Pablo Monsivais

Obesity and Supermarket Access: Proximity or Price?

OBJECTIVES We examined whether physical proximity to supermarkets or supermarket price was more strongly associated with obesity risk. METHODS The Seattle Obesity Study (SOS) collected and geocoded data on home addresses and food shopping destinations for a representative sample of adult residents of King County, Washington. Supermarkets were stratified into 3 price levels based on average cost of the market basket. Sociodemographic and health data were obtained from a telephone survey. Modified Poisson regression was used to test the associations between obesity and supermarket variables. RESULTS Only 1 in 7 respondents reported shopping at the nearest supermarket. The risk of obesity was not associated with street network distances between home and the nearest supermarket or the supermarket that SOS participants reported as their primary food source. The type of supermarket, by price, was found to be inversely and significantly associated with obesity rates, even after adjusting for individual-level sociodemographic and lifestyle variables, and proximity measures (adjusted relative risk=0.34; 95% confidence interval=0.19, 0.63) CONCLUSIONS Improving physical access to supermarkets may be one strategy to deal with the obesity epidemic; improving economic access to healthy foods is another.

Lower-Energy-Density Diets Are Associated with Higher Monetary Costs per Kilocalorie and Are Consumed by Women of Higher Socioeconomic Status

OBJECTIVE Diets of lower energy density are associated with higher diet quality, lower body weights, and better health outcomes. This study examined associations among dietary energy density, energy-adjusted diet costs, and socioeconomic indicators of study participants. DESIGN In this cross-sectional study, energy and nutrient intakes for 164 men and women aged 25 to 65 years were obtained using a food frequency instrument between June 2005 and September 2006. Dietary energy density (kcal/g) was calculated with and without beverages. Energy-adjusted diet costs (

Determinants of action potential propagation in cerebellar Purkinje cell axons

/2,000 kcal) were calculated using food prices in Seattle, WA. Tertile splits of energy density and energy cost were analyzed using tests for linear trend. Linear regression models tested the association between education, income, and dietary variables, adjusting for age and sex. RESULTS Diets of lower energy density were associated with higher absolute nutrient intakes. Diets of lower energy density were also associated with higher energy-adjusted diet costs. Conversely, highest energy density diets were associated with lower intakes of micronutrients and fiber and lower costs. Education and household income showed a negative association with dietary energy density in regression models. Education and household incomes showed a positive association with the energy-adjusted cost of the diet. Education was a stronger predictor of both energy density and energy cost than was household income. CONCLUSIONS Higher-quality diets were not only more costly per kilocalorie but were also consumed by persons of higher educational level. The influence of diet quality on health, observed in some epidemiologic studies, might be modulated by unobserved indexes of socioeconomic status.

Does diet cost mediate the relation between socioeconomic position and diet quality

Axons have traditionally been viewed as highly faithful transmitters of action potentials. Recently, however, experimental evidence has accumulated to support the idea that under some circumstances axonal propagation may fail. Cerebellar Purkinje neurons fire highfrequency simple spikes, as well as bursts of spikes in response to climbing fiber activation (the “complex spike”). Here we have visualized the axon of individual Purkinje cells to directly investigate the relationship between somatic spikes and axonal spikes using simultaneous somatic whole-cell and cell-attached axonal patch-clamp recordings at 200-800 μm from the soma. We demonstrate that sodium action potentials propagate at frequencies up to ∼260 Hz, higher than simple spike rates normally observed in vivo. Complex spikes, however, did not propagate reliably, with usually only the first and last spikes in the complex spike waveform being propagated. On average, only 1.7 ± 0.2 spikes in the complex spike were propagated during resting firing, with propagation limited to interspike intervals above ∼4 msec. Hyperpolarization improved propagation efficacy without affecting total axonal spike number, whereas strong depolarization could abolish propagation of the complex spike. These findings indicate that the complex spike waveform is not faithfully transmitted to downstream synapses and that propagation of the climbing fiber response may be modulated by background activity.

The site of action potential initiation in cerebellar Purkinje neurons.

Background/Objectives:Socioeconomic disparities in diet quality are well established. This study tested the hypothesis that such disparities are mediated, in part, by diet cost.Subjects/Methods:The Seattle Obesity Study (S.O.S) was a cross-sectional study based on a representative sample of 1266 adults of King County, WA, conducted in 2008–09. Demographic and socioeconomic variables were obtained through telephone survey. Income and education were used as indicators of socioeconomic position. Dietary intake data were obtained using a food frequency questionnaire (FFQ). Diet cost was calculated based on retail prices for FFQ component foods. Energy density (KJ/g) and mean adequacy ratio (MAR) were used as two indices of overall diet quality.Results:Higher income and education were each associated with lower energy density and higher MAR scores, adjusting for covariates. Higher income and education were also associated with higher energy adjusted diet cost. Higher quality diets were in turn associated with higher diet costs. All these associations were significant (P<0.0001). In formal mediation analyses, diet cost significantly mediated the pathway between income and diet quality measures, adjusting for covariates (P<0.05 each). Further, income–diet cost–diet quality pathway was found to be moderated by education level.Conclusions:The social gradient in diet quality may be explained by diet cost. Strategies to improve diet quality among lower socioeconomic strata may need to take food prices and diet cost along with nutrition education into account.

Associations between exposure to takeaway food outlets, takeaway food consumption, and body weight in Cambridgeshire, UK: population based, cross sectional study

Knowledge of the site of action potential initiation is essential for understanding how synaptic input is converted into neuronal output. Previous studies have shown that the lowest-threshold site for initiation of action potentials is in the axon. Here we use recordings from visualized rat cerebellar Purkinje cell axons to localize the site of initiation to a well-defined anatomical structure: the first node of Ranvier, which normally forms at the first axonal branch point.

Less-energy-dense diets of low-income women in California are associated with higher energy-adjusted diet costs

Objectives To examine the association between environmental exposure to takeaway food outlets, takeaway food consumption, and body weight, while accounting for home, work place, and commuting route environments. Design Population based, cross sectional study, using data on individual participants’ diet and weight, and objective metrics of food environment exposure. Participants Working adults participating in the Fenland Study, Cambridgeshire, UK (n=5442, aged 29-62 years), who provided home and work addresses and commuting preferences. Takeaway food outlet exposure was derived using data from local authorities for individual environmental domains (at home, at work, and along commuting routes (the shortest route between home and work)), and for exposure in all three domains combined. Exposure was divided into quarters (Q); Q1 being the least exposed and Q4 being the most exposed. Main outcome measures Self reported consumption of takeaway type food (g/day; pizza, burgers, fried foods, and chips) using food frequency questionnaires, measured body mass index, and cut-offs for body mass index as defined by the World Health Organization. Results In multiple linear regression models, exposure to takeaway food outlets was positively associated with consumption of takeaway food. Among domains at home, at work, and along commuting routes, associations were strongest in work environments (Q4 v Q1; β coefficient=5.3 g/day, 95% confidence interval 1.6 to 8.7; P<0.05), with evidence of a dose-response effect. Associations between exposure in all three domains combined and consumption were greater in magnitude across quarters of exposure (Q4 v Q1; 5.7 g/day, 2.6 to 8.8; P<0.001), with evidence of a dose-response effect. Combined exposure was especially strongly associated with increased body mass index (Q4 v Q1; body mass index 1.21, 0.68 to 1.74; P<0.001) and odds of obesity (Q4 v Q1; odds ratio 1.80, 1.28 to 2.53; P<0.05). There was no evidence of effect modification by sex. Conclusions Exposure to takeaway food outlets in home, work, and commuting environments combined was associated with marginally higher consumption of takeaway food, greater body mass index, and greater odds of obesity. Government strategies to promote healthier diets through planning restrictions for takeaway food could be most effective if focused around the workplace.

The quality and monetary value of diets consumed by adults in the United States

BACKGROUND US-based studies are needed to estimate the relation, if any, between diet quality and estimated diet costs. OBJECTIVE We hypothesized that lower cost diets among low-income women in California would be energy dense but nutrient poor. DESIGN Energy and nutrient intakes for 112 women aged 18-45 y living in California were obtained with a food-frequency instrument. Dietary energy density (in MJ/kg or kcal/g) and energy-adjusted diet costs (in

Are socio-economic disparities in diet quality explained by diet cost?

/10 MJ or

Activity-dependent regulation of the potassium channel subunits Kv1.1 and Kv3.1.

/2000 kcal) were calculated with local food prices. Tertile splits of energy density and energy cost were analyzed with one-factor analysis of variance. RESULTS Mean daily energy intake excluding all beverages was 7.1 MJ (1699 kcal), and mean dietary energy density was 6.5 kJ/kg (1.54 kcal/g). Lower dietary energy density was associated with significantly higher intakes of dietary fiber (P = 0.004), vitamin A (P < 0.001), and vitamin C (P < 0.001) and with significantly lower intakes of total fat (P = 0.003) and saturated fat (P < 0.001). Higher diet cost was associated with significantly lower dietary energy density (P < 0.001), total fat (P = 0.024), and saturated fat (P = 0.025) and with significantly higher intakes of vitamins A (P = 0.003) and C (P < 0.001). Each additional dollar in estimated diet costs was associated with a drop in energy density of 0.94 MJ/kg (0.225 kcal/g). CONCLUSIONS The finding that higher quality diets were more costly for these low-income women has implications for the food assistance and education programs of the US Department of Agriculture. Policy interventions may be required to allow low-income families in the United States to improve the quality of their diets given their food budget constraints.