zinc supplements (e.g. to fight off a cold, or sinus problems).
Best source of zinc for Juicers
Zinc can be found in ginger, turnips, parsley, garlic, carrots, grapes, spinach, cabbage, cucumbers and tangerines.
Nearly everyone knows we need calcium, and entire books have been written about magnesium supplements, but most of us forget to take care of our body's needs for zinc. This trace mineral is an essential component of hundreds of enzymes.
Alternative names: Zinc. Zinc oxide is used in sunblock. Zinc sulfate and zinc gluconate are commonly used in nutritional supplements.
What Is Zinc?
Zinc is a metallic element that has many functions similar to those of magnesium. For over three thousand years, metalworkers have combined zinc and tin to make brass. Alchemists burned zinc to make philosopher's wool, and in the modern era zinc has been a popular choice for inexpensive electroplating and for making batteries.
All living organisms need zinc. The bodies of bacteria and other single-celled organisms as well as plants, animals, and people use zinc to make enzymes, as an essential part of their structure, and as a regulator of physiological processes.
Zinc is used to make over 100 different enzymes. Many of the most important antioxidant enzymes, such as zinc-copper superoxide dismutase, contain a protein around molecule-sized “finger” of zinc that gives them a distinctive shape that locks them just the right place to do their work.
Zinc is a component of cell membranes, protecting them from oxidation and the effects of some of the most common toxins. And zinc is an important regulator of gene activity. Zinc fingers lock onto certain genes and switch them on or off. Zinc plays a role in the creation of cellular signal proteins that cells use to communicate with each other. Zinc is involved in the process of apoptosis, which brings cells to end of their life cycle so they can be replaced by newer and healthier cells for the health of a tissue and the entire body.
What Does Zinc Do in the Human Body?
There are just 2 to 4 grams (2,000 to 4,000 mg) of zinc in the human body. It is concentrated in organs that are especially susceptible to attack by free radicals, including the brain, liver, kidneys, and skeletal muscles, but especially in the eyes and in the prostate gland in men. Semen is also contains high levels of zinc compounds that protect sperm from degradation as they are exposed to tiny amounts of air and the mucus lining of the cervix after ejaculation in intercourse intended for creating a child.
What Happens When We Don't Get Enough Zinc?
Zinc deficiency symptoms can be severe. In children who are zinc-deficient, the most debilitating deficiency symptom is diarrhea. Gastrointestinal disturbances caused by zinc deficiency can cause dehydration and death. In adults and in children who get viral infections, the most serious consequence of zinc deficiency is pneumonia. Pneumonia continues to be a leading cause of death all over the world, even in North America and Europe.
What Happens When We Get Too Much Zinc?
Full-fledged zinc poisoning is rare. It can result from industrial accidents, or from drinking a large amount of an acidic beverage such as orange juice in a container that was galvanized with zinc. It can also happen when children swallow coins made with zinc (such as the American penny), stomach acid releasing free zinc which in turns works as an even more powerful acid on the lining of the stomach and intestines.
It takes a single dose of 800 mg or more of zinc to cause a toxic reaction. Since large amounts of zinc use all the stomach's acid, the effects of zinc are eventually limited by the body itself, as long as more zinc is not consumed. Poisoning with zinc, however, can cause intense pain for 24 to 72 hours and other unfortunate events can occur as a result of high acidity in the gastrointestinal tract.
Lower-level zinc poisoning is much more common. Taking 100 mg of zinc per day for 30 days or more causes a deficiency of copper. In one case described in the medical literature, a woman took 400 mg per day for six months to treat a sinus problem. She developed a limp even though she did not have any injury to her foot. She started having dizzy spells.
Doctors discovered this woman had a very low white blood cell count and copper levels of just 7 micrograms per deciliter, compared to the normal range of 77 to 155 micrograms per deciliter. Avoiding zinc and taking supplemental copper brought her white blood cell count back up to normal, but the neurological damage was permanent.
Are You at Risk for Zinc Deficiency?
Zinc deficiency, that is not having enough zinc for avoiding infections and normal growth and repair of tissues, is a surprisingly common condition. The Linus Pauling Institute at Oregon State University reports that about 1/3 of the population of the earth, or over 2 billion people, suffer various degrees of zinc deficiency. People at greatest risk for deficiency include:
- People suffering chronic malnutrition.
- People who have anorexia.
- Infants and small children, because their gastrointestinal tracts are still learning to make the enzymes needed to digest the foods that contain zinc.
- Women who become pregnant before they have completed body growth, usually before the age of 18.
- People over the age of 65, who may not be able to prepare nutritious meals or who may neglect basic nutrition.
- People who have diarrhea that lasts more than 2 weeks.
- Strict vegans and vegetarians, because the phytate in green leafy vegetables and whole grains interferes with the absorption of zinc.
- People who have diseases that interfere with the absorption of nutrients, such as Crohn's disease, ulcerative colitis, ischemic colitis, celiac disease, small intestine bacterial overgrowth, and short bowel syndrome.
- People who have alcoholic liver disease, causing increased zinc excretion.
- People receiving chelation therapy, especially those receiving penicillamine (for copper overload caused by Wilson's disease) or diethylenetriamine pentaacetate, also known as DPTA (for iron overload caused by sickle cell disease or beta-thalassemia).
- People who take sodium valproate (Depakote or Depakene) for seizure disorders or migraines.
People in these categories do not necessarily need large amounts of supplemental zinc. As little as 5 to 15 mg per day may be enough to support optimal health.
How Much Zinc Is Enough?
In the United States, the Institute of Medicine set these recommended daily allowances (RDAs) for zinc:
- Infants up to six months of age should receive at least 2 mg of zinc per day.
- Infants aged six to twelve months and children aged 1 to 3 should receive at least 3 mg of zinc per day.
- Children aged 4 to 8 should receive at least 5 mg of zinc per day.
- Children aged 9 to 13 should receive at least 8 mg of zinc per day.
- Teenaged girls aged 14 to 18 should receive at least 9 mg of zinc per day.
- Teenaged boys aged 14 to 18 should receive at least 11 mg of zinc per day.
- Most adults 19 and older should receive at least 9 mg of zinc per day.
Pregnant teens should 12 mg of zinc per day; older women who are pregnant should receive 11 mg of zinc per day. Teenaged mothers who breastfeed their infants should receive 13 mg of zinc per day; older women who breastfeed their children should receive 12 mg of zinc per day.
How can you get the recommended amount of zinc? In North America, the easiest way to be sure you are getting enough zinc is to eat a small serving of a fortified breakfast cereal such as Kellogg's All-Bran Complete or Complete Bran Flakes every few days. In fact, these two cereals contain almost a toxic level of zinc, 64 mg in a 3-1/2 oz (100 gram) serving. You shouldn't eat them every day! Other fortified cereals contain a full day's supply of zinc in 1 to 3 ounces (28 to 84 grams).
In the rest of the world, where fortifying foods with zinc is not the custom or is even banned (as it is in Sweden and Denmark), it's still easy to get enough zinc with small servings of zinc-rich foods.
- Just one-third of an ounce or 9 grams (less than one) raw oyster contains 10 mg of zinc.
- Just one-half of an ounce (14 grams) of cooked oysters or clams contains 10 mg of zinc.
- Just 1-1/2 ounces (42 grams) of non-fortified wheat germ contains 10 mg of zinc.
- Just a 3-1/2 ounce (100 gram) serving of sunflower seeds, pumpkin seeds, or beans contains 10 mg of zinc.
- A 3-1/2 ounce (100 gram) serving of cold cuts or roast beef contains 10 mg of zinc.
- A 4-ounce (112 gram) serving of dried shiitake mushrooms (be sure to use the soaking water in preparing the dish) contains 10 mg of zinc.
It helps to eat these foods at times you don't consume high-fiber foods, preferably as a snack. A serving of oysters or clams, however, contains so much zinc that it doesn't matter what foods accompany them.
Which Form of Supplemental Zinc Is Best?
The best way to prevent a deficiency of zinc is to take a nutritional supplement containing at least 15 mg of zinc every day. But which kind of zinc is best? Here are five thing about zinc supplements everyone who takes nutritional supplements needs to know.
1. Zinc oxide is used in sunblock. Unlike most ingredients used for sun protection, it blocks UV-A, UV- B, and UV-C rays from the sun. It's not used in supplements you take by mouth, however.
2. Zinc gluconate is the kind of zinc best suited for colds lozenges. The gluconate makes it easier for the zinc to be transported into cells in the lining of the nose and throat. Be sure to suck on the lozenge until it has completely dissolved. Don't chew, and don't swallow. Sucking on the lozenge releases the maximum amount of zinc for your upper respiratory tract.
3. Zinc sulfate is clinically proven for use in children's zinc supplements, although forms of zinc probably will have some benefit. Zinc sulfate is also the kind of zinc used as a male fertility supplement.
4. Zinc interferes with the absorption of copper and magnesium. If you take a zinc supplement for longer than 2 or 3 days, you will also need supplemental copper and magnesium. Zinc can also interfere with iron absorption, but don't take an iron supplement unless you have had a blood test confirming that you have low iron levels.
5. Never take more than 100 mg of zinc per day for longer than two weeks. Don't take more than 75 mg of zinc per day for longer than 30 days.
Syrups and sprays are not a good way to take zinc. Syrups tend to lose their antioxidant power after the bottle is opened, or if it is stored in a hot place. Sprays don't “stick” to the lining of the upper respiratory tract as effectively and can't reach as many places in the upper respiratory tract as zinc dissolved in saliva.
Using Zinc to Fight Colds
Next to vitamin C, zinc is the most popular supplement for fighting colds. The form of zinc you need for stopping a cold before it starts is a lozenge. The idea of sucking on a zinc lozenge every two to three hours just as soon as you notice symptoms is not to get zinc into your bloodstream, but to mix zinc with your saliva which then coats your mouth, the back of your throat, and even the linings of your nostrils.
Zinc is not an immune stimulant. In fact, it reduces the immune system's ability to generate inflammation to kill cells in the lining of your nose and throat that have been infected by colds viruses. But since it also helps block the entry of viruses in the lining of your nose and throat, it reduces both the speed of infection and the severity of symptoms, giving your body a chance to flush the virus away with runny mucus.
It's usually best to have some zinc lozenges on hand just in case you catch a cold. Pop a lozenge in a mouth and suck—don't chew—until it dissolves. You may take the equivalent of up to 200 mg of zinc for one day when you are fighting a cold. This won't cause symptoms of overdose as long as you stop using zinc after the first 24 hours. Much of the zinc that gets into your saliva is actually sneezed away. However, using zinc lozenges on a continuous basis can cause copper deficiency, as described above.
Taking 1,000 to 2,000 mg of vitamin C on the first day you notice symptoms is also helpful for shortening the time it takes to get over a cold. You really should not take this dosage of vitamin C on an ongoing basis because your body will just adjust the rate at which it excretes vitamin C and you will become dependent on the new dosage. For one day, however, this high dose of vitamin C will “max out” its anti-inflammatory effects for controlling colds symptoms.
Zinc lozenges and high-dose vitamin C supplements work hand in hand to fight cold infections. Vitamin C is taken as an oral supplement, not as a lozenge. Both zinc and vitamin C, however, are primarily effective during the first day of symptoms. They are better for prevention than for treatment. However, once a cold sets in, a much lower dosage of zinc may be helpful. Don't use zinc nose sprays. Some nose sprays containing zinc have caused permanent loss of the sense of smell.
One of the best internationally available products for fighting colds is a fizzy drink marketed as Redoxon Vita-Immune Vitamin C and Zinc by Hoffman-La Roche. Each tablet of Vita-Immune contains:
- 10 milligrams of zinc
- 1000 milligrams of vitamin C
- 110 micrograms of selenium
- 2333 IU of vitamin A
- 400 IU of vitamin D
- 400 micrograms of folic acid
- 45 milligrams of vitamin E
- 5 milligrams of iron
- 6.5 milligrams of vitamin B 6
- 9.6 micrograms of vitamin B12
- 900 micrograms of copper
Since the tablet fizzes when it is dropped in water, the nutrients make direct contact with infected and inflamed tissues as well as finding their way into general circulation. Vita-Immune has been on the market since 1934 and it considered one of the oldest and most reliable over-the-counter treatments for colds and flu. Doctors in Austria, Germany, and South Africa sometimes also recommend it for asthma.
Using Zinc to Slow the Progress of Age-Related Macular Degeneration
Macular degeneration, causing loss of the field of vision from the center out, is the leading cause of blindness in people over the age of 65. Because zinc is relatively abundant in the tissues in the eye that are affected by macular degeneration and because low levels of zinc are associated with macular degeneration, some researchers have experimented with the use of zinc supplements to slow the progression of the disease.
Results of these studies have been mixed. One study found that using a relatively high (200 mg per day) dose of zinc for two years slowed the progression of early macular degeneration. Another study found no benefit in using zinc supplements for advanced macular degeneration. The best results have were obtained from a study that asked participants to take daily doses of:
- 80 mg of zinc,
- 2 mg of copper,
- 500 mg of vitamin C,
- 15 mg of beta-carotene, and
- 400 IU of vitamin E.
This combination of nutrients was enough for significant improvement in (but not a complete cure of) moderate to severe age-related macular degeneration in at least one eye for most participants in the study.
Using Zinc to Support Male Fertility
Countless nutritionists have advised men seeking to become fathers who still have some ability to produce sperm to take high doses of zinc. While zinc deficiency can indeed cause male infertility, taking large doses of zinc by themselves is not a good remedy. Increasing zinc without increasing copper increases the sperm count but reduces sperm survivability in the cervical fluid it must transverse to reach and fertilize the egg.
A better approach to using zinc to support male fertility is to take no more than 30 mg of zinc per day but to be sure to take at least 2 mg of copper. The combination of zinc and copper in relatively low doses is far more helpful in raising chances of becoming a father than taking zinc alone.
Using Zinc for Nutritional Support of Diabetes
There were very different results in two studies of the use of zinc as nutritional support for diabetes. Type 1 (insulin-dependent) diabetics given 50 mg of zinc per day actually got worse. Their blood sugar levels became more difficult to control. Type 2 (non-insulin dependent) diabetics given 30 mg of zinc had lower levels of some markers of oxidation that are associated with cardiovascular disease. Diabetics should avoid zinc deficiency, but they should not take zinc specifically to control blood sugar levels.
Zinc for Nutritional Support After Gastric Bypass Surgery
For over 20 years, Kimberley tried every diet she had every heard about. Usually she would lose a few pounds and a few inches, but she would always put them right back on and then gain even more. Before Kimberley decided to have lap band surgery, she carried a remarkable 484 pounds (220 kilos) on her 5 foot 2 inch (150 cm) frame. When she could find clothes, she could only wear XXXXXXL. She so often broke furniture that before she became home bound friends had quietly banned her from their homes.
Within just the first three months after gastric lap band surgery, however, Kimberley lost 121 pounds (55 kilos). She could take short walks without her scooter. She could see her feet, and her diabetes just seemed to disappear. But there were other problems.
Over the next three months, Kimberley lost another 44 pounds (20 kilos), but she was not happy. Her hair started falling out in clumps. Despite eating very little, she had severe diarrhea, and it took a lot of effort to stay hydrated. Kimberley's bariatric surgeon sent her to have blood tests to measure nutrient levels in her bloodstream, and the blood tests revealed a not-unexpected result: Extreme deficiency of both zinc and copper.
In North America and Europe, most people get their zinc and copper from meat and fish. Weight loss surgery simply does not leave enough room in the stomach to eat enough meat and fish to supply adequate amounts of zinc and copper.
“Healthy” food choices pose problems of their own. A much smaller stomach secretes much smaller amounts of stomach acid. This makes it difficult for the stomach to break down even tiny amounts of fiber. Eating a fork full of salad can make it impossible for the stomach to digest meat.
It is necessary to get vitamins and minerals from supplements, but there is not enough room in the stomach for both a multi-vitamin multi-mineral supplement pill and the water needed to swallow it. There are liquid vitamins and minerals, but they begin to react with oxygen in the air (in effect oxidizing the antioxidants) as soon as the bottle is opened. Moreover, the minerals in the mix tend to settle out at the bottom of the bottle so it's essential to remember to shake the bottle before each dose.
Despite their limited shelf life and the need to shake the bottle before each use, liquid vitamin and mineral supplements are a must for people who have had gastric bypass surgery. Just be sure that you get both nutrients and their co-factors, zinc with copper, vitamin C with vitamin E, and calcium with vitamin D.