Physical activity energy expenditure and cardiometabolic health in three rural Kenyan populations.

OBJECTIVES: Physical activity is beneficial for metabolic health but the extent to which this may differ by ethnicity is still unclear. Here, the objective was to characterize the association between physical activity energy expenditure (PAEE) and cardiometabolic risk among the Luo, Kamba, and Maasai ethnic groups of rural Kenya. METHODS: In a cross-sectional study of 1084 rural Kenyans, free-living PAEE was objectively measured using individually-calibrated heart rate and movement sensing. A clustered metabolic syndrome risk score (zMS) was developed by averaging the sex-specific z-scores of five risk components measuring central adiposity, blood pressure, lipid levels, glucose tolerance, and insulin resistance. RESULTS: zMS was 0.08 (-0.09; -0.06) SD lower for every 10 kJ/kg/day difference in PAEE after adjustment for age and sex; this association was modified by ethnicity (interaction with PAEE P < 0.05). When adjusted for adiposity, each 10 kJ/kg/day difference in PAEE was predicted to lower zMS by 0.04 (-0.05, -0.03) SD, without evidence of interaction by ethnicity. The Maasai were predicted to have higher cardiometabolic risk than the Kamba and Luo at every quintile of PAEE, with a strong dose-dependent decreasing trend among all ethnicities. CONCLUSION: Free-living PAEE is strongly inversely associated with cardiometabolic risk in rural Kenyans. Differences between ethnic groups in this association were observed but were explained by differences in central adiposity. Therefore, targeted interventions to increase PAEE are more likely to be effective in subgroups with high central adiposity, such as Maasai with low levels of PAEE.

Hemoglobin levels and blood pressure are associated in rural black africans.

OBJECTIVES: The association between blood levels of hemoglobin (B-hgb) and blood pressure (BP) has been widely investigated in Caucasians and Asians but there is a paucity of data in rural black Africans. The objective was to investigate the association between B-hgb and BP in a rural black African population. METHODS: A cross-sectional study was conducted in three districts in Kenya (Bondo, Kitui, and Transmara) with the inclusion of participants aged ≥17 years. Background information, anthropometry, BP, B-hgb, hepatic insulin resistance (HOMA2-IR), standard lipid profile, and oral glucose tolerance test were obtained in each participant. RESULTS: Background characteristics among 1,167 participants showed that anemic and non-anemic participants differed significantly from each other as there were more women, lower body mass index and waist circumference (WC), lower degree of hepatic insulin resistance and plasma cholesterols among the anemic participants. Furthermore, anemic participants had significantly lower systolic and diastolic BP (P < 0.01) but not a significantly different prevalence of hypertension (P = 0.08). Multivariate linear regression models adjusted for-age, sex, plasma total-cholesterol, WC, Log2(HOMA2-IR), ethnicity, and smoking status-revealed that B-hgb (per mmol/l increment) was significantly associated with systolic BP (estimate: 1.18 (0.37-1.98)) and diastolic BP (estimate: 1.06 (0.54-1.57)) (P < 0.01). CONCLUSIONS: B-hgb is associated with BP in rural black Africans.

Cardiovascular risk factors in rural Kenyans are associated with differential age gradients, but not modified by sex or ethnicity.

BACKGROUND: The relationship between metabolic disease and the non-modifiable risk factors sex, age and ethnicity in Africans is not well-established. AIM: This study aimed to describe sex, age and ethnicity differences in blood pressure (BP) and lipid status in rural Kenyans. SUBJECTS AND METHODS: A cross-sectional study was undertaken among rural Kenyans. BP and pulse rate (PR) were measured while sitting and fasting blood samples were taken for analysis of standard lipid profile. Standard anthropometric measurements were collected. Physical activity energy expenditure was obtained objectively and lifestyle data were obtained using questionnaires. RESULTS: In total, 1139 individuals (61.0% women) participated aged 17-68 years. Age was positively associated with BP and plasma cholesterol levels. Sitting PR was negatively associated with age in women only (sex-interaction p < 0.001). Ethnicity did not modify any of the age-associations with haemodynamic or lipid outcomes. Differences in intercept between women and men were found in all parameters except for diastolic BP (p = 0.154), with men having lower HDL-C but higher values in all other cardiovascular risk factors. CONCLUSION: BP and plasma cholesterol levels increase with age at a similar gradient in men and women, but absolute levels of the majority of the risk factors were higher in men.

Abdominal obesity has the highest impact on metabolic profile in an overweight African population.

AIM: The aim of this study was to determine the association between different anthropometric parameters and metabolic profile in an overweight, adult, black Kenyan population. METHODS: An opportunity sample of 245 overweight adult Kenyans (body mass index (BMI) ≥ 25 kg/m(2)) was analysed. A score of metabolic profile (metabolic Z-score) was constructed on the basis of levels of plasma lipids, blood pressure, blood glucose and serum insulin. Linear regressions using metabolic Z-score as outcome and six anthropometric variables (waist circumference (WC), hip circumference, visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue, arm fat area and arm muscle area) separately as independent variables were carried out. RESULTS: Mean age of study participants was 42.1 years (SD = 9.6) and 26.5% of the participants were men. The median BMI was 28.6 kg/m(2) (Q1 = 26.3; Q3 = 31.3). Of the six anthropometric variables tested, WC and VAT thickness had the strongest negative association with the metabolic profile (ß = 0.17 (0.09; 0.24) and 0.15 (0.08; 0.23), respectively). CONCLUSIONS: WC and VAT thickness were the strongest anthropometric predictors for the metabolic profile in overweight adult Kenyans. WC is useful in clinical practice for the diagnosis of metabolically unhealthy fat accumulation in an African setting.

Dietary patterns, food and macronutrient intakes among adults in three ethnic groups in rural Kenya.

OBJECTIVE: To compare dietary patterns and food and macronutrient intakes among adults in three ethnic groups in rural Kenya. DESIGN: In the present cross-sectional study, dietary intake was estimated in adult volunteers using two non-consecutive interactive 24 h recalls. Dietary patterns were assessed from the number of meals and snacks per day and from the food items and major food groups registered, and their contribution to energy intake (EI) was calculated. Anthropometric values were measured and sociodemographic data obtained using a questionnaire. SETTING: A cross-sectional study was conducted in the Bondo, Kitui and Transmara districts of rural Kenya. A high prevalence of food insecurity in Kenya underlines the importance of describing the dietary patterns and intakes in different Kenyan ethnic groups. SUBJECTS: A total of 1163 (61 % women) adult Luo, Kamba and Maasai, with a mean age of 38·6 (range: 18-68) years, volunteered to participate. RESULTS: Dietary patterns and food groups contributing to EI differed significantly among the ethnic groups. Mean EI ranged from 5·8 to 8·6 MJ/d among women and from 7·2 to 10·5 MJ/d among men, with carbohydrates contributing between 55·7 % and 74·2 % and fat contributing between 14·5 % and 30·2 % of total EI. Mean protein intake ranged from 0·72 to 1·3 g/kg per d, and EI:BMR ratio ranged between 1·1 and 1·6 in both sexes, and was highest among the Luo. Prevalence of underweight (BMI < 18·5 kg/m2) was 13·7 %, 20·5 % and 24·2 % in the Luo, Kamba and Maasai, respectively. CONCLUSIONS: The degree of food insecurity measured as a degree of undernutrition and as dietary patterns differed considerably among the ethnic groups. The Maasai and Kamba in particular were exposed to food insecurity.

Waist circumference and low high-density lipoprotein cholesterol as markers of cardiometabolic risk in Kenyan adults.

BACKGROUND: Abdominal obesity predict metabolic syndrome parameters at low levels of waist circumference (WC) in Africans. At the same time, the African lipid profile phenotype of low high-density lipoprotein (HDL) cholesterol without concomitant elevated triglyceride levels renders high triglyceride levels detrimental to cardiometabolic health unsuitable for identifying cardiometabolic risk in black African populations. OBJECTIVES: We aimed to identify simple clinical measures for cardiometabolic risk based on WC and HDL in an adult Kenyan population in order to determine which of the two predictors had the strongest impact. METHODS: We used linear regression analyses to assess the association between the two exposure variables WC and HDL with cardiometabolic risk factors including ultrasound-derived visceral (VAT) and subcutaneous adipose tissue (SAT) accumulation, fasting and 2-h venous glucose, fasting insulin, fasting lipid profile, and blood pressure in adult Kenyans (n = 1 370), and a sub-population with hyperglycaemia (diabetes and pre-diabetes) (n = 196). The same analyses were performed with an interaction between WC and HDL to address potential effect modification. Ultrasound-based, semi-quantitative hepatic steatosis assessment was used as a high-risk measure of cardiometabolic disease. RESULTS: Mean age was 38.2 (SD 10.7) (range 17-68) years, mean body mass index was 22.3 (SD 4.5) (range 13.0-44.8) kg/m2, and 57.8% were women. Cardiometabolic risk was found in the association between both WC and HDL and all outcome variables (p<0.05) except for HDL and SAT, fasting and 2-h venous glucose. Additive cardiometabolic risk (WC and HDL interaction) was found for SAT, low-density lipoprotein cholesterol, and triglycerides. No differences in the association between WC and HDL and the outcome variables were found when comparing the full study population and the hyperglycaemia sub-population. Increase in WC and HDL were both associated with hepatic steatosis (OR 1.09, p<0.001, and OR 0.46, p = 0.031, respectively). CONCLUSION: In adult Kenyans, increasing WC identified more cardiometabolic risk factors compared to HDL.

Efficacy of iron-fortified whole maize flour on iron status of schoolchildren in Kenya: a randomised controlled trial.

BACKGROUND: Sodium iron edetic acid (NaFeEDTA) might be a more bioavailable source of iron than electrolytic iron, when added to maize flour. We aimed to assess the effect, on children's iron status, of consumption of whole maize flour fortified with iron as NaFeEDTA or electrolytic iron. METHODS: 516 children, aged 3-8 years, from four schools in Marafa, Kenya, were randomly assigned to four groups. All were given the same amount of porridge five times a week. The porridge for one group was made from unfortified whole maize flour; for the other three groups it was fortified with either high-dose NaFeEDTA (56 mg/kg), low-dose NaFeEDTA (28 mg/kg), or electrolytic iron (56 mg/kg). Concentrations of haemoglobin, plasma ferritin, and transferrin receptor were analysed in samples taken at baseline and at the end of the 5-month intervention. The primary outcome was iron-deficiency anaemia. We analysed data on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, number NCT00386074. FINDINGS: The prevalence of iron-deficiency anaemia in children given unfortified flour was 10%. Compared with placebo, the prevalence of iron-deficiency anaemia in children given flour fortified with high-dose NaFeEDTA, low-dose NaFeEDTA, and electrolytic iron changed by -89% (95% CI -97% to -49%), -48% (-77% to 20%), and 59% (-18% to 209%), respectively. Consumption of high-dose NaFeEDTA improved all measured iron-status indicators. Low-dose NaFeEDTA decreased the prevalence of iron deficiency but did not noticeably change the prevalence of anaemia. Electrolytic iron did not improve any of these iron-status indicators. Children who were iron-deficient at baseline benefited more from high-dose and low-dose NaFeEDTA than those with sufficient iron at baseline. INTERPRETATION: Consumption of whole maize flour fortified with NaFeEDTA caused modest, dose-dependent improvements in children's iron status. Fortification with electrolytic iron did not improve their iron status. Therefore, in high-phytate flours, NaFeEDTA is more suitable than electrolytic iron for supplementation of iron in the diet.

The influence and benefits of controlling for inflammation on plasma ferritin and hemoglobin responses following a multi-micronutrient supplement in apparently healthy, HIV+ Kenyan adults.

Hemoglobin and ferritin are important biomarkers of iron status but are both altered by inflammation. We used the inflammation biomarkers C-reactive protein (CRP) and alpha1-acid glycoprotein (AGP) to adjust hemoglobin and ferritin concentrations to clarify interpretation of iron status. Apparently healthy adults who tested positive twice for HIV but who had not reached stage IV or clinical AIDS were randomly allocated to receive a food supplement (n = 17 and 21) or the food plus a micronutrient capsule (MN; 10 men and 34 women, respectively) containing 30 mg iron/d. Hemoglobin, ferritin, CRP, and AGP concentrations were measured at baseline and 3 mo and subjects were divided into 4 groups (reference, no inflammation; incubating, raised CRP; early convalescence, raised AGP and CRP; and late convalescence, raised AGP). Correction factors (the ratios of the median for the reference group over each inflammatory group) improved the consistency of the ferritin but not the hemoglobin results. After correction, ferritin (but not hemoglobin) increased in both men (48 microg/L; P = 0.02) and women (12 microg/L; P = 0.04) who received MN but not in the food-only group. However, hemoglobin did improve in subjects who showed no inflammation both at baseline and mo 3 (P = 0.019), but ferritin did not increase in this group. In conclusion, ferritin concentrations were more closely linked to current inflammation than hemoglobin; hence, correction by inflammation biomarkers improved data consistency. However, low hemoglobin concentrations were the consequence of long-term chronic inflammation and improvements in response to MN supplements were only detected in subjects with no inflammation.

Using plasma acute-phase protein concentrations to interpret nutritional biomarkers in apparently healthy HIV-1-seropositive Kenyan adults.

Inflammation influences the assessment of nutritional status. For example, inflammation reduces plasma retinol concentrations and vitamin A deficiency is overestimated. Conversely inflammation increases plasma ferritin concentrations and Fe deficiency is underestimated. Blood samples were obtained from 163 free-living HIV-1-infected adults, not on continuous medication, anti-retroviral drugs or micronutrients, not unwell and who had not reached WHO stage IV of HIV/AIDS. We used four markers of inflammation, C-reactive protein (CRP), alpha1-acid glycoprotein (AGP), alpha1-antichymotrypsin and erythrocyte sedimentation rate but mainly CRP and AGP were used to separate the subjects into four groups: 'healthy' where both CRP and AGP were normal; 'incubation phase' where CRP was elevated; 'early convalescence' where AGP and CRP were elevated and 'late convalescence' where only AGP was elevated. Correction factors were calculated to remove the influence of inflammation from each biomarker and group where inflammation was present and the data are shown before and after recalculation. The correction increased median plasma retinol concentrations of the whole group from 1.16 to 1.33 micromol/l, comparable with values (mean 1.29 micromol/l) in HIV-negative Kenyan women. Median ferritin concentrations fell by about 50% in both sexes and the number of women with plasma ferritin concentrations < or = 12 microg/l increased from eleven to twenty. The correction also increased plasma carotenoids and Hb but not alpha-tocopherol concentrations. We suggest that the method described to remove the influence of inflammation from nutritional biomarkers should be generally applicable in apparently healthy people and prevents discarding valuable data because of mild inflammation. The method does now need to be tested in other populations.

Obesity and regional fat distribution in Kenyan populations: impact of ethnicity and urbanization.

BACKGROUND: Obesity is increasing rapidly in Africa, and may not be associated with the same changes in body composition among different ethnic groups in Africa. OBJECTIVE: To assess abdominal visceral and subcutaneous fat thickness, prevalence of obesity, and differences in body composition in rural and urban Kenya. SUBJECTS AND METHODS: In a cross-sectional study carried out among Luo, Kamba and Maasai in rural and urban Kenya, abdominal visceral and subcutaneous fat thicknesses were measured by ultrasonography. Height and weight, waist, mid-upper arm circumferences, and triceps skinfold thickness were measured. Body mass index (BMI), arm fat area (AFA) and arm muscle area (AMA) were calculated. RESULTS: Among 1430 individuals (58.3% females) aged 17-68 years, abdominal visceral and subcutaneous fat, BMI, AFA and waist circumference (WC) increased with age, and were highest in the Maasai and in the urban population. AMA was only higher with increasing age among males. The prevalence of overweight (BMI > or = 25) (39.8% vs. 15.8%) and obesity (BMI > or = 30) (15.5% vs. 5.1%) was highest in the urban vs. rural population. CONCLUSION: Abdominal visceral and subcutaneous fat thickness was higher with urban residency. A high prevalence of overweight and obesity was found. The Maasai had the highest overall fat accumulation.

Alpha+ -thalassemia protects against anemia associated with asymptomatic malaria: evidence from community-based surveys in Tanzania and Kenya.

BACKGROUND: In hospital-based studies, alpha(+)-thalassemia has been found to protect against severe, life-threatening falciparum malaria. alpha(+)-Thalassemia does not seem to prevent infection or high parasite densities but rather limits progression to severe disease--in particular, severe malarial anemia. We assessed to what extent alpha(+)-thalassemia influences the association between mild, asymptomatic Plasmodium falciparum infection and hemoglobin concentration. METHODS: The study was based on 2 community-based surveys conducted among afebrile children (0.5-8 years old; n=801) in Kenya and Tanzania. RESULTS: Among children without inflammation (whole-blood C-reactive protein concentration

Micronutrients in childhood and the influence of subclinical inflammation.

In the present paper biomarkers of micronutrient status in childhood and some of the factors influencing them, mainly dietary intake, requirements and inflammation will be examined. On a body-weight basis the micronutrient requirements of children are mostly higher than those of an adult, but most biomarkers of status are not age-related. A major factor that is often overlooked in assessing status is the influence of subclinical inflammation on micronutrient biomarkers. In younger children particularly the immune system is still developing and there is a higher frequency of sickness than in adults. The inflammatory response rapidly influences the concentration in the blood of several important micronutrients such as vitamin A, Fe and Zn, even in the first 24 h, whereas dietary deficiencies can be envisaged as having a more gradual effect on biomarkers of nutritional status. The rapid response to infection may be for protective reasons, i.e. conservation of reserves, or by placing demands on those reserves to mount an effective immune response. However, because there is a high prevalence of disease in many developing countries, an apparently-healthy child may well be at the incubation stage or convalescing when blood is taken for nutritional assessment and the concentration of certain micronutrient biomarkers will not give a true indication of status. Most biomarkers influenced by inflammation are known, but often they are used because they are convenient or cheap and the influence of subclinical inflammation is either ignored or overlooked. The objective of the present paper is to discuss: (1) some of the important micronutrient deficiencies in childhood influenced by inflammation; (2) ways of correcting the interference from inflammation.