How Much Zinc Per Day? Everything You Need to Know about Zinc
Getting Enough Zinc From Your Diet?
Article Written By: Dr. Taylor J. Graber MD
Peer Reviewed By: Dr. Ilona Catalina Juan MD
Date Updated: August 18th, 2021
Physiology
Zinc is an essential nutrient, which is present in many biochemical mechanisms which have various physiologic functions in the body. Zinc has been extensively studies, and has biologic roles in calatytic, structural, and regulatory functions in the body. It is present in the activity of over 300 enzymes. Zinc is present within all human cells, and is critically important to biologic processes, but it is not synthetically produced by the body and must be obtained through the diet. Zinc is the second-most-abundant trace mineral in the body after iron.
Diet:
Zinc is usually obtained from dietary intake present within the food that we eat. Food is broken down once it enters the stomach by various enzymes, and the individual components (such as the ion Zinc) are absorbed later in the gastrointestinal system. Zinc is specifically absorbed in the small intestines (duodenum and jejunum) by carrier proteins. The amount of zinc which is absorbed by these proteins is directly related to the stores of zinc already present in the body (when the body has larger stores of zinc it will absorb less from the small intestine). Zinc deficient humans absorb zinc with increased efficiency compared to humans on a high-zinc diet. The amount of zinc which you would absorb also depends on the source. If the zinc is first coming from solid food which must be broken down, the absorption is less efficient (33%) than if taken in an oral aqueous solution (60-70%). The absorption is also less efficient when bound to phytates which are present in many plants. These phytic acid residues can bind zinc and limit its ability to bind the proteins for uptake in the gastrointestinal tract, thus decreasing absorption. The amount which is not absorbed is excreted. Proteins co-administered with Zinc can influence the amount of zinc absorption. Consumption of animal proteins (such as beef, eggs, cheese) improve the absorption of zinc, as the amino acids from animal proteins keep zinc in a soluble, absorbable form.
Once the zinc ion is absorbed from the small intestine endothelium, it enters into the portal system where it is taken to the liver for processing, until it is distributed back to the systemic circulation and ultimately to the tissues where it is needed for biologic processes.
Ultimately, 50% of zinc is eliminated from the body via the gastrointestinal system, while the rest is excreted in urine, sweat, and skin losses.
Causes of Deficiency:
The most common general cause of zinc deficiency is inadequate intake compared to requirements, malabsorption (inflammatory bowel disease) or increased gastrointestinal losses (fecal loss during acute diarrhea). Inadequate dietary zinc is very common in many parts of the world, and can occur from low dietary intake, heavy reliance on zinc poor foods, or poorly absorbable (highly phytate bound) zinc in dietary intake.
How Much Zinc Per Day? [Recommended Daily Dosages (Link)]
The body can naturally regulate its absorption of zinc from the diet, so that it will maintain homeostasis (a relatively constant amount of zinc over time). The body can regulate these levels in extremes of dietary intake (from 2.8mg/kg/day to 40mg/kg/day). With a constant dietary intake, the body will self-regulate levels within 6-12 days.
The estimated average requirement (EAR) looks to calculate the mean dietary requirement, which is defined as the intake at which 50% of individuals would meet their physiologic requirements. This is calculated as the physiologic requirement by weight, divided by the estimated average absorption. For a 17 year old female weighing 55kg, the requirement by WHO standards of 1.54 mg/day (this is the amount absorbed and active in the body, not consumed from the diet). With an average absorption of 33%, she would need to consume 5mg/day (rounded from 4.67mg) to meet her average daily requirement.
Certain groups have increased requirements for zinc and are at increased risk of dietary/physiologic depletion of zinc stores. These groups are infants, children, pregnant/lactating women, and the elderly. Infants and children have increased zinc requirements during growth. Zinc requirements for malnourished infants and children can be as much as 2-4mg/kg/day (very high compared to 0.2mg/kg for comparative healthy children). Adolescents need more zinc during pubertal growth. Physiologic anemia of pregnancy is very common, and supplemental iron is the most common treatment. Oral supplementation with iron (as low as 60mg/day) has been shown to decrease zinc absorption during pregnancy.
Groups At Elevated Risk of Zinc Deficiency:
1. Individuals with inflammatory bowel disease like Crohn’s Disease or Ulcerative Colitis.
2. Vegetarians
3. Vegans
4. Infants, Children, Adolescents
5. Women who are pregnant or breastfeeding
6. Individuals with eating disorders leaving them malnourished such as anorexia and bulimia.
7. Individuals who chronically abuse alcohol
8. Individuals with chronic kidney disease
In first world countries, outside of high-risk groups, it is normal to obtain the recommended daily intake of zinc through diet alone.
The table estimates a wide range of values for recommended daily intake, but common estimates for these values are 11mg/day for adult men, 8mg/day for adult women which is increased to 11mg/day when pregnant and 12mg/day when breastfeeding.
Foods Highest in Zinc Content:
1. Shellfish: Oysters, crab, mussels, lobster and clams
2. Meat: Beef, pork, lamb and bison
3. Poultry: Turkey and chicken
4. Fish: Flounder, sardines, salmon and sole
5. Legumes: Chickpeas, lentils, black beans, kidney beans, etc.
6. Nuts and seeds: Pumpkin seeds, cashews, hemp seeds, etc.
7. Dairy products: Milk, yogurt and cheese
8. Eggs
9. Whole grains: Oats, quinoa, brown rice, etc.
10. Certain vegetables: Mushrooms, kale, peas, asparagus and beet greens
Supplementation:
The easiest way to supplement normal dietary zinc would be through oral supplementation in the form of absorbable zinc, such as ZnSO4, zinc gluconate, or zinc acetate, or through a multivitamin. Recommended supplementation would range based on age and weight, according to the graph above. If you are supplementing for an acute diarrheal illness, the dosage would be twice the recommended daily allowance. For the calculated 17 year old, 55kg above, this would be double the 5mg per day at a value of 10mg per day for 14 days. Multiple clinical studies have shown that this can decrease the severity and duration of both acute and persistent diarrhea.
Benefits of Proper Dietary Zinc :
Risks of zinc deficiency are varied, depending on the severity and duration of dietary zinc deficiency. Absent specific functional, physical, or chemical signs of deficiency, the diet is assumed to be adequate, although studies have estimated as much as 25% of the world’s population is at risk for zinc deficiency (highest in developing countries). Systems which can be affected include the epidermal, gastrointestinal, central nervous, immune, skeletal, and reproductive.
1. Improves infection Response:
Diarrhea: zinc deficiency results in impairment of the immune system as well as intestinal mucosal cell transport. This can form a vicious cycle, where diarrhea can lead to increased gastrointestinal loss of zinc, and zinc deficiency can predispose to diarrhea.
Pneumonia: zinc supplementation has been show to decrease prevalence of pneumonia in developing countries with high amounts of dietary zinc deficiency
Zinc deficiency is estimated to cause over 450,000 deaths in children under 5 each year.
2. Decreases inflammation
Zinc deficiency is more common in children with accelerated atherosclerosis, and zinc may be protective in the process of inflammation and atherosclerosis.
Zinc decreases oxidative stress and can reduce inflammatory markers in the body.
3. Improves acne control
4. Reduces growth retardation from deficiency: most significant during periods of rapid growth, such as infancy, puberty, and pregnancy, where zinc requirements are the largest.
5.. Improves cognitive function, behavioral issues, impaired memory/learning.
6. Improves wound healing, and improvement of chronic non-healing skin ulcers. Zinc supplementation is frequently used in hospitals in the treatment of burns, ulcers, and other skin injuries to accelerate healing. It forms a critical role in collagen synthesis, immune function, and inflammatory response and is necessary for proper healing.
7. Improves metabolic function markers in disease states like obesity and diabetes. Zinc supplementation might be useful in controlling metabolic aspects of childhood obesity and insulin resistance.
Selected Studies For Review:
1: Zinc for the Common Cold (Viral Upper Respiratory Injection from Rhinovirus) (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6457799/)
Methods: Cochrane Review Article, looking at randomized, double-blind, placebo-controlled trials using zinc for 5 consecutive days of treatment for the common cold, or daily for five months to prevent the common cold.
Size: 1387 and 394 patients.
Findings for Taking during Viral URI: Zinc was associated with a reduction of days of illness (-1.03 days, CI -1.72 to -0.34 days with P=0.003) but not the severity of symptoms (-1.06, CI -2.36 to 0.23 with P=0.11), reduction of symptomatic patients at 7 days of treatment (odds ratio 0.45, CI 0.2 to 1 with P=0.05).
Findings for Prevention: Decreased incidence of developing a cold (0.64 with CI 0.47 to 0.88 with P=0.006), significantly decreased prescription of antibiotics and significantly decreased days of work/school missed (both P= <0.001).
Adverse Events: Bad taste, Nausea.
Conclusions: Supplementing the diet with Zinc (75mg PO Daily) during a viral URI can decrease days of illness and hasten recovery when started within 24 hours of symptom onset. When taken for prevention, Zinc can decrease the amount of cold episodes and decrease the days missed from work or school.
2: Zinc lozenges and the common cold (Link)
Methods: Meta-analysis, looking at placebo-controlled zinc lozenge trials with dosages of >75mg/day.
Size: 7 randomized control trials with 575 patients.
Findings: Mean common cold duration was 33% shorter for the zinc groups than control groups (CI 21% to 45%). These trials included zinc acetate and zinc gluconate lozenges, and found no statistically significant differences between them. There was no increased affect from trials which used 80-92mg/day and trials which used higher doses of 192-207mg/day.
Conclusions: Zinc supplementation of >75mg/day during common cold episodes can decrease duration of symptoms by 33%. There is no benefit for increased supplementation over 100mg/day, and there are no major differences between zinc gluconate and zinc acetate.
3: Zinc Supplementation on Wound Healing in Diabetic Patients (Link)
Methods: Randomized, double-blind, placebo controlled trial with two groups. Randomized to a group with zinc supplementation (220mg zinc sulfate with 50mg elemental zinc) or placebo for 12 weeks.
Size: 60 patients aged 40-85 with grade 3 diabetic foot ulcers. 30 patients in each group.
Findings: After 12 weeks, zinc supplementation group had significant reductions in ulcer length (-1.5cm) and width (-1.4cm), fasting glucose (-40), improvement in insulin concentration (-8) and HbA1c (-0.5). Improvements in HDL cholesterol (+4.1), plasma total antioxidant capacity (+91.7), and total glutathione (+68.1) were also seen.
Conclusions: Zinc supplementation in metabolically effected patients can improve skin healing, wound healing, and improve inflammatory markers.
Risks of Zinc Toxicity:
Elevated risk in affluent countries where food choice and excessive consumption of zinc supplements can lead to an imbalance of zinc intake relative to copper intake and lead to copper deficiency.
1. Nausea and vomiting
2. Diarrhea
3. Loss of appetite
4. Abdominal cramps
TL;DR About Zinc Deficiency:
1. Second most abundant trace mineral in the body after zinc
2. Critically important in many cellular functions
3. Benefits include improved wound healing, increased recovery from viral illnesses, reduced inflammation
4. Low risk of toxicity with short term supplementation
5. Recommended daily intake is 11mg/day for adult men, 8mg/day for adult women which is increased to 11mg/day when pregnant and 12mg/day when breastfeeding.
6. Groups at increased risk of zinc deficiency include: vegans, vegetarians, women who are pregnant or breastfeeding, individuals with chronic inflammatory disease or inflammatory bowel disease such as Crohn’s Disease or Ulcerative Colitis.
7. During acute or persistent episodes of diarrhea, the recommended intake is double the normal recommended intake for 14 days, which would include 20-25mg/day for men and 15-20mg/day for women.
8. During viral upper respiratory infections from the common cold, recommended intake is 75mg/day. This can reduce symptom duration by 33%.
9. These multiple benefits of zinc, especially during viral infections involving URI or diarrhea, are why we at ASAP IVs have formulated zinc as a critical component of our Immunity Booster and Immune Recovery IV drips.