|Year : 2013 | Volume
| Issue : 4 | Page : 209-212
Zinc level and obesity
Doaa S.E. Zaky1, Eman A Sultan2, Mahmoud F Salim3, Rana S Dawod4
1 Department of Internal Medicine, Al-Azhar University, Cairo, Egypt
2 Department of Clinical Pathology, Al-Azhar University, Cairo, Egypt
3 Department of Clinical Nutrition, National Nutrition Institute, Cairo, Egypt
4 Diploma of Clinical Nutrition, National Nutrition Institute, Cairo, Egypt
|Date of Submission||02-Sep-2013|
|Date of Acceptance||02-Oct-2013|
|Date of Web Publication||27-Jan-2014|
Doaa S.E. Zaky
No. 3, Hay'et Tadrees Ein Shams University Towers, El Zaafran Gardens (Ard Elmatbaah), Abbasia, Cairo 11331
Source of Support: None, Conflict of Interest: None
Obesity is a chronic condition that is associated with disturbances in the metabolism of zinc. Therefore, the aim of this study was to investigate the relationship between serum zinc level and different clinical and biochemical parameters in obese individuals.
Patients and methods
Twenty-four individuals with BMI more than 30 kg/m 2 and 14 healthy controls (BMI < 24 kg/m 2 ) were assessed for BMI and waist circumference using anthropometric measurements. Colorimetric tests were carried out for the determination of zinc in serum.
In this study, BMI and waist circumference were higher in the obese group than in the control group (P < 0.05). The mean serum zinc levels were 92 ± 31.1 and 101 ± 70 μg/dl in the obese group and control group (P > 0.05), respectively. There was a significant negative correlation between the serum zinc level and BMI, waist circumference and low-density lipoprotein (P < 0.05).
Plasma zinc concentration in obese individuals showed an inverse relationship with the waist circumference and BMI as well as serum low-density lipoprotein-cholesterol and correlated positively with high-density lipoprotein.
Keywords: Low-density lipoprotein, obesity, serum zinc
|How to cite this article:|
Zaky DS, Sultan EA, Salim MF, Dawod RS. Zinc level and obesity. Egypt J Intern Med 2013;25:209-12
| Introduction|| |
The essential trace element zinc (Zn) is important for several bodily functions such as vision, taste perception, cognition, cell reproduction, growth and immunity. It plays a vital role in metabolisms, particularly as a cofactor of many enzymes, required for natural metabolic processes  . Zinc has three major biological roles: Catalytic, structural and regulatory. It is a structural constituent in numerous proteins, including growth factors, cytokines, receptors, enzymes, and transcription factors belonging to cellular signalling pathways, and is essential for their biological activity  . Moreover, it is implicated as a cofactor in numerous cellular processes for an estimated 3000 human proteins including DNA and protein synthesis, enzyme activity and intracellular signalling  . The human genome bioinformatics study revealed that ∼10% of all proteins may bind with zinc. The biological functions of these zinc-binding proteins are maintained through cellular zinc levels  . Therefore, homoeostatic mechanisms that modulate zinc absorption, distribution, cellular uptake and excretion are vital for maintaining cellular functions. Moreover, zinc's fundamental and diverse roles in many cellular processes require its delivery to the tissues and cells, and also its intracellular availability and intracellular distribution to be tightly controlled. These processes are governed by zinc transporters and channels and by zinc-sensing molecules, such as metallothioneins and metal-responsive element-binding transcription factor-1  . Disturbances in zinc homoeostasis have been observed in many diseases, including diabetes mellitus  , cancer  , autoimmune disease  and cardiovascular disease  . Some studies have also shown that obese individuals have low concentrations of zinc in plasma, erythrocytes and serum, and that it is associated with alterations in the metabolism of the adipose tissue of these patients  . Zinc deficiency may also be associated with insulin resistance, hyperglycaemia and impaired glucose tolerance. The aim of this study was to define the relationship between the plasma zinc level and different clinical and laboratory parameters in obese Egyptian individuals.
| Patients and methods|| |
This study was conducted in the National Nutrition Institute (Cairo, Egypt). The study population consisted of 24 individuals with BMI more than 30 kg/m 2 selected from the outpatient clinic as well as 14 healthy individuals (BMI < 24 kg/m 2 ) as the control group. Both study groups were age-matched and sex-matched. The participants were eligible for the study if they were 20 years of age or older and not taking any vitamin or mineral supplementation. Exclusion criteria included factors that affect serum zinc levels, such as kidney disorders, diabetes, cancer, acute infections, and smoking. Patients and controls included in the study underwent a standard procedure of detailed history taking and a complete physical examination. Blood pressure was recorded as a mean value of three different measurements in the sitting position using a sphygmomanometer. BMI was calculated using the following equation: BMI = weight (kg) divided by the square of the height (m). Those who voluntarily decided to participate in the study were asked to sign an informed consent.
Peripheral blood samples were obtained after 12 h of fasting. Five millilitres of blood were collected in a plain vacuum tube, allowed to clot at room temperature, and the serum was separated by centrifugation. Fasting blood sugar, lipid profile [total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL)] and high-density lipoprotein (HDL) were investigated. Zinc fluid monoreagent was used in the colorimetric test for the determination of zinc in serum. Zinc forms a red chelate complex with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropyl-amino)-phenol. The increase of absorbance was measured and was proportional to the concentration of total zinc in the sample. The values for lipid profile and zinc level were as follows:
- Cholesterol: Normal value, less than 200 mg/dl; borderline, 200-239 mg/dl; and high, 240 mg/dl or above.
- TG: Value less than 150 mg/dl was considered normal and 200-499 mg/dl was considered high; was considered borderline when the level falls within the above values.
- LDL: Value less than 100 mg/dl was considered optimal and up to 129 mg/dl was near-optimal. Borderline high LDL ranged from 130 to 159 mg/dl, whereas 160-189 mg/dl was considered high. Above that level was categorized as very high.
- HDL: For men levels above 40 mg/dl and for women levels above 50 mg/dl were considered normal  .
- Zinc: For men 165-118 μg/dl and for women 59-98 μg/dl were considered normal  .
IBM SPSS Statistics (version 21.0, 2012; IBM Corp., USA) was used for data analysis. Data were expressed as mean ± SD for quantitative parametric measurements in addition to median percentiles for quantitative nonparametric measurements, and both number and percentage for categorized data. The following tests were carried out: (i) comparison between two independent mean groups for parametric data using Student's t-test; (ii) Pearson's correlation test to study the possible association between both the variables among each group for parametric data. The P of error of 0.05 was considered significant, whereas that of 0.01 and 0.001were considered highly significant.
| Results|| |
The anthropometric data revealed a highly significant increase in weight, BMI and waist circumference in the obese group (99 ± 19, 38 ± 6.4 and 111 ± 16, respectively) compared with the control group (61 ± 7, 22.7 ± 1.4 and 80 ± 3, respectively) as expected; however, no significant difference was observed with respect to height. The mean systolic and diastolic blood pressure was normal in both groups; however, they were significantly higher in the obese group (127 ± 16 and 87 ± 11, respectively) compared with the control group (112 ± 9 and 72 ± 7, respectively) [Table 1].
|Table 1: Comparison between control and obese group with respect to demographic, clinical and laboratory data|
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The lipid profile showed no significant difference between both groups in TC; however, LDL was significantly high in the obese group (120.6 ± 26.4) compared with the control group (98 ± 18) and HDL was significantly low in the obese group (36.3 ± 7.1) compared with the control group (53 ± 9.0). The mean TG level was also significantly high in the obese group compared with the control group (108.2 ± 48.9 vs. 80 ± 31) and was within the normal range in both groups. Also serum zinc level was normal in both groups, although lower in the obese than in the control group, yet there was no statistical significant difference between them [Figure 1].
Significant negative correlations were found between serum zinc level and BMI, waist circumference and LDL (P < 0.05); however, no significant correlations were found between zinc level and other clinical parameters such as age, weight, height, blood pressure and other biochemical parameters such as TC, TG and HDL [Table 2].
|Table 2: Correlation between serum zinc level and clinical and laboratory data in obese individuals|
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| Discussion|| |
Our study was performed in 24 obese individuals as well as 14 healthy controls to verify the serum zinc status in obese patients and its relationship with different clinical and laboratory parameters in those patients. The mean concentrations of zinc in the serum showed no statistically significant difference between the control and the obese groups (P > 0.05). Ennes Dourado Ferro et al.  also did not find any significant difference in plasma zinc concentration between the obese and the control groups. However, they found significant difference between both groups with respect to erythrocyte zinc level. Erythrocytes contain about 80% of zinc; however, it is only 16% in plasma. Also, plasma zinc has fast dynamics and is influenced by several pathophysiological factors in response to various conditions such as stress, infection, catabolism, hormones and food intake. This well explains our results of normal mean serum zinc level in both groups. Thus, zinc level in erythrocytes can be considered as a more sensitive parameter of zinc status than plasma or serum level. Zinc concentration in the erythrocytes of obese children and adolescents  and obese adult men  revealed significantly lower concentration than in the control group. Feitosa et al.  explain the lower concentrations of erythrocyte zinc in obese patients as the influence of inflammatory process on the metabolism of zinc as they found significant negative correlation between zinc and TNF-a. With respect to clinical parameters, the mean value of serum zinc showed significant negative correlations with BMI and waist circumference and no correlation with age or blood pressure. The results consistent with the multivariate regression analysis  demonstrated that the waist circumference and BMI had negative correlation with the concentration of zinc in erythrocytes. These data are associated with the fact that there is an accumulation of adipose tissue with an increase in the production of cortisol and adipocytokines, which in turn, results in chronic inflammation. The inflammation promotes the zinc accumulation in the liver and in adipocytes, which may have contributed to the negative correlation of serum zinc level with BMI and waist circumference in obese individuals. Significant negative correlations also were found between serum zinc and TG (LDL-cholesterol); whereas a significant positive correlation was found between serum zinc and HDL. Also, Al-Sabaawy  revealed a significant lower level of serum zinc in hyperlipidemic nonobese patients compared with the control group, as well as a significant negative correlation between serum zinc and TC, LDL and TG. Multiple studies have revealed that zinc supplementation had beneficial effects on lipid profiles in patients with diabetes or metabolic syndrome , . Zinc supplementation increase HDL-cholesterol and reduces TG in patients with type 2 diabetes  . However, the effect of zinc supplementation on lipid profile and other metabolic factors in obesity are more controversial among nondiabetic obese and nonobese individuals. Zinc supplementation at 30 mg daily for 8 weeks increased serum zinc by 15% and urinary zinc by 56%, but no significant difference was found with respect to TG and HDL-cholesterol after zinc supplementation  . Similarly, Beletate et al.  reported that zinc supplementation for 4 weeks did not have a beneficial effect on lipid levels in normal glucose-tolerant obese women aged 25-45 years. However, in another study, after receiving 20 mg elemental zinc on a regular daily basis for 8 weeks, the mean fasting plasma glucose, insulin and HOMA-IR were decreased significantly with no change in BMI, waist circumference, LDL-cholesterol and TG. Further research on the effect of zinc supplementation on the lipid profile and the metabolic risks in obesity should be performed in a larger cohort with a longer follow-up period to determine the potential merits of zinc-based intervention in obese patients. Sarmento et al.  also revealed inverse association between zinc and coronary artery disease, and Afridi et al.  postulated that zinc deficiency may predispose to coronary artery disease in diabetes mellitus patients. Further study are also required to prove LDL as a link between increased cardiovascular risks with decreased zinc concentration in obese nondiabetic individuals.
| Conclusion|| |
Plasma zinc concentration in obese individuals presented an inverse relationship with the waist circumference and BMI as well as serum LDL-cholesterol and correlated positively with HDL.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
| References|| |
|1.||Fukada T, Yamasaki S, Nishida K, Murakami M, Hirano T, et al. Zinc homoeostasis and signaling in health and diseases: zinc signaling. J Biol Inorg Chem 2011; 16:1123-1134. |
|2.||Chasapis CT, Loutsidou AC, Spiliopoulou CA, Stefanidou ME, et al. Zinc and human health: an update. Arch Toxicol 2011; 86:1-14. |
|3.||Andreini C, Banci L, Bertini I, Rosato A, et al. Counting the zinc-proteins encoded in the human genome. J Proteome Res 2006; 5:196-201. |
|4.||Kelleher SL, McCormick NH, Velasquez V, Lopez V, et al. Zinc in specialized secretory tissues: roles in the pancreas, prostate, and mammary gland. Adv Nutr 2011; 2:101-111. |
|5.||Jansen J, Rosenkranz E, Overbeck S, Warmuth S, Mocchegiani E, Giacconi R, et al. Disturbed zinc homoeostasis in diabetic patients by in vitro and in vivo analysis of insulinomimetic activity of zinc. J Nutr Biochem 2012; 23:1458-1466. |
|6.||Hogstrand C, Kille P, Nicholson RI, Taylor KM, et al. Zinc transporters and cancer: A potential role for ZIP7 as a hub for tyrosine kinase activation. Trends Mol Med 2009; 15:101-111. |
|7.||Kawasaki E, Nakamura K, Kuriya G, Satoh T, Kobayashi M, Kuwahara H, et al. Differences in the humoral autoreactivity to zinc transporter 8 between childhood- and adult-onset type 1 diabetes in Japanese patients. Clin Immunol 2011; 138:146-153. |
|8.||Foster M, Samman S. Zinc and redox signaling: Perturbations associated with cardiovascular disease and diabetes mellitus. Antioxid Redox Signal 2010; 13:1549-1573. |
|9.||Konukoglu D, Turhan MS, Ercan M, Serin O, et al. Relationship between plasma leptin and zinc levels and the effect of insulin and oxidative stress on leptin levels in obese diabetic patients. J Nutr Biochem 2004; 15:757-760. |
|10.||Naito HK, David JA Laboratory considerations: Determination of cholesterol, triglyceride, phospholipid, and other lipids in blood and tissues. Lab Res Methods Biol Med 1984; 10:1-76. |
|11.||Johnsen O, Eliasson R. Evaluation of a commercially available kit for the colorimetric determination of zinc in human seminal plasma. Int J Androl 1987; 10:435-440. |
|12.||Ennes Dourado Ferro F, de Sousa Lima VB, Mello Soares NR, Franciscato Cozzolino SM, do Nascimento Marreiro D, et al. Biomarkers of metabolic syndrome and its relationship with the zinc nutritional status in obese women. Nutr Hosp 2011; 26:650-654. |
|13.||Marreiro DN, Fisberg M, Cozzolino SMF Zinc nutritional status and its relationships with hyperinsulinemia in obese children and adolescents. Biol Trace Elem Res 2004; 99:137-150. |
|14.||Ozata M, Mergen M, Oktenli C, Aydin A, Sanisoglu SY, Bolu E, et al. Increased oxidative stress and hypozincemia in male obesity. Clin Biochem 2002; 35:627-631. |
|15.||Feitosa MC, Lima VB, Neto JM, Marreiro Ddo N, et al. Plasma concentration of IL-6 and TNF-a and its relationship with zincemia in obese women. Rev Assoc Med Bras 2013; 59:429-434. |
|16.||Al-Sabaawy OM. The relationship between serum lipid profile and selected trace elements for adult men in Mosul city. Oman Med J 2012; 27:300-303. |
|17.||Farvid MS, Siassi F, Jalali M, Hosseini M, Saadat N, et al. The impact of vitamin and/or mineral supplementation on lipid profiles in type 2 diabetes. Diabetes Res Clin Pract 2004; 65:21-28. |
|18.||Kadhim HM, Ismail SH, Hussein KI, Bakir IH, Sahib AS, Khalaf BH, Hussain SA, et al. Effects of melatonin and zinc on lipid profile and renal function in type 2 diabetic patients poorly controlled with metformin. J Pineal Res 2006; 41:189-193. |
|19.||Kim J, Lee S. Effect of zinc supplementation on insulin resistance and metabolic risk factors in obese Korean women. Nutr Res Pract 2012; 6:221-225. |
|20.||Beletate V, El Dib RP, Atallah AN. Zinc supplementation for the prevention of type 2 diabetes mellitus. Cochrane Database Syst Rev 2007; 24:CD005525. |
|21.||Sarmento RA, Silva FM, Sbruzzi G, Schaan BD, Almeida JC Antioxidant micronutrients and cardiovascular risk in patients with diabetes: a systematic review. Arq Bras Cardiol 2013; 101:240-248. |
|22.||Afridi HI, Kazi TG, Kazi N, Baig JA, Jamali MK, Arain MB, et al. Status of essential trace metals in biological samples of diabetic mother and their neonates. |
[Table 1], [Table 2]