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ORIGINAL ARTICLE
Year : 2013  |  Volume : 2  |  Issue : 1  |  Page : 52-57

Anti-infective antioxidant minerals levels in uncomplicated pregnancy in some rural communities of South East Nigeria


1 Department of Medical Laboratory Sciences, College of Health Sciences, Ebonyi State University, Abakaliki, Nigeria
2 Department of Applied Biochemistry, Faculty of Biosciences, Nnamdi Azikiwe University, Awka, Nigeria
3 Department of Physiology/Obstetrics and Gynecology, College of Medicine, University of Nigeria, Enugu Campus, Nigeria

Date of Web Publication1-Jan-2013

Correspondence Address:
Ogbodo Sylvester
Department of Medical Laboratory Sciences, College of Health Sciences, Ebonyi State University, Abakaliki
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2278-019X.105331

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  Abstract 

Background: Pregnancy is characterized by generation of reactive species and reduction in immune functions of the woman, exposing her to oxidative stress and infections/infestations. In developing countries, pregnant women seldomly seek antenatal care early in their pregnancies, exposing them to pregnancy complications.
Aim: The aim of this study is to measure the levels of anti-infective antioxidant minerals – selenium and zinc, in rural pregnant women who are on their first antenatal visits, to know their status before routine antenatal supplements are commenced.
Materials and Methods: Serum selenium and zinc concentrations were determined using atomic absorption spectrophotometer, in 181 apparently normal pregnant rural women aged between 18 and 40 years, who were on first antenatal visits. They were first grouped according to trimesters and later according to parity. Controls were 50 age-matched, non-pregnant women who were not in their menstrual periods at the time of the study.
Results: Results showed that serum selenium and zinc in pregnant women were significantly lower (P < 0.001) than values obtained from non-pregnant women (controls). However, there was no significant difference between the values from the controls and first trimester in both elements (P = 0.964 and 0.974, respectively), but thereafter, the elements became significantly lower (P < 0.001) and remained so throughout gestation. Though both elements showed significantly lower value in each parity group when compared with the control (P < 0.001), selenium did not show significant difference (P = 0.066) between one parity group and another, while zinc showed significantly higher value (P < 0.001) in high multiparas over preceding parity group.
Conclusion: Our results suggest that pregnant women in the rural areas are prone to oxidative stress and infections ever before they seek for antenatal care. Public health education should be organized regularly in these rural areas to highlight the dangers of late antenatal registration, while the need for consumption of local foods that contain these trace elements by pregnant women should be emphasized on antenatal days.

Keywords: Normal pregnancy, rural women, selenium, zinc


How to cite this article:
Sylvester O, Antoinette O, Uchenna N. Anti-infective antioxidant minerals levels in uncomplicated pregnancy in some rural communities of South East Nigeria. J Med Nutr Nutraceut 2013;2:52-7

How to cite this URL:
Sylvester O, Antoinette O, Uchenna N. Anti-infective antioxidant minerals levels in uncomplicated pregnancy in some rural communities of South East Nigeria. J Med Nutr Nutraceut [serial online] 2013 [cited 2019 Sep 21];2:52-7. Available from: http://www.jmnn.org/text.asp?2013/2/1/52/105331


  Introduction Top


Pregnancy is a physiological process that is characterized by dynamic changes in multiple organ system, [1] resulting in increased oxidative stress. In developing countries, oxidative stress in pregnancy is caused by many physiological and pathological conditions, especially malnutrition, malaria and bacterial infections, and activity of mitochondria-rich placenta that favors free radical production. [2],[3] Oxidative stress ensues when the rate of generation of these radicals overwhelms the synergistic actions of endogenous and exogenous antioxidant systems, and cell regenerating capacity of the body. Hence, the roles of anti-infective antioxidants that have dual functions cannot be over-emphasized, requiring that such nutritional factors need to be monitored, particularly in special individuals like the pregnant women. The monitoring or assessment of these nutritional factors is important to identify patients at risk of malnutrition, [4] and in the case of pregnant women, to assess the need for supplementation.

Selenium is an essential trace element with a wide range of effects on many factors including oxidative stress and immune functions. [5] Selenium-containing enzymes - iodothyronine deiodinases (D 1 , D 2 , and D 3 ) are required for the inter-conversion of thyroid hormones and brain development in early fetal life, hence selenium deficiency during gestation causes under-development of the fetal brain and other pregnancy complications like pre-eclampsia, abortion, stillbirth, pre-term birth, and retention of placenta. [6],[7] In autoimmune deficiency syndrome (AIDS), selenium-deficient patients were found to be nearly 20 times more likely to die from HIV-related causes than patients with adequate selenium, probably due to increased activation of viral replication, which increases the virulence of the virus and production of ROS. [8],[9] An HIV is a disease that disproportionately affects the marginalized and socially disadvantaged, and many of those affected also suffer from chronic food insecurity and malnutrition. [10] Therefore, in rural areas where food insecurity and malnutrition are main problems of the inhabitants, oxidative stress from pregnancy, in addition to inevitable infections (of any type), pose great danger to the mothers and their fetuses. Fortunately, catalase and glutathione peroxidase, which require selenium, are known to decrease viral activation, [11] in addition to other anti-infective properties of selenium. Thus, selenium supplementation was noted to have reduced hospitalization and diarrheal morbidity and improved CD4 count in HIV patients. [10]

Zinc is an essential component of several (>300) important enzyme systems, where it plays critical roles in various functions of the body. [12] It is involved in immune cell (T-cell) production in the thymus gland, hence prolonged zinc deficiency in mammals is associated with depressed T-cell functions, even with normal B-cell functions. [13] Zinc is a component of thymic hormone, which controls and facilitates the maturation of lymphocytes and plays a role in cell division and DNA replication as well as in production of prostaglandins. [14] Zinc deficiency is known to be widespread in developing countries, and it is often aggravated by acute and chronic infections. [15]

With increasing awareness and constant health education during antenatal visits, the consequences of deficiencies of these antioxidants are known by urban dwellers. Also, patients' levels of education and interaction with other people help urban dwellers to observe good routine sanitary conditions. However, such cannot be said about the rural dwellers who hardly seek antenatal care before their last trimesters, [16] unless faced with complications. Most of the complications of pregnancy experienced in the rural areas are mainly due to malnutrition, malaria parasitemia, and bacterial and viral infections, known to be endemic in these areas. [17] It, therefore, becomes absolutely necessary to assess the capacity of these rural pregnant women to withstand the effects of these infections on them and their fetuses. We assessed the serum levels of antioxidant minerals known to have immune functions - selenium and zinc, in normal non-supplemented pregnancy in some rural areas of Southeastern Nigeria to evaluate the effects of uncomplicated pregnancy on these indices.


  Materials and Methods Top


Ethical clearance

Ethical clearance for this study was obtained from the Research Ethics Committee of University of Nigeria Teaching Hospital while additional informed consents were sought and obtained from the subjects.

Study areas

The study was done in two rural communities - Ezzamgbo and Onueke, in Ebonyi State of Nigeria. Inhabitants are artisans, low-level civil servants and subsistent farmers, who are mainly Christians and African traditional religionists. Each community has one health center manned by a nurse/midwife and two or three health technicians with occasional visits by qualified medical doctors - mainly on antenatal days. There were no facilities for blood banking and other laboratory services, except the use of torques paper for rough estimation of hemoglobin and multi-dipsticks for urinalysis.

Subjects

Our subjects included 181 pregnant women aged between 18 and 40 years, who were attending the antenatal clinics of the health centers for the first time during their current respective pregnancies and 50 age-matched, non-pregnant, and apparently healthy women, who were not in their menstrual period at the time of sample collection. Patients were first divided into first trimester, <14 weeks of gestation (45), second trimester, 14-28 weeks of gestation (62), and third trimester, 29 weeks till delivery (74). They were later divided into another 3 groups according to parity, that is, 0-3 children (50), 4-6 children (76), and 7-9 children (55), before the current pregnancy.

Exclusion criteria

Patients who were already taking antenatal drugs before coming to the clinics were excluded from the study. Also, excluded were those with history of repeated cesarean sections, habitual alcohol consumption, and chronic diseases like diabetes, hypertension, and HIV infections, as well as evidence of malaria infections.

Dietary index

The dietary indices were calculated by using 24-hour dietary recall based on the known compositions of commonly eaten foods in Nigeria. [18]

Sample collection

A total of 6.0 ml of venous blood was collected from each subject, put into a chemically clean and dry test tube, and allowed to stand for 30 minutes at room temperature to clot and retract. This was then centrifuged for 10 minutes at 3000 rpm, and serum obtained was stored frozen for the determination of the trace elements using atomic absorption spectrophotometer (Buck Scientific Spectrophotometer Model 205, East Norwalk, Connecticut, USA)

Statistical analysis

Statistical analyzes were done using SPSS 15. Values were expressed as means and standard error means. Differences between means were calculated using one-way analysis of variance (ANOVA), and significance was taken at P0 < 0.05.


  Results Top


[Table 1] shows some demographic characteristics of the subjects, with average age for the pregnant women as 24.9 years and that of the controls as 24.1 years. [Table 2] shows the values of both trace elements in controls and pregnancy. These included 108.85 ± 2.09 μg/dL in control subjects and 88.48 ± 1.45 μg/dL in pregnant women for selenium, showing significant decrease (P < 0.001) in pregnancy, and 4.36 ± 0.29 mg/dL in control subjects and 3.26 ± 0.11 mg/dL in pregnant women for zinc, also showing significant decrease ( P < 0.001) in pregnancy. [Table 3] is the multiple comparisons of both elements over gestation. Serum selenium concentrations were 107.07 ± 2.19 μg/dL in first trimester, 82.37 ± 2.15 μg/dL in second trimester, and 81.50 ± 2.0 μg/dL in third trimester, showing non-significant change ( P = 0.964) between control and first trimester, but significant decrease ( P < 0.001 each) from control to second and third trimesters. However, there was no significant difference ( P = 0.992) between the values in second and third trimesters. Serum zinc concentrations were 4.34 ± 0.20 mg/dL in first trimester, 2.84 ± 0.13 mg/dL in second trimester, and 2.92 ± 0.16 mg/dL in third trimester, also showing the same trend as selenium, with P values of 0.974, <0.001, and 0.996, respectively. [Table 4] is the multiple comparisons of both elements in different parity groups. Serum selenium concentrations were 89.65 ± 2.28 μg/dL in those with 0-3 children, 84.90 ± 2.09 μg/dL in those with 4-6 children and 94.32 ± 2.38 μg/dL in those with 7-9 children, respectively, showing that the difference between the serum selenium concentration in each parity group and the control was significant ( P ≤ 0.003), while there was no significant difference between one parity group and another ( P ≤ 0.066). Likewise, the zinc concentrations in different parity groups were 3.07 ± 0.13 mg/dL, 2.92 ± 0.12 mg/dL, and 3.95 ± 0.26 mg/dL for those with 0-3, 4-6, and 7-9 children, respectively. All the parity groups showed significantly decreased value from that of control subjects ( P < 0.001 each), but unlike selenium, there was significant increase at 7-9 parity group ( P < 0.001) over preceding parity group.
Table 1: Some demographic characteristics of the subjects

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Table 2: Means±SDs of serum selenium and zinc in pregnant women and controls

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Table 3: Multiple comparisons of serum selenium and zinc in different trimesters of pregnancy and control

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Table 4: Multiple comparisons of serum selenium and zinc in different parity groups and controls

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  Discussion Top


The mean serum concentration of selenium in the controls - 108 ± 2.09 μg/dL is consistent with the reference value earlier reported. [19] When compared with the value obtained from the pregnant women - 88.48 ± 1.45 μg/dL, the trace element showed significant decrease ( P < 0.001) in pregnancy. This is consistent with earlier studies, [20],[21] which also demonstrated negative correlation between red cell selenium and recurrent pregnancy loss/habitual miscarriage. Though there was no significant difference ( P = 0.964) between the selenium concentration in first trimester and the control, the differences between the first and subsequent trimesters were statistically significant ( P < 0.001 each). Selenium is an acute-phase reactant, hence the non-significant difference between the values in the controls and first trimester - the onset of pregnancy. However, as pregnancy progressed, the value decreased sharply, implying that there may be negative correlation with gestational age. While selenium is known to decrease oxidative stress and inflammation and improve immune functions, [5] glutathione peroxidase - a selono-protein, is also known to play critical role in regulating antioxidant status, [22] all helping to stable pregnancy. Hence, low serum selenium concentration has been reported in miscarriages and pre-eclampsia. [22],[23] For this, care must be taken, in form of good nutrition and supplementation, to maintain adequate serum/blood concentration of this trace element throughout gestation to ameliorate oxidative stress and guard against infections to prevent these untoward pregnancy outcomes. Adequate supplementation is inevitably required in our rural areas to maintain the needed positive correlation between gestational age and cord blood concentration of selenium. This positive correlation is also to ensure good birth weight [24] and avoid other complications of pregnancy. Though there was significant change ( P ≤ 0.003) in the serum selenium concentration between each parity group and the control, there was no significant change in its concentration between one parity group and another ( P ≥ 0.066). Therefore, primigravidae have no advantage over multigravidae in terms of selenium metabolism during pregnancy.

The mean serum zinc concentration in our controls - 4.46 ± 0.29 mg/dL is significantly lower than other earlier reported reference values of the element for all ages. [19] The difference may be a reflection of soil and food contents of the element in the different areas. Our result is consistent with earlier report that zinc deficiency is known to be prevalent in the developing world where only cereals are consumed by the populace as staple food. [25] Our study areas are not only in a developing country, but also are in rural areas of the country where cereals are almost next to nothing as the staple foods. Therefore, low serum zinc level in these apparently healthy non-pregnant women (controls) may be in line with their dietary pattern. Despite low level of this antioxidant in apparently healthy population, it subsequently decreased significantly ( P < 0.001) in pregnancy. This is consistent with results earlier reported from different parts of the world including Zaire, [26] Kuwait, [27] Spain, [28],[29] India, [30] and Nigeria. [31] Over gestation, serum zinc level showed non-significant change between first trimester and the control ( P = 0.974) but significant decrease in second and third trimesters ( P < 0.001 each). This later decrease also agrees with earlier report that zinc requirement in the third trimester of pregnancy is approximately twice that of non-pregnant women. [32] Thus, the value of serum zinc in non-pregnant subjects - 4.46 ± 0.29 mg/dL is approximately 1.5 times the value in the third trimester in this study - 2.99 ± 0.16 mg/dL. This deficiency at term will definitely lead to zinc deficiency in infants, especially premature infants, who will be deprived of incorporated fetal zinc. Low serum zinc levels impair innate and acquired immunity and may cause many untoward pregnancy outcomes including growth retardation, frequent abortion, prolonged gestation, teratogenicity, stillbirth, difficulty in parturition, pre-eclamptic toxemia, adverse neurobehavioral and immunological development, low birth weight of infants, low head circumferences of babies, and other malformations. [26],[30],[33],[34] General observation in our study areas was delivery of small-for-age (SFA) babies, even when delivered at term. Zinc deficiency in these areas may be one of the causative factors of these small-sized babies. Therefore, zinc supplementation is of great importance in these rural areas, especially during parturition. Despite initial decrease, serum zinc showed significant increase ( P < 0.001) as parity increased, thus the value in 7-9 parity group showed relative recovery and significant increase over the preceding group ( P < 0.001). Zinc level is said to increase immediately after delivery; [35] therefore, this may be cumulative, ensuring that multigravidae may not suffer absolute zinc deficiency. For this, proper assessment of the zinc status is necessary before commencement of supplementation in pregnancy, and this should be individualized, especially in mutligravidae.

The significantly lower values of these elements in pregnant women when compared with the controls, and significant higher values in first trimester when compared with subsequent trimesters suggest that pregnant women from our rural areas are prone to selenium and zinc deficiencies. This situation does not augur well for the development of the fetuses and health of the pregnant women who are greatly exposed to increased oxidative stress and reduced immune functions. Hitherto, the routine antenatal drugs in these rural areas were vitamin B-complex (B1, B2, and B6), vitamin C, folic acid, and fesolate (as iron tablet). Recently, many pregnancy care-givers have resorted to use of multivitamin capsules that contain some antioxidant minerals. This is because these routine drugs have not met the expectations of the pregnancy care-givers, except in terms of reducing anemia in pregnancy. However, the contents of some of these capsules used in our study area showed that many of them contain less of these elements when compared with the recommended Dietary Reference Intake (DRI) of the elements for pregnant women. [36] This confirms the absolute need for supervised supplementation of these antioxidant minerals during pregnancy if the untoward pregnancy complications are to be averted. In addition, we suggest constant public health education in the rural areas emphasizing the need for early antenatal registration for early assessment. There is also absolute need for nurses and other pregnancy care-givers to emphasize the need for adequate consumption of locally produced vegetables and fruits to augment supplements. These vegetables and fruits are usually produced in adequate quantity in the villages but transported to the nearby urban areas for paltry financial returns. We also suggest intermittent intervention programs by governments, government agencies, and non-governmental organizations in rural areas of developing countries to augment poor antenatal drug intake by pregnant women, occasioned by poverty and ignorance.

 
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]


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