Zinc is an essential mineral the body uses in several key processes. Specifically, the body requires zinc to produce proteins and DNA (the genetic material present in cells). Zinc is especially critical for proper growth and development during pregnancy, infancy, and childhood. Zinc acts as an antioxidant and immune-boosting supplement. This mineral can help the immune system fight off invading bacteria and viruses. In fact, zinc is one of the only substances proven to help prevent, ease the symptoms, and shorten the duration of the common cold.
Benefits of Zinc
Zinc is an incredibly well researched essential mineral. It is considered an essential mineral because it is absolutely critical for proper bodily function. In normal, healthy individuals, zinc supplementation is unnecessary but may be beneficial. However, there are a number of health conditions that will benefit from zinc supplementation.
Type 2 Diabetes
Several studies have shown that zinc supplementation improves blood sugar control in patients with type 2 diabetes. There is also some evidence that high doses of zinc may improve peripheral neuropathy associated with diabetes. Type 2 diabetes is a disorder that causes high blood sugar, insulin resistance, and insulin reduction. Symptoms include increased thirst, frequent urination, and unexplained weight loss. Approximately 9% of the population in the US has type 2 diabetes.
Research shows that taking zinc in combination with antioxidant vitamins (vitamins C and E, and beta-carotene) might slow the progression of advanced macular degeneration. Macular degeneration is a type of blindness. It happens when the central portion of the retina starts to break down with age. About 2% of people over that age of 40 have macular degeneration.
Zinc supplementation has been researched as an alternative to traditional acne treatments; clinical trials suggest that zinc can improve symptoms of acne. Acne is a skin condition that occurs when hair follicles become plugged with oil and dead skin cells. While effective treatments are available, some people find their acne to remain persistent. Acne is most common among teenagers, with a reported prevalence of 70 to 87 percent.
Since zinc is lost through sweat, professional athletes or males who exercise to excess may have low serum levels of zinc, which has been linked to low testosterone and infertility. There have only been a handful of double-blind clinical trials performed on the relationship between zinc and low testosterone. However, all of them were able to find a direct correlation between zinc supplementation and improved testosterone levels.
Other traits or conditions that zinc supplementation may be beneficial towards include: depression, hyperglycemia, psoriasis, pneumonia and osteoporosis. Clinical research on the effects of zinc supplementation on these conditions is promising.
What is Zinc Found In?
Zinc is found naturally in most animal meats and animal products. Due to its necessity in our bodily functions, a number of common processed foods (such as cereals) are now fortified with zinc to prevent deficiencies in the larger population. Below are some of the food sources of zinc:
- Crab, Alaska king
- Baked beans
- Chicken (dark meat)
- Pumpkin seeds
- Cocoa powder
Do I Need A Zinc Supplement?
True zinc deficiencies are rare in the US since so much of our food is now fortified with essential vitamins and minerals. Even so, there are certain lifestyles and medications that are known to cause or contribute to zinc deficiencies. Because zinc is found predominantly in animal foods, vegetarians and vegans are at a higher risk of zinc deficiencies than the general population. Vegetarian diets are often high in grains and legumes, which contain phytate – a compound that binds with zinc and reduces the body’s ability to absorb it.
Since zinc absorption is likely to be lower in vegetarians and vegans, and this type of diet is considered a risk factor for zinc deficiency or depletion. However, the human body adapts over time, becoming more efficient at absorbing zinc and reducing zinc losses in bile and intestinal secretions. Zinc plasma levels in vegetarians and vegans are generally at the lower end of the normal range. Zinc is lost through sweat. Therefore, people who sweat more than average, such as athletes or individuals with hyperhidrosis, are at a higher risk to become zinc deficient. Vegetarian and vegan athletes are subsequently at a higher risk for deficiency as well. Zinc deficiency may also occur in people with severe diarrhea, digestive disorders (such as IBS or Crohn’s Disease), liver disease, alcoholism, and after surgery or dialysis.
The following medications/supplements can lower or deplete zinc levels, requiring zinc supplementation to avoid health problems:
Deferoxamine increases urinary zinc excretion in a dose-dependent manner. The effect on serum and blood cell levels of zinc is subsequently variable. In some people zinc levels remain normal (presumably due to compensatory mechanisms) while in others they are low.
Symptomatic zinc deficiency due to deferoxamine is rare, although visual and hearing loss corrected by zinc supplements has been reported. Monitor patients taking deferoxamine for signs of zinc deficiency and give supplements if necessary.
Calcium disodium EDTA, when used in the treatment of lead poisoning, binds with zinc and can increase urinary zinc excretion 10- to 17-fold, and decrease serum zinc levels by about 40% (in clinical evidence). Serum levels recover rapidly when the 5-day course of treatment finishes, but repeated courses may cause zinc depletion.
Zinc supplements have been used in some cases, although there’s concern they could decrease the effectiveness of EDTA therapy. Monitor patients closely and use zinc supplements only if clinically necessary.
Penicillamine binds to zinc and forms a compound known as a chelate. This increases urinary zinc excretion, but also increases intestinal zinc absorption. In human research trials these two effects seem to cancel each other out. However, there is a case report of severe, symptomatic zinc deficiency after two years of treatment with up to 2 grams/day of penicillamine.
Monitor patients for signs and symptoms of zinc deficiency. If a zinc supplement is necessary, the dose should be separated from penicillamine by 1-2 hours.
Propofol infusion contains a very small amount of EDTA, which can bind to zinc and increase urinary zinc excretion. Critically ill patients excrete zinc at a higher rate than healthy individuals. When a critically ill patient is placed on a propofol infusion, the rate of zinc excretion doubles. Serum zinc levels are decreased in critically ill patients and then gradually recover as the patient’s condition improves. However, this recovery is blunted in patients on propofol.
It has been suggested that reduced zinc levels in critical illness may reduce the acute inflammatory response to stress, and the effects of zinc supplements in this population aren’t fully understood. If patients are on propofol infusions for several days, monitor for symptoms of zinc deficiency and consider supplements if necessary.
Thiazide diuretics increase urinary zinc excretion by 50% to 60%, and this is likely sustained during at least 3 years of treatment (according to human research). Decreased serum zinc levels sometimes occur, although they usually remain within the normal range, possibly due to compensatory mechanisms. However, prolonged thiazide therapy might deplete tissue zinc.
Thiazide-related zinc deficiencies may contribute to the impotence sometimes seen with thiazide therapy. Monitor patients on long-term thiazide therapy for symptoms of zinc deficiency.
Amiloride is zinc-sparing and can counteract zinc losses caused by thiazides. Thiazides include chlorothiazide (Diuril), hydrochlorothiazide (Esidrex, HydroDIURIL), chlorthalidone (Hygroton), indapamide (Lozol), metolozone (Zaroxolyn), and others.
If you suspect you have, or have already been diagnosed with a zinc deficiency, start a zinc supplement immediately to avoid permanent damage. Taking a zinc supplement can prevent and treat zinc deficiency. Be aware that high doses of zinc may decrease levels of copper in the body and lead to anemia. This side effect can be avoided by supplementing with both zinc and copper at the same time.
How Much Zinc Do I Need?
As with many other essential minerals, the amount your body needs to properly function depends on your age, activity levels, and health conditions. The RDA (recommended daily allowance) according to age is as follows:
- Infants up to 6 months old: 2mg
- 7 months – 3 years: 3 mg
- 4-8 years: 5 mg
- 9-13 years: 8 mg
- Males 14 and older: 11 mg
- Females 14-18 years: 9 mg
- Females 19 and older: 8 mg/day
- Pregnant women 14 to 18: 13 mg
- Pregnant women 19 and older: 11 mg
- Lactating women 14 to 18: 14 mg
- Lactating women 19 and older: 12 mg
What are the side effects of Zinc?
Zinc is safe when consumed in amounts that don’t exceed the tolerable upper intake level of 40 mg/day. Side effects from zinc supplements are uncommon and usually mild when they do occur. Reported side effects from zinc supplementation include altered perception of taste, nausea, and vomiting. Taking a zinc supplement along with certain antibiotics reduces the amount of both zinc and the antibiotic that the body absorbs. Taking antibiotics at least 2 hours before or 4-6 hours after taking zinc helps minimize this effect.
There is some concern that higher doses might decrease copper absorption and result in anemia. Copper is also an essential mineral needed by antioxidant enzyme systems in the body. Copper may be combined with zinc to prevent copper deficiency, as taking large amounts of zinc may deplete copper levels.Zinc and Copper supplementation has been deemed safe to consume when pregnant or breastfeeding as long as the dosage does not exceed the upper limit.
Are There Any Medications or Supplements I Shouldn’t Take With Zinc?
Zinc is one of the most researched minerals known to man, with over 4000 articles published about it or in relation to it. Most potential interactions are mild and easy to work around, but there are a few interactions that may be serious. Review this list thoroughly before starting a supplement regimen.
Herbs, Supplements and Drugs with Hypoglycemic Effects
Large amounts of zinc seem to lower blood glucose levels in humans. Theoretically, it might have additive effects when used with other herbs and supplements that also lower glucose levels. This could increase the risk of hypoglycemia (low blood sugar) in some patients. Some herbs and supplements with hypoglycemic effects include alpha-lipoic acid, bitter melon, chromium, devil’s claw, fenugreek, garlic, guar gum, horse chestnut, Panax ginseng, psyllium, Siberian ginseng, and others.
Prescription Drugs that may interact with Zinc:
Amiloride can reduce urinary zinc excretion, especially at doses of 10 mg/day or more. This zinc-sparing effect can help to counteract zinc losses caused by thiazide diuretics, but it is unlikely to cause zinc toxicity at usual amiloride doses (human research). Other potassium-sparing diuretics, such as spironolactone (Aldactone) and triamterene (Dyrenium), do not seem to have a zinc-sparing effect.
Clinical evidence suggests that zinc 600-660 mg daily for up to 60 days seems to lower blood glucose levels. Theoretically, zinc can have additive effects and may cause hypoglycemia in patients treated with antidiabetic agents; use with caution. Dose adjustments to diabetes medications might be necessary.
Some antidiabetes drugs include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, metformin (Glucophage), pioglitazone (Actos), rosiglitazone (Avandia), and others.
Penicillamine (Cuprimine, Depen)
Zinc forms an insoluble complex with penicillamine, meaning it interferes with penicillamine absorption and activity. Zinc supplements reduce the efficacy of low-dose penicillamine (0.5-1 gram/day), but do not seem to affect higher doses (1-2.75 gram/day), provided dosing times are separated (human research). It is advised to take zinc and penicillamine at least 2 hours apart. Penicillamine also reduces absorption of dietary zinc.
Quinolones bind with zinc in the gastrointestinal tract, reducing absorption of both the quinolone and zinc if taken at the same time (in human research trials). It is advised to take these drugs at least 2 hours before, or 4-6 hours after, zinc supplements.
Quinolones include ciprofloxacin (Cipro), levofloxacin (Levaquin), ofloxacin (Floxin), moxifloxacin (Avelox), gatifloxacin (Tequin), and others.
Tetracyclines bind with zinc in the gastrointestinal tract, which can reduce absorption of both the tetracycline and zinc when taken at the same time (in human research trials). Taking zinc sulfate 200 mg with tetracycline (Achromycin, Sumycin) reduces absorption of the antibiotic by as much as 30% to 40%.
Demeclocycline (Declomycin) and minocycline (Minocin) cause a similar interaction. However, doxycycline (Vibramycin) does not seem to interact significantly with zinc. It is advised to take tetracyclines at least 2 hours before, or 4-6 hours after zinc supplements to avoid any interactions.
Supplements that may interact with Zinc:
Clinical research suggests that high doses of zinc supplements (600 mg/day) can decrease serum carotene levels.
Theoretically, metal ions such as zinc might inhibit the enzymatic activity of bromelain. However, there are no clinical reports of this interaction.
Calcium supplements might decrease dietary zinc absorption in humans. This usually does not have a clinically significant effect on zinc balance. However, this interaction can be avoided by taking calcium supplements at bedtime instead of with meals.
Preliminary evidence from animal research suggests that chromium and zinc share a transport site in the intestine, and each could reduce the absorption of the other. This is not likely to be clinically significant at normal supplemental doses of zinc and chromium.
Large amounts of zinc can decrease copper retention and competitively inhibit copper absorption. Toxic levels of zinc intake can cause significant copper deficiency and associated anemia. Some signs of copper deficiency have also occurred in adults and infants taking 150 mg/day or more of zinc for up to 2 years.
Calcium disodium EDTA, when used in the treatment of lead poisoning, binds with zinc and can increase urinary zinc excretion 10- to 17-fold, and decrease serum zinc levels by about 40% (clinical evidence). Serum levels recover rapidly when the 5-day course of treatment finishes, but repeated courses may cause zinc depletion.
Zinc supplements have been used in some cases, although there’s concern they could decrease the effectiveness of EDTA therapy. Monitor patients closely and use zinc supplements only if clinically necessary..
The data on effects of folic acid supplements on dietary zinc absorption in humans is conflicting. Normal supplemental doses of folic acid are not likely to affect zinc balance in people with adequate dietary zinc intake.
Phytic acid found naturally in foods can bind zinc and reduce its absorption; however this interaction is modified by several other dietary factors. Symptomatic zinc deficiency due to high dietary phytic acid levels has not been reported in Western populations. The effect on zinc of increasing phytic acid intake with IP-6 supplements is not known. Avoid IP-6 supplements in people with other risk factors for zinc deficiency.
Under some circumstances iron and zinc can interfere with each other’s absorption (in human research trials). When high supplemental doses of zinc are taken on an empty stomach there is a measurable reduction in iron absorption. High supplemental doses of non-heme iron taken on an empty stomach can reduce zinc absorption, especially when dietary mineral intake is low. This is probably because the carriers for iron and zinc in the gut become saturated at high doses, and the ions then compete for non-specific carriers. If one of the ions is present in excess, absorption of the other will be decreased. When food is present, the ions bind with food components and do not compete for absorption.
Therefore, there is not a significant interaction between dietary iron and zinc, or between supplemental iron and zinc when taken with food.
High doses of zinc supplements (142 mg/day), or high dietary zinc intake (53mg/day) seem to decrease magnesium balance in humans. This may be due to competition between zinc and magnesium for transport systems in the intestine. Conversely, high intakes of magnesium might enhance binding of zinc to dietary phytic acid, reducing its absorption. The clinical significance of these effects isn’t clear.
Preliminary clinical data suggests zinc supplements more than double the amount of manganese absorbed from supplements taken under fasting conditions.
Preliminary data suggests riboflavin and its active form, flavin adenine dinucleotide (FAD), improve zinc absorption in humans. It is suggested that they form a complex with zinc, keeping it in solution in the gut, and acting as a carrier across the intestinal wall. The clinical significance of this is not clear.
Clinical evidence suggests that zinc supplements can increase plasma levels of retinol. Significant increases have occurred with doses of up to 30 mg/day for 6 months in children and adults.
Preliminary clinical data suggests vitamin D is involved in zinc absorption. However, data is conflicting on whether vitamin D supplements improve zinc absorption.
Taking zinc sulfate 220 mg with black coffee instead of water reduced zinc absorption by 50% in humans. The constituent of coffee causing this interaction, and the clinical significance, are not known.
Calcium-Fortified Foods and Dairy Products
Calcium can decrease zinc absorption, probably by potentiating formation of complexes. In general, this does not have a clinically significant effect on zinc balance. The risk of zinc depletion may be increased when high calcium intake is combined with other dietary characteristics, such as a high intake of unrefined grains, legumes, and soy protein, and a low intake of animal protein. However, the body adapts over the long-term, becoming more efficient at absorbing zinc and reducing zinc losses in bile and intestinal secretions.
Fiber alone does not have a major effect on zinc absorption, but it is often bound with phytate. Large amounts of insoluble cereal and vegetable fibers, such as cellulose and lignin, can exacerbate effects of phytate on zinc absorption. However, over time the body adapts to increased dietary fiber by increasing zinc absorption.
Should you be supplementing with Zinc?
Zinc deficiency or depletion is dangerous to your overall health and wellness. If you suspect you may be deficient or have already been told you have a zinc deficiency, you should be on a zinc supplement unless specifically directed not to by a physician. Vegans, vegetarians, and athletes are advised to take a zinc supplement due to the increase risk of deficiency. As are individuals with digestive disorders or any kind of chronic illness. Studies also show that zinc supplements are beneficial for immune support – particularly at the onset and first days of a cold.
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