Protein Intake and Long-term Change in Glomerular Filtration Rate in the Jackson Heart Study.

OBJECTIVE: Dietary protein intake could have deleterious renal effects in populations at risk for chronic kidney disease. Here, we examined whether higher protein intake (≥80th percentile of energy from protein) is associated with decline in kidney function and whether this decline varies by diabetes status. DESIGN: Observational cohort study. SUBJECTS AND SETTINGS: Participants were African-Americans (n = 5,301), who enrolled in the Jackson Heart Study between 2000 and 2004. METHODS: Dietary intake was assessed using a validated food-frequency questionnaire at baseline, and serum creatinine was measured at baseline (visit 1) and 8 years later (visit 3). Estimated glomerular filtration rates (eGFRs) at baseline and follow-up were computed using the chronic kidney disease epidemiology collaboration equation. MAIN OUTCOME MEASURE: The change in eGFR was computed by subtracting eGFR at visit 1 from that at visit 3. RESULTS: Of 3,165 participants with complete data, 64% were women, 57% had hypertension, and 19% had diabetes. The median (25th, 75th percentile) percent energy intake from protein was 14.3 (12.4, 16.4), comparable to that reported for the general US population (15% of energy). During a median (25th, 75th percentile) follow-up of 8.0 (7.4, 8.3) years, eGFR declined by 10.5% from a mean (SD) of 97.4 (17.5) to 86.9 (21.3) mL/min/1.73 m2. In the fully adjusted model, consumption of protein as percent of energy intake in lowest and highest quintiles was associated with decline in eGFR among diabetic subjects. The analysis of variance with a robust variance estimator was used to determine whether long-term change in eGFR significantly varies by protein intake. CONCLUSIONS: Our results show that, among African-Americans with diabetes, higher protein intake as a percent of total energy intake is positively associated with greater decline in eGFR in analyses that accounted for risk factors for kidney disease.

Total antioxidant performance is associated with diet and serum antioxidants in participants of the diet and physical activity substudy of the Jackson Heart Study.

Total antioxidant performance (TAP) measures antioxidant capacities in both hydrophilic and lipophilic compartments of serum and interactions known to exist between them. Our objective was to assess TAP levels in a subset of Jackson Heart Study (JHS) participants and to examine associations with dietary and total (diet + supplement) intakes of alpha-tocopherol, gamma-tocopherol (diet only), beta-carotene, vitamin C, fruit, vegetables, and nuts, and serum concentrations of alpha-tocopherol, gamma-tocopherol, and beta-carotene. We conducted a cross-sectional analysis of 420 (mean age 61 y; 254 women) African American men and women participating in the Diet and Physical Activity Sub-Study of the JHS in Jackson, Mississippi. In multivariate-adjusted models, we observed positive associations between total alpha-tocopherol, total and dietary beta-carotene, and total vitamin C intakes and TAP levels (P-trend < 0.05). Positive associations were also observed for vegetable, fruit, and total fruit and vegetable intakes (P-trend < 0.05). For serum antioxidant nutrients, alpha-tocopherol but not beta-carotene was associated with serum TAP levels. There were inverse associations for serum gamma-tocopherol and TAP levels. Associations for alpha-tocopherol were seen at intake levels much higher than the current Recommended Dietary Allowance. It may, therefore, be prudent to focus on increasing consumption of fruit, vegetables, nuts, and seeds to increase total antioxidant capacity.

Patterns of Beverages Consumed and Risk of Incident Kidney Disease.

BACKGROUND AND OBJECTIVES: Selected beverages, such as sugar-sweetened beverages, have been reported to influence kidney disease risk, although previous studies have been inconsistent. Further research is necessary to comprehensively evaluate all types of beverages in association with CKD risk to better inform dietary guidelines. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a prospective analysis in the Jackson Heart Study, a cohort of black men and women in Jackson, Mississippi. Beverage intake was assessed using a food frequency questionnaire administered at baseline (2000-2004). Incident CKD was defined as onset of eGFR<60 ml/min per 1.73 m2 and ≥30% eGFR decline at follow-up (2009-13) relative to baseline among those with baseline eGFR ≥60 ml/min per 1.73 m2. Logistic regression was used to estimate the association between the consumption of each individual beverage, beverage patterns, and incident CKD. Beverage patterns were empirically derived using principal components analysis, in which components were created on the basis of the linear combinations of beverages consumed. RESULTS: Among 3003 participants, 185 (6%) developed incident CKD over a median follow-up of 8 years. At baseline, mean age was 54 (SD 12) years, 64% were women, and mean eGFR was 98 (SD 18) ml/min per 1.73 m2. After adjusting for total energy intake, age, sex, education, body mass index, smoking, physical activity, hypertension, diabetes, HDL cholesterol, LDL cholesterol, history of cardiovascular disease, and baseline eGFR, a principal components analysis-derived beverage pattern consisting of higher consumption of soda, sweetened fruit drinks, and water was associated with significantly greater odds of incident CKD (odds ratio tertile 3 versus 1 =1.61; 95% confidence interval, 1.07 to 2.41). CONCLUSIONS: Higher consumption of sugar-sweetened beverages was associated with an elevated risk of subsequent CKD in this community-based cohort of black Americans.

Dietary Phosphorus and Ambulatory Blood Pressure in African Americans: The Jackson Heart Study.

BACKGROUND: Higher dietary phosphorus is associated with left ventricular hypertrophy and mortality, which are blood pressure (BP)-related outcomes. For this reason, we hypothesized that dietary phosphorus may be associated with adverse clinic and ambulatory BP patterns. METHODS: Our study included 973 African American adults enrolled in the Jackson Heart Study (2000-2004) with 24-hour ambulatory BP monitoring (ABPM) data at baseline. We quantified dietary phosphorus from a validated Food Frequency Questionnaire as follows: (i) absolute daily intake, (ii) ratio of phosphorus-to-protein intake, (iii) phosphorus density, and (iv) energy-adjusted phosphorus intake. Using multivariable linear regression, we determined associations between dietary phosphorus intake and systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure in clinic and over daytime, nighttime, and 24-hour periods from ABPM. Extent of nocturnal BP dipping was also assessed. Using logistic regression, we modeled relationships between dietary phosphorus intake and clinically relevant qualitative BP phenotypes, such as masked, sustained, or white-coat hypertension and normotension. RESULTS: There were no statistically significant associations between phosphorus intake and SBP or pulse pressure in adjusted models. Most metrics of higher phosphorus intake were associated with lower daytime, nighttime, and clinic DBP. Higher phosphorus intake was not associated with clinic or ABPM-defined hypertension overall, but most metrics of higher phosphorus intake were associated with lower odds of sustained hypertension compared to sustained normotension, white-coat hypertension, and masked hypertension. There were no associations between dietary phosphorus and nocturnal BP dipping. CONCLUSIONS: These data do not support a role for higher phosphorus intake and higher BP in African Americans.

Serum carotenoid and tocopherol concentrations vary by dietary pattern among African Americans.

BACKGROUND: Intakes and biochemical concentrations of carotenoids and tocopherols have been associated with chronic diseases. OBJECTIVE: To describe dietary patterns in Jackson Heart Study participants and to determine if biochemical measurements of antioxidants differ across these. DESIGN: Cross-sectional analysis of data for 373 African-American men and women (age 35 to 80 years), participating in the Diet and Physical Activity Substudy of the Jackson Heart Study. METHODS: Dietary intake was assessed with a region specific food frequency questionnaire. Patterns were defined by cluster analysis of food groups, as percent of energy intake. RESULTS: Four dietary patterns were identified: fast food, Southern, prudent, and juice. Individuals in the fast-food pattern (n=153) had significantly lower serum concentrations of lutein plus zeaxanthin and beta-cryptoxanthin; those in the Southern cluster (n=99) had significantly lower serum alpha-carotene; and those in the prudent (n=63) and juice (n=58) clusters had significantly higher serum alpha-carotene and beta-cryptoxanthin (P<0.05) relative to those in at least one other cluster (all P<0.05). The juice cluster also had higher serum alpha-tocopherol concentrations relative to the fast-food cluster. CONCLUSIONS: Diets high in fast foods, snacks, soft drinks, and meat were associated with relatively low concentrations of carotenoids and alpha-tocopherol. This pattern contained the largest number of participants, and could contribute to the extensive health disparities seen in this region.

Dietary patterns, abdominal visceral adipose tissue, and cardiometabolic risk factors in African Americans: the Jackson heart study.

OBJECTIVE: To examine the relative association of abdominal visceral adipose tissue (VAT) with cardiometabolic risk factors between African and European Americans. DESIGN AND METHODS: We conducted a cross-sectional study of 2035 African Americans from Jackson Heart Study (JHS) and 3170 European Americans from Framingham Heart Study (FHS) who underwent computed tomography assessment of VAT and subcutaneous adipose tissue (SAT). The FHS participants were weighted to match the age distribution of the JHS participants and the metabolic risk factors were examined by study groups in relation to VAT. RESULTS: JHS participants had higher rates of obesity, hypertension, diabetes and metabolic syndrome than FHS participants (all p = 0.001). The associations were weaker in JHS women for VAT with blood pressure, triglycerides, HDL-C, and total cholesterol (pinteraction = 0.03 to 0.001) than FHS women. In contrast, JHS men had stronger associations for VAT with high triglycerides, low HDL, and metabolic syndrome (all pinteraction = 0.001) compared to FHS men. Similar associations and gender patterns existed for SAT with most metabolic risk factors. CONCLUSIONS: The relative association between VAT and cardiometabolic risk factors is weaker in JHS women compared to FHS women, whereas stronger association with triglycerides and HDL were observed in JHS men.

Validity and calibration of food frequency questionnaires used with African-American adults in the Jackson Heart Study.

OBJECTIVE: To examine the relative validity of two food frequency questionnaires (FFQs) developed for use in investigating diet and disease relationships within the adult African-American population in the southern United States. DESIGN: Cross-sectional analyses of dietary nutrient intake data, comparing four 24-hour dietary recalls with an FFQ developed by the Lower Mississippi Delta Nutrition Intervention Research Initiative, and its shorter version adapted for use in the Jackson Heart Study. SUBJECTS: A representative subset of participants (n=499, aged 35 to 81 years) from the baseline Jackson Heart Study cohort (N=5,302) was selected for this study. Data collection took place between winter 2000 and spring 2004. STATISTICAL ANALYSES: Pearson's correlation coefficients (energy adjusted and de-attenuated) for 26 nutrients estimates from each of the FFQs, comparing them with the mean of four 24-hour dietary recalls. The ability of the FFQs to rank individuals based on nutrient intakes was compared to that of the mean of four 24-hour dietary recalls and attenuation coefficients were also calculated. RESULTS: Median nutrient intake estimates tended to be higher on the long and lower on the short FFQ compared to the median for the mean of four 24-hour dietary recalls. Energy adjusted and deattenuated correlations of FFQ intake estimates with recalls ranged from 0.20 for sodium to 0.70 for carbohydrate for the short FFQ and from 0.23 for polyunsaturated fat to 0.75 for dietary fiber and magnesium for the long. Attenuation coefficients for men on average were 0.42 for the short and 0.49 for the long FFQ. For women, these were 0.31 for the short and 0.42 for the long FFQ. CONCLUSIONS: Both FFQs appear to be reasonably valid for assessment of dietary intake of adult African Americans in the South. The Lower Mississippi Delta Nutrition Intervention Research Initiative FFQ exhibited higher intake estimates and stronger correlations with recalls than the Jackson Heart Study FFQ for most nutrients analyzed, more so for women than men.

Carotenoid intakes, assessed by food-frequency questionnaires (FFQs), are associated with serum carotenoid concentrations in the Jackson Heart Study: validation of the Jackson Heart Study Delta NIRI Adult FFQs.

OBJECTIVES: Intake and status of carotenoids have been associated with chronic disease. The objectives of this study were to examine the association between carotenoid intakes as measured by two regional food-frequency questionnaires (FFQs) and their corresponding measures in serum, and to report on dietary food sources of carotenoids in Jackson Heart Study (JHS) participants. DESIGN: Cross-sectional analysis of data for 402 African American men and women participating in the Diet and Physical Activity Sub-Study (DPASS) of the JHS. RESULTS: Mean serum carotenoid concentrations and intakes in this population were comparable to those reported for the general US population. After adjustment for covariates, correlations between serum and dietary measures of each carotenoid, for the average of the recalls (deattenuated), the short FFQ and the long FFQ, respectively, were: 035 and 0-carotene; 026 and 0-carotene; 017 and 0-carotene; 034 and 0-cryptoxanthin; 015 and 037, 014 for lycopene. Major dietary sources of -carotene and lutein plus zeaxanthin, mustard, turnip and collard greens; of beta-cryptoxanthin, orange juice; and of lycopene, tomato juice. CONCLUSIONS: On average, carotenoid intakes and serum concentrations are not lower in this southern African American population than the general US population. The two regional FFQs developed for a southern US population and used as dietary assessment tools in the JHS appear to provide reasonably valid information for most of these carotenoids.