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Zinc: Important Health Aspects as Micronutrient
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Tuesday, 01 November, 2022, 13 : 00 PM [IST]
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Abhinash Polekkad & Dhanya Suresh
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In the present age of technology driven life filled with stress, polluted resources and adverse climatic conditions, human body becomes more prone and an easy prey to diseases.
Moreover, the insurgence of newer and newer pathogens, especially the viruses, every now and then imposes newer challenges to the medical sciences. It is wiser to understand that one can no longer rely on the modern medicines alone for his/her wellbeing, rather, one needs to have inner strength. In simpler words, a strong immunity and better nutrition is the right way to lead a healthy life. Among nutrition much focus is given on major nutrients: carbohydrates, proteins, fats, etc. But the micronutrients, nutrients required by the body in traces, such as minerals, are not given due importance.
Minerals are the vital inorganic nutrients required by the human body for its normal functioning and are further, classified as micro and macro-minerals based on their quantitative requirement. Iron, zinc, copper, iodine, manganese, selenium and fluoride are the micro-minerals, whereas calcium, phosphorous, magnesium, sodium, potassium, chloride and sulphite are macro-minerals.
Among these, zinc is a very important micro-mineral essential for normal health and physiology. Zinc plays crucial role in cell growth, healing, immunity mechanisms, bone mineralization, reproduction, blood clotting, cognitive functions and intellectual development. Zinc plays a curative role in many metabolic functions of the body and hence, it is considered as a powerful therapeutic tool to manage long list of illnesses.
The role of zinc in human metabolism starts from the early neonatal brain development and it remains significant throughout the entire life span of a human because of its direct involvement or associative roles for performing critical functions in the body. Zinc is unique in the sense that it is the only micronutrient that acts as a cofactor to more than 300 enzymes in the body. As zinc is not stored in the body, it needs to be replenished through our daily diet.
Red meat is an important source of zinc and 100 g of red meat contains 5 mg of zinc. In addition, seafood, poultry, egg, dairy, pumpkin seed and spinach are good sources of zinc. Most of the Indian soils are deficient of zinc. According to the International Zinc Association (IZA), 26% of the Indian population is under the risk of zinc deficiency. RDA requirement of zinc is 8 and 11 mg/day for women and men, respectively. Zinc is transported in the body through albumin, so a deficiency of albumin also causes poor zinc absorption. The following are some of the important functions of zinc in human life.
Growth and Development
Zinc acts as a cofactor for more than 300 enzymes by contributing to their structure, catalytic mechanisms and controlling actions. Zinc has an important role in the synthesis, secretion and action of growth hormone (GH). The concentration of zinc in the bone is more as compared to any other tissue in the body.
though, it is important for bone growth, higher consumer do not ensure better growth i.e. zinc does not show pharmacological effect. At the same time, zinc supplementation can correct the pre-existing zinc deficiency and thereby growth. Several studies implied that deficiency of zinc during pregnancy affects the foetal growth and development.
Immunity
The human immune system relies on two major groups of cells: innate cells and adaptive cells. The Innate immune cells perform immediate immune response e.g. macrophages and neutrophil granulocytes that directly attack the pathogen (bacteria and fungi).
These are also called as natural killer cells. The Adaptive immune cells can be B and T cells. Each B and T cell has an individual receptor to recognize and bind the unidentified entities i.e. antigens. Combinedly the T cells, B Cells and natural killer cells are known as lymphocytes. Zinc is essential for the production of lymphocytes. The B cells are generated in thymus and has the capacity to recognize antigen. The B cells are produced in bone marrow and has the ability to bind to the antigen so as to remove it from body. The natural killer cells posses the ability to kill other cells and thus they can kill the virus-affected cells.
The natural killer cells have also been found capable to kill tumour cells in the body. Zinc is essential for the production of these lymphocytes. It is also essential for the B cells to identify the pathogen and send the signals through chemical pathways. Zinc is essential part of the pathways. as cofactor for the acts as receptor.
Adequate supplementation of zinc through nutrition has proven effective therapeutic tool in preliminary stages to prevent diarrhoea, chronic hepatitis C, shigellosis, leprosy, tuberculosis, pneumonia, acute lower respiratory tract infection, common cold, and leishmaniasis. The occurrence of blindness in old age and the respiratory diseases in children can be reversed by Zinc intake.
Studies showed that zinc supplementation is the key tool to diminish oxidative stresses and generation of inflammatory cytokines. Zinc oxide nanoparticles were found to have bactericidal effects on both gram positive and negative bacteria and on the spores as well.
Reproduction
Zinc is a crucial element for human reproduction, which can be understood by its numerous actions on the metabolism of progesterone, oestrogen and androgen hormones. Zinc is vital for the maturation of sperms, release of ovaries i.e., ovulation and the fertilisation.
Deficiency of zinc during pregnancy can causes abortion or may have adverse effect in delivery Zinc deficiency in adolescence or later can impart male sterility and Zinc supplementation in such condition have been beneficial. Reproductive cycle of various species can not be complete without zinc. Lack of zinc first harms angiotensin converting enzyme activity, and this, in turn, results in depletion of testosterone and thereby inhibition of spermatogenesis. A large number of scientific evidences support that reproduction is significantly influenced by the zinc content in the body.
Gene Expression
A major portion of zinc is found in the nucleus, which helps in genetic stability and gene expression. The DNA and RNA polymerase enzyme essential for DNA and RNA synthesis are basically zinc metalloenzymes. Additionally, the zinc plays an important role in repair of DNA strands as well as RNA transcription.
Recently, increasing prominence has been placed on the significant role of zinc in zinc finger protein, which is internal machinery of proteins for nuclear transcription factors essential for controlling cell proliferation, differentiation and apoptosis through controlled gene expression. Zinc is recognized to be imperative for stabilizing DNA and it resides for more time in the nucleus than in any other cell compartment. Thus, this omnipresent trace element has an important role in gene expression.
Skin Health
Skin is the largest organ in the body and it frequently regenerates itself that demand proteins. The process of skin regeneration is mediated by the zinc-based enzymes. Zinc has a long history of treating skin related illness.
Inflammation reduction and wound healing are the main functions of zinc. Dermatologic abnormalities can be cured by supplementation of zinc. Furthermore, the antioxidant property of zinc acts as a defence mechanism that protects the skin against UV radiation and reduces the risks of subsequent health hazards including cancer. Zinc is an essential mineral for treating dandruff and it is a common ingredient for dandruff shampoos.
Cardiovascular Diseases
Cardiovascular Diseases is one of the largest life-killer throughout the world and it is believed to cause by the deposition of plaque, mostly blood cholesterol, inside the arteries. Zinc has a defensive effect on coronary artery disease and cardiomyopathy. Zinc homeostasis is important in cardiovascular health. Various studies demonstrated that zinc can reduce bad cholesterol level in the blood. Zinc supplementation reduces diabetic related cardiovascular diseases.
Central Nervous System
The central nervous system (CNS) consisting of the brain and the spinal cord. The CNS records the information received through all senses, integrates the information and coordinates the activities of all parts of the body. Zinc acts as a neurosecretory or cofactor in the CNS.
Significance of zinc in nervous system starts from early neonatal brain development to the entire life span. It helps in the maintenance of brain functions. Deficiency of zinc causes certain neurological disorders such as impaired brain development and neurodegenerative disease includes Alzheimer’s disease and depression. Brain zinc homeostasis is an important factor to avoid neurological disorders.
Taste and Smell Senses
Zinc deficiency results in taste buds and olfactory epithelial disorders. The major enzyme, which supports smell and taste function is carbonic anhydrase VI. It is a metalloenzyme having zinc as its molecular part. The enzyme induces the maturation of taste cells, which maintain the taste and smell functions active. Hence, proper functioning of senses depends on zinc level in the body.
Sources of Zinc
It is evident that zinc is an important element for overall human physiology. Without zinc, the human biological cycle is not possible. The most critical thing about the zinc is that it can not be stored inside the body, hence, regular supplementation of zinc to the body through diet is very important. Some of the sources of the zinc are meat, shell fish, legumes, nuts, eggs, dairy , whole grains etc.
Though zinc is identified as micronutrient, it’s significance for leading normal and healthy life can not be underestimated. One needs to keep an eye on the regular consumption of zinc through balances diet and through pharmaceuticals available in the market, if required.
It is also important to note that excess consumption of zinc can cause ‘zinc toxicity’. Primary symptoms of excess zinc intake are nausea, vomiting, stomach pain, diarrhea and cramps. A balanced diet for maintaining and regulating optimum level of zinc in the body is therefore recommended.
(Polekkad belongs to Dairy Engineering Division, ICAR-NDRI, Karnal; Suresh belongs to FSSAI, New Delhi. They can be reached at abhinashurambath@gmail.com)
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