SELENIUM, ZINC AND IRON STATUS OF PREGNANT WOMEN AND ZINC CONTENT OF SELECTED TRADITIONAL FOODS IN OBIO-AKPOR L.G.A RIVERS STATE, NIGERIA

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                                                                ABSTRACT

The study was designed to have both survey and biochemical components. Three communities were selected randomly from twelve communities in Obio-Akpor local government area. The sample size was calculated using the maternal mortality ratio for pregnant women in Nigeria which was 30%. Two hundred pregnant women were purposively selected from health care centers, public and private clinics providing ante-natal care and from traditional birth attendants and local delivery homes. The survey component assessed the socio-economic and demographic characteristics of the respondents using a structured questionnaire to collect information on mothers’ age, pregnancy age, number of deliveries, education, occupation, food frequency consumption, weighed food intake and clinical signs of malnutrition. Biochemical assessment was carried out using standard procedures in assessing iron, selenium and zinc status of pregnant women and zinc content of selected traditional foods consumed in Obio-Akpor LGA. Serum iron, selenium, and zinc were determined using atomic absorption spectrometry model number Buck 210/11. The analytical procedures of the Association of the Official Analytical Chemists were used for proximate composition, and mineral composition of the traditional foods. The questionnaire were coded and entered into computer using the Statistical Package for Social Sciences (SPSS) version 16. The data were analyzed using descriptive statistics. Chi-square analysis and Pearson’s correlation were used to identify variables that had a significant role in influencing micronutrient (iron, selenium and zinc) status. The study showed that 40% of the pregnant women were iron deficient and 97.3% were zinc deficient. No case of selenium deficiency was identified in the present study. Occupation of women, pregnancy age and ‘‘who receives best portion of food” had a significant (P<0.05) association with the iron and zinc status of the pregnant women. There was a significant (P<0.05) association between iron status and signs and symptoms of iron deficiency namely weakness and reduced physical activity. There was a significant (c2 = 39.304; P= 0.05) association between education and occupation. Educational status significantly (c2 =44.475; P=0.05) differed with age at marriage. Educational status and number of children was equally highly significant (c2 =32.024; P=0.05). There was a positive association between income and availability of money to purchase food (c2 =17.240; P= 0.05). Occupation and availability of money to purchase food also had a positive relationship (c2 =16.808; P=0.05). There was a positive association between weakness and fatigue (r=0.355; P< 0.05); weakness and reduced physical activity (r=0.351; P< 0.05) in relation to iron: loss of appetite and diarrhoea (r=0.157; P<0.05) in relation to zinc. The mineral composition of zinc in the foods ranged from figures 4.37mg/100g (shark fish) to 55.55mg/100g (oysters). The iron contents of the foods ranged from shark fish (2.91mg/100g) to sardine fish (14.93mg/100g). When compared with FAO/WHO requirement values, the pregnant women had lower dietary intakes of nutrients crucial in pregnancy such as zinc (72.9%), niacin (74.11%), thiamin (78.567%), riboflavin (87.85%) and calcium (96.99%). There were differences in food consumption pattern among the pregnant women, indicating that the foods consumed were determined by availability, affordability and seasonality.

                                                       CHAPTER ONE

  •                                                     INTRODUCTION

1.1       Background to the Study 

            Micronutrients encompass vitamins and minerals which are essential for human development and functioning. They are needed in small amount. Micronutrients are well known to play an important role in the maintenance of health. Alterations in maternal – fetal disposition of some essential nutrients could be a potential health risk for the mothers as well as the fetus. Micronutrient malnutrition is primarily related to inadequate dietary intake and pregnancy places women at risk of nutritional problems due to increased need for both macro and micronutrients during pregnancy. Deficiencies of micronutrients (iron, selenium and zinc) during pregnancy continue to be a problem of considerable magnitude in most developing countries of the world. Child birth remains one of the biggest health risks for women especially in the developing countries. Fifteen hundred women (1,500), die every day during delivery, which is a half a million mothers every year (UNICEF, 2009). The WHO, (2007) estimated that about 80% of maternal deaths are due to direct causes which are hemorrhage, sepsis, eclampsia and unsafe abortion. About 20% are due to indirect causes including anemia, malaria and heart disease (WHO, 2007). The micronutrient status of mothers can affect hemorrhage, anemia, eclampsia, sepsis and perhaps malaria. In addition, micronutrients can reduce morbidity. Adequate micronutrient nutrition for pregnant women is critical for the health and survival prospects of both mothers and newborns. Micronutrient deficiencies of mothers increase their health risks as well as that of their babies. The high incidence of micronutrient deficiencies in pregnant women predisposes them to high maternal mortality especially in the developing countries. In Africa maternal mortality is estimated at 820 per 100,000 births. In Nigeria, the maternal mortality ratio is 1,100 deaths per 100,000 live births and the lifetime risk of maternal death, at 1 in 8. Approximately 1 in every 9 maternal deaths occurs in Nigeria alone (UNICEF, 2009).

            Iron is an essential micronutrient which helps in normal human physiology. It is an integral part of many proteins and enzymes that maintain good health. Iron is essential for regulation of cellular growth and differentiation. It is also an essential component of protein involved in oxygen transport (Dallman, 1986). Iron deficiency anemia affects over 2 billion people and the world health organization estimates that a disproportionate percentage of iron deficiency anemia occur in low income countries, accompanied by adverse pregnancy outcomes such as preterm birth, low birth weight, and increased maternal mortality (UNICEF, 2009). It has been estimated that over half the pregnant women in the world have a hemoglobin level indicative of anemia. In Africa the prevalence ranges from 35% to 72% (UNICEF, 2009). The 2003 Nigeria Demographic and Health Survey conducted in Nigeria estimates that 35% of pregnant women were iron deficient (Maziya et al., 2003). Iron deficiency anemia, (especially severe form) has been shown to the associated with increased maternal mortality. The mild form of iron deficiency anemia may increase the rate of premature delivery and prenatal mortality (Carriaga, Skikne, Finley, Cutler and Cook, 1991).

            Zinc is an essential micronutrient that participates in carbohydrate and protein metabolism. Zinc is required for cellular division and differentiation, and is an essential nutrient for normal embryogenesis. Zinc plays an important role in growth and development. It takes part in deoxyribonucleic and ribonucleic synthesis. It also interacts with hormones important in bone growth such as testosterone, insulin and the thyroid hormone. Through these functions, zinc plays an important role in intrauterine growth (Nishi, 1996). Several studies have shown an association between maternal plasma zinc levels and birth weight (Neggers et al., 1990). Studies have also shown how maternal serum zinc concentrations are associated with increased incidence of foetal malformations and foeto-maternal complication (Scholl, Hediger, Schall, and Khoo, 1993). Maternal morbidities such as pregnancy induced hypertension, prolonged labour and pre-and post-term deliveries may be increased in zinc deficient pregnant women. However, zinc deficiency is one of the most common nutritional problems of pregnant women especially in the developing countries. Caulfield, Zavaleta, Shankar, and Merialdi (1998) estimated that 82% of pregnant women worldwide have inadequate intakes of zinc to meet the normative needs of pregnancy. Zinc deficiency was reported as 43% in pregnant women in a food consumption and nutrition survey in Nigeria (Maziya et al., 2003).

             Nutritional metals such as zinc do occur naturally in foods as essential trace elements needed for good health, but they could be toxic when their concentrations exceed units of safe exposure (Reilly, 1991). Knowledge of heavy metal contents in crops is important for the identification of adequate, sub adequate and marginal intake levels for humans so that diseases related to trace elements deficiency can be overcome (Iyengar, 1974).   Presence of trace elements in foods has been ascribed to their absorption from the soil and sources such as type of fertilizer, agricultural chemicals and contaminating dirt’s (Banu, Preda and Vasu, 1985).  Other sources of heavy metals contamination of most food stuff may also include adaptation of mechanized farming, sprays and seed preservatives. Zinc can be absorbed orally from food. There have been some reports on the zinc contents of fruits and vegetables consumed in north-central zone of Nigeria (Iyaka, 2007). But few have covered zinc content measured for a wide variety of foods consumed in Rivers State, Nigeria.

          Selenium has attracted particular attention in recent years. Selenium is an essential trace element for human beings. It is needed for the activity of glutathione peroxidase and other antioxidant functions (Combs and Combs, 1984). Selenium status during pregnancy is of great importance because of the significance of selenium for fetus growth and antioxidant protection of neonates. Many factors can influence the selenium contents of biological fluids and therefore values can vary in a significant way from one person to another. The factors that influence selenium content are: the geographical location of the population, which affects the content of selenium in the soils; the availability of the element in soil and in vegetables; its chemical form and its bioavailability; the origin of the foods ingested; eating habits; alcohol and tobacco consumption; the use of oral contraceptives; as well as the physiological conditions of the subject, e.g. age, sex, pregnancy, lactation and other pathological situations can have  an effect on the metabolism of the element. The selenium requirements of women seem to increase during pregnancy. The prevalence of selenium deficiency in the world is not documented since there are a few large scale surveys that have been conducted in respect to selenium. This study was an attempt to assess the mineral status (iron, selenium and zinc) of pregnant women and also determine the zinc contents of selected traditional foods in Rivers State, Nigeria.

  • Statement to the Problem
SELENIUM, ZINC AND IRON STATUS OF PREGNANT WOMEN AND ZINC CONTENT OF SELECTED TRADITIONAL FOODS IN OBIO-AKPOR L.G.A RIVERS STATE, NIGERIA