|Year : 2018 | Volume
| Issue : 1 | Page : 1-7
Association between serum phosphate and iron concentrations with body mass index in a population of adults in Orlu, Imo State, Nigeria
Jude Nnabuife Egwurugwu1, Celestine N Ekweogu2, Promise Nwamkpa2, Moses C Ohamaeme3, Patrick C Ugwuezumba1, Frances U Ogunnaya4
1 Department of Human Physiology, College of Medicine, Imo State University, Owerri, Imo State, Nigeria
2 Department of Medical Biochemistry, College of Medicine, Imo State University, Owerri, Imo State, Nigeria
3 Department of Community Medicine, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra State, Nigeria
4 Department of Internal Medicine, Imo State University Teaching Hospital, Orlu, Imo State, Nigeria
|Date of Web Publication||20-Dec-2018|
Dr. Jude Nnabuife Egwurugwu
Department of Human Physiology, College of Medicine, Imo State University, Owerri, Imo State
Source of Support: None, Conflict of Interest: None
Background: To investigate the association between body mass index (BMI) with serum iron and phosphate levels. Materials and Methods: Five hundred adults aged 18–65 years in Orlu, Imo State, participated in the study. BMI was determined from the participants' height and body weight. Serum iron and phosphorus levels were measured after 8–12 h fast. Results: The mean serum iron level for individuals with overweight, moderate obesity, and severe obesity was 64.21 ± 4.81, 59.11 ± 3.17, and 54.73 ± 3.44, respectively, for males and 52.86 ± 4.16, 44.77 ± 4.87, and 39.62 ± 5.11, respectively, for females as compared to 72.58 ± 5.43 and 61.19 ± 3.48 for males and females with normal BMI, respectively. Further, the mean serum phosphate level for individuals with overweight, moderate obesity, and severe obesity was 2.71 ± 1.82, 2.55 ± 1.17, and 2.51 ± 1.46, respectively, for males and 2.52 ± 1.87, 2.51 ± 1.67, and 2.48 ± 2.16, respectively, for females as compared to 3.72 ± 2.41 and 3.28 ± 2.11 for males and females with normal BMI, respectively. The serum iron and phosphate levels of obese individuals were significantly lower than in their counterparts with normal BMI (P < 0.05). The prevalence of overweight and obesity for males and females was 36.33%, 35.97% and 36.93%, 33.78%, respectively. Conclusion: BMI inversely correlated with serum iron and phosphate levels. Regular assessment of nutritional status of the obese and intake of high iron and phosphate foods should be encouraged with a view to preventing iron and phosphate deficiency diseases.
Keywords: Body mass index, obese, phosphate, serum iron
|How to cite this article:|
Egwurugwu JN, Ekweogu CN, Nwamkpa P, Ohamaeme MC, Ugwuezumba PC, Ogunnaya FU. Association between serum phosphate and iron concentrations with body mass index in a population of adults in Orlu, Imo State, Nigeria. Niger J Exp Clin Biosci 2018;6:1-7
|How to cite this URL:|
Egwurugwu JN, Ekweogu CN, Nwamkpa P, Ohamaeme MC, Ugwuezumba PC, Ogunnaya FU. Association between serum phosphate and iron concentrations with body mass index in a population of adults in Orlu, Imo State, Nigeria. Niger J Exp Clin Biosci [serial online] 2018 [cited 2019 Mar 23];6:1-7. Available from: http://www.njecbonline.org/text.asp?2018/6/1/1/248008
| Introduction|| |
Noncommunicable diseases have overtaken communicable diseases as the leading causes of mortality and morbidity in Nigeria., This change in disease pattern has been conventionally attributed to the recent advances in medicine, resulting in the development of drugs and vaccines for the effective control of communicable diseases, such as HIV/AIDS, tuberculosis, measles, and hepatitis B. Other factors driving this transition include changes in diet, cigarette smoking, alcohol consumption, and inadequate exercise. There is also rural to urban migration as well as fetal malnutrition, which predisposes individuals to development of noncommunicable diseases in adulthood. Leading among these noncommunicable diseases is obesity. Overweight and obesity have been defined by the World Health Organization as a body mass index (BMI) ≥25 kg/m2 and ≥30 kg/m2, respectively. These are associated with several diseases including cardiovascular diseases, diabetes mellitus, and several types of cancer, which are gradually assuming epidemic dimension in the world with Nigeria also having its own share of the burden.,
In 2016, worldwide, more than 1.9 billion adults aged 18 years and above were overweight. Of these, over 650 million adults were obese. This translates to 39% of adults 18 years and above being overweight and 13% obese in the same year. It has been projected that by 2030, there will be approximately 2.2 billion overweight and 1.1 billion obese persons globally. The World Health Organization Global Info Base on individuals aged 30 years and above showed that prevalence of overweight and obesity in Nigeria increased by 23% in men and 18% in women while the prevalence of obesity alone increased by 47% in men and 39% in women between 2002 and 2010., Surveys have shown that the increasing trend of obesity in the world is even more pronounced in the developing countries., In addition, several studies have also documented the prevalence of obesity in Nigeria. For instance, a study in Ile-Ife, Southwest Nigeria, documented the prevalence of obesity and overweight to be 12.5% and 20.3%, respectively. A similar study in Ilorin North-Central showed the prevalence of obesity and overweight to be 9.8% and 35.1%, respectively. Furthermore, another study in Lagos, Southwest Nigeria, also documented the prevalence of obesity and overweight to be 22.2% and 32.7%, respectively. There is a paucity of such data as mentioned above in the Southeastern Nigeria where Imo State is located.
This current trend of obesity has been attributed to the socioeconomic and epidemiological transition of Nigeria from a low-income country to a low-middle-income country, resulting from the changes in lifestyle behaviors and dietary intake. Many Nigerians now live sedentary lifestyle with high energy intake and low calorie expenditure., Whatever the cause of obesity may be, its long-term impact on the life of adult Nigerians is well documented. Obesity has been shown to be a predisposing factor in the rising prevalence of morbidity and mortality associated with noncommunicable diseases such as Type-2 diabetes mellitus, hypertension, cancer, and stroke among adults.,, Obese individuals are not only susceptible to complications such as hypertension, dyslipidemia, and Type-2 diabetes but also exposed to a variety of micronutrient deficiencies due to poor diet caused by the consumption of foods high in calorie but low in nutrients.,
Iron deficiency is the most common form of nutritional deficiency worldwide, and it is a significant public health problem in both developed and underdeveloped countries. The prevalence of iron deficiency is often higher in developing countries and is also associated with lower economic status.,,,, Iron deficiency anemia has been reported to affect 50%–60% of young children and pregnant women and 20%–30% of nonpregnant women in the developing countries. In a national representative cross-sectional study in the USA, the prevalence of iron deficiency was 9%–11% for adolescent girls and women of childbearing age, corresponding to approximately 8 million women with iron deficiency. Populations in the developing countries, premenopausal females, pregnant women, children, vegetarians, and frequent blood donors are largely affected by iron deficiency due to low dietary intake, inadequate bio-available iron, increased iron demand required for growth and development, iron losses, and changes in blood volume. Previous studies have reported that obesity has an adverse effect on iron status.,,,, Some studies showed that obese people are almost two times more likely to be diagnosed with iron deficiency. Iron deficiency anemia is significantly higher among obese than normal weight people.,, It has also become clear that iron deficiency and obesity do not merely represent the coincidence of two frequent conditions but are molecularly linked and mutually affect each other. The mechanism explaining the relationship between iron status and obesity remains unclear; this may be due to lower iron intakes and/or increased iron requirements in overweight individuals. In addition, the chronic inflammation and increased leptin production characteristic of obesity increase hepcidin secretion from the lower gastrointestinal tract, which, along with hepcidin produced by adipose tissue, could reduce dietary iron absorption.
Phosphorus is an element that is directly involved in carbohydrate metabolism, thus hypophosphatemia could contribute to impaired utilization of glucose and obesity.,, Recently, studies in adults have shown that patients with metabolic syndrome-associated diseases (obesity, hypertension, and diabetes) show significantly lower phosphate levels than healthy individuals.,, Low phosphorus status has been positively associated with increased body weight. This may be attributed to the impact of hepatic adenosine triphosophate (ATP), which depends on adequate dietary supply of phosphorous on suppressing food intake.,, This mechanism is supported by an inverse relation between body weight and hepatic ATP status.,, Modernization, including food industrialization, and globalization of food markets have been correlated with increased consumption of products containing negligible amounts of phosphorus, such as refined cereals (which reduces phosphorus content by 70%), oils, sugars, and sweeteners that are currently contributing to >50% of the food supply (kcal per capita per day) in most countries. This has decreased phosphorus ingestion to approximately 1–1.5 g/day, as compared with our ancestors estimated intake of 2.5 g per day (based on primarily raw, unprocessed food with a 2500 kcal/day diet, and approximately 1 mg phosphorus per kcal).
The association between iron and phosphorus status with BMI is one that should be explored further especially in developing countries as obesity and iron deficiency are diseases that continue to evolve worldwide with significant public health implications that are felt more in underdeveloped world were poverty, lack of education, and ignorance predispose dwellers to micronutrient deficiencies and obesity. This therefore necessitated this study.
| Materials and Methods|| |
This was a descriptive, cross-sectional study conducted among 500 randomly selected adults (18–65 years) who live in Orlu, Imo State, Nigeria, between February 2017 and February 2018. They were apparently healthy adults comprising 278 males and 222 females. Their permission was sought and informed consent obtained from each subject after proper explanation of the purpose of the research. Exclusion criteria for this study were conditions that will affect serum iron and phosphate levels as well as BMI. Such criteria were diabetes mellitus, hypertension, regular administration of drugs that affect body weight, lactation, pregnancy, clinical evidence of hemorrhage in the preceding 6 months, and blood donation within the previous 6 months. Persons on concomitant infection or on specific regimen were also excluded.
Anthropometric measurements including height and weights were taken. The heights were obtained by making each subject stand barefoot against a wall that had been calibrated using a meter rule and the measurement taken by an assistant with a height of over 1.75 m to avoid error due to parallax. Weight was measured with light clothing and without shoes using a weighing scale (Soen Le, Germany) with subtraction of 1 kg to correct for the weight of the clothing. The BMI was calculated as weight divided by square of height (kg/m2). For adults, overweight and obesity were defined as 25 ≤ BMI < 30 and BMI ≥30, respectively, according to the World health Organization criteria.
All laboratory measurements were performed on fasting blood samples. Phosphate was measured using Human Kit utilizing the photometric ultraviolet test for the determination of phosphorus. Iron was measured using Adult Diagnostic Kit utilizing the iron ferrozine test.
Data obtained from this study were analyzed using IBM-Statistical Package for the Social Sciences, Version 21.0 for Windows. Descriptive studies, analysis of variance, and bivariant Pearson's correlation were done. Statistical significant was set at P < 0.05. The results thereof were presented as mean ± standard deviation.
| Results|| |
A total of 500 adults participated in the research comprising 278 males (55.6%) and 222 females (44.4%). The results are presented in tables and graphs.
[Table 1] shows the general characteristics of the participants as well as the prevalence of obesity and overweight among them. The mean age, height, weight, and BMI were 41.50 ± 1.82, 1.60 ± 0.81, 68.00 ± 5.83, and 26.56 ± 2.54, respectively. The mean phosphorus and iron levels were 2.79 ± 1.84 and 56.14 ± 4.31, respectively. The prevalence of obesity among the males and females was 35.97% and 33.78%, respectively, while that of overweight was 36.33% and 36.93%, respectively.
|Table 1: General characteristics of the participants and prevalence of obesity/overweight|
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[Table 2] shows a summary of the relationship between BMI and serum iron levels of the participants in the study. In this study, the mean serum iron levels of overweight to severely obese individuals were seen to be statistically lower (P < 0.05) than the mean serum iron levels of subjects with normal weight in both males and females. Furthermore, there is a statistically significant reduction in the serum iron levels of the moderately to severely obese individuals when compared with normal subjects and those with overweight. This is also presented in [Figure 1].
|Figure 1: Serum iron levels in individuals with different body mass index range|
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[Table 3] shows the relationship between BMI and serum phosphate levels of both male and female participants in the study. The mean serum phosphate level of individuals with overweight, moderate obesity, and severe obesity was significantly (P ≤ 0.05) lower when compared with the normal. This is presented in [Figure 2].
|Table 3: Relationship between body mass index and serum phosphorus level|
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|Figure 2: Serum phosphorous levels in individuals with different body mass index range|
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| Discussion|| |
Obesity is a risk factor for many diseases such as Type-2 diabetes, hypertension, heart diseases, stroke, dyslipidemia, osteoarthritis, gynecological and obstetric problems, sleep apnea, Pickwickian syndrome (obesity hypoventilation syndrome), and respiratory problems.,,, The present study examined the association of BMI with some biochemical minerals namely iron and phosphorus.
This study showed that there was statistically significant negative correlation between BMI and serum iron levels in the study population. Increase in BMI was associated with decrease in serum concentration. This finding is consistent with the study of Chambers et al. in which they reported lower iron levels in obese individuals. Furthermore, other researchers have also demonstrated lower levels of serum iron in obese adults compared to nonobese-matched controls, with fat mass shown to be a significant negative predictor of serum iron concentration., In contrast, another study has shown that there is no clear difference in serum iron levels with different levels of BMI among boys and girls.
The first report of a potential connection between iron status and obesity appeared over 40 years ago., The precise cause of iron deficiency in obesity is unclear. However, some postulations have been advanced in efforts to unravel the possible mechanism(s) and/or reasons.
First, the significant relationship between obesity and iron deficiency can be attributed to a combination of nutritional and functional parameters and genetic disposition such as poor diet and low iron-rich foods, lack of physical activity, reduction in iron intake, increase in needs for iron caused by a larger blood volume and disorder in iron absorption and less lysis of myoglobin, and a subsequent decrease in the release of iron in the blood in obese subjects.,,
Second, hepcidin is an important regulator of iron homeostasis, inhibiting iron absorption at the enterocyte and sequestering iron at the macrophages, which could lead to decreased iron stores and hypoferremia. Obesity causes chronic inflammation, which is associated with the expression and release of pro-inflammatory cytokines, including interlenkin-6 and tumor necrosis factor-α. These pro-inflammatory cytokines may result in the release of hepcidin from the liver or adipose tissues., In addition, the chronic inflammation and decreased leptin production characteristic of obesity also increase hepcidin secretion from the liver, which along with hepcidin produced by adipose tissue, could further reduce dietary iron absorption. The potential role of hepcidin in the development of iron deficiency in the obese is supported by the discovery of elevated hepcidin levels in tissues from patients with severe obesity and the positive correlation between adipocyte hepcidin expression and BMI.
Third, chronic low-grade inflammation associated with obesity leads to sequestration of iron through inflammatory-mediated mechanisms, and this is one of the proposed causes of iron deficiency in obesity., In addition, it has been speculated that pro-inflammatory cytokines interfere with erythropoietin production and also blunt the response of erythroid precursors to erythropoietin which is a well-recognized mechanism in the development of anemia of chronic diseases and may thus also contribute to anemia in obese subjects.
This study also showed that there is a negative correlation between BMI and serum phosphate level. Obese subjects had low mean concentrations of serum phosphate. The relationship between serum phosphate levels and obesity has been investigated both in experimental studies and clinical trials in adults.,,, The findings of this study are in consonance with those of Park et al., where it was shown in a study involving 46,798 Korean women that plasma phosphate was negatively correlated with BMI, triglyceride level, and fasting glucose. Low phosphorus level has been positively associated with body weight.,, This may be attributable to the impact of hepatic ATP, which depends on plasma phosphorus level on suppressing food intake.,, This mechanism is supported by an inverse relation between body weight and hepatic ATP status.,, Furthermore, the mechanism of low phosphate levels in obese subjects was thought to be attributed to an overcompensation of energy (diet with low nutrient density), in particular, overcompensation of carbohydrates accompanied by low protein intake which is a main source of phosphate.
| Conclusion|| |
BMI has an inverse statistically significant correlation with serum iron and phosphate concentrations. Periodical assessment of nutritional status of obese individuals and intake of high iron and phosphorus foods by such individuals should be considered, especially in developing countries where malnutrition is prevalent.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]