Asian Journal of Medical Sciences 1(3): 94-96, 2009
ISSN: 2040-8773
© Maxwell Scientific Organization, 2009

Submitted Date: August 14, 2009 Acceptance Date: September 02, 2009 Published Date: November 25, 2009

Corresponding Author: A. Abubakar, Department of Human Physiology Ahmadu Bello University, Zaria, Nigeria
94

Relation of Body Mass Index with Lipid Profile and Blood Pressure in Healthy
Female of Lower Socioeconomic Group, in Kaduna Northern Nigeria

1A. Abubakar, 1M.A. M abruok, 2A.B. Gerie, 3A.A. Dikko, 4S. Aliyu, 1T. Yusuf,
3R.A. Magaji, 1M.A. Kabir and 1U.W. Adama
1Department of Human Physiology, Ahmadu Bello University, Zaria, Nigeria
2Department of Medicine, Ahmadu Bello University, Teaching Hospital Shika, Zaria, Nigeria
3Department of Human Physiology, Bayero University Kano, Nigeria
4Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria

Abstracts: In Nigeria 30 million people suffer from this hypertension which is the main risk factor for stroke, and renal failure. Elevated levels of triglyceride, cholesterol and LDL-C are documented as risk factors for atherogenesis. LDL-C in its oxidized or acetylated form has been identified as a major atherogenic particle. Fifty two women between 19-32 years of age attending Primary Health Care center (PH C) in Kaduna and its environment were use in this study. Their height, weight and systolic and diastolic blood pressures were recorded. Body Mass Index (BMI) was calculated by using their height (m2) and weight (kg). On the basis of BMI, all participants were divided into three groups that is under weight whose BMI was less than 19 kg / m2, normal who’s BMI was between 19 and 26 kg / m2and overweight who’s BMI was more than 26 kg / m2. The mean BMI of the three groups in the 52 participants was 150.1 mg/dl ±31.7, mean LDL-C was 91.6 mg/dl ±22.6, mean HDL-C was 39.7 mg/dl ±9.1 and mean triglycerides were 93.9 mg/dl ±41.6. Mean systolic blood pressure was 114.1 mmHg ±11.8 and mean diastolic blood pressure was 74.1 mmHg ±7.9. There were significant differences in mean serum HDL-C, triglycerides, systolic and diastolic blood pressure among three BMI groups (P<0.05) but none in mean serum cholesterol and LDL-C. No significant correlation was found between any of the lipid profile variables and blood pressure variables with BMI. The importance of this finding is to enable “care-givers” in hypertension pay more attention to the control of obesity so that several complications associated with it might be prevented.

Key words: Hypertension, body mass index and cholesterol

INTRODUCTION

Blood cholesterol, Obesity and high Blood pressure have been identified as risk factors in developing hypertension Jones et al. (1992) People with Obesity and high blood pressure are also more likely to have lipid abnormality than those with normal blood pressure Wannarinthee et al. (1998). Furthermore blood pressure is strongly related to body weight and control of obesity is a critical component of prevention and control of hypertension Kummayinka (1997). Clinical trials have also suggested a reduction in the incidence of Ischemic heart disease by lowering serum cholesterol levels.

Hypertension is now a global epidemic affecting 1.5 billion people world wide and claiming about 7 million lives every year. In Nigeria 30 million people suffer from this conditions which is the main risk factor for stroke, and renal failure. In Nigeria, as well as in many other countries in Africa the situation is complicated even further by wide spread presence of substandard or fake drugs in the markets which make hypertension and hyperclosterolemia even more deadly silent killers, yet awareness about hypertension and hyperclosterolemia very poor among the Nigerian public D aily Trust (2009).

The prevalence of hypertension is probably on the increase in Nigeria where adoption of western lifestyles and the stress of urbanization both of which are expected to increase the morbidity associated with unhealthy lifestyles are not on the decline FMOH (2009). Genetic and environmental factors are reported to play a key role in IHD, 90% of which are better classified as idiopathic.

Hypertension in adults has a high impact on the economy and on the quality of life of individuals with important implications for resource expenditures Jones et al. (1992).

Elevated levels of triglyceride, cholesterol and LDLC are documented as risk factors for atherogenesis Lipid. Research Clinic Program (1984).LDL-C in its oxidized or acetylated form has been identified as a majoratherogenicparticle; as it not only load macrophages with cholesterol for the formation of foam cells but also because it ischemotacticfor circulatingmonocytes, iscytotoxicand can adversely alter coagulation pathways Fogelman et al. (1980).The blood level of HDL-C in contrast bears an inverse relationship of the risk of atherosclerosis and coronary heart disease that is higher the level, smaller the risk Witztum et al. (1991)and Palinski et al. (1989). Asian J. Med. Sci., 1(3): 94-96, 2009

Different plasma lipids vary significantly in various population groups due to difference in geographical, cultural Hart et al. (1997) economical, social conditions Vartiainen et al. (1997), dietary habits and genetic makeup. Age and gender differences also affect serum lipids considerably Malik et al. (1995) and Shahid et al. (1985). This study was conducted to assess serum lipids and blood pressure among non pregnant normotensive women belonging to a lower socioeconomic group, in Kaduna Northern Nigeria.

MATERIALS AND METHODS

Fifty two women between 19-32 years of age attending Primary Health Care center (PHC) in Kaduna and its environment were use in this study betw een A pril and July 2009. Their height, weight and systolic and diastolic blood pressures were recorded. Body Mass Index (BMI) was calculated by using their height (m2) and weight (kg). On the basis of BMI, all participants were divided into three groups that is under weight whose BMI was less than 19 kg / m2, normalwho’sBMI was between 19 and 26 kg / m2and overweight who’s BMI was more than 26 kg / m2. After twelve hours fast, serum samples were collected and total cholesterol, HDL-C, LDL-C andntriglycerides were estimated on photometer 5010 and 911- Hitachiauto-analyzer. Statistical analysis was done on Epi-Info-6. The means of the three groups were compared by ANOVA at the significance level ofa= 0.05.Correlationcoefficient was determined for the dependent variables of lipid profile and blood pressure with BMI (in kg/m 2) as the independent variable.

RESULTS

The height, weight, mean systolic and diastolic blood pressure and lipid profile levels were available for all the 52 women included in the study. The mean BMI of the three groups in the 52 participants was 150.1 mg/dl ±31.7, mean LDL-C was 91.6 mg/dl ±22.6, mean HDL-C was 39.7mg/dl ±9.1 and mean triglycerides were 93.9 mg/dl ±41.6. Mean systolic blood pressure was 114.1 mmHg ±11.8 and mean diastolic blood pressure was 74.1 mmHg ±7.9

Among 52,23 were underweight that is their BMI was less than 19 kg/m2, 17 were normal that is their BMI was between 19 kg/m2and 26 kg/m2and 12 were overweight that is their BMI was more than 26Kg/m2.

Mean values of serum cholesterol, LDL-C, HDL-C, triglycerides, systolic and diastolic blood pressure with their standard deviations according to three BMI groups are given in Table 1. There were significant differences in mean serum HDL-C, triglycerides, systolic and diastolic blood pressure among three BMI groups (P<0.05) but none in mean serum cholesterol and LDL-C. No significant correlation was found between any of the lipid profile variables and blood pressure variables with BMI.

In this study, comparison of three BMI groups (underweight, normal and overweight) with regards to serum total cholesterol, LDL-C, HDL-C, triglycerides, mean systolic and diastolic blood pressure were also examined. Finding of this study shows there is positive and significant association betw een BMI and triglycerides which is similar to the findings of Donahue et al. (1985) and Prineas et al. (1980)., this study also found no significant difference (P > 0.05) in serum total cholesterol and LDL-C but there is significant difference (p< 0.05) in mean serum HDL-C, triglycerides, mean systolic and mean diastolic blood pressure in three BMI groups.

The percentage of subjects who’s BMI was> 30 in this study was 23% which is similar to the findings of
Yekeen et al. (2003). who found 33%. Okosun et al. (1999) had suggested that the prevalence of hypertension was closely linked to abdominal adiposity; however since waist-hip ratio was not measured in this study, it is difficult to confirm their observation with the findings of the present study. Ezenwaka et al. (1997) had also reported a higher prevalence of obesity and high blood pressure in women and in urban settings.

DISCUSSION

It has been estimated that risk of hypertension is 35% to 55% less in adults and normal weight as compared to obese adults Manson et al. (1992).However, the influence of obesity on cardiovascular risk begins before adulthood and overweight during adolescence is associated with an increased risk of coronary heart disease in male and female subjects DiPietro et al. (1984)as 23.1% of our total study populations are overweight, so the number of at-risk individuals is not much higher.

As the prevalence of hypertension in several population studies has overshot the 10% trigger- point, it is necessary to activate intervention to lower this rate. The control of dietary energy intake, sodium consumption and inactivity are areas of potential interventions. So far the prevalence of coronary heart disease is still low in Africa; paradoxically the risk factors of hypertension, obesity and high serum cholesterol associated with coronary heart disease are emerging.

CONCLUSION

The importance of this finding is to enable “caregivers” in hypertension pay more attention to the control of obesity so that several complications associated w ith it might be prevented. The risk factors of hypertension already seen in several of the obese patients can be lowered by dietary intervention, as well as other medical control of hypertension. It is clear that the population prevalence of obesity, hypertension and hyper-cholesterol if known will be useful in planning interventions,

Therefore, strategies designed to limit cardiovascular risk should address weight reduction.

REFERENCES

Daily Trust Tuesday, July 21, 2009. 22(17): 46 http//www.dailytrustonline.com

DiPietro, L., H.O. Mossberg and A.J. Stunkard, 1994. 40 year history of overweight children inStockholm: life-time overweight, morbidity, and mortality.Int. J. Obes., 18: 585-590.

Donahue, R.P., T.J. Orchard, L.H. Kuller and AL. Drash, 1985. Lipids and lipoproteins in young adult population Am. J. Epidemiol., 240: 458-67.

Ezenwaka, C.E., A.O. Akanji, B.O. Akanji, N.C. Unwin, and C.A. Adejuwon, 1997. The prevalence of insulin resistance and other cardiovascular disease risk factors in healthy elderly south western Nigerians

Artherosclerosis 128(2): 201-211. FMOH, 2009. Ministe r i a l press brie fing http//www.fmoh.org.ng

Fogelman, A., I. Schechter and J. Seager, 1980. Alteration of low density lipoproteins leads tocholesterylester accumulation in humanmonocytemacrophages. Proc. Natl. Acad. Sci., USA,77: 2214-2218.

Hart, C., R. Ecob, and G.D. Smith, 1997. People, places and coronary heart disease risk factors: a multilevel analysis of the Scottish Heart Health Study archive. Soc. Sci. Med., 45: 893-902.

Jones, J. and K.A. Davis, 1992. Risk factors for coronary disease in a black population, J. Am. Med. Assoc.,
84:393-398.

Kummayinka, S.K., 1997. The impact of obesity on hypertension management in African. Am. J. Healthcare Poor Underser., (3): 352-355.

Lipid Research Clinic Program, 1984. The lipid research clinic coronary primary prevention trial results II. J. Am. Med. Assoc., 251: 364-374.

Malik, R., Z.A. Pirzado, S. Ahmed and M. Sajid, 1995. Study of lipid profile, blood pressure and blood glucose in rural population. Pak. J. M ed. Res., 34: 152-155.

Manson, J.E., H. Tosteson, P.M. Ridker, S. Satterfield, P. Hebert, and G.T. O'Connor, et al. 1992. The primary prevention of myocardial infarction. N. Engl. J. Med., 326: 1406-1416.

Okosun, I.S., T.E. Forrester, C.N. Rotimi, B.O. Osotimehin, W.F. Muna and R.S. Cooper, 1999. Abdominal adiposity in six populations of West African descents: prevalence and population attributable fraction of hypertension. O besity Res., 7(5): 453-462.

Palinski, W., M. Rosenfeld and S. Yla-Herttuala, 1989. Low density lipoprotein undergoes oxidative modification in vivo., Proc. N atl. Acad. Sci., USA. 86: 1372-1376.

Prineas, R.J., R.F. Gillum, H. Horibe, and P.J. Hannan, 1980. The Minneapolis Children’s Blood Pressure
Study: standards of measurement for children’s blood pressure. Hypertention, 2(supplI): S18-24. Shahid,

A., S.J. Zuberi, and N. Hasnain, 1985. Lipid pattern in healthy subjects. Pak. J. Med. Res., 24:
33-37. Vartiainen, E., J. Pekkanen, S. Koskinen, P. Jousilahti,

V. Salomma and P. Puska, 1981. Do changes in cardiovascular risk factors explain the increasing socioeconomic difference in mortality fromischaemicheart disease inFinland? J. Epidemiol. Community. Health., 52: 416-419.

Wannarinthee, S.C., A.G. Shaper, P.N. Durington and M. Perry, 1998. Metabolic Syndrome. J. Human Hypertension, 12(2): 1059-1064.

Witztum, J.L. and D. Steinberg, 1991. Role of oxidized low densitylipoproteininatherogenesis. J. Clin. Invest, 88: 1785-1792

Yekeen, L.A., R.A. Sanusi and A.O. Ketiku, 2003. Prevalence of obesity and high level of cholesterol in hypertension: Analysis of Data from the University College Hospital, Ibadan. Afr. J. Biomed. Res., 6: 129 -132.

Body Mass Index and Blood Pressure Pattern of Students in a Nigerian University

Received: 05-Jul-08 Revised: 10-Sep-08 Accepted: 01-Mar-09

Kenneth E Oghagbon1, Valentine U Odili2*, Eze K Nwangwa3, Kevin E Pender3
Department of Chemical Pathology, Faculty of Clinical Medicine, College of Health Sciences, Delta State University, Abraka, Nigeria.

Department of Clinical Pharmacy, Faculty of Pharmacy, University of Benin, Benin City, Nigeria.

Department of Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Delta State University, Abraka, Nigeria.

Abstract

Purpose: Reports in Nigeria and other developing countries have indicated a rise in the prevalence of obesity among adults. In identifying at what age in our environment obesity starts becoming a problem, we measured the burden of overweight and obesity among young adults.

Methods: Four hundred and sixty four under graduate students, who were undergoing medical examination as part of admission process, were recruited. Their weight, height and blood pressure (BP) were measured and their body mass index (BMI) was calculated. The prevalence of obesity, overweight and under-nutrition among these students were determined according to international guidelines.

Results: The prevalence of obesity (3.4%) and undernutrition (3.1%) among the students, were similar. Female students had higher prevalence of obesity (4.02%) and under-nutrition (3.1%) than the males. Overweight was found to be commoner in male subjects (26.78%) than in females (20.98%). The prevalence of hypertension was 3.4% in the study population and was commoner in males (5.9%) than in females (0.89%). Mean systolic blood pressure and diastolic blood pressure were significantly higher in males than females (p < 0.05).

Conclusion: Obesity and under-nutrition are prevalent among the fresh undergraduate students. As part of the orientation programme for fresh undergraduate students in Nigerian Universities, nutrition education should be carried out. The need to always conduct blood pressure monitoring for all University students is also recommended.

Keywords: Body mass index; Blood pressure; Obesity; University students; Nigeria.
.
Introduction

According to estimates by the Global Burden of Disease (GBD) study, deaths due to noncommunicable diseases (NCD) in developing countries will be four times that due to communicable diseases by 2020 [1]. Such communicable diseases includes hypertension, diabetes mellitus, coronary heart disease, stroke and metabolic syndrome. Commonly, these diseases have obesity as a common denominator. Obesity is now seen as an emerging public health disaster throughout the world [2,3] (including sub-Saharan Africa) [1]. The relationship between obesity and the potentially attendant increase in NCDs in adult African population may have its origin early in life [4,5]. A possible point in early life when this problem begins varies from infancy to early childhood, adolescence and early adulthood [6]. The recent inclusion of developing societies in the world map of rising overweight/obesity is worrisome. This is because the countries being affected cannot afford financial cost presently borne by the developed worlds in the fight against obesity epidemic. Added to this, developing countries like the sub-Saharan African countries do not have the kind of health care system that can effectively handle the disease burden occasioned by overweight/obesity.

The essence of this work is to identify the burden of overweight/obesity in early adolescents with a view to arresting the rising prevalence of obesity in middle aged populations. A population that is likely just behind middle aged and readily accessible, is university student population. It is hoped that if the point at which a rise in obesity rate occurs is identified, a public health approach which is cheaper and less technically demanding can be applied for maximal benefit.

Methods

This study was carried out in University Clinic of Delta State University, Abraka, Nigeria. The subjects comprised newly admitted students of the university who came to the clinic for their routine medical examination. We briefed the students on the essence of this work and sought their consent before they were recruited for the study. Thereafter, consecutive, consenting students were recruited.

After collecting data on their age and sex, we measured their blood pressure (BP, using a mercury sphygmomanometer with the appropriate cuffs size) as well as their weight and height (using a beam balance scale), from which their body mass index (BMI) were calculated. In measuring BP, each student was made to rest for at least five min, in a sitting position with uncrossed legs, before the BP reading was taken. A student was considered to be hypertensive if the BP was equal to or greater than 140/90 mmHg, according to the WHO/ISH guidelines [7].

The students who had BP values consistent with hypertension on first reading were reevaluated as appropriate. If the BP was still the same, such a student was recorded as hypertensive.

The body weight of each subject was recorded while putting on minimal clothing. We took their height readings from a measuring scale drawn on the walls in the clinic. Before the height was measured, the subjects were asked to remove their shoes or sandals, and made to stand against the marked wall with their calcaneus, gluteus and occiput touching it. All readings were personally taken by the authors of the study.

BMI was determined from the weight (kg) and height (metres) of the subjects and the subjects were classified into malnutrition (18.5 kg/m2), normal (20.0-24.9kg/m2), overweight (25.0-29.9 kg/m2) or obesity (30 kg/m2) as appropriate. The mean of these variables were determined in the whole population and in the male and female

Table 1: The distribution of studied parameters in male and female subjects
Parameters Male [mean (sd)] Female [mean (sd)] P value
Age (years)* 22.49 (2.97) 21.57 (2.35) 0.0002
BMI (Kg/m2)* 25.54 (3.19) 23.38 (3.28) 0.0001
SBP (mmHg)_ 116.50 (19.96) 111.39 (12.02) 0.001
DBP (mmHg)_ 75.25 (11.29) 72.46 (8.73) 0.003
Prev. Hypert. (%) 5.86 0.89 0.001
Prev. Obesity (%) 3.44 2.93 4.02
Prev. Undernutri. (%) 3.10 1.26 4.91
SD, Standard deviation; SBP, Systolic blood pressure; DBP, Diastolic blood pressure
Prev. Hypert, Prevalence of hypertension; Prev. Obesity, Prevalence of obesity;
Prev. Undernutri, Prevalence of under-nutrition; (*) male (n) =238, female (n) =226;
(_) male (n) =236, female (n) =226 groups. At 95% confidence interval, differences in mean values were compared using the Student T-test or Chi-square test, as appropriate. The prevalence of malnutrition was also determined in the whole population as well as the male and female groups. Correlation among the variables (age, gender, BP and BMI) was carried out using regression analysis. The minimum p values considered significant was 0.05.

Results

Four hundred and sixty four (464) students were recruited for the study, out of which 238 (51.3%) were males and the rest (48.7%) females. The mean age of the study subjects was 22.0±2.72 years. There was a significant difference between the ages of the males as compared to the females (p < 0.05) (Table 1).

The mean systolic blood pressure (SBP) in the study was 114.78±13.7 mmHg. Mean SBP in the females was significantly lower than the mean SBP in males (p < 0.05).

Similarly, the mean DBP was significantly higher in the males than in the females (p < 0.05). The prevalence of hypertension in the study was 3.4%. This was higher in the males who had a prevalence of 5.9%, as against the 0.9% noted in the females (Table 1). There was no good correlation between age and BP, age and BMI and BMI versus BP. Gender was also not well correlated.

A distribution of BMI in the study sample is provided in Table 2. About 62% of the population had BMI values (20.0-24.9 kg/m2) in the normal BMI interval. Those who were overweight constituted 23.9% while 3.4% of them were obese. Notably, about 3.1% of these students were under-nourished with BMI less than 18.5 kg/m2. More females were under-nourished as compared to males. About 4% of female students were obese and this was higher than the 2.9% noted in the males (Table 2).

Table 2: Body mass index distribution in the study population BMI (Kg/m2)
Study
sample
(%)
Male
%
Female
%
<18.5 3.10 1.26 4.91
20.0 – 24.9 62.15 61.09 64.29
25.0 – 29.9 23.87 26.78 20.98
_30.0 3.44 2.93 4.02
% are based on total number in each category

Discussion

Delta State is composed of varied ethnic groups, which are represented in this study in addition to other ethnic groups in the country. However, comparison based on ethnicity could not be carried out, because of very wide variations in the number of students in the various groups. This will not allow for reasonable statistical inferences.

The mean age of 22 years in the study suggests that the results of this work may apply to young adults in Nigeria. Therefore, they may represent the situation in the immediate period before the middle ages, in terms of some cardiovascular risk factors that we studied. It is hoped that the results will provide information on the stage at which adults’ population BMI and BP starts it upward trend in our community.

When the mean BMI of the study group is subjected to gender influence, the mean BMI was significantly higher in males (25.54kg/m2) than in the female (23.38 kg/m2). In some studies done in older populations [8,9], there was no such difference. The suggestion from this is that there is an obliteration of this difference by increase in the BMI of females as the population gets older. This tends to suppose that weight gain in older subjects could be more in females. This is unlike the situation in younger ages, as suggested in this study, where males had higher prevalence of overweight (27% vs 20.9%). The higher prevalence of overweight in young men, have also been noted by other workers [10,11].

The obesity rate observed in our study is not much different from the 1.6% reported for males, and 4.9% for females in the data from a World Bank report on Nigeria in 2002 [3]. A likely reason for the higher obesity found in females is that, they are more prone to progressing from overweight to obesity, than males. This higher prevalence of obesity in females is found both in young and old persons [8,10,12,13].

In a study involving young African-Americans, obesity was however commoner in males [11]. Except for a study carried out in a rural area in Maiduguri, Nigeria [12], studies in older Nigerians had a higher prevalence of obesity than seen in this study. The implication of this finding is that efforts at addressing overweight/obesity of adult population should commence at earlier ages. This will in turn help to address diseases associated with elevated BMI. The university students or even students at lower educational levels might be good targets for such exercises.

Some workers have advised that such effort should target, not only those young persons who are overweight/obese, but also those who are moving up the BMI ladder [14].

An admixture of overweight/obesity and under-nutrition signifies a population in nutrition transition. This is typical of developing nations, in which those who belong to the high socio-economic class are overweight/obese and the low socioeconomic class individuals are commonly under-nourished. This is unlike the situation in developed countries where overweight/ obesity is commoner in those in the low socio-economic stratum [16,17]. Therefore the issue of addressing increase in BMI in Nigeria should be focused on high socioeconomic group individuals, more so on females. Better still, the target population should be addressed in their earlier ages. It is also important that the level of undernutrition in this environment should receive enough scientific attention.

One reason why medical sciences focus on overweight/obesity, is its potentially attendant increase in cardiovascular risk. The origin of obesity in early life is thought to increase the propensity for the development of cardiovascular risk factors and atherosclerosis [18]. Hypertension is one of the factors that have been clearly identified as a cardiovascular risk factor. In this study, the prevalence of hypertension (3.4%) is much lower than the 17-20% in the whole Nigeria population [19,20]. The higher prevalence of hypertension in males as compared to females in our study has been reported in some other studies [20,21] but contrarily reported in others [8,22]. Possible reasons for the high prevalence of hypertension in males in the study group include the higher mean age and prevalence of overweight in males. In 1998, a study showed that the contribution of obesity to hypertension in Africans was only 10% [23].

We suggest that overweight rather than obesity is more associated with hypertension in this environment. It would also appear that the effect of obesity on BP level was not much, as the mean SBP and DBP were also higher in males. A similar picture was found in another Nigerian study [10]. But in this latter study, the mean values of SBP and DBP were higher than in the present one. This is thought to be due to the higher mean age of the study subjects. This is in keeping with previous observations that increase in BP and prevalence of hypertension, is related to age [20-22] more so SBP [21]. The observation of low prevalence of hypertension noted above in the present study could be associated with the lower mean age compared to adult populations [19,20].

Conclusion

The prevalence of obesity and undernutrition among the fresh undergraduate students has been documented. The problem of overweight/obesity noted in studies in adult Nigerian population, seem that of older ages with feeder from younger persons.

As part of the orientation programme for fresh undergraduate students in Nigerian Universities, nutrition education should be carried out. The need to always conduct blood pressure monitoring for all University students is also recommended. Particular attention should be paid to obesity in the female population, and high BP in young men. This action is imperative now considering the huge and unsustainable cost of medical care, occasioned by obesity and related diseases, in developed countries [3].

Body Mass Index and Health

Authors
Hazel A. Hiza, Ph.D., R.D., Charlotte Pratt, Ph.D. R.D., Anne L.
Mardis, M.D., M.P.H., and Rajen Anand, Ph.D.

March 2000

Many Americans are becoming overweight or obese (1-3). These conditions can lead to chronic diseases such as high blood pressure, diabetes, stroke, cancer, and diseases of the gallbladder, heart, and lungs (1-8). Such diseases can reduce the quality of life and can also lead to death (1, 4, 9). Body Mass Index (BMI) is one of the commonly used measures of obesity.

What is Body Mass Index (BMI)?

BMI is a ratio of a person’s weight to height. BMI is commonly used to classify weight as “healthy” or “unhealthy.”

How is BMI determined?

BMI can be determined by using the following equation:

What does BMI mean?

BMI values between 18.5 and 24.9 are considered “normal” or “healthy” weight (Table 1). BMI values between 25 and 29.9 are considered “overweight” and 30 and above are considered, “obese.” BMIs above 25 are unhealthy and have been shown to increase the risk of certain chronic diseases (1-8). BMIs under 18.5 are considered “underweight.”

B M I WEIGHT CATEGORY

Less than 18.5 Underweight
18.5 - 24.9 Normal weight
2 5 - 2 9 . 9 Overweight
30 and above Obese
BMI = 705 ÷

Source: Evidence Report of Clinical Guidelines on the Identification,
Evaluation, and Treatment of Overweight and Obesity in Adults, 1998.
NIH/National Heart, Lung, and Blood Institute (NHLBI)
Source: National Institutes of Health (NIH), 1998

Can BMI be used by everyone?

For most people, BMI provides a good measure of obesity. However, BMI does not provide actual information on body composition (i.e. the proportions of muscle, bone, fat, and other tissues that make up a person’s total body weight), and may not be the most appropriate indicator to determine health status for certain groups of people. For example, athletes with dense bones and well developed muscles or people with large body frames may be obese by BMI standards (i.e. they have BMIs greater than 30), but yet have little body fat. On the other hand, inactive people may seem to have acceptable weights when, in fact, they may have as the focal point within the U.S. Department of Agriculture for linking scientific research to the consumer.

The United States Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, and marital and family status. USDA is an equal opportunity provider and employer. too much body fat. Similarly, a petite gymnast may be considered underweight but not unhealthy (10). BMI, when used for children and adolescents who are still growing (11), pregnant women, people with large body frames, or petite and highly muscular individuals, should be interpreted cautiously.

How does BMI relate to health?

BMI is generally related to body fat. Higher BMIs usually mean higher body fat (3). As body fat or BMI increases, especially from values equal to or greater than 30, health risks increase (3). Being overweight (BMI of 25 to 30) or being obese (BMI greater than 30) increases the risk of having high blood pressure, heart disease, stroke, diabetes, certain types of cancer, arthritis, and breathing problems (4-8). Research shows that being obese lowers one’s life expectancy (4, 9). When overweight or obese people lose weight, they also lower their blood pressure, total cholesterol, LDL (or “bad”) cholesterol, increase their HDL (or “good”) cholesterol, improve their blood sugar levels, and reduce their amount of abdominal fat (4).

What Research Studies Relate BMI to Diseases and Longevity?

In 1998, the National Institutes of Health issued a report to identify and treat obesity and overweight. Many scientific research studies suggest that weight loss reduces chronic diseases and improves the life span of people who are overweight. This report provided recommendations to clinicians and the public about weight management (3). In developing this report, more than 43,627 research articles were obtained from a search of the scientific literature and reviewed by a panel of researchers. Researchers have examined the importance of weight reduction in people with high blood cholesterol (4), high blood pressure (5), diabetes (6), cancer (7), and osteoarthritis (8), and reported that weight loss reduces the risks for these diseases.

Conclusions

The link between BMI and health shows that overweight or obese people are more likely than those at normal weight to have medical problems such as high blood pressure, high cholesterol, stroke, diabetes, and heart disease. Research studies have shown that even a weight loss of 1-2 pounds per week for six months can improve the health of overweight people (3). The goal of weight loss should be to improve health. Rapid weight loss, swings in weight, and improper dieting should not be the goal (12, 13).

Healthy BMI Prevents High Blood Pressure
Lifelong Weight Control Keeps High Blood Pressure at Bay

By Jeanie Lerche Davis
WebMD Health News

Oct. 9, 2003 -- Keeping your weight under control, from childhood through middle age, can offset high blood pressure in later years a new study shows.

In the study from Great Britain, researchers tracked more than 3,000 men and women born in 1946. Each was regularly contacted since birth, and various tests, including blood pressure and body mass index (BMI, a measure of body fat through weight for height), -- were done at ages 36, 43, and 53.

Researchers also factored in each person's birth weight and their father's job in their early years. Typically, this is an indicator used to assess the child's nutrition while growing up. The researchers looked to see if birth weight, long suspected of influencing blood pressure later in life, had an effect on increasing blood pressure during a person's lifetime.

They found that high BMI throughout life had "a strong effect" on high blood pressure between ages 36 to 53, reports researcher Rebecca Hardy, PhD, an epidemiologist with the Royal Free and University College Medical School in London. Weight Control Is Key

"These findings suggest that weight control throughout life is key to prevention of [high] blood pressure during middle age," writes Hardy.

The study also showed that in men, the lowest birth weight groups consistently had the highest systolic blood pressures. In women, this association of low birth weight leading to higher systolic blood pressures was not evident until women reached the age of 42.

The systolic blood pressure is the upper numbers of a blood pressure reading and is the force that the heart pumps against when it is beating. Higher systolic blood pressures are associated with more distress to the functioning heart and therefore heart disease.

Adults at all ages who were children from a manual social class had higher blood pressures than those raised in a nonmanual social class.

Understanding the mechanism linking the childhood socioeconomic environment and adult BMI may make prevention strategies more effective writes Hardy.

SOURCE: Hardy, R. Lancet, Oct. 11, 2003; vol 362: pp 1178-1183.

Blood pressure and body mass index in an ethnically diverse sample of adolescents in Paramaribo, Suriname

Charles Agyemang1*, Eline Oudeman1, Wilco Zijlmans2, Johannes Wendte1 andKarien Stronks1
*Corresponding author: Charles Agyemang c.o.agyemang@amc.uva.nl

Author Affiliations
1Department of Social Medicine, Academic Medical Centre, Amsterdam, The Netherlands
2Department of Pediatrics, Diakonessen Hospital, Paramaribo, Suriname

BMC Cardiovascular Disorders 2009, 9:19 doi:10.1186/1471-2261-9-19

Received: | 2 October 2008 | Accepted: | 21 May 2009 | Published: | 21 May 2009 |

© 2009 Agyemang et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Abstract
Background
High blood pressure (BP) is now an important public health problem in non-industrialised countries. The limited evidence suggests ethnic inequalities in BP in adults in some non-industrialised countries. However, it is unclear whether these ethnic inequalities in BP patterns in adults reflect on adolescents. Hence, we assessed ethnic differences in BP, and the association of BP with body mass index (BMI) among adolescents aged 12–17 years in Paramaribo, Suriname.
Methods
Cross-sectional study with anthropometric and blood pressure measurements. A random sample of 855 adolescents (167 Hindustanis, 169 Creoles, 128 Javanese, 91 Maroons and 300 mixed-ethnicities) were studied. Ethnicity was based on self-reported ethnic origin.
Results
Among boys, Maroons had a lower age- and height-adjusted systolic BP than Creoles, and a lower diastolic BP than other ethnic groups. However, after further adjustment for BMI, only diastolic BP in Maroons was significantly lower than in Javanese (67.1 versus 70.9 mmHg). Creole boys had a lower diastolic BP than Hindustani (67.3 versus 70.2 mmHg) and Javanese boys after adjustment for age, height and BMI. Among girls, there were no significant differences in systolic BP between the ethnic groups. Maroon girls, however, had a lower diastolic BP (65.6 mmHg) than Hindustani (69.1 mmHg), Javanese (71.2 mmHg) and Mixed-ethnic (68.3 mmHg) girls, but only after differences in BMI had been adjusted for. Javanese had a higher diastolic BP than Creoles (71.2 versus 66.8 mmHg) and Mixed-ethnicity girls. BMI was positively associated with BP in all the ethnic groups, except for diastolic BP in Maroon girls.
Conclusion
The study findings indicate higher mean BP levels among Javanese and Hindustani adolescents compared with their African descent peers. These findings contrast the relatively low BP reported in Javanese and Hindustani adult populations in Suriname and underscore the need for public health measures early in life to prevent high BP and its sequelae in later life.
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Background
The increasing prevalence of cardiovascular diseases (CVD) is putting a tremendous pressure on already overburdened resources in non-industrialised countries. [1] High blood pressure (BP) is a leading cause of CVD. [2] The rising prevalence of hypertension in non-industrialised countries reflects well on the high prevalence of CVD. [2]

In children, BP tracking patterns confirm that persistent BP increase may be related to hypertension in adulthood. [3-5] Increased BP in childhood has also been linked with left ventricular hypertrophy. [6] Consequently, in most industrialised countries assessment and management of BP in childhood is strongly recommended to promote improved cardiovascular health in adulthood. [7] However, in some non-industrialised countries, BP data on children and adolescents are very scarce. In Suriname, for example, there is no published data on BP in children and adolescents. Information on BP in adults in Suriname is also very limited. A report from II PAHO-DOTA Workshop on Quality of Diabetes Care in 2003 indicates that hypertension is a major public health burden with prevalence rates ranging from 24% in Javanese to as high as 33% in African-Surinamese in Suriname. [8] The annual report of the Regional Health Service in 2000 also showed that hypertension care alone accounted for 15% of the total number of consultations. [8] This reflected the mortality data with CVD being the leading cause of death in Suriname.

Suriname's population is made up of several ethnic groups. As in industrialised countries, [9-12] the limited data in Suriname suggest ethnic inequalities in BP and hypertension in adults. [8] However, it is unclear whether these BP patterns in adults reflect on adolescents. In some industrialised countries such as the UK, ethnic differences in BP in adults [9-12] do not correspond with children's and adolescents' BP patterns. [13,14] In addition, the prevalence of overweight and obesity in children and adolescent have increased dramatically over the past few decades. This may have an impact on BP. In the United States of America, for example, overweight children have been shown to be 2–4 times more likely than non-overweight children to have high BP. [15-17] However, information on the relationship between body sizes and BP among different ethnic groups in non industrialised countries is limited. There is an urgent need for research in children and adolescents so that appropriate cost-effective interventions can be introduced early in life to prevent the burden of CVD in adulthood. [18,19] The main objective of this study was to assess BP patterns, and to determine the association of BP with BMI among adolescents from different ethnic backgrounds in Paramaribo, Suriname. We hypothesised that the BP patterns in adults would reflect adolescents' BP patterns in various ethnic groups in Suriname.
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Methods
Study area
Suriname is located in Northern South America. It borders French-Guyana to the east, British-Guyana to the west, Brazil to the south and the Atlantic Ocean to the north (Figure 1). It has a total area of 163,820 square kilometres. According to the World Factbook, the total population in 2007 was about 449,000 people. The life expectancy was 66 years for men and 71 years for women. Suriname's population is made up of several ethnic groups: Hindustani, Creoles, Javanese, Maroons, Amerindian, Chinese, White and other. About 28% of the population is under 15 years of age (ca. 132,000). Data for this study were collected between March and June 2007 in Paramaribo, the capital city of Suriname. The vast majority of people (about 90%) live in Paramaribo and its surroundings.
Figure 1. Map of Suriname.

Study design

Data were collected in nine schools among healthy adolescents between the ages of 12 to17 years. All schools were randomly selected from the 103 government schools' list. The schools were visited prior to data collection to obtain permission from the relevant school principals as well as from the pupils. After agreeing to this, participants were advised not to smoke, drink alcohol or take vigorous exercise during the 30 minutes preceding the BP measurement. Data collection took place during normal school hours. Verbal informed consent was sought from each participant before measurements were taken. None of the children refused to participate in this study. Forty three children were excluded because they were below 12 years old, and one child was excluded because she reported suffering from severe heart disease. The Ethical Board of the Ministry of Education in Suriname approved the study protocols.
Measurements

Height was measured without shoes with a measuring tape to the nearest 0.01 metre. Weight was measured to the nearest 0.1 kg after removal of shoes, jackets, heavy clothing and pocket contents (using an Electronic Korona Profirmed scale). BMI was calculated as weight divided by height squared (kg/m2). Overweight and obesity were defined using the sex- and age-specific BMI criteria of the International Obesity Task Force. [20] BP was measured in the morning with a validated oscillometric automated digital BP device (Omron M-5, Japan). Using appropriate cuff sizes, three readings with one minute interval were taken on the right arm in a seated position after at least five minutes rest. The mean of the last two readings was used for analysis. Sex-, age- and height-specific percentile levels were defined using US normative BP tables for children and adolescents. [21] High BP was defined as systolic BP and/or diastolic BP ≥ 95th percentile.

In addition to the physical measurements, participants were asked to complete a short questionnaire including questions on age, sex, ethnic background and physical activity. The ethnicity of these groups was identified using self-reported ethnicity. Hindustanis originate from India (South Asia). Javanese originate from Indonesia (East Asia). Creoles are descendants of West Africans who live in Paramaribo.
The Maroons are descendants of West Africans who fled the colonial Dutch forced labour plantations in Suriname and established independent communities in the interior rainforests. They have retained a distinctive identity based on their West African origins. There are no secondary schools in their villages, so they attend schools in Paramaribo. Because of the important differences between these two West African descent groups in terms of lifestyle and history, we have separated these groups. Physical activity was based on the frequency of leisure physical exercise per week outside of school. The same trained final year medical student made anthropometric and blood pressure measurements in all schools.
Data analysis

Age specific mean systolic BP and diastolic BP levels were determined for boys and girls. Multivariate linear regression analysis enabled age, height and BMI adjusted comparisons of systolic BP and diastolic BP levels to be made between different ethnic groups. Multiple linear regression analyses were performed separately for each ethnic group to assess the relationship between BMI and BP adjusted for other factors. All statistical tests were two-tailed and P-value < 0.05 was considered statistically significant. All statistical analyses were performed using SPSS for Windows version 14.2 (SPSS Inc. Chicago, USA) and STATA 9.2 (Stata Corp, College Station, Texas).
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Results
Table 1 shows the characteristics of the study population by sex and ethnicity. Javanese boys and girls were shorter than all the ethnic groups (P < 0.05). Maroon boys had a lower BMI than Creole boys (P = 0.03) and Mixed-ethnicity boys (P = 0.05). Maroon boys were more likely than other boys to exercise 5–7 days/week. Creole girls were taller than all the ethnic groups (P < 0.001). Maroon girls had a higher BMI than Hindustani girls (P = 0.03) and Javanese (P < 0.01) girls.

Table 1. Characteristics of the study population by ethnicity and sex

Blood pressure levels
The mean systolic BP and diastolic BP increased with age in both boys and girls (Figure 2a and2b). The mean systolic BP levels were higher in boys than in girls in all age groups (Figure 2a). The sex differences in diastolic BP were, however, less pronounced (Figure 2b). BMI was associated with systolic BP and diastolic BP in both boys and girls (Figure 3a and 3b). Table 2shows the relationships between BMI and systolic BP, and diastolic BP in each ethnic group. BMI was independently associated with systolic BP and diastolic BP in all ethnic groups except for diastolic BP in Maroons.

Figure 2. Mean systolic and diastolic BP by age and sex.
Figure 3. Mean systolic and diastolic BP in relation to BMI by sex.

Table 2. Multiple regression analysis of factors associated with SBP and DBP for each ethnicity

Figure 4a and 4b show mean systolic BP and diastolic BP by ethnic group and sex. After adjustment for age and height, Maroon boys had a significantly lower mean systolic BP than Creole boys and a lower mean diastolic BP than all the other ethnic groups (Table 3). Further adjustment for BMI abolished the significant mean systolic and diastolic BP differences between Maroon boys and other ethnic groups except for the higher mean diastolic BP in Javanese boys (P= 0.04). Creole boys had a relatively low age- and height-adjusted mean diastolic BP compared to other boys. After further adjustment for BMI, the differences became more pronounced between Creole and Hindustani boys (P = 0.04) and Javanese boys (P = 0.02).

Figure 4. Mean systolic and diastolic BP by ethnicity and sex.

Table 3. Adjusted mean systolic and diastolic blood pressure levels by ethnicity and sex

Among girls, Javanese had a significantly higher age- and height-adjusted mean diastolic BP than all other ethnic groups except for Hindustani girls. The differences persisted after further adjustment for age, height and BMI (P < 0.01). Maroon girls had a significantly lower mean diastolic BP than all ethnic groups, except for Creole girls, but only after differences in BMI had been adjusted for. There were no significant differences in mean systolic BP between the ethnic groups.

Maroon boys and Hindustani boys and girls had a relatively low prevalence of high BP compared with other ethnic groups although the differences were not statistically significant (Figure 5a and5b).

Figure 5. Prevalence of high BP in boys and girls.
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Discussion
As far as we know, this is the first study on BP patterns amongst adolescents in Suriname, and one of the few studies in adolescents comparing different ethnic groups in a non-industrialised country. Maroon boys had a lower BP than all ethnic groups including Creoles with similar West African descent. The lower BP in Maroon boys as compared to other ethnic groups was accounted for by their lower BMI. This might reflect differences in environmental factors such as lifestyle between Maroons and other ethnic groups. Maroon adolescents moved from the Suriname interior to Paramaribo to continue their education. Most Maroon people in Suriname interior still live traditional African lifestyles with female subsistence horticulture and male hunting and fishing.[22] Most Maroon villages are located along the rivers of the interior of Suriname and access is heavily dependent on canoes and other watercraft. [22] This population is therefore isolated and is less exposed to unhealthy urban lifestyles such as excessive consumption of energy-dense foods and frequent use of automobiles [23,24] in urban Paramaribo. It is possible they were still benefiting from their earlier exposure to the traditional lifestyles, which have been suggested to be protective against high BP. [25] Maroon girls, however, had relatively high prevalence of overweight and obesity compared with other ethnic groups. The lower BP in Maroon girls became apparent only after further adjustment for BMI. It is possible that they have adopted different lifestyles such as excessive energy intake and decreasing physical activity once in unban Paramaribo, which may contribute to their rapid increase in BMI and subsequently higher BP. In this study, only 4% of Maroon girls reported ≥ 5–7 days/week physical activity outside of school. These findings clearly indicate the need to promote physical activity among this group in Suriname.

Studies in adults have consistently shown higher BP levels in African descent people than in other ethnic groups. [5,9-11] Studies in Suriname and the Netherlands, for example, showed higher BP levels in African-Surinamese than in other ethnic groups. [8,9] In this present study, however, African descent adolescents in Suriname (both Creoles and Maroons) had lower mean diastolic BP levels than other ethnic groups. The lack of higher BP levels in African descent adolescents in Suriname is consistent with the findings in the UK. Studies in the UK show higher BP levels in African descent adults than in other ethnic groups. [10,26] By contrast, in adolescents, BP levels were either lower or similar in African descent youth than in other ethnic groups. [13,14] A recent study, for example, found that BP in ethnic minority adolescents was generally lower than in White adolescents except for diastolic BP among Indian girls in the UK. [13]

The explanations for the different patterns of BP in adolescents and adulthood among African descent populations are unclear and require a cohort study to unravel the possible mechanisms underlying these differences. These observations suggest that environmental factors may be very important. The higher BP among Javanese adolescents was unexpected given the lower BP reported among the Javanese adult population in Suriname. The reason for the higher mean BP among Javanese adolescents is unclear. One possible explanation may relate to generational differences or changes in lifestyles. This requires further study. Left unchecked, the comparatively high BP among Javanese adolescents may abolish or reverse the current lower BP advantage enjoyed by the Javanese adult population in Suriname. These observations clearly indicate the need for early intervention in adolescents for preventing high BP in later life. [13]

The relationship between BMI and BP is well established in children and adolescents. [15-17] The strong and independent relationship between BMI and BP in our present study is consistent with previous findings. Although the mechanisms by which BMI may lead to high BP are not well understood, it is now generally recognised that high BMI significantly increases the risk of high BP. [27] Sinaiko and colleagues' prospective study showed that increases in BMI in early life were significantly related to an increased risk of high BP and other CVD in adulthood. [27] Our findings clearly indicate the need to prevent the increasing prevalence of overweight and obesity especially in Maroon girls early in life to prevent future sequelae of overweight/obesity related diseases.

Our study has limitations. As in many epidemiological studies, our BP level was based on an average of two measurements at a single visit. A more precise estimate of BP level would be obtained by multiple measurements obtained during several visits. Also, evidence suggests that during puberty BP increases more rapidly, with a significant gender difference in the age of onset.[28] In the present study, pubertal status was not assessed and this may affect the study conclusions. Nevertheless, in the recent UK study, late puberty was not associated with high BP in ethnic minority groups. [13] Another possible limitation is the combined mixed-ethnicities due to the small study samples. It is possible that BP patterns differ among these different ethnic groups. [29] Future studies should assess this possibility. In addition, social circumstances between the groups were not assessed, which might also affect our study conclusions. Despite these limitations, our present findings provide very important insights into ethnic differences in BP in adolescents in non-industrialised setting.
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Conclusion

The study findings indicate a higher mean BP among Hindustani boys and Javanese boys and girls whereas in the adult population these groups have lower mean BP levels in Suriname. BMI was positively related to BP in all the ethnic groups. These observations underscore the urgent need for public health measures early in life to prevent high BP and its sequelae in later life. BP reductions in adolescents can be achieved by weight loss through reducing excessive energy intake [30] and increasing physical activity strategies. [31] These cost-effective measures may lead to an important reduction in BP in adolescents thereby sparing the next generation from hypertension related complications [32].