|Year : 2018 | Volume
| Issue : 1 | Page : 13-18
Relationship between body mass index and serum calcium and magnesium in an adult population in Owerri, Nigeria
Celestine N Ekweogu1, Jude Nnabuife Egwurugwu2, Moses C Ohamaeme3, Patrick C Ugwuezumba2, Promise Nwankpa1, Bede C Azudialu4
1 Department of Medical Biochemistry, College of Medicine, Imo State University, Owerri, Imo State, Nigeria
2 Department of Human Physiology, College of Medicine, Imo State University, Owerri, Imo State, Nigeria
3 Department of Community Medicine, Nnamdi Azikiwe University Teaching Hospital, Nnewi, Anambra, Nigeria
4 Department of Family Medicine, Federal Medical Center, Owerri, 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: Micronutrients are important risk factors in the assessment of the nutritional status of the obese. Aim: This study aims to investigate the association between body mass index (BMI) with serum calcium and magnesium levels. Materials and Methods: Five hundred adults, aged between 18 and 68 years, resident in Owerri Municipal, Imo State, Nigeria, participated in this study. Serum calcium and magnesium levels were measured after 8–12 h fast. BMI was calculated using the participant's height and body weight. The participants were further grouped into four based on BMI as follows: normal, overweight, moderate, and severe obesity. Results: The mean serum calcium levels of participants with overweight, moderate, and severe obesity were 2.62 ± 0.32, 2.76 ± 0.18, and 2.80 ± 0.26, respectively, for males and 2.34 ± 0.13, 2.46 ± 0.12, and 2.50 ± 0.18, respectively, for females as compared to 2.32 ± 0.41 and 2.02 ± 0.11 for males and females with normal BMI, respectively. Furthermore, the mean serum magnesium levels for individuals with overweight, moderate, and severe obesity were 0.95 ± 0.03, 0.90 ± 0.05 and 0.84 ± 0.03, respectively, for males and 0.91 ± 0.01, 0.88 ± 0.01, 0.81 ± 0.02, respectively, for females as compared to 0.98 ± 0.05 and 0.94 ± 0.02 for males and females with normal BMI, respectively. The serum calcium levels of moderately and severely obese individuals were significantly higher than their counterparts with normal BMI (P < 0.05). Conversely, the serum magnesium levels of moderately and severely obese patients were significantly lower than their counterparts with normal BMI (P < 0.05). Conclusion: BMI correlated directly with serum calcium and inversely with serum magnesium levels in obese patients. Micronutrients such as calcium and magnesium should be considered in the management of obesity/overweight.
Keywords: Body mass index, calcium, magnesium, micronutrients, obesity
|How to cite this article:|
Ekweogu CN, Egwurugwu JN, Ohamaeme MC, Ugwuezumba PC, Nwankpa P, Azudialu BC. Relationship between body mass index and serum calcium and magnesium in an adult population in Owerri, Nigeria. Niger J Exp Clin Biosci 2018;6:13-8
|How to cite this URL:|
Ekweogu CN, Egwurugwu JN, Ohamaeme MC, Ugwuezumba PC, Nwankpa P, Azudialu BC. Relationship between body mass index and serum calcium and magnesium in an adult population in Owerri, Nigeria. Niger J Exp Clin Biosci [serial online] 2018 [cited 2019 Jan 18];6:13-8. Available from: http://www.njecbonline.org/text.asp?2018/6/1/13/248009
| Introduction|| |
Nontransmissible chronic diseases are global health challenges. They impact negatively on the health, quality of life of the people, and high costs for the society. Chronic diseases such as cardiovascular diseases, cancer, chronic respiratory diseases, and diabetes account for 60% of deaths worldwide. Obesity and overweight which according to the World Health Organization is defined as a body mass index (BMI) of ≥30 kg/m2 and ≥25 kg/m2, respectively, stand out among the nontransmissible chronic diseases because they are risk factors for other diseases such as dyslipidemia, cardiovascular diseases, diabetes, hypertension, and cancer.,,
Obesity has been referred to as a complex medical condition characterized by excess adipose tissue mass and body fat distribution that negatively impact on health and well-being. The fundamental challenge of obesity is an energy imbalance between caloric intake and energy expenditure. It has been observed that an obese person can accumulate more than 70% of body mass as fat and is usually the consequence of both hypertrophy and hyperplasia of adipocytes. Obesity arises from decreased physical activity, behavioral, social, environmental and genetic factors, urbanization, and modernization influences. The prevalence of obesity has increased geometrically in the past three decades and has been recognized as a global epidemic by the World Health Organization in 1997. Globally, one in six adults is obese and nearly 2.8 million individuals die each year due to overweight or obesity.
Recent studies have suggested that some of the obesity-related ailments, especially metabolic disorders, hypertension, and cardiovascular diseases are linked by common defects in metabolism of some divalent cations including calcium and magnesium., Calcium, the most abundant mineral in the human body, plays crucial roles in numerous physiological processes such as muscle contraction, hormones and neurotransmitter release, glycogen metabolism, cell proliferation and differentiation, blood clotting, nerve or sympathetic impulse transmission and structural support of the skeleton, and second messenger in several signaling pathways.,,,, Intracellular calcium plays a key role in modulating the regulation factors involved in hypertension, insulin resistance, and obesity.
Two postulations have been advanced to explain the role of calcium in weight control. When high quantities of calcium is consumed, it tends to bind to dietary fats, forming insoluble compounds, thereby reducing fat absorption and hence the amount of calories generated., Researchers have also noted that intracellular calcium is modulated by calcitropic hormones such as parathyroid hormone (PTH) and 1, 25-dihydroxy vitamin D and the levels of these hormones are increased by low dietary calcium intake, which consequently enhances high levels of intracellular calcium in adipocytes. High levels of calcium in adipocytes stimulate lipogenesis and inhibit lipolysis. Levels of PTH and 1, 25-dihydroxycholecalciferol are decreased by high dietary calcium intake, so it lowers intracellular calcium, inhibits lipogenesis, and stimulates lipolysis.,,
An obesity gene expressed in human adipocytes called “agouti” has also been used to elucidate the anti-obesity effect of dietary calcium. Agouti protein stimulates calcium influx, and promotes energy storage in human adipocytes by stimulating the expression and activity of fatty acid synthase and inhibiting lipolysis. Calcium channel agonists mimicked this action of agouti and it was inhibited by calcium channel antagonists., Moreover, using a calcium channel antagonist (e.g., nifedipine) for 4 weeks, in transgenic mice overexpressing agouti, resulted in significant decreases in lipogenesis and in adipose tissue mass.
Reduced serum magnesium has been associated with cardiovascular events such as hypertension, metabolic syndrome, hyperlipidemia, diabetes, and obesity.,, Many studies have linked obesity with low serum magnesium levels and it has been speculated that magnesium deficiency plays an important role in the pathophysiology of the abovementioned disorders.,, Magnesium is a very important divalent metal ion and a cofactor for several enzymes involved in the metabolism of fats, proteins, carbohydrates, and action of insulin. Hypomagnesemia is also associated with oxidative stress.
Several earlier works have concentrated on the identification of the combination of macronutrients capable of regulating body weight, but the effect of micronutrients still needs to be further explored,,,, especially among Nigerians. Hence, this research on the association between serum calcium and magnesium levels with BMI in a population adults in Owerri, Imo State, Nigeria.
| Materials and Methods|| |
This study was conducted among 500 randomly selected adults aged between 18 and 68 years who live in Owerri, Imo State, Nigeria, between March 2017 and February 2018. They were apparently healthy adults made up of 271 males and 229 females. Their permission was sought and consent was obtained from each participant after proper explanation of the purpose of the research. Exclusion criteria for this study were those conditions that can affect serum calcium and magnesium levels as well as BMI. Patients with genetic, endocrine, or syndromic causes of obesity were excluded. Preexisting hypertension, diabetes mellitus, cardiovascular disease, renal and liver disease, as well as patients on oral calcium and vitamin D supplements were excluded. Furthermore, patients who have gastroenteritis or on drugs that could predispose to hypomagnesemia such as diuretics and amphotericin were excluded.
The study protocol was approved by the Ethics Committee of the Imo State University Teaching Hospital, Orlu.
Weight was measured to the nearest 0.1 kg using a weighing scale (Soen Le, Germany) while participants had light clothes and no shoes. Height (in meters) was measured with each participant standing erect on a stadiometer without shoes to the nearest 0.5 cm. 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.
Blood samples were collected from a forearm vein after an overnight fast. The serum samples were refrigerated at −20°C for no longer than 2–4 days before analysis for calcium and magnesium. Calcium was measured using human kit utilizing the photometric test for calcium while magnesium was measured using human kit utilizing the photometric colorimetric test for magnesium with lipid clearing factors principle.
Data obtained from this study were analyzed using the Statistical Package for the Social Sciences (IBM-SPSS) software for Windows, version 21.0, New York, USA. Numerical data were expressed as mean and standard deviation (SD). Qualitative data were expressed as frequency and percentage. Analysis of variance was done at 0.05 level of significance. Bivariant Pearson's correlation was done at 0.01 level of significance to estimate correlation between variables.
| Results|| |
The results obtained were presented as mean ± SD The data were presented in tables. The mean age, height, weight, and BMI of the respondents were 43.80 ± 4.91, 1.59 ± 0.80, 66.83 ± 5.88, and 26.43 ± 3.51, respectively. The prevalence of overweight and obesity among the males were 35.79% and 36.90%, respectively. The females had a prevalence of 37.55% and 35.37%, respectively, for overweight and obesity. The mean serum calcium and magnesium levels of the participants were 2.48 ± 0.22 and 0.91 ± 0.03, respectively. These general characteristics of the participants are shown in [Table 1] above.
|Table 1: General features of the patients and prevalence of overweight/obesity|
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[Table 2] shows a summary of the relationship between BMI and serum magnesium levels of the participants in this study. The mean serum magnesium levels of moderately-severely obese individuals were statistically lower (P < 0.05) than the levels of participants with overweight and normal BMI in both males and females. There was, however, no statistical difference in the serum magnesium levels of the respondents with overweight when compared with those with normal BMI.
|Table 2: Relationship between serum magnesium levels and body mass index|
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[Table 3] shows the relationship between BMI and serum calcium levels of the participants in the study. The mean serum calcium levels of individuals with moderate and severe obesity were significantly higher (P < 0.05) when compared to participants with overweight and normal BMI. There was, however, no statistically significant difference in mean serum calcium level between the overweight individuals and those with BMI.
Correlation studies show that BMI correlated positively and significantly with serum calcium levels in obese patients (r = 0.72, P = 0.002). Conversely, the serum magnesium levels correlated negatively and significantly with BMI in obese individuals (r = −0.47, P = 0.004).
| Discussion|| |
Obesity is a complex, systemic, and nontransmissible chronic disease with multifactorial pathophysiology. It is now recognized as a pandemic disease whose spread is associated with lifestyle changes, better socioeconomic conditions, and reduced physical activity., Several studies have shown a direct link between obesity and micronutrient deficiencies.,,
This study demonstrated that obese respondents have increased serum total calcium levels as compared to the overweight and normal body weight (P < 0.05). It also showed significant positive correlation between serum calcium level and BMI in individuals with moderate-to-severe obesity (P < 0.05). These findings are consistent with earlier studies,,,,,,,, which reported increased serum calcium level in obese individuals as well as a positive correlation between BMI and serum calcium. However, other studies showed no significant difference in serum total calcium levels in obese and nonobese individuals., The participants' dietary habits might have contributed to the above negative findings in their reports.
The relationship between serum calcium and obesity is complex and the exact mechanism(s) is/are still unclear. However, the following plausible explanations have been adduced:
Evidences abound that obese individuals usually have low basal vitamin D and high PTH levels than nonobese persons.,, Reduced vitamin D and high PTH enhances calcium influx into cells such as adipose tissues. Increased intracellular calcium favors the activity of fatty acid synthase, inhibits the expression of hormone-sensitive lipase, thus stimulating lipogenesis and inhibiting lipolysis.,,, It has also been found that morbid obese patients may have less exposure to sunlight. Furthermore, it could be that 25-hydroxy vitamin D is sequestered in fat tissues, thus, making it less bioavailable.
Intracellular calcium may have effect on energy metabolism by affecting adipocyte apoptosis. It has also been observed that the interaction of calcium with fatty acids to form soluble soaps may reduce the absorption and increase the excretion of these fatty acids, with attendant reduction in body weight.,,
Obesity is a state of chronic, low-grade systemic inflammation, associated with increased oxidative stress and production of pro-inflammatory cytokines. These effects stimulate increased osteoclastic activity and bone resorption leading to increased serum calcium level.,, Increased levels of circulating pro-inflammatory cytokines have been linked with obesity and increased risk of type 2 diabetes.
This study also showed significant inverse correlation between BMI and serum magnesium level. Obese respondents had lower levels of serum magnesium compared to nonobese persons. Our results are comparable with the previous studies,, that found significantly lower serum magnesium concentrations and negative correlation between serum magnesium and BMI in obese/overweight individuals. These earlier workers proposed that lower dietary magnesium intake in obese individuals may be the main reason for magnesium deficiency in obese group. Some researchers have however demonstrated that magnesium intake in obese and nonobese patients do not show significant difference.
The link between obesity and magnesium deficiency is complex and unclear. However, the followings have been postulated:
It could be due to dietary habits that may lead to decreased intestinal absorption and/or increased excretion of magnesium. Increased intake of calcium or fats can interfere with intestinal absorption of magnesium. High intake of dairy products and carbonated beverages, a common phenomenon among overweight/obese patients, interfere with magnesium absorption while caffeine can increase renal excretion of Mg. These dietary habits can decrease appetite and thus reduced intake of healthier foods.,,,
It can also partly be due to the presence of inflammatory markers in obese patients. Obese persons have higher adipose tissues than nonobese controls and production of inflammatory cytokines by the adipose tissues is the cause of increased inflammatory markers in obese individuals. Cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 are secreted by adipose tissues. Furthermore, it has been established that a strong relationship exists between low serum magnesium and TNF-α. Again, another study has reported strong negative correlation between serum magnesium and C-reactive protein in obesity.,,,, One of the plausible explanation for the link between low serum magnesium and inflammatory markers in obesity is that inflammatory markers, especially TNF-α tend to increase renal 1-α-hydroxylase activity, thus affecting the level of active vitamin D. This active metabolite promotes renal calcium reabsorption with attendant increased urinary excretion of magnesium.
| Conclusion|| |
This study has demonstrated a direct relationship between BMI and serum calcium level and inverse association between BMI and serum magnesium level. Micronutrients such as calcium and magnesium should be considered in the assessment and management of obese/overweight individuals.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]