Zinc deficiency
Zinc deficiency | |
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phytate -containing whole grains |
Zinc deficiency is defined either as insufficient zinc to meet the needs of the body, or as a serum zinc level below the normal range. However, since a decrease in the serum concentration is only detectable after long-term or severe depletion, serum zinc is not a reliable biomarker for zinc status.[1] Common symptoms include increased rates of diarrhea. Zinc deficiency affects the skin and gastrointestinal tract; brain and central nervous system, immune, skeletal, and reproductive systems.
Zinc deficiency in humans is caused by reduced dietary intake, inadequate absorption, increased loss, or increased body system use. The most common cause is reduced dietary intake. In the U.S., the
The highest concentration of dietary zinc is found in oysters, meat, beans, and nuts. Increasing the amount of zinc in the soil and thus in crops and animals is an effective preventive measure. Zinc deficiency may affect up to 2 billion people worldwide.[3]
Signs and symptoms
Skin, nails and hair
Zinc deficiency may manifest as
Mouth
Zinc deficiency can manifest as non-specific
Vision, smell and taste
Severe zinc deficiency may disturb the sense of
Immune system
Impaired immune function in people with zinc deficiency can lead to the development of respiratory, gastrointestinal, or other infections, e.g., pneumonia.
Diarrhea
Zinc deficiency contributes to an increased incidence and severity of diarrhea.[15][16]
Appetite
Zinc deficiency may lead to loss of appetite.[18]
Cognitive function and hedonic tone
Cognitive functions, such as learning and
Psychological disorders
Low plasma zinc levels have been alleged to be associated with many psychological disorders. Schizophrenia has been linked to decreased brain zinc levels.[23] Evidence suggests that zinc deficiency could play a role in depression.[23][24][25] Zinc supplementation may be an effective treatment in major depression.[26][27]
Growth
Zinc deficiency in children can cause delayed growth[5] and has been claimed to be the cause of stunted growth in one third of the world's population.[28]
During pregnancy
Zinc deficiency during pregnancy can negatively affect both the mother and fetus. Animal studies indicate that maternal zinc deficiency can upset both the sequencing and efficiency of the birth process. An increased incidence of difficult and prolonged labor, hemorrhage, uterine
Zinc deficiency can interfere with many metabolic processes when it occurs during infancy and childhood, a time of rapid growth and development when nutritional needs are high.[30] Low maternal zinc status has been associated with less attention during the neonatal period and worse motor functioning.[31] In some studies, supplementation has been associated with motor development in very low birth weight infants and more vigorous and functional activity in infants and toddlers.[31]
Testosterone production
Zinc is required to produce testosterone. Thus, zinc deficiency can lead to reduced circulating testosterone, which could lead to sexual immaturity, hypogonadism, and delayed puberty.[5]
Causes
Dietary deficiency
Zinc deficiency can be caused by a diet high in
In the U.S., the
Food | mg in one serving | Percentage of 11 mg recommended daily intake |
---|---|---|
Oysters, cooked, breaded and fried, 3 ounces (85g) (about 5 average sized oysters) | 74.0 | 673% |
Beef chuck roast, braised, 3 ounces (85g) | 7.0 | 64% |
Crab, Alaska king, cooked, 3 ounces (85g) | 6.5 | 59% |
Beef patty, broiled, 3 ounces (85g) | 5.3 | 48% |
Cashews, dry roasted, 3 ounces (85g) | 4.8 | 44% |
Lobster, cooked, 3 ounces (85g) | 3.4 | 31% |
Pork chop, loin, cooked, 3 ounces (85g) | 2.9 | 26% |
Baked beans, canned, plain or vegetarian, 1⁄2 cup | 2.9 | 26% |
Almonds, dry roasted, 3 ounces (85g) | 2.7 | 25% |
Chicken, dark meat, cooked, 3 ounces (85g) | 2.4 | 22% |
Yogurt, fruit, low fat, 8 ounces (230g) | 1.7 | 15% |
Shredded wheat, unfortified, 1 cup[36] | 1.5 | 14% |
Chickpeas, cooked, 1⁄2 cup | 1.3 | 12% |
Cheese, Swiss, 1 ounce (28g) | 1.2 | 11% |
Oatmeal, instant, plain, prepared with water, 1 packet | 1.1 | 10% |
Milk, low-fat or non-fat, 1 cup | 1.0 | 9% |
Kidney beans, cooked, 1⁄2 cup | 0.9 | 8% |
Chicken breast, roasted, skin removed, 1⁄2 breast | 0.9 | 8% |
Cheese, cheddar or mozzarella, 1 ounce (28g) | 0.9 | 8% |
Peas, green, frozen, cooked, 1⁄2 cup | 0.5 | 5% |
Flounder or sole, cooked, 3 ounces (85g) | 0.3 | 3% |
Recent research findings suggest that increasing atmospheric carbon dioxide concentrations will exacerbate zinc deficiency problems in populations that consume grains and legumes as staple foods. A meta-analysis of data from 143 studies comparing the nutrient content of grasses and legumes grown in ambient and elevated CO2 environments found that the edible portions of wheat, rice, peas and soybeans grown in elevated CO2 contained less zinc and iron.[37] Global atmospheric CO2 concentration is expected to reach 550 p.p.m. in the late 21st century. At this CO2 level the zinc content of these crops was 3.3–9.3% lower than that of crops grown in the present atmosphere. A model of the nutritional impact of these lower zinc quantities on the populations of 151 countries predicts that an additional 175 million people could face dietary zinc deficiency as the result of increasing atmospheric CO2.[38]
Inadequate absorption
Numerous small bowel diseases which cause destruction or malfunction of the gut mucosa enterocytes and generalized malabsorption are associated with zinc deficiency.[citation needed]
Increased loss
Exercising, high alcohol intake, and diarrhea all increase loss of zinc from the body.[5][39] Changes in intestinal tract absorbability and permeability due, in part, to viral, protozoal, or bacteria pathogens may also encourage fecal losses of zinc.[40]
Chronic disease
The mechanism of zinc deficiency in some diseases has not been well defined; it may be multifactorial.[citation needed]
Wilson's disease, sickle cell disease, chronic kidney disease, chronic liver disease have all been associated with zinc deficiency.[41][42] It can also occur after bariatric surgery, mercury exposure[43][44] and tartrazine. [citation needed]
Although marginal zinc deficiency is often found in depression, low zinc levels could either be a cause or a consequence of mental disorders and their symptoms.[24]
Mechanism
As biosystems are unable to store zinc, regular intake is necessary. Excessively low zinc intake can lead to zinc deficiency, which can negatively impact an individual's health.
Zinc is a critical component of the
Pra1 (pH regulated antigen 1) is a candida albicans protein that scavenges host zinc.[52]
Diagnosis
Diagnosis is typically made based on clinical suspicion and a low level of zinc in the blood. Any level below 70 mcg/dL (normal 70-120 mcg/dL)is considered as zinc deficiency. Zinc deficiency could be also associated with low alkaline phosphatase since it acts a cofactor for this enzyme.[citation needed]
There is a paucity of adequate zinc biomarkers, and the most widely used indicator, plasma zinc, has poor sensitivity and specificity.[53]
Classification
Zinc deficiency can be classified as acute, as may occur during prolonged inappropriate zinc-free
Prevention
Five interventional strategies can be used:
- Adding zinc to soil, called agronomic biofortification, which both increases crop yields and provides more dietary zinc.
- Adding zinc to food, called food fortification. The Republic of China, India, Mexico and about 20 other countries, mostly on the east coast of sub-Saharan Africa, fortify wheat flour and/or maize flour with zinc.[54]
- Adding zinc rich foods to diet. The foods with the highest concentration of zinc are proteins, especially animal meats, the highest being oysters.phytates which bind zinc and reduce its bioavailability.[5]
- Oral repletion via tablets (e.g., zinc gluconate) or liquid (e.g., zinc acetate). Oral zinc supplementation in healthy infants more than six months old has been shown to reduce the duration of any subsequent diarrheal episodes by about 11 hours.[56]
- Oral repletion via multivitamin/mineral supplements containing zinc gluconate, sulfate, or acetate. It is not clear whether one form is better than another.[55]
Epidemiology
Zinc deficiency affects about 2.2 billion people around the world.[3] Severe zinc deficiency is rare, and is mainly seen in persons with acrodermatitis enteropathica, a severe defect in zinc absorption due to a congenital deficiency in the zinc carrier protein ZIP4 in the enterocyte.[5] Mild zinc deficiency due to reduced dietary intake is common.[5] Conservative estimates suggest that 25% of the world's population is at risk of zinc deficiency.[34] Providing micronutrients, including zinc, to humans is one of the four solutions to major global problems identified in the Copenhagen Consensus from an international panel of economists.[57]
History
Significant historical events related to zinc deficiency began in 1869 when zinc was first discovered to be essential to the growth of an organism
Phytate was recognized as removing zinc from nutrients given to chicken and swine in 1960. That it can cause human zinc deficiency however was not recognized until Reinhold's work in Iran in the 1970s. This phenomenon is central to the high risk of zinc deficiency worldwide.[62]
Soils and crops
Soil zinc is an essential micronutrient for crops. Almost half of the world's cereal crops are deficient in zinc, leading to poor crop yields.[63] Many agricultural countries around the world are affected by zinc deficiency.[64] In China, zinc deficiency occurs on around half of the agricultural soils, affecting mainly rice and maize. Areas with zinc deficient soils are often regions with widespread zinc deficiency in humans. A basic knowledge of the dynamics of zinc in soils, understanding of the uptake and transport of zinc in crops and characterizing the response of crops to zinc deficiency are essential steps in achieving sustainable solutions to the problem of zinc deficiency in crops and humans.[65]
Biofortification
Soil and foliar application of zinc fertilizer can effectively increase grain zinc and reduce the phytate:zinc ratio in grain.[66][67] People who eat bread prepared from zinc enriched wheat have a significant increase in serum zinc.[citation needed]
Zinc fertilization not only increases zinc content in zinc deficient crops, it also increases crop yields.[65] Balanced crop nutrition supplying all essential nutrients, including zinc, is a cost effective management strategy. Even with zinc-efficient varieties, zinc fertilizers are needed when the available zinc in the topsoil becomes depleted.
Plant breeding can improve zinc uptake capacity of plants under soil conditions with low chemical availability of zinc. Breeding can also improve zinc translocation which elevates zinc content in edible crop parts as opposed to the rest of the plant.
Central Anatolia, in Turkey, was a region with zinc-deficient soils and widespread zinc deficiency in humans. In 1993, a research project found that yields could be increased by 6 to 8-fold and child nutrition dramatically increased through zinc fertilization.[68] Zinc was added to fertilizers. While the product was initially made available at the same cost, the results were so convincing that Turkish farmers significantly increased the use of the zinc-fortified fertilizer (1 percent of zinc) within a few years, despite the repricing of the products to reflect the added value of the content. Nearly ten years after the identification of the zinc deficiency problem, the total amount of zinc-containing compound fertilizers produced and applied in Turkey reached a record level of 300,000 tonnes per annum. It is estimated that the economic benefits associated with the application of zinc fertilizers on zinc deficient soils in Turkey is around US$100 million per year. Zinc deficiency in children has been dramatically reduced.
References
- S2CID 13748442.
- ^ a b c "Zinc" Archived 19 September 2017 at the Wayback Machine, pp. 442–501 in Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academy Press. 2001.
- ^ PMID 22664333.
- PMID 6451820.
- ^ ISBN 978-1-4051-6911-0.
- ^ ISBN 9780702053047.
- ISBN 9780702049484.
- ISBN 9780702030574.
- S2CID 35435439.
- PMID 17651517.
- PMID 16254578.
- PMID 17374022.
- PMID 16768159.
- ISBN 9780124046061.
- ^ a b Penny M. Zinc Protects: The Role of Zinc in Child Health. 2004. Archived 13 May 2008 at the Wayback Machine
- ^ PMID 27915460.
- ^ PMID 22852057.
- PMID 21846317.
- S2CID 13332474.
- ^ ISBN 9780080924694. Retrieved 18 August 2015.
- S2CID 18669835.
- S2CID 14925322.
- ^ PMID 28713269.
- ^ S2CID 381132.
- PMID 22095091.
- PMID 21798601.
- S2CID 1725139.
- ^ ISBN 9780702051036.
- ^ PMID 16491666.
- ^ Sanstead HH, et al. (2000). "Zinc nutriture as related to brain". J. Nutr. 130: 140S–146S.
- ^ PMID 9701161.
- S2CID 74543530.
- PMID 1858720.
- ^ PMID 16632171.
- ^ Adapted from http://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/#h3.
- ^ "Shredded wheat". eatthismuch.com. Retrieved 20 February 2019.
- PMID 24805231.
- S2CID 91727337.
- PMID 3411389.
- PMID 11110854.
- ^ "zinc deficiency". GPnotebook.
- PMID 12595353.
- S2CID 32876828.
- PMID 2881702.
- PMID 23493534.
- PMID 7946529.
- PMID 12730443.
- PMID 14535585.
- S2CID 41978978.
- PMID 11908743.
- PMID 11115789.
- PMID 22761575.
- PMID 12612181.
- ^ "Map: Count of Nutrients in Fortification Standards". Food Fortification Initiative. 2018. Retrieved 24 January 2019.
- ^ a b "Zinc in diet: MedlinePlus Medical Encyclopedia". medlineplus.gov. 2 February 2015. Retrieved 21 February 2017.
- PMID 27996088.
- ^ "Copenhagen Consensus Center". Retrieved 30 August 2014.
- ^ Raulin J (1869). "Chemical studies on vegetation". Annales des Sciences Naturelles. 11: 293–299.
- .
- PMID 13985937.
- ISBN 9781550093612.
- PMID 23319126.
- S2CID 33142627.
- ^ "IFA : International Fertilizer Industry Association - Zinc in Soils and Crop Nutrition / Publications / LIBRARY / Home Page / IFA". Archived from the original on 19 December 2008. Retrieved 23 April 2009.
- ^ a b Alloway BJ (2008). "Zinc in Soils and Crop Nutrition, International Fertilizer Industry Association, and International Zinc Association". Archived from the original on 19 February 2013. Retrieved 15 December 2012.
- S2CID 16068957.
- PMID 18311920.
- S2CID 34821888.
Further reading
- Maret W (2013). "Zinc and the Zinc Proteome". In Banci L (ed.). Metallomics and the Cell. Metal Ions in Life Sciences. Vol. 12. Springer. pp. 479–501. PMID 23595681.