Zinc is a major player in the creation of DNA, growth of cells

Zinc and its effects on our body
Zinc is the second most abundant trace mineral in our bodies, after iron. Zinc is found in cells throughout the body. The total amount of zinc in the body is approximately 1.5g in women and 2.5g in men. Most of this zinc is stored in skeletal muscle and bone. Zinc is involved in many aspects of cellular metabolism. It is required for the catalytic activity of hundreds of enzymes, and it plays a role in enhancing immune function, protein and DNA synthesis, wound healing, and cell signaling and division. Because it helps cells to grow and multiply, adequate zinc is required during times of rapid growth, such as childhood, adolescence, and pregnancy. Zinc is also involved with the senses of taste and smell.

The processes that maintain zinc homeostasis are absorption of zinc from the diet, excretion into the gastrointestinal tract, and reabsorption in the gastrointestinal lumen. In general, as zinc intakes rise, the amount of zinc absorbed also increases, but its fractional absorption drops.

 

Health risks if zinc deficiency
Because zinc has many functions throughout the body, zinc deficiency affects many different tissues and organs. Zinc deficiency can affect, for example, skin; bones; and the digestive, reproductive, central nervous, and immune systems.

In both infants and children, zinc deficiency can impair growth and lead to a loss of appetite and reproductive problems when they reach adulthood. In populations with low intakes of absorbable zinc (e.g., from meat and fish), including many low-income and middle-income countries, zinc deficiency affects the health of pregnant people and their infants by increasing the risk of child morbidity (including premature birth and low birthweight) and mortality, maternal morbidity, and adverse birth outcomes. In addition, zinc deficiency can interfere with the senses of taste and smell. Zinc deficiency in older adults can cause delays in wound healing and changes in cognitive and psychological function.

Health risks from excessive zinc
High zinc intakes can cause nausea, dizziness, headaches, gastric distress, vomiting, and loss of appetite. If used for weeks, doses of 50mg zinc or more —typically from supplements or excessive use of denture adhesive creams that contain zinc—can interfere with copper absorption, which can cause low copper status, reduce immune function, and lower HDL cholesterol levels. The amount of zinc obtained from food is rarely as high as 50mg, so the zinc in foods is unlikely to cause zinc toxicity. Very high doses of zinc from supplements (142mg/day) might also interfere with magnesium absorption and disrupt magnesium balance.

 

What amount of zinc is enough?
RDA: The Recommended Dietary Allowance (RDA) for adults 19+ years is 11 mg a day for men and 8 mg for women. Pregnancy and lactation requires slightly more at 11 mg and 12 mg, respectively.

UL: The Tolerable Upper Intake Level is the maximum daily intake unlikely to cause harmful effects on health. The UL for zinc is 40 mg daily for all males and females ages 19+ years.

Rich zinc food sources:
1. AnimalsThe amount of zinc in each serving about 84grams:
- Oysters, Eastern, farmed, raw: 32mg
- Oysters, Pacific, cooked: 28.2 mg
- Beef, bottom sirloin, roasted: 3.8mg
- Blue crab, cooked: 3.2mg
- Pork, center loin (chops), bone in, broiled: 1.9mg
- Turkey breast, meat only, roasted: 1.5 mg
- Shrimp, cooked: 1.4mg
- Sardines, canned in oil, drained solids with bone: 1.1 mg
- Fish, salmon, cooked: 0.5 mg

2. PlantsThe amount of zinc in each serving is about 24grams:
- Peanuts, dry roasted: 0.8 mg
- Pumpkin seeds, roasted: 2.2 mg
- Broccoli, chopped, cooked (½ cup): 0.4 mg
- Cherry tomatoes, raw (½ cup): 0.1 mg
- Blueberries, raw (½ cup): 0.1 mg
- Lentils, boiled (½ cup): 1.3 mg
- Kidney beans, canned (½ cup): 0.6 mg
- Rice, brown, long grain, cooked(½ cup): 0.7 mg
- Rice, white, long grain, cooked (½ cup): 0.3 mg
- Bread, white (1 slice): 0.2 mg
- Bread, whole wheat (1 slice): 0.6 mg

3. Dairy foods- Cheese, cheddar (42grams): 1.5mg
- Greek yogurt, plain (168grams): 1.0mg
- Milk, 1% milk fat (1 cup): 1.0mg
- Egg, large (1 egg): 0.6mg

 

Zinc and health
1. ImmunityBecause zinc supports the growth and normal functioning of immune cells, even a mild or moderate deficiency can slow down the activity of lymphocytes, neutrophils, and macrophages that protect the body from viruses and bacteria. Zinc deficiency is a common health problem in children from low and middle-income countries that contributes to stunting of growth, diarrhea, pneumonia, and malaria. The elderly who may have low zinc intakes from a poor appetite due to multiple diseases and medications are at risk for infections, such as pneumonia and skin ulcers.

2. Wound healingAdequate zinc is needed to create new cells, particularly collagen and fiber-like tissues, a necessary function in repairing damaged cells. Zinc also supports immune cell activity that combats inflammation from a wound. Therefore the greatest benefit of zinc appears to be in people who are deficient in the mineral and who have severe wounds such as decubitus ulcers or extensive burns. Because people with these conditions have higher zinc needs and may have poor appetites, supplements or topical creams are used rather than relying on food intake alone. In these cases, zinc is often combined with other nutrients like protein, vitamin C, and L-arginine that also promote wound healing such as in a nutritional shake. However, a benefit of zinc supplementation has not been shown in people with skin ulcers who have normal blood levels of zinc.

 

3. Age-related macular degenerationAMD is the leading cause of significant vision loss in older people. The human retina has a high zinc concentration, and research has shown that supplements containing both zinc and antioxidants might delay the progression of AMD and vision loss, possibly by preventing cellular damage in the retina.

Clinical trial evidence has confirmed the benefits of zinc supplementation, in combination with certain antioxidants, for slowing the progression of AMD. The Age-Related Eye Disease Study (AREDS) was a clinical trial in 4,757 participants age 50 to 80 years with a high risk of advanced AMD (i.e., they had intermediate AMD or advanced AMD in one eye and good vision in the other eye). AREDS found that participants who took a supplement each day containing 80 mg zinc in the form of zinc oxide, 15 mg (7,500 mcg retinol activity equivalent [RAE]) beta-carotene, 180 mg (400 International Units [IU]) vitamin E in the form of dl-alpha-tocopheryl acetate, 500 mg vitamin C, and 2 mg copper for 5 years had a 25% lower risk of advanced AMD than those taking a placebo.

The follow-up AREDS2 study confirmed the value of the AREDS supplement in reducing the progression of AMD in 4,203 participants over a median follow-up period of 5 years. AREDS2 also showed that a formulation providing 25 mg zinc (about one-third the amount in the original formulation) provided the same protective effect against advanced AMD. However, because AREDS2 had fewer participants than the original AREDS study, and fewer than half took the formula containing less zinc, the researchers viewed this finding as preliminary. The National Eye Institute recommends use of an AREDS formulation providing 80 mg zinc.

Individuals who have or are developing AMD should talk to their health care provider about their zinc intakes and the supplement formulations used in the AREDS studies.

Groups at Risk of Zinc Inadequacy
The following groups are among those most likely to have inadequate zinc status.

People with gastrointestinal disorders or who have had bariatric surgeryZinc inadequacy is common in people with inflammatory bowel disease (IBD, which includes ulcerative colitis and Crohn’s disease) or bariatric surgery involving resection of the gastrointestinal tract because of poor dietary intakes, decreased absorption, or increased urinary excretion as a result of inflammation. Approximately 15% to 40% of people with IBD have zinc deficiency during active disease states and while in remission. In patients with zinc deficiency, the risk of IBD-related symptoms (including anemia, hemorrhage, and abdominal or perianal fistula) increases, and these patients are more likely to need hospitalization or surgery. Zinc supplementation might reduce these risks. Approximately 50% of people with newly diagnosed celiac disease have a high risk of zinc inadequacy or deficiency; potential contributors to this risk might include zinc malabsorption and mucosal inflammation. These deficiencies sometimes persist even when people with celiac disease avoid foods containing gluten.

Vegetarians (especially vegans)The bioavailability of zinc from vegetarian diets is lower than from nonvegetarian diets because vegetarians typically eat large amounts of legumes and whole grains, which contain phytates that bind zinc and inhibit its absorption. In addition, meat is high in bioavailable zinc. As a result, vegetarians and vegans usually have lower dietary intakes of zinc and lower serum zinc levels than nonvegetarians. Vegetarians and vegans might benefit from using certain food preparation techniques that reduce the binding of zinc by phytates and increase its bioavailability, such as soaking beans, grains, and seeds in water for several hours before cooking them. In addition, organic acids in fermented foods might increase zinc absorption. Vegetarians and vegans might also benefit from zinc supplements.

People who are pregnant or lactatingDuring pregnancy, the amount of zinc needed increases to accommodate fetal growth, and the FNB therefore recommends that pregnant people consume 3 mg/day more zinc than nonpregnant people in the same age group. Similarly, the zinc requirement increases by 4 mg/day during lactation.

Older infants who are exclusively breastfedZinc concentrations in breast milk peak during the first month after birth and then decline by approximately 75% by the ninth month. Because of this sharp drop, human breast milk alone is not sufficient to meet the infant’s zinc requirement after age 6 months. The FNB recommends that in addition to breast milk, infants age 7–12 months consume age-appropriate foods or formula containing zinc.

Children with sickle cell diseaseChildren with sickle cell disease (SCD) have a high risk of zinc insufficiency or deficiency, possibly as a result of the chelation therapy used to treat iron overload. Children with SCD and low zinc status often are shorter and weigh less than age-matched peers, and they also have a higher risk of maturation delays, vaso-occlusive pain crises (blockages of blood flow to an area of the body), and associated hospitalizations. Supplemental zinc might enhance growth in children with SCD and decrease the risk of bacterial infections, hospitalizations, and vaso-occlusive pain crises.

People with alcohol use disorderLow zinc status has been observed in 30% to 50% of people with alcohol use disorder. Ethanol consumption decreases intestinal absorption of zinc and increases urinary zinc excretion. In addition, the variety and amount of food consumed by many people with alcohol use disorder is limited, leading to inadequate zinc intake.

Signs of Deficiency and Toxicity
1. Deficiency:A zinc deficiency is rare and is seen most commonly in people who do not absorb zinc well due to digestive disorders such as inflammatory bowel diseases or who have undergone gastrointestinal surgery. Those with chronic liver or kidney disease are also at risk. Excessive or prolonged diarrhea can lead to a zinc deficiency, as well as severe conditions with increased zinc needs like burns and sepsis (an infection caused by harmful bacteria entering the blood). Zinc is more efficiently absorbed when taken in smaller doses and in people who are deficient in the mineral.

Signs of deficiency include: Loss of taste or smell; Poor appetite; Depressed mood; Decreased immunity; Delayed wound healing; Diarrhea; Hair loss.

2. Toxicity:Toxicity occurs almost exclusively from zinc supplements rather than food. There have been no reports of eating too much zinc from the diet alone.

Signs of toxicity include: Nausea, vomiting; Poor appetite; Abdominal pain or cramping; Headaches; Diarrhea.

Did You Know?
Zinc oxide was used in ointments to treat wounds, as noted in ancient Greek medical texts. Today, zinc oxide is still a popular over-the-counter treatment skin treatment. It can defend against sunburns by reflecting and scattering ultraviolet rays so they do not penetrate the skin. It is also used to treat inflamed skin conditions like burns, eczema, bedsores, and diaper rash. The compound forms a protective barrier on the skin’s surface, repelling away moisture and allowing the skin to heal. It may also aid enzymes to break down damaged collagen tissue so that new tissue can be formed. No negative side effects have been reported.

Interactions with Medications
Zinc has the potential to interact with certain medications. In addition, several types of medications might adversely affect zinc levels. A few examples as Antibiotics, Penicillamine, Diuretics. Individuals taking these and other medications on a regular basis should discuss their zinc status with their health care providers.

Compiled and penned by Crocus Media