Zinc

Summary (The Good, The Bad, and all other Essential Benefits/Effects/Facts Information)

Zinc is one of the 24 classical micronutrients needed for survival. It can be found in various meat, egg, and legume products and is especially high in oysters. Zinc is known as an aphrodisiac and Testosterone Booster, although the former is anecdotal and the latter only applies to the deficient (directly).

Zinc is highly involved in many enzyme systems in the body. Keeping normal zinc levels helps with the maintenance of these enzyme systems and acts as a hormonal and immune system aid. In very high doses, zinc can act as an aromatase inhibitor and lower estrogen levels but is a potent oxidant; especially in the male prostate. It is also implicated in repair of the intestinal mucosa at similarily high levels.

Zinc is also lost in sweat, as are many minerals, making mineral supplementation almost a necessity for athletes underconsuming the nutrient through food.

Zinc has it's intestinal uptake hindered by the other divalent minerals calcium, Magnesium, and iron when all four together exceed their transporter's uptake limit (around 800mg or so). Consuming these minerals alongside each other below this threshold is fine.

Is a Form of

• Health Support
• Essential Vitamin or Mineral

Goes Well With

• Green Tea (increased absorption)

Does Not Go Well With

• Divalent minerals (Calcium, Magnesium, Iron)

• Chlorogenic acid (Decreased absorption of Zinc)

(Note: Divalent Mineral (Z.I.M.C) competition only occurs at high acute doses exceeding 800mg, combinations below this dose do not exhibit much competitive inhibition)

How to Take (recommended dosage, active amounts, other details)

15mg is the dose used for sedentary populations who may be deficient in zinc (vegetarians/vegans, caloric restriction) and 30mg the more common dose catered to athletes who lose zinc in sweat.

Doses up to 100-150mg are used as a cheap and potent aromatase inhibitor and doses around 300mg have shown efficacy in treatment of some gut dysfunction. Doses at this level, however, are probably not safe for chronic health given the Tolerable Upper Limit of Intake (TUL) is 40mg.

Things to Note

• Zinc is non-stimulatory

Frequently Asked Questions Related to Zinc

• Does ZMA cause weird dreams?

Caution Notice (just some FYI - if needed)

Caution should be taken when using zinc supplementation surpassing the Tolerable Upper Limit of Intake (TUL) of 40mg, and if possible alternate supplements with better toxicology profiles should be used for those purposes desired.

Detailed Summary

1. Sources in the diet
2. Roles in the body through adequate intake
3. Maintaining Zinc Status
4. Roles in the body through higher levels of supplementation
5. Steroid Metabolism
6. Gut permeability

Edit1. Sources in the diet

Zinc is one of the 24 essential vitamins and minerals, specifically a mineral. It is found in high levels in animal tissues and eggs, legumes, and fish; it is exceptionally high in shellfish such as oyster.^[1][2] It may also be fortified into cereal grains in developed countries.^[3]

Edit2. Roles in the body through adequate intake

Zinc's main role in the body is as a prosthetic group for several enzymes called metalloproteins, one of which is the Superoxide Dismustase enzyme; an endogenous anti-oxidant involving both zinc and copper.^[4][5][6] Zinc is also involved in regulating the immune system.^[7][8] A deficiency in zinc is related to delayed growth in youth and hypogonadism in adult males^[9] as well as general mental lethargy and skin abnormalities.^[10]

The RDA values for zinc are an Estimated Average Requirement (EAR) of 6.5mg for females, 8.5-10mg for pregnant or lactating females, and 12mg a day for men. The Recommended Daily Intake (RDI) values are 8mg for females, 10-12mg for pregnant or lactating females, and 14-15mg for males, and the Tolerable Upper intake Limit (TUL) is in the range of 35-40mg for adults of both genders (all numbers daily requirements).^[11][12]

Zinc is known as a mineral regulatory of testosterone levels, and body stores are positively correlated with testosterone levels.^[13]

Edit3. Maintaining Zinc Status

Supplementation is not generally needed if one has a good zinc intake through the diet. Thus practises to increase zinc absorption or to decrease zinc excretion could be potentially useful.

Zinc is lost during sweat and exercise^[14][15] and may be a contributing factor to why testosterone levels seem to be depressed after exhaustive exercise.^[16][17]

Edit4. Roles in the body through higher levels of supplementation

Edit5. Steroid Metabolism

Supra-physiological levels of zinc have been noted to influence steroid metabolism. Zinc has been used as an aromatase inhibitor in doses of 100-150mg. It has been noted to reduce aromatization of testosterone (via aromatase) in the rat liver^[18]. In addition to aromatase, Zinc has also been noted as an inhibitor as 5-alpha reductase^[19], which converts testosterone into dihydrotestosterone (DHT).

As stated earlier, zinc is a regulator of testosterone levels. Supplementation of zinc increases testosterone if one was deficient in zinc before yet does not necessarily increase testosterone above baseline levels.^[20] That being said, it can reduce the exercise-induced depression of testosterone and exert a protective effect during periods of intense exercise.^[21][22][23]

Edit6. Gut permeability

Very high levels of zinc intake (330mg daily) has been implicated in alleviating leaky gut syndrome in those with Crohn's Disease.^[24] It can also prevent or alleviate damage to the intestinal mucosa and some to the liver done by alcohol^[25][26][27] and due to alcohol causing zinc depletion, can also provide therapeutic-like benefit in treating alcohol-induced damage to the gut and liver.^[28][29] Many of these effects were noted as dose dependent, but were seen at 3-5mg/kg bodyweight (an incredibly high dose).

Scientific Support & Reference Citations

References

1. Guéguen M, et al. Shellfish and residual chemical contaminants: hazards, monitoring, and health risk assessment along French coasts. Rev Environ Contam Toxicol. (2011)
2. Maret W, Sandstead HH. Zinc requirements and the risks and benefits of zinc supplementation. J Trace Elem Med Biol. (2006)
3. Brown KH, Hambidge KM, Ranum P; Zinc Fortification Working Group. Zinc fortification of cereal flours: current recommendations and research needs. Food Nutr Bull. (2010)
4. Anzellotti AI, Farrell NP. Zinc metalloproteins as medicinal targets. Chem Soc Rev. (2008)
5. Vallee BL, Auld DS. Zinc metallochemistry in biochemistry. EXS. (1995)
6. Abreu IA, Cabelli DE. Superoxide dismutases-a review of the metal-associated mechanistic variations. Biochim Biophys Acta. (2010)
7. Prasad AS. Zinc in human health: effect of zinc on immune cells. Mol Med. (2008)
8. Prasad AS. Clinical, immunological, anti-inflammatory and antioxidant roles of zinc. Exp Gerontol. (2008)
9. Prasad AS. Clinical manifestations of zinc deficiency. Annu Rev Nutr. (1985)
10. Prasad AS. Zinc deficiency in human subjects. Prog Clin Biol Res. (1983)
11. Nutrient Reference Values for Australia and New Zealand: Zinc
12. Recommended Dietary Allowances: 10th Edition
13. Chang CS, et al. Correlation between serum testosterone level and concentrations of copper and zinc in hair tissue. Biol Trace Elem Res. (2011)
14. Lukaski HC. Magnesium, zinc, and chromium nutriture and physical activity. Am J Clin Nutr. (2000)
15. Campbell WW, Anderson RA. Effects of aerobic exercise and training on the trace minerals chromium, zinc and copper. Sports Med. (1987)
16. Galbo H, et al. Thyroid and testicular hormone responses to graded and prolonged exercise in man. Eur J Appl Physiol Occup Physiol. (1977)
17. Hackney AC, et al. Comparison of the hormonal responses to exhaustive incremental exercise in adolescent and young adult males. Arq Bras Endocrinol Metabol. (2011)
18. Om AS, Chung KW. Dietary zinc deficiency alters 5 alpha-reduction and aromatization of testosterone and androgen and estrogen receptors in rat liver. J Nutr. (1996)
19. Stamatiadis D, Bulteau-Portois MC, Mowszowicz I. Inhibition of 5 alpha-reductase activity in human skin by zinc and azelaic acid. Br J Dermatol. (1988)
20. Koehler K, et al. Serum testosterone and urinary excretion of steroid hormone metabolites after administration of a high-dose zinc supplement. Eur J Clin Nutr. (2009)
21. Kilic M, et al. The effect of exhaustion exercise on thyroid hormones and testosterone levels of elite athletes receiving oral zinc. Neuro Endocrinol Lett. (2006)
22. Kaya O, et al. Zinc supplementation in rats subjected to acute swimming exercise: Its effect on testosterone levels and relation with lactate. Neuro Endocrinol Lett. (2006)
23. Kilic M. Effect of fatiguing bicycle exercise on thyroid hormone and testosterone levels in sedentary males supplemented with oral zinc. Neuro Endocrinol Lett. (2007)
24. Sturniolo GC, et al. Zinc supplementation tightens "leaky gut" in Crohn's disease. Inflamm Bowel Dis. (2001)
25. Zinc Supplementation Inhibits Hepatic Apoptosis in Mice Subjected to a Long-Term Ethanol Exposure
26. Preservation of Intestinal Structural Integrity by Zinc Is Independent of Metallothionein in Alcohol-Intoxicated Mice
27. Zhou Z, et al. Zinc supplementation prevents alcoholic liver injury in mice through attenuation of oxidative stress. Am J Pathol. (2005)
28. Zinc Deficiency Mediates Alcohol-Induced Alveolar Epithelial and Macrophage Dysfunction in Rats
29. Kang YJ, Zhou Z. Zinc prevention and treatment of alcoholic liver disease. Mol Aspects Med. (2005)
30. Ebben M, Lequerica A, Spielman A. Effects of pyridoxine on dreaming: a preliminary study. Percept Mot Skills. (2002)

Last Updated: Nov 10, 2011 10:27:16