Republished with permission from drfuhrman.com.
Zinc is a mineral essential for immune function, growth, wound healing, reproduction, protein structure, neurotransmitter secretion and insulin secretion, and supports hundreds of chemical reactions.1-3
Zinc-rich foods include beef, oysters, crab, veal, lamb, pumpkin and sesame seeds, pine nuts, peanuts, soybeans, cashews, wild rice, oats and mushrooms.4 However, zinc-rich plant foods also contain substances that inhibit zinc absorption, phytate in particular.5,6 It is important to note, however, that phytate has beneficial health effects despite its tendency to lower zinc absorption. Phytate is a storage form of phosphorus and minerals in plant seeds. Originally viewed as an “anti-nutrient,” its beneficial actions were eventually discovered, such as antioxidant and anti-cancer effects. The presence of phytate also reduces glycemic effects of the foods it is present in, and may bind toxic metals, reducing our absorption of these harmful substances. Preliminary research has also suggested that phytate could help to prevent kidney stones and vascular calcification. Grains, beans, seeds, and nuts are the foods highest in phytate.7
In addition to phytate, a number of other factors reduce zinc absorption, including older age, iron, calcium, protein quality, protein intake and folic acid.8-11 Zinc can be lost in food milling and cooking processes, eventually resulting in a low consumption of zinc.
Zinc Status in Vegetarians and Vegans
A 2013 review of 34 studies concluded that zinc status is lower in vegetarians than omnivores; especially for females and vegans.12 Zinc requirements for those on a completely plant-based diet are estimated to be about 50 percent higher than the standard recommendations of 12 mg/day for females, 16.5 mg/day for males.1,2,13 Therefore, in addition to eating natural foods rich in zinc, it is reasonable to take extra supplemental zinc to assure adequacy on a vegan or near-vegan diet.
Zinc May Protect Against Depression
Zinc is a crucial nutrient for the brain; as mentioned above, zinc is needed for neurotransmitter release.3,14 Zinc may also act to reduce oxidative stress in the brain.14 Low zinc levels could potentially lead to a tendency toward anxiety and depression. In scientific studies, blood zinc concentrations are consistently lower in depressed vs. control subjects. Furthermore, the severity of depression was found to increase with the magnitude of the zinc deficiency.15 Because of these findings, zinc supplementation is being investigated as an adjunct treatment for depression, with promising results.16 I have observed some female vegans, in my medical practice, who developed depression and anxiety which both resolved after supplementing zinc. The association between low zinc and depression appears to be stronger in women compared to men.14
Zinc and The Prostate
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Normal prostate cells contain higher levels of zinc than any other body tissue. However, if prostate cells become cancerous, they lose their ability to accumulate zinc.17,18 There is evidence that zinc has anti-cancer effects in the prostate, however, the relationship between zinc and prostate cancer risk is somewhat unclear.19 Some studies have reported increased cancer risk,20-24 some have reported decreased risk25-28 and others found no relationship at all.8,29
One study, which placed mice on one of three different diets—zinc-deficient, normal, and supplemented, suggested that optimal levels of zinc are protective, but deficiency or excess promotes prostate tumor growth.30
This is relevant for humans too. The VITAL study followed over 35,000 men for 3.5 years, who completed a questionnaire asking about their supplement use over the previous 10 years. Men who had been supplementing with 15 mg of zinc or more per day had a 66 percent decrease in the risk of advanced prostate cancer compared to men who didn’t supplement. There was no association between zinc supplements and overall prostate cancer—except in men who ate more vegetables. Importantly, the authors found that men who both supplemented 15 mg or more of zinc per day and had a higher intake of vegetables did have a reduced risk of overall prostate cancer. However, men taking the same amount of supplemental zinc with a lower intake of vegetables did not reduce their risk.26 Another study found that long-term (10 or more years) supplementation with zinc was associated with a 53 percent reduction in breast cancer risk.31 This research suggests supplementing with zinc most likely is of significant benefit, especially in those that eat a healthful vegan or near-vegan diet.
Symptoms of Zinc Deficiency
This is a medical term used for improper functioning of the reproductive system that results in a defect in the proper operation of gonads (ovaries or testes). The gonads have two functions: to produce hormones and to produce eggs or sperm. The deficiency of sexual and reproductive hormones can result in defective primary or secondary sexual development. This is a serious disorder that can be avoided by consuming zinc-rich foods.
Zinc deficiency can have a bad effect on skin’s health. The skin can turn pale or rough. Stretch marks, acne, and greasy skin are also possible symptoms of zinc deficiency. Zinc performs collagen synthesis which helps in the healing process of wounds on the skin. There is evidence that suggests zinc can assist in the management of herpes types 1 and 2.
Zinc deficiency can affect your brain, which can lead to many emotional disturbances in your daily life. Anger, sudden fright, depression, and low confidence are some symptoms that can occur, while the most common symptom is frequent mood changes. If zinc deficiency is not paid proper attention to, it may result in Attention Deficit Hyperactivity Disorder (ADHD).
Hair loss is a common symptom of zinc deficiency and is caused by the formation of dandruff in the hair. As long as your hair is deprived of zinc, it will not grow normally. People with a long-term lack of zinc can even experience hair loss on other parts of the body. However, similar symptoms can also be a sign of an abundance of zinc in one’s system, this will also lead to hair loss.
Joint and Hip Pain
Painful hip and knee joints have been linked to zinc deficiency. Bones contain a large amount of zinc, and deficiency of this essential mineral will cause pain and other complications. Research has shown that a zinc deficiency can be more detrimental to bone development than general diet restriction.
Deficiency of zinc causes diarrhea, but the mechanism which causes this symptom is unknown. In some registered cases, the level of severity was lessened by nearly 15% with zinc supplementation. Zinc medications are easily available at medical stores, but they should only be taken after a consultation by a health practitioner.
Improper intake of zinc in the body may lead to a severe loss of appetite, which may then result in serious problems like anorexia (not to be confused with anorexia nervosa, which is an eating disorder stemming from a mental issue). Eating less causes malnutrition and lowers zinc intake, making the condition all the more dangerous as zinc levels continue to drop. A loss of appetite can result in weight loss or hinder the growth of new cells and tissues in the body. Children with a zinc deficiency when they are born may also be underweight. Moreover, a weak body weakened by malnutrition is more prone to infections and lower immunity levels.
Zinc is a necessary dietary mineral for a healthy body and its deficiency symptoms should not to be ignored. One should eat healthy foods such as pecans, cashews, and pine nuts as well as fish and eggs. Another way to overcome symptoms of this deficiency would be by taking zinc supplements under the supervision of a qualified medical practitioner.
1. Hunt JR. Bioavailability of iron, zinc, and other trace minerals from vegetarian diets. Am J Clin Nutr 2003, 78:633S-639S.
2. Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Fact Sheet: Zinc.[http://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/]
3. King JC. Zinc: an essential but elusive nutrient. Am J Clin Nutr 2011, 94:679S-684S.
4. USDA National Nutrient Database for Standard Reference [http://ndb.nal.usda.gov/ndb/search/list]
5. Reddy NR, Pierson MD, Sathe SK, Salunkhe DK: Phytates in Cereals and Legumes. CRC Press; 1989: 88-91
6. Miller LV, Krebs NF, Hambidge KM. A mathematical model of zinc absorption in humans as a function of dietary zinc and phytate. J Nutr 2007, 137:135-141.
7. Schlemmer U, Frolich W, Prieto RM, Grases F. Phytate in foods and significance for humans: food sources, intake, processing, bioavailability, protective role and analysis. Mol Nutr Food Res 2009, 53 Suppl 2:S330-375.
8. Costello LC, Feng P, Milon B, et al. Role of zinc in the pathogenesis and treatment of prostate cancer: critical issues to resolve. Prostate Cancer Prostatic Dis 2004, 7:111-117.
9. Lonnerdal B. Dietary factors influencing zinc absorption. J Nutr 2000, 130:1378S-1383S.
10. Chiplonkar SA, Agte VV. Predicting bioavailable zinc from lower phytate forms, folic Acid and their interactions with zinc in vegetarian meals. J Am Coll Nutr 2006, 25:26-33.
11. Campbell NR. How safe are folic acid supplements? Arch Intern Med 1996, 156:1638-1644.
12. Foster M, Chu A, Petocz P, Samman S. Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans. J Sci Food Agric 2013, 93:2362-2371.
13. Frassinetti S, Bronzetti G, Caltavuturo L, et al. The role of zinc in life: a review. J Environ Pathol Toxicol Oncol 2006,25:597-610.
14. Gower-Winter SD, Levenson CW. Zinc in the central nervous system: From molecules to behavior. Biofactors 2012,38:186-193.
15. Swardfager W, Herrmann N, Mazereeuw G, et al. Zinc in depression: a meta-analysis. Biol Psychiatry 2013, 74:872-878.
16. Ranjbar E, Shams J, Sabetkasaei M, et al. Effects of zinc supplementation on efficacy of antidepressant therapy, inflammatory cytokines, and brain-derived neurotrophic factor in patients with major depression. Nutr Neurosci 2014,17:65-71.
17. Huang L, Kirschke CP, Zhang Y. Decreased intracellular zinc in human tumorigenic prostate epithelial cells: a possible role in prostate cancer progression. Cancer Cell Int 2006, 6:10.
18. Costello LC, Franklin RB. Novel role of zinc in the regulation of prostate citrate metabolism and its implications in prostate cancer. Prostate 1998, 35:285-296.
19. Franklin RB, Costello LC. Zinc as an anti-tumor agent in prostate cancer and in other cancers. Arch Biochem Biophys2007, 463:211-217.
20. Leitzmann MF, Stampfer MJ, Wu K, et al. Zinc supplement use and risk of prostate cancer. J Natl Cancer Inst 2003,95:1004-1007.
21. Zhang Y, Coogan P, Palmer JR, et al. Vitamin and mineral use and risk of prostate cancer: the case-control surveillance study. Cancer Causes Control 2009, 20:691-698.
22. Lawson KA, Wright ME, Subar A, et al. Multivitamin use and risk of prostate cancer in the National Institutes of Health-AARP Diet and Health Study. J Natl Cancer Inst 2007, 99:754-764.
23. Gallus S, Foschi R, Negri E, et al. Dietary zinc and prostate cancer risk: a case-control study from Italy. Eur Urol 2007,52:1052-1056.
24. Kolonel LN, Yoshizawa CN, Hankin JH. Diet and prostatic cancer: a case-control study in Hawaii. Am J Epidemiol 1988,127:999-1012.
25. Kristal AR, Stanford JL, Cohen JH, et al. Vitamin and mineral supplement use is associated with reduced risk of prostate cancer. Cancer Epidemiol Biomarkers Prev 1999, 8:887-892.
26. Gonzalez A, Peters U, Lampe JW, White E. Zinc intake from supplements and diet and prostate cancer. Nutr Cancer2009, 61:206-215.
27. Epstein MM, Kasperzyk JL, Andren O, et al. Dietary zinc and prostate cancer survival in a Swedish cohort. Am J Clin Nutr2011, 93:586-593.
28. Key TJ, Silcocks PB, Davey GK, et al. A case-control study of diet and prostate cancer. Br J Cancer 1997, 76:678-687.
29. Platz EA, Helzlsouer KJ. Selenium, zinc, and prostate cancer. Epidemiol Rev 2001, 23:93-101.
30. Prasad AS, Mukhtar H, Beck FW, et al. Dietary zinc and prostate cancer in the TRAMP mouse model. J Med Food 2010,13:70-76.
31. Pan SY, Zhou J, Gibbons L, et al. Antioxidants and breast cancer risk- a population-based case-control study in Canada. BMC Cancer 2011, 11:372.
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