Description
CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
This research is on Assessment of the relationship between some trace elements and antioxidant enzymes in under-five children with protein-energy malnutrition.
Severe malnutrition is common among developing countries both in rural and urban areas (Psaki et al., 2012). It is responsible for at least half of the 7.6 million child?s deaths each year in developing countries (Park et al., 2012). Children who are poorly nourished suffer up to 160 days of illness each year (UNICEF, 2008). Malnutrition magnifies the effects of every disease, including measles and malaria. The estimated proportions of deaths in which malnutrition is an underlying cause are diarrhoea (61%), malaria (57%), pneumonia (52%) and measles (45%) (Black et al., 2003). Protein-energy malnutrition (PEM) is one of the most prevalent and devastating forms of malnutrition in the world (Whitney and Rolfes, 2008).
PEM is defined by the WHO as the cellular imbalance between the supply of nutrients and energy and the body’s demand for them to ensure growth, maintenance, and specific functions (WHO, 1993). It has long been recognized as a common problem, especially for children in the developing countries whose nutritional intake is deficient for socioeconomic reasons (Collins et al., 2006). PEM results from inadequate intake and absorption which may be due to diseases, insufficient household food security, inadequate maternal and child care, poor sanitation and ignorance (UNICEF, 1990). The earliest symptoms include subtle changes in the mood of the child while further changes include loss of appetite and interest in the surroundings, which lead to decreased social interaction with peers or siblings (Allen, 1995). When PEM becomes more severe, it has adverse effects on the child’s cognitive and behavioral development, both in the short and long term (Mendez and Linda, 1999). It may also affect children’s mental performance by other indirect mechanisms such as social and economic disadvantages (Johnston and Low,
1987), differences in parental education (Levine and Levine, 1991), years of schooling (Ceci, 1991), inadequate attention or affection from caregivers and other environmental factors .
Marasmus, kwashiorkor and marasmic-kwashiorkor are clinical forms of severe PEM (Scrimshaw and Viteri, 2010 ). Marasmus is characterized by muscle wasting, anaemia, severe weight loss, growth impairment as well as dry and thin hair (Jahoor et al., 2008). Kwashiorkor is characterized by apathy, increased susceptibility to infection, hypoalbuminemia, oedema, weight loss, growth impairment as well as dry and brittle hair and skin lesions (Jahoor et al., 2008). However, the clinical onset of kwashiorkor usually takes place in a shorter period of time as compared to marasmus. Marasmic-kwashiorkor occurs when there are symptoms of both marasmus and kwashiorkor (Wellcome, 1970).
Of all children under the age of five who suffer from PEM in developing countries, about 38% are stunted (low height-for-age), 31% are underweight (low weight-for-age) and 9% are wasted (low weight-for-height) (Brabin and Coulter, 2003). In Nigeria, about 52.6% of under-five children are stunted, 35.1% are underweight and 19.9% are wasted (NDHS, 2008). In Kaduna state, 6.8% prevalence of PEM was reported in Zaria (Alegbejo and Yakubu, 1993).
Free radicals are chemicals or molecular fragments that have a charge due to an excess or deficient number of electrons (Riley, 1994). Examples of free radicals are the superoxide anions, hydroxyl radicals, transition metals such as nitric acid and ozone. Free radicals are highly unstable because they have one or more unpaired electron, to regain its stability, the free radicals quickly find a stable but vulnerable compound from which to steal or grab an electron (Martin et al., 2003). With the loss of an electron, the formerly stable molecule becomes a free radical itself and steals an electron from another nearby molecule. Thus, an electron snatching chain reaction occurs with free radicals producing more free radicals thereby damaging the cells, proteins and DNA (Martin et al., 2003).
Malnutrition leads to depletion of hepatic antioxidant stores and enhances hepatic release of free radicals (Robinson et al., 1996). The harmful effects of these free radicals have been documented in children with PEM which is responsible for cell damage leading to oedema, fatty liver and skin lesions (Golden et al., 1990).
An antioxidant defense system exists in the cells to keep the concentration of these free radicals at a non-harmful level. Antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) are directly involved in the detoxification of free radicals through catalytic action (Stahl and Sies, 1997). These antioxidant enzymes are synthesized by the body but the trace elements (Selenium, Zinc and Copper) needed as cofactors must be supplied by the diet. Selenium (Se) is a cofactor in glutathione peroxidase (Chan et al., 1998). The superoxide dismutase present in the cytosol contains zinc (Zn) and copper (Cu) (Fridovich, 1986). Reduced levels of these antioxidant enzymes (SOD and GPx) and their cofactors have been found in children with severe PEM (Sive et al., 1993; Houssaini et al., 1997) which results in the buildup of free radicals. In addition to trace elements that serve as cofactors of antioxidative enzymes, the diets also provide antioxidant vitamins (vitamin A, C and E) that react directly with free radicals in a non catalytic manner (Halliwell, 1995).
1.2 Statement of the Research Problem
Malnutrition remains a major health burden in developing countries. It is recognized globally as the most important risk factor for illness and death, contributing to half of death in young children worldwide (W.H.O, 2002). PEM has a great adverse effect on health resulting in poor 3
growth, impaired immunologic factors, irritability, apathy and delayed cognitive development (Ugwuja et al.,2007). Oedema, skin lesion, fatty liver found in severe protein-energy malnourished children has been reported to be as a result of the harmful effects of free radicals (Golden et al., 1990) and reduced level of antioxidant defense system. Therefore, there is need to carry out a comprehensive study that will provide information for the better management of malnourished children.
1.3 Justification for the Study
Although evidence on the relationship between trace elements and PEM is known (Ugwuja et al.,
2007), there is no sufficient evidence or data on the relationship between trace elements and antioxidant enzymes among under-five children with PEM in Nigeria. Therefore, the results of this study could broaden the understanding of the relationship between trace elements and antioxidant enzymes in protein-energy malnourished children in Nigeria with a view to formulating nutrition intervention programmes and policies targeted at reducing the prevalence of this disease and its detrimental effect among under-five children.
1.4 Aim and Objectives of the Study
The aim of the present study was to establish the relationship between some trace elements and antioxidant enzymes in under-five children with PEM.
The specific objectives of the present study were as follows:
1. To determine the demographic and feeding characteristics of patients with PEM and the socio-economic characteristics of the parents and controls.
2. To determine the concentration of serum total protein, albumin, trace elements (zinc and copper), and serum antioxidant enzymes (superoxide dismutase and glutathione peroxidase) levels in patients with PEM and controls.
3. To compare the results of serum total protein, albumin, trace elements (zinc and copper) and antioxidant enzymes (superoxide dismutase and glutathione peroxidase) obtained from patients with PEM and controls.
4. To establish the relationship between some trace elements (copper and zinc) and antioxidant enzymes (superoxide dismutase and glutathione peroxidase) in patients with PEM and controls.