Flora A. Ukoli

Physical activity and cardiovascular risk factors in a developing population.

PURPOSE Noncommunicable diseases are emerging in developing countries. However, few studies have been conducted in those countries to evaluate the role of physical activity in the development of cardiovascular diseases. This study investigated physical activity and its relationship to risk factors for cardiovascular disease in a large population (N = 799) of civil servants from Benin City, Nigeria. METHODS Physical activity levels were estimated by an interviewer-administered questionnaire, which determined the average hours per week over the past year spent in occupational and leisure activities. Time spent walking or biking to work was assessed as well. Other major measures included body mass index (BMI), waist-hip ratio (WHR), blood pressures, plasma insulin level, lipid profiles, and diet. RESULTS More of the physical activity was attributed to occupational than to leisure activities. Compared with women, men had a higher activity level. No significant trend was observed across age groups. Male senior staff (a marker of higher socioeconomic status) had a lower physical activity level than male junior staff. Physical activity, especially time walking or biking to work, was inversely correlated with weight, BMI, WHR, blood pressures, insulin, total cholesterol, LDL and HDL cholesterol, and triglycerides in men, while such correlations were not consistent in women. In multivariate analysis in men, blood pressure and insulin were independently associated with BMI but not with walking, while an independent inverse association was seen between walking and BMI. CONCLUSION Lack of physical activity was associated with adverse risk profiles for cardiovascular disease in this developing population.

Factors associated with hypertension in Nigerian civil servants

BACKGROUND Study of hypertension in segments of West African populations in transition toward Westernization may lead to better understanding of the high risk for hypertension among Westernized blacks. METHODS Five hundred fifty-nine urban civil servants, ages 25-54, were recruited from six ministries of Bendel State, Nigeria. Blood pressure, physical measurements, urinary protein and glucose, fasting blood glucose, and demographic data were collected at the workplace. Subjects were classified as senior staff (professionals or administrators) or junior staff (non-administrators). RESULTS Among 172 male senior staff, the age-adjusted rate of hypertension (diastolic blood pressure > or = 90 mm Hg, systolic blood pressure > or = 140 mm Hg, or on an antihypertensive medication) was 43% and occurrence rose dramatically from 21 to 63% across age groups 25-34 to 45-54, respectively. Among 266 male junior staff, the age-adjusted rate of hypertension was 23%, and occurrence did not rise with age. Logistic regression showed that body mass index (kg/m2), age, alcohol drinking, and being senior staff were all independently related to hypertension in men. On the other hand, the age-adjusted rate of hypertension in 121 women was 20% and was significantly related only to body mass index. CONCLUSION Male urban civil servants appeared to have a risk for hypertension similar to that of U.S. black males. Age, body mass index, alcohol drinking, and other unidentified factors related to higher socioeconomic status were strong determinants of hypertension in this population.

Genetic association of five apolipoprotein polymorphisms with serum lipoprotein-lipid levels in African blacks

Genetic studies carried out mainly in European and European‐derived populations have shown that common polymorphisms in genes coding for apolipoproteins are significant determinants of serum lipoprotein‐lipid levels variation. However, except for a few sporadic studies, the distribution of apolipoprotein polymorphisms and their association with serum lipoprotein‐lipid levels have not been evaluated systematically in African or African‐derived populations. In this investigation we have studied five apolipoprotein polymorphisms, including APOA1/MspI –75 bp, APOA1/MspI +83 bp, APOC3/PvuII, APOE, and APOH in 786 Africans (493 men, 293 women) from Nigeria. The sample is comprised of Nigerian civil servants consisting of 462 junior staff (less affluent) and 324 senior staff (more affluent) where staff status is a correlate of their socioeconomic status. We first examined genetic associations in the total sample stratified by gender to determine the role of apolipoprotein polymorphisms in affecting serum lipid profile in the general population, and then by staff status to evaluate possible gene‐environment interactions. In the total sample, the APOC3/PvuII polymorphism showed significant effect on HDL‐cholesterol (P = 0.029) and HDL3‐cholesterol (P = 0.009) in women, and the APOE polymorphism was significantly associated with total cholesterol (P = 0.031) and LDL‐cholesterol (P = 0.0006) in women. Multiple regression analyses showed that the APOC3/PvuII polymorphism accounts for about 2 and 3% of the variation in HDL‐cholesterol and HDL3‐cholesterol, respectively, in women; while the APOE polymorphism accounted for about 5 and 6% of the variation in total‐ and LDL‐cholesterol, respectively, in women. Whereas the association of the APOE polymorphism was independent of the staff status, the significant affect of the APOC3/PvuII polymorphism on HDL‐ and HDL3‐cholesterol was confined to senior staff women where it explained about 7% of their variation. We also observed an interaction between staff and the APOH polymorphism in affecting cholesterol levels. The APOH polymorphism showed significant association with total cholesterol (P = 0.010) and LDL‐cholesterol (P = 0.016) in senior staff women and explained about 7 and 5% of their phenotypic variations, respectively. These data indicate that gene‐environment interaction may play an important role in affecting serum lipid profile in African populations. Genet. Epidemiol. 16:205–222, 1999.

Weight Threshold and Blood Pressure in a Lean Black Population

Hypertension is virtually absent in very lean rural African populations but is becoming more common in higher-weight urban African populations and is very common in predominantly obese Westernized black populations. This implies that there is a threshold above which weight is related to blood pressure. We studied urban Nigerian civil servants, a lean population in transition toward a more Westernized lifestyle. Blood pressure, fat-related measurements, fasting insulin, physical activity, alcohol intake, macronutrient intake, and electrolyte excretion were measured in 500 male and 299 female civil servants in Benin City, Nigeria, in 1992. Median body mass index (BMI) was 21.5 kg/m2 in men and 24.0 kg/m2 in women. Examination of age-adjusted mean blood pressure across quantiles of BMI in men and women suggested a threshold of 21.5 kg/m2 below which blood pressure was not correlated with BMI. Above this threshold blood pressure was correlated with BMI. Comparison of groups above and below the lower BMI threshold found that differences in blood pressure-BMI covariation were not explained by differences in alcohol intake, caloric or macronutrient intake, or electrolyte excretion. Physical activity was higher in men below the threshold. Fasting insulin and waist-hip ratio were strongly correlated with BMI even in this very lean population but neither was independently related to blood pressure. We conclude that there is a threshold below which little relationship between blood pressure and weight is observed. Above this threshold even at levels considered lean in US blacks, weight is a major determinant of blood pressure in this population of African blacks, which shares ancestry with US blacks.

Prevalence of elevated serum prostate‐specific antigen in rural Nigeria

Background: Recent hospital and cancer registry data show increasing prostate cancer incidence in Nigeria, which was previously regarded as a low incidence region. This study investigates the prevalence of prostate cancer risk in a previously unscreened cohort of rural Nigerians.

Correlates of serum lipids in a lean black population.

Exposure to an urban, sedentary work environment and higher socioeconomic status (SES) may stimulate adoption of Westernized lifestyles by populations in developing countries reversing the historically low risk for coronary heart disease. In a study of serum lipids in 1407 Nigerian civil servants, aged 25-54 years, we found a more atherogenic lipid profile among higher SES males and females compared with lower SES (LDL-cholesterol, 113 vs. 97 mg/dl, males, 125 vs. 114 mg/dl, females). Mean body mass index (BMI, kg/m2) in higher and lower SES was 22.6 and 21.3, respectively, males, and 24.7 and 24.4, respectively females. A strong relationship was observed between BMI and lipids although this relationship was absent among the leanest half of the population (BMI < 21.8). In multiple regression, SES and BMI were both strong and independent predictors of cholesterol. Both high and low SES consumed a typical Nigerian low fat, high carbohydrate diet, but somewhat higher meat, milk and egg intake suggested that some Westernization of the diet had occurred among the higher SES. Physical activity was lower among the higher SES. We conclude that SES related changes in lifestyle contribute to substantially higher total and LDL-cholesterol even in a generally lean population consuming a low fat diet.

The role of socioeconomic status and serum fatty acids in the relationship between intake of animal foods and cardiovascular risk factors

Little is known regarding the relationship of serum fatty acids to cardiovascular risk factors in Nigerian populations. Civil servants with higher socioeconomic status (SES) in Nigeria appear to be in cultural transition toward a more Westernized lifestyle. For this study the food intakes of 397 civil servants were estimated from two 24-h recalls. Fatty acids in serum total lipids were measured in both absolute weight concentration and percentage composition. Daily meat intake was 43.5 g, and fish intake was 70.5 g. The intakes of meat, eggs, and milk were higher in high SES Nigerians than in low SES Nigerians. The concentration of total fatty acids (TFA, the sum of 12 serum fatty acids) was also higher in high SES men and women, as compared with low SES men and women (2064, 2060, 1831, and 1776 mg/L, respectively). There were significant direct associations between meat intake and serum level of arachidonic acid, and between fish intake and serum levels of eicosapentaenoic acid and docosahexaenoic acid. TFA was positively associated with cholesterol, low-density-lipoprotein cholesterol (LDLc), and triglycerides across gender and SES groups after adjustment for body mass index, fasting insulin level, and age. Nigerian women were compared with two groups of American women. We concluded that fatty acids in absolute weight concentration reflected the amount of fat intake. The level of TFA was directly related to cardiovascular risk factors in Nigerians. Follow-up of such populations in cultural transition can facilitate the understanding of the true roles of animal food intake in the early evolution of atherosclerosis.

Lipoprotein (a) distribution in a Nigerian population

OBJECTIVES To determine the distribution and determinants of lipoprotein (a) (Lp(a)) concentration among Nigerians. METHODS Subjects were recruited from civil servants living in Benin City, Nigeria. The height and weight of the individuals were measured and their use of alcohol and tobacco estimated by questionnaire. Laboratory analyses of blood samples involved Lp(a), total cholesterol (TC), high-density lipoprotein (HDLc), HDL2c, HDL3c, triglyceride (TG) and insulin. RESULTS The analyses indicate that the Lp(a) concentrations are elevated among Nigerian populations and more skewed towards high levels than is observed for caucasian and oriental groups. The median levels for Lp(a) were 24.0 mg dl-1 and 19.0 mg dl-1 for women and men, respectively. This difference was significant (P < 0.05) but after stratifying by age, only the 45-54 year-old group of women (30.1 mg dl-1) had significantly higher (p < 0.001) median concentrations of Lp(a) than men (18.4 mg dl-1). Age, 20-64, had no influence on Lp(a) levels in men but in women Lp(a) concentrations increased significantly with age (p < 0.05). Among males alcohol consumption, smoking and body mass index (BMI) were not related to Lp(a) concentrations but a significant effect (p < 0.05) was noted for waist-hip ratio (WHR). Among females no relationship was observed between Lp(a) levels and alcohol consumption, BMI and WHR. All serum lipids measured (TC, HDLc, HDL2c, HDL3c, low-density lipoprotein (LDLc), and TG) were correlated with Lp(a) concentrations among men. A significant association with TC and LDLc remained after correcting for Lp(a) cholesterol. Among women, the Lp(a) levels were associated with TC, HDLc, HDL3c, and LDLc but not with HDL2c, and TG. The correlations with TC and LDLc were not significant after correcting for Lp(a) cholesterol. Insulin did not correlate with Lp(a) levels in either men or women. CONCLUSIONS Lp(a) concentrations are high in Nigerians, particularly among women, and the association between the Lp(a) concentrations and other lipoproteins is stronger than in white populations.

John Henryism and blood pressure among Nigerian civil servants.

STUDY OBJECTIVE: Among urban Nigerian civil servants, higher socioeconomic status is related to increased blood pressure. In the United States, the relation between increased blood pressure and low socioeconomic status or low level of education has been found to be potentiated by high effort active coping (John Henryism) among African-Americans. Thus, the potentiating effect of high effort active coping as measured by the John Henryism Active Coping Scale, on socioeconomic status, as measured by job grade, was considered in relation to blood pressure in a Nigerian civil servant population. DESIGN: The influence of John Henryism on the association between educational level or socioeconomic status and increased blood pressure was examined during a comprehensive blood pressure survey. John Henryism refers to a strong behavioural predisposition to actively cope with psychosocial environmental stressors. SETTING: Benin City, Nigeria. PARTICIPANTS: Nigerian civil servant sample of 658 adults, aged 20 to 65 years. MAIN RESULTS: Among those with high John Henryism scores of upper socioeconomic status, whether measured by education level or job grade, there was a trend toward higher systolic and diastolic blood pressures, adjusted for age and body mass index, in men and women, though not statistically significant. CONCLUSIONS: This trend is consistent with recent findings of increased blood pressure among women and African-Americans with high John Henryism and high status jobs.

Assessment of cardiovascular risk factors in Nigerian students.

The present study assessed the prevalence of cardiovascular risk factors in 65 Nigerian medical students attending the University of Benin, Benin City, Nigeria. Their ages ranged from 17 to 28 years with a mean age for men of 20.9 years and for women of 18.8 years. Approximately 8% of the men and 0% of the women were current cigarette smokers, whereas alcohol use was observed in 14.6% of the men and in 0% of the women. The Nigerian men had significantly higher diastolic blood pressures than did American black and white men. Compared to American black men, the Nigerian men had considerably lower total cholesterol and triglyceride concentrations. The Nigerian women did not differ from American black women with respect to total cholesterol, but had significantly lower triglyceride concentrations.