This study was designed to assess iodine and nutritional status of primary school children in a rural community, Okpuje, using recommended quantifiable indicators. A total of 395 school children, 6-12 years (204 males and 191 females) were selected through a multi-stage sampling procedure. Structured questionnaire was used to obtain information on socioeconomic status (name, age, class, sex, parents occupation and household size). Dietary information was obtained using 24hour dietary recall and food frequency questionnaire. Heights and weights of the children were measured using approved methods. Age was assessed using school records. The WHO Z score system was used to classify stunting, wasting and underweight among the children. Goiter was assessed clinically by a trained nurse using the standard palpation method. Salt samples were collected from Okpuje market and the children were asked to bring salts (10g) from their mother’s kitchen to test for iodine content. Urinary iodine excretion (UIE) levels of 20% sub-sample study subjects, selected through simple random sampling by balloting without replacement, were analyzed using the Sandell-Koltholf reaction to determine the urinary levels of iodine. Data obtained were analyzed using descriptive statistics and chi-square analysis. Results showed that children were from predominantly farming communities and consumed monotonous diets. Twenty four hour dietary recall revealed that majority of the children ate 3 times a day and consumed cereals and cassava based diets for breakfast, lunch and supper. No child was found with goiter. The prevalence of stunting, wasting and underweight were 19.5%, 8.9% and 8.5%, respectively. Wasting was more in male children than in female children. Underweight and stunting were more in females than males. Stunting and wasting was more in older children (10-12 years) while underweight was more in younger children (6-9years). The mean UIE was 124.7mcg/l. About 96% of the children had UIE value consistent with adequate intake (UIE > 100mcg/l). A total of 3.8% of the children had UIE less than 100mcg/l. Iodine content of 395 salt samples from home, tested with spot testing kit revealed that 94.2% had iodine greater than 15ppm and 5.8% had iodine less than 15ppm. No salt sample was found without iodine. The entire salt sample collected from the market had iodine greater than 15ppm. The mean urinary excretion of 124.7mcg/l obtained in this study suggests no biochemical iodine deficiency in majority of the respondents and indicates that Okpuje in Nsukka LGA is in the transition phase of iodine deficiency to iodine sufficiency.
1.1 Background to the Study
Iodine is an essential mineral required by the body to synthesize thyroid hormones (thyroxine and triiodothyronine). The most important of which is thyroxine, a metabolism regulating substance (Kennedy, Nantel & Shetty,2003). The trace element (iodine) is an essential nutrient for human growth and development.
The daily recommended intake of iodine for school children (6-12yrs) is 120mcg/day (WHO/UNICEF/International Council for Control of Iodine Deficiency Disorders (ICCIDD), 2007). Iodine deficiency disorders are primarily the result of inadequate amounts of iodine in the soil, water and food as well as consumption of foods rich in goitrogenic substances (Ene-Obong, 2001). Apart from intake of goitrogenic and inadequate amounts of iodine, other factors are known to interfere with adequate iodine nutrition and these include protein energy malnutrition (Brahmbhatt et al., 2007), and vitamin A deficiency (ACC/SCN, 1994). The world’s natural supply of iodine is mostly from the ocean in the form of iodide. The adequacy of dietary iodine is usually determined by the measurement of urinary excretion of iodine (Lee, Bradley & Dwyer, 1999). The commonest manifestation of iodine deficiency is goiter. It occurs when the iodine level of the blood is low; the cells of the thyroid gland enlarge in an attempt to trap as many particles of iodine as possible. Sometimes the gland enlarges until it is visible as a swelling in the anterior part of the neck (Chatterjea & Rana, 2004).
Inadequate dietary iodine leads to reduced synthesis of thyroid hormones (Thyroxine (T4) and Triiodothyronine (T3)). A lower level of T4 stimulates the pituitary gland to stimulate thyroid stimulating hormone (TSH) to fulfill the production of thyroid gland hormones. It is important not to over consume iodine as it has a relatively narrow range of intakes that reliably support good thyroid function. Consumption of an excessive amount of iodized salt or seaweeds could readily result to complex disruptive effect on the thyroid gland and may cause hyperthyroidism in susceptible individuals, as well as increasing the risk of thyroid cancer (Chatterjea & Rana, 2004).
The supply of adequate iodine in the diet and the elimination of goitrogens are ways to prevent endemic goitre. However, there is increasing evidence that endemic goitre could be provoked by genetic as well as environmental factors including emotional stress, smoking and infections (Abuye, Omwega & Imungi, 1999).
Iodine is an important micronutrient required for proper brain development. One of the millennium development goals (MDG) of the United Nations is to reduce child mortality by 2015 (Andy & Andrew, 2004). Severe iodine deficiency in the mother has been associated with miscarriages, still births, preterm delivery and congenital abnormalities in their babies (Benoist, McLean, Anderson & Rogers, 2008). Iodine deficiency in its most extreme form, results in cretinism. Of much greater public health importance, are more subtle degrees of brain damage and reduced cognitive capacity, which could affect the whole population (World Health Organization (WHO), 2001). Iodine is the world’s leading cause of mental retardation. More than two billion children suffer from lowered intelligent quotient (IQ) and retardation due to iodine deficiency (United Nations Children’s Fund (UNICEF), 2002). Iodine deficiency disorder can be corrected by re-supplying iodine in the diet (Delange, 2000). The impact of IDD is enormous and it affects all the stages of life (ICCIDD/UNICEF/WHO, 2001).
As part of the strategies to reduce the prevalence of IDD in Nigeria, the universal salt iodization (USI) program was introduced in 1995. In most countries of the world, universal salt iodization has been employed as a means of eliminating disorders secondary to iodine deficiency. WHO, UNICEF and ICCIDD has brought iodine sufficiency within reach of about 1.5 billion people of the world who were deficient decades ago; and now rely on the urinary iodine concentration as the primary indicator of effectiveness (WHO, ICCIDD, 1999). In Africa and indeed Nigeria, great progress has been made towards the elimination of iodine deficiency saving millions of children from its adverse effects, largely due to the increased household availability of iodized salt (ICCIDD, 2003; WHO, 2007; Lantum, 2009).
Most iodine absorbed in the body eventually appears in the urine; therefore, urinary iodine concentration is a good marker for very recent dietary iodine intake. Urine iodine excretion is a good biomarker of dietary intake of iodine over days and is the measure of choice for assessment of iodine status (WHO/UNICEF/ICCIDD, 2007). For epidemiological studies, a population distribution of urinary iodine is required and, because the frequency distribution is typically skewed towards high values, the median rather than the mean is judged the best indicator of iodine status. WHO, ICCIDD, and UNICEF (2007) recommend that for national surveys of iodine nutrition, the median urinary iodine from representative samples of spot urine collections from children aged 6—12 years can be used to define a population’s iodine status. School-age children 6-12 years old form a useful study group for assessing iodine deficiency because of their physiological vulnerability to disease, their accessibility through school and a representation of iodine deficiency disorders (Joshi et al, 2006). In Nigeria, the National Agency for Food and Drug Administration and Control (NAFDAC) has greatly promoted salt iodization using public campaigns (Lantum, 2009).
In many developing countries, however, children hardly grow to their full potential as a result of many environmental factors such as malnutrition and infections (Van de Poel, Hosseinpoor, Speybroeck, Van ourti & Vega, 2008). Children from poor or less privileged families in those countries are the most affected due to food insecurity, inadequate facilities, infection and poor general environmental sanitations. The causes of child under nutrition are complex, multidimensional, and interrelated, ranging from factors as fundamental as political instability and slow economic growth to those as specific in their manifestation as respiratory infection and diarrhea disease (ACC/SCN, 2000). Lack of progress to combat malnutrition is damaging to children and nations. For every visibly undernourished child, there are several more, battling a hidden nutritional crisis. Many are seriously deficient in essential vitamins and minerals such as Iodine, Vitamin A and Iron (Clements, 2006).
This study was therefore carried out to assess the iodine and anthropometric status of primary school children in a Nigerian community, Okpuje.
1.2 Statement of the Problem
IDD is a serious public health problem in developing countries. It is one of the oldest and most insidious of human health problems. WHO (2011) estimated that two billion people worldwide including 285 million children of school age have iodine deficiency despite major national and international efforts to increase iodine intake, mainly through voluntary or mandatory intake of salt (WHO, 2011). Recent estimates by the World Health Organization (WHO, 2011) indicate that 54 countries are still affected by iodine deficiency and nearly 2 billion individuals worldwide are iodine-deficient. A large percentage of the world population is at risk of iodine deficiency disorder (IDD) (Delange & Hetzel, 2003). Poor nutrition remains a global epidemic contributing to more than half of all children’s deaths, about 5.6 million per year. It has been known that as severity of iodine deficiency increases, the occurrence of poor pregnancy outcome such as miscarriage, still birth, and increased infant mortality is more likely (Bruno & Maria, 2004).
Several parts of Nigeria have been identified with goitre endemicity and labeled the “goitre belt” (Abua, Ajayi & Sanusi, 2008; Isichie et al., 1987; Olurin, 1975; Nwokolo & Ekpechi, 1966). In 1993, a National goitre rate of 20% was reported and 20 million Nigerians were estimated to be affected by IDD (UNICEF, 1993). The Participatory Information Collection Study (1993), using thyroid hormone concentrations as indicators of iodine status reported an iodine deficiency prevalence of 65.6% in south-east, 41% in south-west, 43% in the north-west of Nigeria. Surveys found that the population in Nigeria affected by goiter prevalence in 30 states dropped from 40 million in 1990 to less than 11 million in 1999 (IDD Newsletter, 2000).
Enugu State in south east and Kogi state in south western Nigeria has long been identified as a goiter endemic area with a goiter prevalence rate of 16-40% (Egbuta, Onyezili & PHN 2002). Nwamarah and Okeke (2012) reported an iodine deficiency prevalence of 58.3% among school children in Obukpa, a community in Nsukka, Enugu state. Okpuje situated in Nsukka is mountainous, where the top layer of the soil has been eroded for decades leading to leaching away of nutrients including iodine. This made the people prone to iodine deficiency.