Are people consuming the diets they say they are? Self-reported versus estimated adherence to low carbohydrate and low fat diets: National Health and Nutrition Examination Survey, 2007-2018.

BACKGROUND: Mischaracterization of dietary intake by patients and study participants is a common problem that presents challenges to clinical and public health approaches to improve diet quality, identify healthy eating patterns, and reduce the risk of chronic disease. OBJECTIVE: This study examined participants' self-reported adherence to low carbohydrate and low fat diets compared to their estimated adherence using up to two 24-hour recalls. DESIGN: This cross-sectional study acquired data on dietary intake from respondents in the National Health and Nutrition Examination Survey (NHANES) 2007-2018. PARTICIPANTS/SETTING: This study included 30,219 respondents ≥20 y who had complete and reliable dietary data and were not pregnant or breastfeeding. MAIN OUTCOME MEASURES: The main outcome was prevalence of self-reported and estimated adherence to low carbohydrate or low fat diet patterns. STATISTICAL ANALYSES PERFORMED: Self-reported adherence to low carbohydrate or low fat diets was evaluated using responses to questionnaires. Estimated adherence to these diets was assessed using data from up to two 24-hour recalls and usual intake methodology developed by the National Cancer Institute. RESULTS: Of the 1.4% of participants that reported being on a low carbohydrate diet, estimated adherence (<26% energy from carbohydrates) using 24-hour recalls was 4.1%, whereas estimated adherence among those that did not report following a low carbohydrate diet was <1% (P-difference=0.014). Of the 2.0% of participants who reported being on a low fat diet, estimated adherence (<30% energy from fat) was 23.0%, whereas estimated adherence among those that did not report following a low fat diet was 17.8% (P-difference=0.048). CONCLUSIONS: This research demonstrates that most individuals mischaracterized their diet pattern when compared to up to two 24-hour recalls. These findings emphasize the need for clinicians and public health professionals to be cautious when interpreting individuals' self-reported diet patterns, and should aim to collect more detailed dietary data when possible.

Restricted carbohydrate diets below 45% energy are not associated with risk of mortality in the National Health and Nutrition Examination Survey, 1999-2018.

Introduction: Cardiometabolic diseases (CMD) are the leading causes of death for people living in the United States. Dietary strategies, such as restricting carbohydrate intake, are becoming popular strategies for improving health status. However, there is limited and often contradictory evidence on whether restricting carbohydrate intake is related to all-cause, CMD, or cardiovascular disease (CVD) mortality. Methods: The objective of the present study was to evaluate the association between restricted carbohydrate diets (<45%en) and mortality from all-causes, CMD, and CVD, stratified by fat amount and class. Data were acquired using the National Health and Nutrition Examination Survey (1999-2018) linked with mortality follow-up until December 31, 2019 from the Public-use Linked Mortality Files. Multivariable survey-weighted Cox proportional hazards models estimated hazard ratios for 7,958 adults (≥20 y) that consumed <45%en from carbohydrates and 27,930 adults that consumed 45-65%en from carbohydrates. Results: During the study period a total of 3,780 deaths occurred, including 1,048 from CMD and 1,007 from CVD, during a mean follow-up of 10.2 y. Compared to individuals that met carbohydrate recommendations (45-65%en), those that consumed carbohydrate restricted diets (<45%en) did not have significantly altered risk of mortality from all-causes (HR: 0.98; 95% CI: 0.87, 1.11), CMD (1.18; 0.95, 1.46), or CVD (1.20; 0.96, 1.49). These findings were maintained when the restricted carbohydrate diet group was stratified by intake of total fat, saturated fat (SFA), monounsaturated fat (MUFA), and polyunsaturated fat (PUFA). Discussion: Carbohydrate restriction (<45%en) was not associated with mortality from all-causes, CVD, or CMD. Greater efforts are needed to characterize the risk of mortality associated with varied degrees of carbohydrate restriction, e.g., low (<26%en) and high (>65%en) carbohydrate diets separately.

Micronutrient intake from three popular diet patterns in the United States: modeled replacement of foods highest in added sugar and sodium using the National Health and Nutrition Examination Survey, 2005-2018.

Introduction: Fifty-two percent of adults in the United States reported following a popular diet pattern in 2022, yet there is limited information on daily micronutrient intakes associated with these diet patterns. The objective of the present study was to model the impact on micronutrient intake when foods highest in added sugar and sodium were replaced with healthier alternatives to align with the Dietary Guidelines for Americans recommendations. Methods: Dietary data were acquired from 34,411 adults ≥ 20 y in the National Health and Nutrition Examination Survey, 2005-2018. The National Cancer Institute methodology was used to estimate usual dietary intake at baseline of 17 micronutrients using information from up to two dietary recalls per person. A food substitution model was used to evaluate the impact on micronutrient intake when three servings of foods highest in added sugar and sodium were substituted with healthier alternatives. Results: Dietary modeling to replace foods highest in added sugar with healthier alternatives increased the mean intake of fat-soluble vitamins (0.15% for vitamin A to 4.28% for vitamin K), most water-soluble vitamins (0.01% for vitamin B1 to 12.09% for vitamin C), and most minerals (0.01% for sodium to 4.44% for potassium) across all diet patterns. Replacing foods highest in sodium had mixed effects on the mean intake of micronutrients. The intake of most fatsoluble vitamins increased by 1.37-6.53% (particularly vitamin A and D), yet while the intake of some water-soluble vitamins and minerals increased by 0.18-2.64% (particularly vitamin B2, calcium, and iron) others decreased by 0.56-10.38% (notably vitamin B3 and B6, magnesium, sodium, and potassium). Discussion: Modeled replacement of foods highest in added sugar led to more favorable changes in mean micronutrient intake compared to modeled replacement of foods highest in sodium. Due to the composite nature of mixed dishes that include multiple ingredients, food substitutions may result in both favorable and unfavorable changes in micronutrient intake. These findings highlight the challenges of making singleitem food substitutions to increase micronutrient intake and call for further research to evaluate optimal combinations of replacement foods to maximize the intake of all micronutrients simultaneously.

Fat Intake Modifies the Association between Restricted Carbohydrate Diets and Prevalent Cardiometabolic Diseases among Adults in the United States: National Health and Nutrition Examination Survey, 1999-2018.

Background: Cardiometabolic diseases (CMDs), which include heart disease, stroke, and diabetes, account for over one-third of the mortality burden in the United States annually. Nearly one-half of all deaths from CMD are attributable to suboptimal diet quality, and many Americans are turning to special diets for general health improvement. Among the most popular of these diets restrict daily carbohydrate intake to <45% of energy, yet their association with CMD is not well understood. Objectives: This study evaluated the association between restricted carbohydrate diets and prevalent CMD, stratified by fat intake. Methods: Dietary and CMD data were retrieved from 19,078 participants aged ≥20 y in the National Health and Nutrition Examination Survey, 1999-2018. The National Cancer Institute methodology was used to assess usual dietary intake. Results: Compared to participants that met recommendations for all macronutrients, those that consumed restricted carbohydrate diets were 1.15 (95% CI: 1.14, 1.16) times as likely to have CMD; and those that met recommendations for carbohydrates, but not all macronutrients, were 1.02 (95% CI: 1.02, 1.03) times as likely to have CMD. Higher intakes of saturated and polyunsaturated fat were associated with greater prevalence of CMD in restricted and recommended carbohydrate intake groups. Higher intake of monounsaturated fat was associated with lower prevalence of CMD among participants that met carbohydrate, but not all macronutrient, recommendations. Conclusions: To our knowledge, this is the first nationally representative study to evaluate the relationship between carbohydrate restriction and CMD, stratifying by fat intake. Greater efforts are needed to understand longitudinal relationships between carbohydrate restriction and CMD.

Carbohydrate Intakes Below Recommendations With a High Intake of Fat Are Associated With Higher Prevalence of Metabolic Syndrome.

BACKGROUND: More than one-third of adults in the United States have metabolic syndrome, and dietary carbohydrate intake may modify the likelihood of developing this condition. Currently, there is a lack of consistent evidence demonstrating the relationship between carbohydrate intake that falls below recommendations and metabolic syndrome. Not accounting for the differences in fatty acid classes of these dietary patterns may be a reason for inconsistent findings. OBJECTIVE: This study evaluated the association between a carbohydrate intake below recommendations and metabolic syndrome stratified by fat quantity and fatty acid classes in a nationally representative sample of US adults. DESIGN: This cross-sectional study acquired data on food and nutrient intake and markers of metabolic syndrome from respondents in the National Health and Nutrition Examination Survey 1999-2018. PARTICIPANTS/SETTING: This study included 19,078 respondents who were aged 20 years or older, had reliable and complete data on food and nutrient intake and markers of metabolic syndrome, and were not pregnant or breastfeeding. MAIN OUTCOME MEASURES: The main outcome was prevalence of metabolic syndrome. STATISTICAL ANALYSES PERFORMED: Usual dietary intake was estimated using the National Cancer Institute's usual intake methodology. Multivariable logistic regression models assessed the relative odds of prevalent metabolic syndrome between those who had a carbohydrate intake below recommendations and those who met carbohydrate recommendations. RESULTS: Those who had a carbohydrate intake below recommendations had 1.067 (95% CI 1.063 to 1.071) times greater odds of having metabolic syndrome compared with those who met carbohydrate recommendations (P < 0.001). High intake of fat of any class was associated with higher odds of metabolic syndrome (total fat: 1.271, 95% CI 1.256 to 1.286; saturated fatty acid: 1.072, 95% CI 1.060 to 1.085; monounsaturated fatty acid: 1.317, 95% CI 1.300 to 1.333; polyunsaturated fatty acid: 1.056, 95% CI 1.047 to 1.066; P < 0.001 for all comparisons) in those who had a carbohydrate intake below recommendations. CONCLUSIONS: The odds of prevalent metabolic syndrome were higher among individuals who had a carbohydrate intake below recommendations compared with individuals who met carbohydrate recommendations.

Consumption of Key Food Groups by Individuals Consuming Popular Diet Patterns: Mixed Effects of Replacing Foods High in Added Sugar, Sodium, Saturated Fat, and Refined Grains.

Adults in the United States are increasingly following 'popular' diet patterns that restrict food groups, macronutrients, or eating time. However, the intake of food groups associated with these diet patterns has not been well characterized. The objectives of this study were to (1) characterize the mean intake of food groups among consumers of popular diet patterns in the US, and (2) model the effect of targeted food substitutions on the intake of food groups. Data were acquired from the National Health and Nutrition Examination Survey, 2005-2018 (n = 34,411). A diet model was developed to assess the effects of replacing one serving each of foods highest in added sugar, sodium, saturated fat, and refined grains with healthy alternatives on the intake of key food groups for each diet pattern. Modeled replacement resulted in increased intake of fruit and whole grains and decreased intake of dairy for most diet patterns, while the effects on the intake of vegetables, protein foods, and oils were variable across diet patterns. The complexity of the natural eating environment, in which many people consume mixed dishes that include both healthy and less healthy ingredients, produces a challenge for health professionals when providing dietary counseling. Nevertheless, this substitution approach may help improve adherence to dietary guidelines, especially if used as a steppingstone for further dietary improvement.

Quality of Popular Diet Patterns in the United States: Evaluating the Effect of Substitutions for Foods High in Added Sugar, Sodium, Saturated Fat, and Refined Grains.

Background: Many Americans have adopted popular diet patterns for general health improvement that restrict specific foods, macronutrients, or eating time. However, there is limited evidence to characterize the quality of these diet patterns. Objectives: This study 1) evaluated the quality of popular diet patterns in the United States and 2) modeled the effect of targeted food substitutions on diet quality. Methods: Dietary data from 34,411 adults ≥20 y old were acquired from the NHANES, 2005-2018. Dietary intake was assessed using the National Cancer Institute's usual intake methodology, and the Healthy Eating Index-2015 was used to evaluate diet quality. A diet model was used to evaluate the effect of targeted food substitutions on diet quality. Results: A pescatarian diet pattern had the highest diet quality (65.2; 95% CI: 64.0, 66.4), followed by vegetarian (63.0; 95% CI: 62.0, 64.0), low-grain (62.0; 95% CI: 61.6, 62.4), restricted-carbohydrate (56.9; 95% CI: 56.6, 57.3), time-restricted (55.2; 95% CI: 54.8, 55.5), and high-protein (51.8; 95% CI: 51.0, 62.7) diet patterns. Modeled replacement of ≤3 daily servings of foods highest in added sugar, sodium, saturated fat, and refined grains with alternative foods led to an increase in diet quality and a decrease in energy intake for most diet patterns. Conclusions: Low diet quality was observed for all popular diet patterns evaluated in this study. Modeled dietary shifts that align with recommendations to choose foods lower in added sugar, sodium, saturated fat, and refined grains led to modest improvements in diet quality and larger reductions of energy intake. Greater efforts are needed to encourage the adoption of dietary patterns that emphasize consumption of a variety of high-quality food groups.

Consumption of a high-fat diet alters transcriptional rhythmicity in liver from pubertal mice.

Introduction: Childhood obesity is associated with adult obesity, which is a risk factor for chronic diseases. Obesity, as an environmental cue, alters circadian rhythms. The hypothesis of this study was that consumption of a high-fat diet alters metabolic rhythms in pubertal mice. Methods: Weanling female C57BL/6NHsd mice were fed a standard AIN93G diet or a high-fat diet (HFD) for 3 weeks. Livers were collected from six-week-old mice every 4 h over a period of 48 h for transcriptome analysis. Results and discussion: The HFD altered rhythmicity of differentially rhythmic transcripts in liver. Specifically, the HFD elevated expression of circadian genes Clock, Per1, and Cry1 and genes encoding lipid metabolism Fads1 and Fads2, while decreased expression of circadian genes Bmal1 and Per2 and lipid metabolism genes Acaca, Fasn, and Scd1. Hierarchical clustering analysis of differential expression genes showed that the HFD-mediated metabolic disturbance was most active in the dark phase, ranging from Zeitgeber time 16 to 20. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis of differentially expressed genes showed that the HFD up-regulated signaling pathways related to fatty acid and lipid metabolism, steroid and steroid hormone biosynthesis, amino acid metabolism and protein processing in the endoplasmic reticulum, glutathione metabolism, and ascorbate and aldarate metabolism in the dark phase. Down-regulations included MAPK pathway, lipolysis in adipocytes, Ras and Rap1 pathways, and pathways related to focal adhesion, cell adhesion molecules, and extracellular matrix-receptor interaction. In summary, the HFD altered metabolic rhythms in pubertal mice with the greatest alterations in the dark phase. These alterations may disrupt metabolic homeostasis in puberty and lead to metabolic disorders.

Superior inhibitory efficacy of butyrate over propionate and acetate against human colon cancer cell proliferation via cell cycle arrest and apoptosis: linking dietary fiber to cancer prevention.

Intake of dietary fiber may protect against colon cancer. The anticancer property is associated with an increased production of short chain fatty acids (SCFAs), including acetate, propionate and butyrate, during dietary fiber fermentation in the colon. However, the mechanisms remain to be determined. We hypothesized that butyrate exhibits a stronger inhibitory potential against colon cancer cell proliferation compared with acetate and propionate. We determined the half maximal inhibitory concentrations (IC50) of SCFAs in HCT116 human colon cancer cell proliferation by examining cell growth curves. At 24- and 48-hour time points, IC50 (mmol/L) concentrations of acetate, propionate, and butyrate were [66.0 and 29.0], [9.2 and 3.6], and [2.5 and 1.3], respectively. Consistent with the greater anti-proliferative effect, butyrate exhibits >3-fold stronger potential for inducing cell cycle arrest at the G2 phase with a drop in S-phase fraction (including c-Myc/p21 signaling) and apoptosis when compared with acetate and propionate. Subsequently, we focused on the effect of butyrate on apoptotic gene expression. Using a PCR array analysis, we identified 17 pro-apoptotic genes, 6 anti-apoptotic genes, and 4 cellular mediator genes with >1-fold increase or decrease in mRNA levels out of 93 apoptosis related genes in butyrate-treated HCT116 cells when compared with untreated HCT116 cells. These genes were mainly involved in the TNF, NFκB, CARD, and BCL-2 regulated pathways. Taken together, our data indicate a greater inhibitory efficacy of butyrate over propionate and acetate against human colon cancer cell proliferation via cell cycle arrest and apoptosis.

High-Fat Diet Alters Circadian Rhythms in Mammary Glands of Pubertal Mice.

Childhood obesity in girls is associated with early puberty and menarche. Breast tissue exhibits circadian rhythms. These rhythms may be altered by environmental factors. We hypothesized that a high-fat diet (HFD) disrupts circadian rhythms in pubertal mammary glands. Weanling female C57BL/6 mice were fed the standard AIN93G diet or a HFD (providing 16% or 45% of energy from soybean oil) for 3 weeks. Mammary glands were harvested from 6-week-old mice every 4 h on Zeitgeber time over a 48-h period; rhythmic expressions of circadian genes and genes encoding estrogen receptor and progesterone receptor were analyzed by using the Cosinor model. HFD, compared to AIN93G diet, altered diurnal oscillations of circadian genes in pubertal mammary glands. These included changes in amplitude of Per2, Cry1 (reduced), Clock, Rev-erbα, and Per1 (elevated), a delay in acrophase (the hour at which the rhythm peaks) of Bmal1 by 2.2 h, and changes in mesor (the mean of the rhythm from peak to trough) of Bmal1, Per2, Cry1 (reduced), Rev-rebα, and Per1 (elevated). Furthermore, HFD altered diurnal expression of estrogen receptor and progesterone receptor at both mRNA and protein levels. These findings indicate that HFD alters circadian regulation in pubertal mammary glands, which may contribute to the disturbance of hormonal homeostasis and lead to early development and growth of mammary glands in pubertal mice.

Reported nutrient intake over 7 years after Roux-en-Y gastric bypass in the Longitudinal Assessment of Bariatric Surgery-3 (LABS-3) psychosocial study.

BACKGROUND: Bariatric surgery is the most effective therapy for severe obesity. It reduces gastric capacity and may modify regulation of appetite, satiety, insulin, and other physiologic processes, resulting in weight loss. OBJECTIVE: Long-term data on postsurgical nutrient intake are lacking. SETTING: The Longitudinal Assessment of Bariatric Surgery-3 psychosocial study. METHODS: Reported dietary intake was assessed in a subset of participants (n = 72) of the Longitudinal Assessment of Bariatric Surgery-3 psychosocial study who underwent Roux-en-Y gastric bypass surgery. Two 24-hour diet recalls at presurgery and annual assessments over 7 years were obtained. Reported diets were evaluated for energy, macro- and micronutrient intake, and assessed for adequacy by comparison to the dietary reference intakes. RESULTS: After surgery, reported intake of total energy, and all macronutrients were significantly reduced. At least a quarter of participants reported protein intake below the recommended dietary allowance. Over half of participants reported intake of several vitamins (C, D, A, E, thiamin, folate) and minerals (zinc, calcium) below recommended levels over 7 years. Compared with presurgery, reported energy intake was reduced over 7 years. This study was registered at ClinicalTrials.gov as NCT02495142. CONCLUSIONS: The reduction in energy resulted in intakes below the dietary reference intakes for many micronutrients among the majority of participants and below the recommended dietary allowance for protein in a substantial subgroup. These data support continued long-term nutrition education, monitoring, and supplementation.

Butyrate Inhibits Deoxycholic-Acid-Resistant Colonic Cell Proliferation via Cell Cycle Arrest and Apoptosis: A Potential Pathway Linking Dietary Fiber to Cancer Prevention.

SCOPE: Butyrate, an intestinal microbiota metabolite of dietary fiber, exhibits colon cancer preventive effects. In contrast, a high fat intake increases fecal secondary bile acids, such as deoxycholic acid (DCA, a potential cancer promoter), which selectively enrich mutant epithelial cells with an abnormally high resistance to DCA-induced apoptosis in the colon. This study is conducted to test the hypothesis that physiological concentrations of butyrate inhibit DCA-resistant colonic cell proliferation. METHODS AND RESULTS: With human HCT-116 cells as parental colonic cells, a human DCA-resistant colonic cell line (DCA-RCL) is developed. DCA treatment increases apoptosis and intracellular reactive oxygen species (an apoptotic trigger) at a rate threefold greater in HCT-116 cells than in DCA-RCL cells. Subsequently, 41 apoptosis related genes (including signaling pathways) with greater than onefold (mRNA) change in DCA-RCL cells are identified compared with HCT-116 cells. Moreover, butyrate treatment inhibits DCA-RCL cell proliferation with similar efficacy when compared with HCT116 cells via cellular myelocytomatosis oncogene (c-Myc)/p38 mitogen-activated protein kinase pathway. CONCLUSION: It is demonstrated that butyrate inhibits DCA-RCL cell proliferation at the cellular and molecular level. These data provide a proof of concept that butyrate can protect against colon carcinogenesis through a specific targeting of DCA-resistant colonic cells.

Active Videogames to Promote Traditional Active Play: Increasing the Reinforcing Value of Active Play Among Low-Active Children.

Background: Exercise reinforcement predicts physical activity of children. Repeated exposures of physical activity may increase physical activity reinforcement (incentive sensitization). Active videogame (AVG) play produces light-to-moderate-intensity physical activity. Ideally, AVG play would transition to nonscreen-based active play through incentive sensitization of traditional active play (TAP), providing AVG does not increase sedentary videogame (SVG) reinforcement. Greater autonomy increases motivation toward traditional physical activity, but whether autonomy enhances incentive sensitization has not been studied. Objectives: To determine whether autonomy over AVG play promotes incentive sensitization of TAP or SVG. Methods: Inactive children (ages 8-12; 5th-97th body mass index percentile) were provided with AVG and SVG for 6 weeks and assigned to either a high autonomy (n = 25) or low autonomy (n = 24) group, differentiated by AVG choice and more freedom over amount of play. Both groups played AVG 3 days per week. SVG were played ad libitum. Participants completed an operant responding task to measure the relative reinforcing value (RRV) of AVG versus SVG (RRVAVG vs. SVG) and AVG versus TAP (RRVAVG vs. TAP) at baseline, 6 weeks, and 10 weeks. Results: RRVAVG vs. SVG increased over time (P = 0.056) but did not differ by autonomy or autonomy × time (P = 0.184). RRVAVG vs. TAP decreased over time (P = 0.033) but did not differ by autonomy or autonomy × time (P = 0.73). Conclusion: AVG play does not increase motivation toward SVG and increases motivation to play AVG relative to TAP. Providing higher autonomy did not promote incentive sensitization of play.

Increasing the Reinforcing Value of Exercise in Overweight Adults.

Objectives: This study determined whether a moderate- or high-dose exercise program increases exercise reinforcement. Increasing the relative reinforcing value of exercise (RRVexercise; i.e., incentive sensitization of exercise) may increase the usual physical activity (PA) participation. Preference and/or tolerance for the intensity of exercise was also assessed. Design: Sedentary men and women (body mass index, BMI: 25-35 kg/m2) were randomized into parallel exercise training groups expending either 300 (n = 18) or 600 (n = 18) kcal/exercise session, five sessions/week, for 12 weeks. Methods: The RRVexercise was determined by how much work was performed for exercise relative to a sedentary alternative in a progressive ratio schedule task. Preference and tolerance for exercise intensity were determined by questionnaire. Results: RRVexercise increased (P < 0.05) in both groups. Exercise reinforcement, defined as the amount of work completed for exercise without taking sedentary activity into account, increased (P < 0.01) in the 600 kcal group only. Preference and tolerance for exercise intensity increased (P < 0.01) in both groups, which predicted increases in RRVexercise. Conclusion: Expending 300 or 600 kcal, 5 days/week increases RRVexercise, while 600 kcal, 5 days/week may be needed to increase exercise reinforcement.

Concurrent validity of skin carotenoid status as a concentration biomarker of vegetable and fruit intake compared to multiple 24-h recalls and plasma carotenoid concentrations across one year: a cohort study.

BACKGROUND: Biological markers of vegetable and fruit (VF) intake are needed both for nutrition surveillance and for the evaluation of nutrition interventions. Optically assessed skin carotenoid status (SCS) has been proposed as a marker of intake but there are few published validity studies to date. Therefore, the objective of the study was to examine the concurrent validity of multiple methods of assessing VF intake cross-sectionally and seasonally over one year and to discuss the relative merits and limitations of each method. METHODS: Fifty-two 40-60 y old women completed a 1-year longitudinal study that included 1) SCS assessment using resonance Raman spectroscopy (RRS) and using pressure-mediated reflection spectroscopy (RS) at 12 timepoints, 2) thirty-six 24-h recalls using the Automated Self-Administered 24-Hour Dietary Assessment Tool (ASA24; total 1866 recalls), and 3) plasma carotenoid concentrations measured every 3 months. Pearson correlation coefficients and mixed linear models were used to estimate pairwise correlations between RRS, RS, ASA24, and plasma carotenoids. RESULTS: RS and RRS were strongly correlated at baseline and over the year (r = 0.86 and 0.76; respectively, P < 0.001). RS was strongly correlated with plasma carotenoids at baseline (r = 0.70) and moderately across the year (r = 0.65), as was RRS (r = 0.77 and 0.69, respectively, all P < 0.001). At baseline, self-reported VF was weakly correlated with RRS (r = 0.33; P = 0.016), but not with RS or plasma carotenoids. Across the year, self-reported VF intake was weakly correlated with both RS (r = 0.37; P = 0.008), RRS (r = 0.37; P = 0.007), and with plasma carotenoids (r = 0.36; P < 0.008). CONCLUSIONS: SCS as measured by RS and RRS is moderately to strongly correlated with plasma carotenoid concentrations both cross-sectionally and longitudinally, indicating that it can be a powerful tool to assess carotenoid-rich VF intake in populations. CLINICAL TRIAL REGISTRY: This trial was registered at ClinicalTrials.gov as NCT01674296.

Genetic variations in the dopamine reward system influence exercise reinforcement and tolerance for exercise intensity.

BACKGROUND: Exercise is a reinforcing behavior and finding exercise highly reinforcing is characteristic of habitual exercisers. Genotypes related to dopamine metabolism moderate the reinforcing value of behaviors, but genetic moderators of exercise reinforcement have not been established. PURPOSE: Determine whether singular nucleotide polymorphisms (SNPs) that moderate central reward pathways and pain neurotransmission are associated with exercise reinforcement, tolerance for exercise intensity, and usual physical activity. METHODS: Adults (n = 178) were measured for the reinforcing value of exercise relative to sedentary activities (RRVexercise), minutes of moderate-to-vigorous physical activity (MVPA) and completed the Preference for and Tolerance of the Intensity of Exercise Questionnaire. Genotyping of 23 SNPs known to influence central dopamine tone, pain, or physical activity was performed. ANOVA tested differences in RRVexercise, tolerance, and MVPA among genotype groups. Linear regression controlling for BMI, sex, and liking of exercise was used to further predict the association of genotype on RRVexercise, tolerance, and MVPA. RESULTS: Having at least one copy of the G allele for the DRD2/ANKK1 polymorphism (rs1800497) conferred greater RRVexercise. Greater tolerance for exercise intensity was observed among those homozygous for the T allele for the CNR1 polymorphism (rs6454672), had at least one copy of the G allele for the GABRG3 polymorphism (rs8036270), or had at least one copy of the T allele for the LPR polymorphism (rs12405556). Homozygous individuals for the T allele at rs6454672 exhibited greater MVPA. CONCLUSION: Similar to other reinforcing behaviors, there is a genetic contribution to exercise reinforcement, tolerance for exercise intensity, and MVPA.

Inducing incentive sensitization of exercise reinforcement among adults who do not regularly exercise-A randomized controlled trial.

BACKGROUND: Increasing exercise reinforcement, or decreasing sedentary reinforcement, may reduce sedentary activity and promote habitual exercise. Repeated exposures to a reinforcer may increase its reinforcing value (i.e., incentive sensitization). It is not yet known whether incentive sensitization occurs for exercise or factors associated with incentive sensitization for exercise reinforcement. The purpose was to determine whether exercise exposures increase exercise reinforcement relative to a sedentary alternative and whether this sensitization of exercise reinforcement would alter physical or sedentary behavior. This work also determined whether exercise dose, intensity, and preference and tolerance for exercise intensity were associated with incentive sensitization of exercise. METHODS: 104 sedentary men and women were randomized to exercise training groups with 89 completing the study. Groups included exercise exposures of 150 (n = 35) or 300 kcal/session (n = 34), 3 sessions/week for 6 weeks, or a non-exercise control group (n = 35). Assessments for exercise and sedentary behavior reinforcement (primary dependent variables) and activity and tolerance for exercise intensity were performed at baseline (week 0), post training (week 6), and post washout (week 10). RESULTS: The control group reduced (P = 0.022) relative reinforcing value of exercise, such that the 150 kcal group had a greater relative reinforcing value of exercise after the exercise treatment 150 kcal: 0.69 ± 0.07 to 0.74 ± 0.07; 300 kcal: 0.72 ± 0.07 to 0.63 ± 0.08, control: 0.72 ± 0.07 to 0.57 ± 0.08 mean ± SE. Increases in tolerance for exercise intensity discomfort were associated with increases in relative reinforcing value of exercise. Sedentary behavior reinforcement decreased in both exercise groups (150 kcal: 5.4 ± 4.3 to 1.8 ± 1.3; 300 kcal: 5.4 ± 4.3 to 3.1 ± 2.4, P<0.05), but remained unchanged in the control group (5.1 ± 4.0 to 6.1 ± 4.9, P>0.05). Sedentary activity decreased baseline to post-training in the 300 kcal group (546.5 ± 10.7 to 503.8 ± 11.8 minutes, P<0.01). CONCLUSION: Small amounts of regular exercise may reduce the reinforcing value sedentary behavior. The process of incentive sensitization of exercise may include reducing the reinforcing value of competing sedentary activities. Developing tolerance to exercise discomfort of exercise may be critical to increasing exercise reinforcement.

Decreasing the Consumption of Foods with Sugar Increases Their Reinforcing Value: A Potential Barrier for Dietary Behavior Change.

BACKGROUND: The Dietary Guidelines for Americans (DGA) have recommended reducing added sugar intake since its inception in 1980. Nearly 40 years later, added sugar consumption still exceeds 2015-2020 DGA recommendations among most of the population. The reinforcing value of food influences eating behaviors, and foods high in added sugars are highly reinforcing. Restricting intake of foods high in added sugars as part of a low-sugar diet may increase their reinforcing value such that reducing consumption may be difficult to maintain. If so, this would present a mechanistic barrier to making the necessary dietary changes to meet 2015-2020 DGA recommendations. PURPOSE: To determine whether the relative reinforcing value of foods high in added sugars is altered when reducing intake of all foods high in sugars. METHODS: Obese (n=19) and normal weight (n=23) men and woman who habitually consumed over 10% of their calories from added sugars completed the study. Reinforcing value of foods high in added sugars was measured via progressive ratio schedules of reinforcement before and on day 7 of a weeklong controlled feeding intervention where added sugars comprised 2.5% to 4.0% of daily calories and total sugars 7.3% to 8.6% of daily calories. RESULTS: The reinforcing value of foods high in added sugars increased (P<0.01) after consuming a diet low in total added sugars for 1 week in both obese and normal weight participants. CONCLUSION: Adhering to a low-sugar diet for 1 week increases the reinforcing value of foods high in added sugars. Future studies should examine whether consuming a diet low in added sugars, but not other sugar, increases reinforcing value of foods high in added sugars and whether high-added sugar food reinforcement returns to baseline after longer-term reductions in added sugars.

Dietary saturated fatty acid type impacts obesity-induced metabolic dysfunction and plasma lipidomic signatures in mice.

Saturated fatty acid (SFA) intake is associated with obesity, insulin resistance, and hepatic steatosis, but scant work examines the impact of SFA type upon these outcomes. We tested the hypothesis that an obesogenic diet prepared with medium chain SFA (MCSFA), mostly as lauric acid-derived from coconut oil, reduces obesity-induced outcomes compared to obesogenic diets prepared with increasing amounts long chain SFA (LCSFA), primarily palmitic acid. Mice were fed (16 weeks) a control, low fat diet or obesogenic diets prepared with differing content of MCSFA or LCSFA in which polyunsaturated and monounsaturated fatty acids (PUFA; MUFA) were kept constant. Inclusion of MCSFA in an obesogenic diet prevented hepatic lipid accumulation and lowered indices of insulin resistance. Obesogenic diets reduced hepatic levels of de novo lipogenesis proteins (SCD1 and FASN) but elevated the adipose levels of mRNA for the pro-inflammatory markers Mcp-1 and Tnfα. Lipidomic analysis of plasma indicated that MCSFA intake resulted in a different lipidomic signature than LCSFA intake, prevented elevation of pro-inflammatory ceramides, but elevated concentrations of some lipids associated with elevated cardiovascular disease risk. Intake of the obesogenic diets in an SFA-type dependent manner elevated plasma concentrations of several phosphatidylcholine (PC) lipids having the long chain PUFA (LCPUFA) arachidonic acid (ARA) and docosahexaenoic acid (DHA), altered phospholipid ethers, and changed the triacylglyceryl environments of these LCPUFA. Our data indicate that (1) MCSFA reduce the severity of some obesogenic co-morbidities, (2) SFA-type modulates lipidomic signatures associated with cardiovascular disease and diabetes, and (3) dietary SFA type impacts LCPUFA metabolism.

Youth and Adult Visitation and Physical Activity Intensity at Rural and Urban Parks.

Less physical activity among rural residents may contribute to rural-urban health disparities. Parks can be ideal community resources for promoting physical activity. This study compared park visitation and activity intensity at 15 urban and 15 rural parks matched for acreage and amenities. Parks were observed in the morning, afternoon, and evening on 4 days to determine number of visitors, activity intensity, and amenity use. A total of 5486 visitors were observed with no differences in percentages of males (55.5% vs. 53.9%) and females (44.5% vs. 46.1%) or percentages of weekday (82.4% vs. 81.9%) and weekend (17.6% vs. 18.1%) visitors. The probability of visitors sitting was greater and in moderate intensity activity lower at rural parks. A greater proportion of children (25.0% vs. 14.5%) in rural parks, and teens in urban parks (8.0% vs. 69.6%), were observed on sport fields. A greater proportion of adults in urban areas (12.5% vs. 46.0%) were observed spectating sports. Greater proportions of rural children (10.9% vs. 3.5%), teens (34.1% vs. 12.4%), and adults (38.9% vs. 10.1%) were observed using shelters. Thus, when similar amenities are available, rural and urban parks are used differently, especially by youth. The urban park study results cannot be wholly applied to rural parks.