Arterialized venous bicarbonate is associated with lower bone mineral density and an increased rate of bone loss in older men and women.

CONTEXT: Higher dietary net acid loads have been associated with increased bone resorption, reduced bone mineral density (BMD), and increased fracture risk. OBJECTIVE: The objective was to compare bicarbonate (HCO3) measured in arterialized venous blood samples to skeletal outcomes. DESIGN: Arterialized venous samples collected from participants in the Health, Aging and Body Composition (Health ABC) Study were compared to BMD and rate of bone loss. SETTING: The setting was a community-based observational cohort. PARTICIPANTS: A total of 2287 men and women age 74 ± 3 years participated. INTERVENTION: Arterialized venous blood was obtained at the year 3 study visit and analyzed for pH and pCO2. HCO3 was determined using the Henderson-Hasselbalch equation. MAIN OUTCOME MEASURE: BMD was measured at the hip by dual-energy x-ray absorptiometry at the year 1 (baseline) and year 3 study visits. RESULTS: Plasma HCO3 was positively associated with BMD at both year 1 (P = .001) and year 3 (P = .001) in models adjusted for age, race, sex, clinic site, smoking, weight, and estimated glomerular filtration rate. Plasma HCO3 was inversely associated with rate of bone loss at the total hip over the 2.1 ± 0.3 (mean ± SD) years between the two bone density measurements (P < .001). Across quartiles of plasma HCO3, the rate of change in BMD over the 2.1 years ranged from a loss of 0.72%/y in the lowest quartile to a gain of 0.15%/y in the highest quartile of HCO3. CONCLUSIONS: Arterialized plasma HCO3 was associated positively with cross-sectional BMD and inversely with the rate of bone loss, implying that systemic acid-base status is an important determinant of skeletal health during aging. Ongoing bone loss was linearly related to arterialized HCO3, even after adjustment for age and renal function. Further research in this area may have major public health implications because reducing dietary net acid load is possible through dietary intervention or through supplementation with alkaline potassium compounds.

Dietary patterns, insulin sensitivity and inflammation in older adults.

BACKGROUND/OBJECTIVES: Several studies have linked dietary patterns to insulin sensitivity and systemic inflammation, which affect risk of multiple chronic diseases. The purpose of this study was to investigate the dietary patterns of a cohort of older adults, and to examine relationships of dietary patterns with markers of insulin sensitivity and systemic inflammation. SUBJECTS/METHODS: The Health, Aging and Body Composition (Health ABC) Study is a prospective cohort study of 3075 older adults. In Health ABC, multiple indicators of glucose metabolism and systemic inflammation were assessed. Food intake was estimated with a modified Block food frequency questionnaire. In this study, dietary patterns of 1751 participants with complete data were derived by cluster analysis. RESULTS: Six clusters were identified, including a 'healthy foods' cluster, characterized by higher intake of low-fat dairy products, fruit, whole grains, poultry, fish and vegetables. In the main analysis, the 'healthy foods' cluster had significantly lower fasting insulin and homeostasis model assessment of insulin resistance values than the 'breakfast cereal' and 'high-fat dairy products' clusters, and lower fasting glucose than the 'high-fat dairy products' cluster (P≤0.05). No differences were found in 2-h glucose. With respect to inflammation, the 'healthy foods' cluster had lower interleukin-6 than the 'sweets and desserts' and 'high-fat dairy products' clusters, and no differences were seen in C-reactive protein or tumor necrosis factor-α. CONCLUSIONS: A dietary pattern high in low-fat dairy products, fruit, whole grains, poultry, fish and vegetables may be associated with greater insulin sensitivity and lower systemic inflammation in older adults.

Misclassification of nutrient and energy intake from use of closed-ended questions in epidemiologic research.

The authors investigated the effect of collecting food frequency intake data using questionnaires that record response intervals rather than exact frequencies of consumption. Measures of energy and 24 nutrients were calculated using both types of frequency data for subjects' mean intakes, rank classifications and group mean values. Frequency data obtained between 1987 and 1989 using the open-ended Health Habits and History Questionnaire (HHHQ) developed by Block and associates at the National Cancer Institute were recoded into the interval response formats used by the computer-scannable version of the HHHQ and into the format used in the food frequency questionnaire developed by Willett for the Nurses' Health Study and other studies. Compared with the open-ended HHHQ, for otherwise identical data sets, the closed-ended HHHQ and Willett response categories produced significantly different (p < 0.05) measures of intake on the individual level for 18 (72%) (HHHQ) and 16 (64%) (Willett) of the 25 nutrient and energy measures studied, and they ranked 13-53% (HHHQ) and 16-52% (Willett) of subjects in different quintiles for the various measures. Use of food frequency questionnaires with closed-ended response categories causes nondifferential misclassification that could bias study results. To reduce such misclassification in epidemiologic studies, the authors recommend that food frequency questionnaires obtain exact frequencies of intake for measurement of diet exposure, and they describe an open-ended questionnaire layout which does so and also permits computer scanning of data.

Hereditary and environmental influences on blood pressure values of premenopausal women and their college-age daughters.

Blood pressure (BP) and environmental (dietary/lifestyle) variables were measured in 62 healthy normotensive pairs of premenopausal mothers (44.3 years) and their college-age consanguineous daughters (18.7 years) to estimate the relative contributions of genetic vs environmental factors on BP. As expected, the mothers had significantly higher systolic (SBP) and diastolic (DBP) blood pressures than the daughters (p less than 0.004 and 0.012, respectively). Among the dietary/lifestyle variables measured, mothers were found to have significantly higher mean weight and body mass index (BMI) (p less than 0.009 and 0.001, respectively), and significantly lower lean body mass (LBM) and calcium intake than their daughters (p less than 0.003 and 0.037, respectively). Significant correlations were found between mean BP of the mothers and their mean weight and BMI. No significant correlations existed for the daughters. The familial resemblances between BP of the mothers and daughters were relatively low, i.e., 0.14 for SBP and 0.19 for DBP. From these findings we conclude that the higher BP values with increased age among this healthy female population primarily result from an increase in BMI and a shift from lean to fat mass, as measured by midarm circumference. Our results suggest that environmental factors, i.e., excessive energy intake over time, accompanied by decreased physical activity, are primarily responsible for the greater indices of body fat and the higher BPs observed in this sample of healthy premenopausal women.

PIP: Blood pressure (BP) and environmental (dietary/lifestyle) variables were measured in 62 healthy, normotensive pairs of premenopausal mothers (44.3 years) and their college age consanguineous daughters (18.7 years) to estimate the relative contributions of genetic vs environmental factors on BP. As expected, the mothers had significantly higher systolic (SBP) and diastolic (DBP) BP than the daughters (p0.004 and 0.012, respectively). Among the dietary/lifestyle variables measured, mothers were found to have significantly higher means for smoking cigarettes and using oral contraceptives; weight and body mass index (BMI; p0.009 and 0.001, respectively), and significantly lower lean body mass (LBM) and calcium intake than their daughters (p0.0003 and 0.037, respectively). Significant correlations were found between mean BP of the mothers and their mean weight and BMI. No significant correlations existed for the daughters. The familial resemblances between BPs of mothers and daughters were relatively low, i.e., 0.14 for SBP and 0.19 for DBP. From these findings, the authors conclude that the higher BP values with increased age among this healthy female population primarily result from an increase in BMI and a shift from lean to fat mass, as measured by midarm circumference. The results suggest that environmental factors, such as excessive energy intake over time, accompanied by decreased physical activity, are primarily responsible for the greater indices of body fat and the higher BPs observed in this sample of healthy premenopausal women.