Zinc deficiency can cause a lack of taste and smell and the reason zinc effects the presence or absence of bitter taste receptors on the tongue suggests it would also effect the number of bitter taste – or other types of taste receptors – in any location of the body. Zinc is needed to tell the cell’s genes* to make the RNA and proteins needed to form the taste receptors which then can implant at the cell membrane surface – ready to sense a taste of food on the tongue. (4)
*”Zinc-dependent amidohydrolases,” for example, are proteins involved in “DNA replication and repair” and are involved in epigenetic control of gene’s “histone acetylation and methylation,” – turning the genes on or off by having methyl groups added – like putting the cap back on the toothpaste tube – will the gene or won’t it be used to encode a strand of RNA? RNA is then used as a pattern for the cell to make proteins whether bitter taste receptors, or other proteins – whatever the DNA/RNA pattern has encoded for a chain of amino acids to be joined together into a long protein chain. Once the straight chain of protein is made various amino acids may have a bend or an electrically active zone causing the protein to fold into a complex shape – such as a membrane receptor. (See Table 3, 10)
Taste sensations & other symptoms of zinc deficiency in older people:
In older people, for whom zinc deficiency may be an increased risk, loss of taste sensations, or altered taste (metallic or other changes in perception of the taste may be a side effect of prescription medications or other causes) are due to: “drug use (21.7%), zinc deficiency (14.5%) and oral and systemic diseases (7.4% and 6.4%, respectively).” (5)
“Zinc administration improves taste in 50–82% of patients suffering from taste disorders (a common symptom of zinc deficiency). Effects of zinc administration do not appear immediately, and therapy should be continued for at least three months. ”
“Zinc deficiency is known often to accompany severe physical disabilities, liver cirrhosis, chronic hepatitis, chronic inflammatory bowel diseases, type 2 diabetes mellitus, chronic kidney disease, cardiac insufficiency, short stature, and is also more common in the elderly and professional athletes [6,7,8,9,10,11,12,13,14,15].“
– Excerpts from an article based on “the Japanese Society of Clinical Nutrition recently issued…Japan’s Practical Guideline for Zinc Deficiency 2018…” which focuses on the role of zinc deficiency in intestinal inflammation of inflammatory bowel disease and the nitrogen metabolic disorder common with liver cirrhosis. (6)
(Kodama, et al., 2020) (6)
Lack of taste sensations from eating that is due to zinc deficiency, and lack of taste receptors on the tongue, can usually be fairly quickly reversed by providing adequate zinc in the diet or by supplementation, (3), possibly a little taste sensation being restored within days of increased zinc intake. How quickly the taste receptors are made may also depend on other individual factors such as protein intake and general health.
Excess copper in the diet may also be a factor in zinc deficiency, because zinc and copper share transport proteins (2) which is how a limited supply of trace minerals is stored in the body. Otherwise they might cause damage due to being electrically active – able to attract or donate electrons; or they are involved in enzyme and signaling roles which might cause too much cellular activity, or the wrong messages. Zinc is involved in the process of apoptosis the immune cell killing and safe removal of infected or damaged cells. (1)
Which taste receptors are formed first and where on the tongue may also vary after zinc intake is increased by diet or supplementation; the sweet and bitter taste receptors may be restored earliest. (3)
Bitter and sweet tastes may work in balance in a healthy diet – bitter taste receptors help regulate appetite and blood sugar levels. “Bitter taste receptors influence glucose homeostasis.” (5) Glucose is blood sugar, bitter taste receptors are involved with reducing insulin resistance and may help prevent Type 2 diabetes and Metabolic Syndrome.
Background info for new readers: the ability to taste sweet and bitter may have impacts on health throughout the body – bitter taste receptors and other types of taste receptors are found in other areas of the body besides the tongue. They sense the environment in the case of sweet or sour – the body wants to have enough blood sugar but not too much, and the same thing with acidity – just the right range of pH is needed for health. If we get too acidic it is more likely to promote cancer. Too alkaline is less likely to occur in typical health scenarios.
Chronic kidney disease may also involve a problem with bitter taste receptors, or lack of them. “Bitter taste receptors could affect kidney function via Ca2+ intake. Alkaloids such as phenylthiocarbamide stimulate these receptors and cause an increase in Ca2+ intake.” (7) Excessive calcium within a brain cell can over-activate it, and even lead to cell death, while in the kidney maybe it would be helping health by removing excess calcium.
Some of our immune cells also may have taste and odor receptors. The taste receptors identified included the types that detect bitter, sweet, and umami (protein flavor). (8) These sensory receptors on a white blood cell (leukocyte) would not be sending nerve signals to the brain in the way taste buds or olfactory sensors in the nose are connected to nerve signals connected to the brain. They might be involved in patrolling our internal environment and detecting if our levels of blood glucose, bitter chemicals and amino acid supply is adequate – or they might be performing some function for us such as modifying the immune cell’s response based on the levels of bitter, sweet, or umami tasting chemicals that were detected in the surrounding fluid filled environment of a blood vessel. Leukocytes are the type of white blood cell that can detect, kill, and remove an infected cell or an infectious pathogen. White blood cells are our front line offensive team against pathogens. (They need magnesium in order to be able to kill the pathogen – but that is a different story.)
Physiology can have many ways to do something, but also tends to stick with the same design – if zinc is needed for cells to make taste receptors on the tongue then it is probable that it also would promote taste receptors in whatever cell types that have taste receptors.
Bitter taste receptors are far more sensitive, 10,000 times more sensitive than sweet, so a tiny amount of a bitter tasting chemical can activate them. Bitter taste receptors lining the intestines will send a satiety, “I’m full now,’ signal to the brain if enough are activated by bitter tasting phytonutrients in the meal or snack. Bitter taste receptors in the lungs if activated by enough bitter tasting phytonutrients (or bitter tasting medications such as quinines perhaps) will cause the lung cells to open the airways wider, increase the production of thin mucus and increase the motion of hair-like cilia lining the airways to move the mucus up and out with a coordinated wave like motion. More info: Bitter taste receptors in the lungs & Hesperidin’s decongestant properties.
This is not done, part one maybe.
Disclaimer: This information is provided for educational purposes within the guidelines of Fair Use. It is not intended to provide individual guidance. Please seek a health care provider for individualized health care guidance.
Reference List
- Haase H, Rink L. The immune system and the impact of zinc during aging. Immun Ageing. 2009;6:9. Published 2009 Jun 12. doi:10.1186/1742-4933-6-9 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2702361/ “There are remarkable parallels in the immunological changes during aging and zinc deficiency, including a reduction in the activity of the thymus and thymic hormones, a shift of the T helper cell balance toward T helper type 2 cells, decreased response to vaccination, and impaired functions of innate immune cells. Many studies confirm a decline of zinc levels with age. Most of these studies do not classify the majority of elderly as zinc deficient, but even marginal zinc deprivation can affect immune function.” — “On the cellular level, zinc is essential for proliferation and differentiation, but zinc homeostasis is also involved in signal transduction [5,6] and apoptosis [7]. Cells depend on a regular supply of zinc and make use of a complex homeostatic regulation by many proteins [8], but the plasma pool, which is required for the distribution of zinc, represents less than one percent of the total body content [1]. Despite its important function, the body has only limited zinc stores that are easily depleted and can not compensate longer periods of zinc deficiency. Additionally, during infections pro-inflammatory cytokines mediate changes in hepatic zinc homeostasis, leading to sequestration of zinc into liver cells and subsequently to hypozincemia [9]. Alterations in zinc uptake, retention, sequestration, or secretion can quickly lead to zinc deficiency and affect zinc-dependent functions in virtually all tissues, and in particular in the immune system. “
- Levenson C.W., Tassabehji N.M. (2007) Role and Regulation of Copper and Zinc Transport Proteins in the Central Nervous System. In: Lajtha A., Reith M.E.A. (eds) Handbook of Neurochemistry and Molecular Neurobiology. Springer, Boston, MA. https://doi.org/10.1007/978-0-387-30380-2_13 https://link.springer.com/referenceworkentry/10.1007%2F978-0-387-30380-2_13
- Kitagoh H, Tomita H. [Healing process of taste receptor disturbance]. Nihon Jibiinkoka Gakkai Kaiho. 1995 Feb;98(2):267-80. Japanese. doi: 10.3950/jibiinkoka.98.267. PMID: 7707185. https://pubmed.ncbi.nlm.nih.gov/7707185/ Abstract in English, article in Japanese. “Patients with taste receptor disturbance were treated with zinc dosage, […] With respect to differences in the recovery process of the four primary tastes, a tendency for the sweet and bitter taste qualities to recover earlier than the others was observed in the simultaneous improvement type.”
- *less zinc, fewer bitter taste receptors Sekine H, Takao K, Yoshinaga K, Kokubun S, Ikeda M. Effects of zinc deficiency and supplementation on gene expression of bitter taste receptors (TAS2Rs) on the tongue in rats. Laryngoscope. 2012 Nov;122(11):2411-7. doi: 10.1002/lary.23378. Epub 2012 Oct 15. PMID: 23070743. https://pubmed.ncbi.nlm.nih.gov/23070743/
- Imoscopi, A., Inelmen, E.M., Sergi, G. et al. Taste loss in the elderly: epidemiology, causes and consequences. Aging Clin Exp Res 24, 570–579 (2012). https://doi.org/10.3275/8520 https://link.springer.com/article/10.3275/8520
- Kodama H, Tanaka M, Naito Y, Katayama K, Moriyama M. Japan’s Practical Guidelines for Zinc Deficiency with a Particular Focus on Taste Disorders, Inflammatory Bowel Disease, and Liver Cirrhosis. Int J Mol Sci. 2020;21(8):2941. Published 2020 Apr 22. doi:10.3390/ijms21082941 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7215354/
- Liang J, Chen F, Gu F, Liu X, Li F, Du D. Expression and functional activity of bitter taste receptors in primary renal tubular epithelial cells and M-1 cells. Mol Cell Biochem. 2017 Apr;428(1-2):193-202. doi: 10.1007/s11010-016-2929-1. Epub 2017 Feb 24. PMID: 28236092.
https://pubmed.ncbi.nlm.nih.gov/28236092/ - Malki A, Fiedler J, Fricke K, Ballweg I, Pfaffl MW, Krautwurst D. Class I odorant receptors, TAS1R and TAS2R taste receptors, are markers for subpopulations of circulating leukocytes. J Leukoc Biol. 2015;97(3):533-545. doi:10.1189/jlb.2A0714-331RR https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5477889/
- Wessels, I.; Maywald, M.; Rink, L. Zinc as a Gatekeeper of Immune Function. Nutrients 2017, 9, 1286. https://www.mdpi.com/2072-6643/9/12/1286
- Itika Arora, Manvi Sharma, Liou Y. Sun,Trygve O. Tollefsbol, The Epigenetic Link between Polyphenols, Aging and Age-Related Diseases. Genes 2020, 11(9), 1094; https://doi.org/10.3390/genes11091094 https://www.mdpi.com/2073-4425/11/9/1094/htm
Covid related references, section to be written
- ZINC IS KEY TO HCQ PROTOCOL SEPTEMBER 21, 2020, Editorials 360, The group given zinc with hydroxychloroquine had less mortality, discharged sooner, less likely to need a ventilator compared to the group given hydroxychloroquine but no zinc sulfate: “The docs discovered that those that obtained zinc sulfate have been discharged residence extra often and have been much less prone to want a ventilator. General, members of this group had decrease danger of mortality because of the virus and decrease possibilities of needing hospice or the ICU. They concluded, “This examine gives the primary in vivo proof that zinc sulfate together with hydroxychloroquine could play a task in therapeutic administration for COVID-19.”
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- Adam Drewnowski, Carmen Gomez-Carneros, Bitter taste, phytonutrients, and the consumer: a review, The American Journal of Clinical Nutrition, Volume 72, Issue 6, December 2000, Pages 1424–1435, https://doi.org/10.1093/ajcn/72.6.1424 https://academic.oup.com/ajcn/article/72/6/1424/4729430 “Bitter phenolics, such as quercetin, are the most common bitter compounds in immature apples and other fruit (17).“
- The Cure for Malaria Could be in Your Backyard, ctegd.uga.edu, https://ctegd.uga.edu/the-cure-for-malaria-could-be-in-your-backyard/ “Quinine, which comes from the bark of a cinchona tree, was first isolated as an antimalarial compound in the 1800s, though there is evidence that bark extracts have been used to treat malaria since the 1600s. …native to Peru.“
- Quinine in Tonic Water: What Is It and Is It Safe?, healthline.com, https://www.healthline.com/health/quinine-in-tonic-water “Quinine is still in tonic water, which is consumed around the world as a popular mixer with spirits, such as gin and vodka. It’s a bitter beverage, though some manufacturers have tried to soften the taste a little with added sugars and other flavors.“
- Samer Singh, Rakesh Kumar Singh, Assessing the Role of Zinc in COVID-19 Infections and Mortality: Is Zinc Deficiency a Risk Factor for COVID-19?, medRxiv preprint doi: https://doi.org/10.1101/2020.06.12.20105676. this version posted June 14, 2020. a CC-BY-ND 4.0 International license “Zinc is essential to good health and immunocompetence. Its deficiency is generally associated with a negative impact on overall health, increased susceptibility to disease, and infections [9-12].” “A negative correlation between the Zinc deficiency prevalence estimate for the countries and the reported cases of COVID-19 was consistently observed at all three time-points analyzed that covered pre infections peak, i.e.,8 April 2020, and post infections peak, i.e., 12 and 26 May 2020 (see Table 2). The Zinc deficiency of the populations also negatively covaried with adverse outcomes (mortality) per million population and the correlation seemed to better with the passage of the current wave of COVID-19 infections.
- I am not sure about the ‘negative correlation’ if wording issue or if there were less illness with zinc deficiency. Infection causes zinc to be sequestered, so maybe the sicker people get the more zinc is sequestered. I haven’t read the full paper yet.
- Samer Singh, Covariation of Zinc Deficiency with COVID-19 Infections and Mortality in European Countries: Is Zinc Deficiency a Risk Factor for COVID-19?, https://www.medrxiv.org/content/10.1101/2020.06.12.20105676v2 Journal of scientific research doi: 10.37398/JSR.2020.640222
- This is the same paper as the above link except not the preprint version.
- Vitamin D Can Help Reduce COVID-19 Risks: Here’s How, https://www.healthline.com/health-news/vitamin-d-can-help-reduce-covid19-risks
