|Year : 2017 | Volume
| Issue : 3 | Page : 115-121
Correlation of body mass index and blood pressure of adults of 30–50 years of age in Ghana
Department of Nutrition and Food Science, School of Biological Sciences, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
|Date of Submission||28-Oct-2016|
|Date of Acceptance||17-Aug-2017|
|Date of Web Publication||6-Oct-2017|
Department of Nutrition and Food Science, School of Biological Sciences, College of Basic and Applied Sciences, University of Ghana, P. O. Box LG 134, Legon, Accra
Source of Support: None, Conflict of Interest: None
Aims: There is an increase in the prevalence rates of overweight and obesity across the globe. Blood pressure (BP) has been found to increase among populations with high body mass index (BMI). Overweight and high BP both have independent fatal health consequences as they carry serious risk factors for several noncommunicable diseases such as heart disease, stroke, type II diabetes, and even death. It is against this background that this research was carried out to corroborate similar result in Ghana. The objective of this study was to determine the correlation of BMI and BP of adults of 30–50 years. Materials and Methods: the WHO STEPwise questionnaires modified to obtain information on demography and lifestyle. Weight and height were measured using seca scale and stadiometer, respectively. BP was also recorded using digital sphygmomanometer. A 24-h recall method was used to assess the dietary intake of participants. Results: The prevalence of overweight and obesity was found to be 20.0% and 7.5%, respectively. About 32.5% of the participants (200) were hypertensive (systolic blood pressure [SBP] ≥140 mm Hg). A significant difference existed between high and normal SBP of the participants (P = 0.01). Conclusion: An increase in BMI positively influenced BP among these study adults' population.
Keywords: Body mass index, high blood pressure, obesity, overweight, prevalence
|How to cite this article:|
Vuvor F. Correlation of body mass index and blood pressure of adults of 30–50 years of age in Ghana. J Health Res Rev 2017;4:115-21
|How to cite this URL:|
Vuvor F. Correlation of body mass index and blood pressure of adults of 30–50 years of age in Ghana. J Health Res Rev [serial online] 2017 [cited 2018 Sep 24];4:115-21. Available from: http://www.jhrr.org/text.asp?2017/4/3/115/216068
| Introduction|| |
The prevalence of obesity throughout Europe has increased sharply over the past 20 years, second only to that in the USA, and closely followed by many developing nations in Asia. In the majority of European countries, the prevalence of obesity increased by 10%–40% between 1980 and the late 1990s. Current rates of obesity in European countries are in the range 10%–20% for men and 10%–25% for women. According to statistics from the Centers for Disease Control and Prevention, in 1994, 56% of the USA population were classified as overweight and 23% were classified as obese. In 2002, the overweight figure was 65% and the obesity figure was 31%.
In a study by Biritwum on the epidemiology of obesity in Ghana, the prevalence of obesity was found to be 5.5% and higher among females 7.4% compared to males 2.8%. The increased rate of overweight and obesity in developing countries is as a result of rapid economic, epidemiologic, and nutrition transitions. According to the World Health Organization, overweight and obesity are now so common that they are replacing the more traditional public health concerns such as undernutrition and infectious diseases. Globally, there are now as many overnourished people as undernourished people.
Globally, the overall prevalence of high blood pressure (BP) in adults aged 25 and over was around 40% in 2008. The proportion of the world's population with high BP or uncontrolled hypertension fell modestly between 1980 and 2008. However, because of population growth and aging, the number of people with uncontrolled hypertension rose from 600 million in 1980 to nearly 1 billion in 2008. Across the WHO regions, the prevalence of high BP was highest in Africa, where it was 46% for both sexes combined. In 2003, the prevalence of hypertension in urban community in Ghana was found to be 28.3% in the Greater Accra Region  and 28.7% in the Ashanti Region.
Body mass index (BMI) is a measure of the human body weight in relation to the height, calculated by dividing the weight of a person in Kg by the square of the height in meters. The WHO  classifies BMI as normal (18.5–25 kg/m 2), overweight (26–30 kg/m 2), and obese (>30 kg/m 2). BP is the pressure of the resistance of blood flow against the walls of the arteries. Systolic blood pressure (SBP) is the top number refers to the amount of pressure in your arteries during contraction of your heart muscle. Diastolic pressure, however, is the pressure required to allow constant flow in the blood vessels and filling of the ventricles before the next systole.
According to Saxon et al., high BP is defined as a systolic reading of ≥140 mmHg and/or higher over a diastolic reading of ≥90 mmHg. Studies have shown that BMI and BP are both on the increase worldwide and epidemiological studies show positive correlation between the two. Winnick  observed that the causes of overweight and obesity are multifaceted. Some factors seem to play a significant role, such as consuming too much calories coupled with not physical exercising enough to burn out the excess calories, a combination that easily results in becoming overweight. The main objective was to determine the correlation between BMI and BP of adults between the ages of 30–50 years in Shama, Ghana.
| Materials and Methods|| |
The WHO STEPwise questionnaires were modified to collect background and lifestyle information. Anthropometric measurements (weight and height) were taken using the weighing scale and stadiometer, respectively. BP and pulse were recorded using digital sphygmomanometer. A 24-h recall method was used to assess the dietary intake of the people. The subtotal participants (200) were 103 males and 97 females.
The study was reviewed and approved by the Noguchi Memorial Institute for Medical Research at the University of Ghana Legon–Accra Ghana, with the approval code: #036/14-15.
The data were analyzed using SPSS version 16 (SPSS Inc. Chicago, IL) software to compute descriptive analysis such as means and frequencies. Chi-square analysis was used to determine the association between variables such as BMI and BP, BMI and exercise, and salt consumption and BP. Correlation analysis was used to determine the strength of the association between BMI and BP.
BMI classification was <18.5 kg/m 2 = underweight; 18.5–25 kg/m 2 = normal; and 26–30 = overweight and >30 kg/m 2 = obesity. BP was classified as high or normal according to the classification of SBP (high ≥140 mmHg) and normal <140 mmHg. Dietary data were analyzed using food composition tables to calculate the amount of energy, fat, protein, and carbohydrate consumed by the participants per day. The individual intakes were compared to the mean intakes of the group to determine adequacy.
| Results and Analysis|| |
[Table 1] describes the background characteristics of the respondents. There are significant differences in the occupations engaged in by the participants and levels of education of both sexes. Fewer of the males were uneducated as compared to the females, and larger proportion of the males (7%) had had tertiary education as compared to the females (1%).
[Table 2] shows the lifestyle variables of the study participants. Only 18.5% of the participants engaged in any exercise. About 3.5% of the participants smoked cigarette and 31.5% drank alcoholic beverages.
[Table 3] gives an indication of the dietary intake inadequacy among the participants as <50% showed insufficiency of macronutrients.
[Figure 1] shows the percentage distribution of BMI classifications of the respondents. Majority of the people were of normal BMI (62.5%). About 20.0% were overweight while 7.5% were obese.
|Figure 1: Percentage distribution of body mass index classification of respondents|
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[Figure 2] shows the percentage distribution of BMI classification of respondents according to sex. Majority of the males were of a normal BMI (41.0%). Females were overweight and obese more than males. Among 7.5% of the sample population that were obese, 7.0% were females while the remaining 0.5% were males.
|Figure 2: Percentage distribution of respondents' body mass index classifications according sex|
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[Figure 3] indicates the percentage distribution of BMI classification according to levels of exercise. A low exercise level was observed in this study population. All the underweight and obese respondents did not engage in any exercise. Only 15.5% of the respondents had normal BMI and also exercised. The overweight respondents who exercised were only 3.0%.
|Figure 3: Percentage distribution of body mass index of respondents according to level of exercise|
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[Figure 4] shows the percentage distribution of BMI classification based on age groups. BMI was observed to increase with an increase in age. The highest percentage of respondents of a normal BMI across the age groups was 26.5%, which was recorded by the 30–35 years' group. Within the 45–50 years' group, the percentage that had a normal BMI was 22.5%. Furthermore, only 1.5% of the 30–35 years' group were obese, but 4.0% of the 45–50 years' group were obese.
|Figure 4: Percentage distribution of body mass index of respondents based on age groups|
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[Table 4] shows the BP profile of participants. Nearly 32.5% of the study population had high SBP while 67.5% had normal SBP. About 23.0% of the respondents had high diastolic blood pressure while 77.0% had normal diastolic blood pressure.
[Table 5] shows the correlation between BMI and BP of respondents. More of the overweight respondents had high SBP than the overweight individuals with normal SBP. An association was observed between BMI and BP. However, the r value shows a weak negative correlation (r = −0.21).
|Table 5: Correlation between body mass index and blood pressure of respondents|
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| Discussion|| |
BMI as a measure of body weight was classified according to the WHO  as underweight, normal, overweight, and obese. Overweight and obesity are risk factors for many diseases, including high BP. Hence, the prevalence of overweight and obesity is of a great importance to this study. Forty participants (20.0%) were overweight and 15 (7.5%) were obese.
There was a significant difference between the BMI of males and females (P < 0.01). Females had a higher prevalence of overweight and obesity than males. Among the males, 15 (7.5%) were overweight while 1 (0.5%) was obese. The prevalence of overweight and obesity in females was 25 (12.5%) and 14 (7.0%), respectively. This observation is in line with results from literature. For example, Preedy  observed in a study on BMI and mortality that more women than men were obese in all age groups. This could be due to the fact that men are physically active than women. Only 4 (2.0%) women engage in exercise whereas 33 (16.5%) men engage in exercise. A significant difference was observed between exercise in males and females (P < 0.01).
It was also found that men work longer hours than women. For instance, 34 (17.0%) men work for 10–12 h whereas 27 (13.5%) women work for the same 10–12 h. Since working is a form of physical activity for most people (manual workers), it implies that working many hours will help to decrease the risk of becoming overweight or obese. Even among workers in white-collar jobs, working can help to reduce the risk of obesity because working increases energy expenditure since the brain utilizes the energy from food leaving little or none to be stored as fat. This implies that females are at risk of diseases associated with overweight and obesity, such as Type 2 diabetes mellitus, heart diseases, and stroke than males.
Age is a factor that affects the BMI of individuals. Across the age groups, the highest rate of obesity (4.0%) was recorded by the 46–50 years' age group. The increased rate of obesity with respect to an increase in age could be due to the fact that older people are less physically active but maintain the same energy intake as during their earlier years. Hence, the excess energy that is not expended is stored as fat, increasing their chances of becoming obese.
A high prevalence of high BP was observed in this study, and 65 (32.5%) of the participants were hypertensive (SBP greater or equal to 140 mmHg). Among these, 35 (17.5%) males and 30 (15.0%) females were hypertensive. This observation is expected because similar results were found in literature. Khurana, for instance, observed that before menopause, women have a lower SBP than men. The increased incidence of hypertension in males than females could be due to differences in lifestyle. For instance, more men smoke cigarette than women. In this study, there was a significant difference between males and females on smoking (P = 0.01). No female smoke cigarette, but 7 (3.5%) of the male participants smoke cigarette. Since smoking is a risk factor for high BP, this observation is not surprising. This places men at a greater risk of hypertension and its consequent diseases than women.
There was a significant difference between high and normal SBP (P = 0.01). However, a negative correlation was obtained between BMI and SBP (r = −0.21). This is a weak correlation. According to results from literature, this is unexpected. However, it could be due to the fewer number of participants who were obese as compared to the ones with normal BMI. Furthermore, BP has a lot of confounders which could lead to this unexpected outcome. BMI is not the best indicator of body fat. A high BMI does not necessarily mean there is increased body fat. A high BMI can be as a result of increased bone density or muscles. Central adiposity gives a better indication of body fat and can be used to show the relationship between body fat and BP.
People are becoming less physically active in recent times due to urbanization. These days, most people prefer taking cars to walking. Furthermore, we do not engage in regular exercise. This study found that only 37 (18.5%) of the participants engage in exercise. Hence, it is not surprising that there is a high rate of overweight and obesity since a reduction in physical activity (sedentary lifestyle) is associated with overweight and obesity.
From the results obtained in this study, it is very evident that overweight and obesity occur as a result of less physical activity. All the obese participants do not engage in any form of exercise. Furthermore, the overweight individuals who do not engage in any exercise were 34 (17.0%). Exercise is a very important factor to consider in decreasing the incidence of overweight and obesity in populations. This is because exercise helps the body to burn fat and utilizes excess calories.
Consumption of energy in excess is one of the factors that lead to increased BMI (especially when it is coupled with less physical activity). From the results obtained in this study, it was observed that majority of the participants consumed excess energy and macronutrients. Another significant number of the people also consumed inadequate amounts of nutrients when their intakes were compared to the mean intake of the group. A significant difference was observed between the intake of males and females for energy, protein, and carbohydrate (P < 0.01 for all three). However, there was no significant difference between the fat consumption of males and females (P = 0.08).
More males consumed energy and the macronutrients in excess as compared to the females. For instance, 57 (28.5%) males consumed excess energy as opposed to the 24 (12.0%) females who consumed excess energy. Even though energy consumption is higher in males, overweight and obesity rates were less in males and high in females. This could be because males are more physically active than females and hence are able to burn the excess energy. Unlike males, females may end up storing the excess energy as body fat. The excess protein, fat, and carbohydrates can also be easily converted to fats if not expended.
Aging is one of the factors that influence the incidence of high BP. The occurrence of elevated SBP increased across the age groups. The highest prevalence of high BP was observed in the oldest age group (46–50 years). The number of hypertensive participants who were 46–50 years was 32 (16.0%). The increased rate of hypertension with respect to age is due to weakening of the metabolic functions of the kidney in excreting salt, hardening of the arteries, and increasing obesity.
Salt intake has been found in this study to affect BP. An increased intake of salt is associated with an increased rate of hypertension and vice versa. When salt consumption decreased, hypertension also decreased. The incidence of high BP in participants who prepared food with ½ and ¼ teaspoon of salt was 1 (0.5%) for both. Furthermore, 35 (17.5%) of the participants were hypertensive and add 1 teaspoon of salt to food when cooking.
Salt contains sodium which increases BP when taken in excess. The US Food and Drug Administration recommends that people take no more than 2300 mg of sodium (4 g of salt) per day. Certain groups such as hypertensive individuals and children are to limit their sodium intake to <1500 mg.
Salt intake was high among the participants (both normal and hypertensive). Eighty-nine (42.5%) of the participants add 2 teaspoons to food when cooking and 105 (52.5%) add 1 teaspoon of salt to food. One teaspoon of salt is about 2.0 g. This indicates that in a day, most people consume more than the 4 g of salt recommended by the FDA. Salt intake should be reduced in the whole population, not only among the hypertensive individuals. This will help to decrease the prevalence of high BP. Processed foods are high in sodium and hence must be consumed moderately in order not to increase sodium intake above the recommendation.
| Conclusion|| |
The prevalence of overweight and obesity was found to be 20.0% and 7.5%, respectively, in Shama. All the obese participants were females. The prevalence of high BP was recorded as 32.5% (SBP). An association was found between high and normal SBP (P = 0.01). However, the correlation analysis showed a negative correlation between BMI and BP (r = −0.21). Exercise was observed to affect BMI. All the 7.5% obese people did not engage in any exercise. BMI also increased with an increase in age and high caloric intake.
The author expresses his appreciation to the study participants, Nutrition Teaching/Research Assistants, Miss Worna Harriet Etornam, Prof. Matilda Steiner-Asiedu, and Prof. Emmanuel Ohene Afoakwa, all of the Department of Nutrition and Food Science, University of Ghana, for their kind support of this work.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]