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Scholarly Works (21 results)

  • Article
  • Peer Reviewed
UC Davis Previously Published Works (2023)
The executive brain mediates and facilitates a set of cognitive functions, such as decision making, planning, self-regulation, emotional regulation, and attention. Executive dysfunction and related diseases are a rising public health concern. Evidence supports a link between nutritional factors and executive function (EF), but relatively little information exists about the relationship between diet patterns and this higher order cognitive ability. We and others have reported on the relationships between body weight regulation and affective decision making, as measured by performance in the Iowa Gambling Task (IGT). However, little is known about the relationships between performance in this decision-making task and whole diet patterns. In this study, we tested whether data-derived diet patterns based on energy-adjusted food intake data from the Block Food Frequency Questionnaire were associated with decision-making performance in the IGT. Secondarily, we examined the influence of these diet patterns on self-reported chronic stress exposure and heart rate variability, which is a marker of autonomic nervous system (ANS) activity. In prior studies, stress and ANS activity were shown to influence decision-making performance in the IGT. In this study, five distinct diet patterns were identified by cluster and factor analyses. A diet pattern best characterized by elevated sugar-sweetened beverage and added sugar consumption was associated with the lowest decision-making performance (p = 0.0049) and higher stress exposure (p = 0.0097). This same diet pattern was associated (p = 0.0374) with an IGT-affiliated decline in high-frequency HRV and an increase in low-frequency HRV, suggesting diet-induced ANS regulatory shifts in response to performing the EF task. Compared to the sugar-sweetened beverage diet pattern, diet patterns defined by more fruits/vegetables and low red meat (p = 0.0048) or higher omega-3 fatty acids and seafood (p = 0.0029) consumption were associated with lower chronic stress exposure. All outcomes were statistically adjusted for differences in BMI, age, sex, education level, and sensorimotor ability. Our findings provide new information that further supports the potential importance of whole diet patterns on cognitive disease prevention.
    Cover page: A Diet Pattern Characterized by Sugar-Sweetened Beverages Is Associated with Lower Decision-Making Performance in the Iowa Gambling Task, Elevated Stress Exposure, and Altered Autonomic Nervous System Reactivity in Men and Women.
    • Article
    • Peer Reviewed
    Research Theses and Dissertations (1999)

    Stress results in a cost to normal biological fimction (e.g. growth). This cost may be related to a shifting of energy from normal biological function to defense activities, accounting for the impairment of energy sensitive functions such as growth. While the effects of multiple stressors, by themselves, may not alter normal biological function to an appreciable degree, summation of the individual effects may result in a total effect that significantly impairs biological function. This hypothesis was addressed by examining in male C57BV6 mice the biological cost of repeated behavioral stress (4 h restraint, once/day for 7 days) and repeated behavioral stress, combined with immunological stress (LPS injection, i.p. @ µg/g). Additionally, we investigated the short term (24 h) effect of acute behavioral stress (4 h restraint) and acute behavioral stress, coupled with immunological stress (LPS injection). The biological cost was quantified by determining the effects of these multiple stressors on the animal's capacity for growth (body weight gain) and, to account for the stress-induced alteration in growth, we quantified the partitioning of energy among lean tissue, fat tissue, and heat production. We also examined the effect of multiple stress on circulating concentrations of corticosterone, IGF-I, and IL-1.

    This work demonstrated that the summation of repeated behavioral stress significantly (P400%, P300%, P 80%, P<0.05).

    The additive cost in growing animals exposed to repeated behavioral stress may have resulted from the reduction in food intake and the repeated elevation of circulating corticosterone. Repeated alterations of circulating IGF-I may have also accounted for the impaired growth and energy deposition following long-term behavioral stress. When repeatedly restrained animals also encountered an immunological challenge, the activation of the immune system and the consequent increase in circulating cytokines, such as IL-1, may have summated with the previously engaged behavioral stress response to bring about greater changes in metabolism, alterations IGF-I, and food intake. Together, the results of the present work support the hypothesis that the effects of repeated or multiple stressors summate to significantly disrupt normal biological function, but results also indicate that the interaction of multiple stressors is complex, and may or may not summate in their overall effect on biological function.

      Cover page: The Biological Cost of Repeated and Multiple Stress in the Growing Mouse
      • Thesis
      • Peer Reviewed
      UC Davis Electronic Theses and Dissertations (2021)

      It is widely recognized that dietary intake can influence stress and stress-related health outcomes. Appreciating differences in age, sex and gender, genetic, physiological, metabolic, cognitive, and microbial contexts and interactions are several critical factors to consider when determining the effects of diet on stress and stress-associated health outcomes. A primary aim of this work is to increase awareness of the need and importance for precise, developmental stage-specific nutrition strategies to prevent or mitigate stress-related disease throughout the lifespan.

      Three studies were developed to investigate the interrelationships between food intake, stress, and stress-related health outcomes in humans of varying stages of development. One study was designed to target the infant gut microbiome through a specific dietary component. The study evaluated the effects of feeding the human gut symbiont B. infantis EVC001 on diaper rash in infants, crying/fussiness, and naptime and nighttime sleep behavior. Results showed reductions in all three outcome variables, which are indicators of perceived and physiologic neonatal stress. Another study aimed to assess the ability of a wearable nutritional-tracking device to capture individualized dietary intake information, and metabolic responses to food, in adults. Repeated engagements in “fad” diets can increase risk for physiological stress in the body; thus, advances in wearable technology have potential to empower users to achieve and maintain personalized lifestyle behaviors, body composition, and health, rather than relying on misinformed nutritional information. Study results highlight the need for technologies that can reliably measure diet to improve nutrition-based guidance and facilitate precision-based nutrition interventions. Finally, a study was designed to examine sex-dependent associations between allostatic load, that is a biomarker of physiological stress load, and diet quality in the form of the Healthy Eating Index in adults. Results showed that sex and diet quality pattern interacted to affect allostatic load, and a significantly different allostatic load for men and women consuming a diet pattern more closely aligned with the Dietary Guidelines for Americans for dairy, refined grains, and sodium consumption, but less aligned for added sugar, saturated fat, and fruit/vegetable intake.

      Cumulatively, the results of this dissertation highlight the need for methods to accurately assess stress, diet, and health, in real-time and under free-living conditions. This research has the potential to inform precise nutrition interventions to mitigate stress-related disease risk in humans at differing life stages.

        Cover page: A Multi-Modal Approach to Investigate the Intersection of Stress and Health Throughout the Lifespan: Implications for a Precision Nutrition Strategy
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2022)

        Background

        Diet and cortisol are independently linked to cardiometabolic function and health, but underlying alterations in circulating cortisol may influence beneficial cardiometabolic effects of consuming a healthy diet.

        Objective

        This study was a secondary analysis to examine whether baseline concentrations of waking salivary cortisol interacted with 8-wk whole-food diet interventions to affect cardiometabolic outcomes.

        Methods

        A randomized, double-blind, controlled 8-wk diet intervention was conducted in 44 participants. The trial was conducted at the Western Human Nutrition Research Center in Davis, California. Participants were overweight or obese women aged 20-64 y, minimally active, and insulin resistant and/or dyslipidemic. Diets were randomly assigned and based on the 2010 Dietary Guidelines for Americans (DGA) or a typical American diet (TAD). Cardiometabolic risk factors and salivary cortisol were assessed at baseline and at 8 wk. Primary outcome measures included 8-wk change in overnight fasted cardiometabolic risk factors, including blood pressure, BMI, and circulating triglycerides, cholesterol, glycated hemoglobin (HbA1c), nonesterified fatty acids, and high-sensitivity C-reactive protein. This trial was approved by the University of California, Davis, Institutional Review Board.

        Results

        Baseline waking cortisol concentrations interacted (P = 0.0474) with diet to affect 8-wk changes in fasting total cholesterol. Compared with a TAD, a DGA diet was associated with 8-wk decreases in total cholesterol in participants with low (10th percentile of all participants; 2.76 nmol/L) or average (7.76 nmol/L) but not higher (90th percentile of all participants; 13.44 nmol/L) baseline waking cortisol. Consistent with this finding, there was a DGA-specific positive association (P = 0.0047; b: 2.88 ± 0.94) between baseline waking cortisol and 8-wk increases in total cholesterol.

        Conclusions

        The underlying status of waking cortisol may explain interindividual variability in total cholesterol responses to whole-food diets. This trial was registered at www.clinicaltrials.gov (https://clinicaltrials.gov/ct2/show/NCT02298725) as NCT02298725.
          Cover page: Waking Salivary Cortisol Associated with Magnitude of Cholesterol Reduction in Women Fed a Healthy Whole-Food Diet for 8 Weeks
          • Article
          • Peer Reviewed
          UC Davis Previously Published Works (2019)
          It is largely unknown whether and how whole food diets influence psychological stress and stress system responsiveness. To better understand the effects of whole diets on stress system responsiveness, we examined randomized control trial effects of a whole food diet based on the Dietary Guidelines for Americans (DGA) on cortisol responsiveness. A randomized, double-blind, controlled 8-week intervention was conducted in overweight and obese women to examine differentiated effects between two diet intervention groups: one based on the 2010 DGA and the other one based on a typical American diet (TAD). During a test week that occurred at baseline and again after 8 weeks of the intervention, we assessed salivary cortisol collected at 14 selected times across the day, including upon awakening, at bedtime, and during a test visit, and administered a standardized social stress task (Trier Social Stress Test, TSST). There were no statistical differences between the diet groups in salivary cortisol at baseline or after 8 weeks. However, when considering differences in dietary carbohydrate, but not fat or protein, from the pre-intervention (habitual) to the intervention period, there was a significant (P = 0.0001) interaction between diet group, intervention week, saliva sample, and level of intervention-based change in carbohydrate consumption. This interaction was reflected primarily by an 8-week reduction in salivary cortisol during a period just prior to (log Δ -0.35 ± 0.12 nmol/L) and 30 (log Δ -0.49 ± 0.12 nmol/L), 60 (log Δ -0.50 ± 0.13 nmol/L), 90 (log Δ -0.51 ± 0.13 nmol/L), and 120 (log Δ -0.4476 ± 0.1231 nmol/L) min after the TSST in the DGA group having the highest increase (90th percentile) in carbohydrate consumption. In support of this finding, we also found significant (P < 0.05) and inverse linear associations between dietary carbohydrate and log salivary cortisol, with the strongest negative association (β: -0.004 ± 0.0015, P = 0.009) occurring at 30 min post-TSST, but only in the DGA group and at week 9 of the intervention. Together, increasing dietary carbohydrate as part of a DGA-based diet may reduce circulating cortisol and dampen psychological stress-related cortisol responsiveness.
            Cover page: Increasing Dietary Carbohydrate as Part of a Healthy Whole Food Diet Intervention Dampens Eight Week Changes in Salivary Cortisol and Cortisol Responsiveness
            • Article
            • Peer Reviewed
            UC Davis Previously Published Works (2018)
            Increased oxidative stress contributes to development and progression of several human chronic inflammatory diseases. Cherries are a rich source of polyphenols and vitamin C which have anti-oxidant and anti-inflammatory properties. Our aim is to summarize results from human studies regarding health benefits of both sweet and tart cherries, including products made from them (juice, powder, concentrate, capsules); all referred to as cherries here. We found 29 (tart 20, sweet 7, unspecified 2) published human studies which examined health benefits of consuming cherries. Most of these studies were less than 2 weeks of duration (range 5 h to 3 months) and served the equivalent of 45 to 270 cherries/day (anthocyanins 55-720 mg/day) in single or split doses. Two-thirds of these studies were randomized and placebo controlled. Consumption of cherries decreased markers for oxidative stress in 8/10 studies; inflammation in 11/16; exercise-induced muscle soreness and loss of strength in 8/9; blood pressure in 5/7; arthritis in 5/5, and improved sleep in 4/4. Cherries also decreased hemoglobin A1C (HbA1C), Very-low-density lipoprotein (VLDL) and triglycerides/high-density lipoprotein (TG/HDL) in diabetic women, and VLDL and TG/HDL in obese participants. These results suggest that consumption of sweet or tart cherries can promote health by preventing or decreasing oxidative stress and inflammation.
              Cover page: A Review of the Health Benefits of Cherries
              • Article
              • Peer Reviewed
              UC Davis Previously Published Works (2018)
              Very little is known about how whole food diets, such as those based on the Dietary Guidelines for Americans (DGA), influence psychological stress and physiological stress load. To better understand the effects of whole food diets on stress, we examined in a randomized control trial the effects of a DGA-based diet on markers of psychological and physiological stress. A randomized, double-blind, controlled 8-week intervention was conducted in overweight and obese women randomly assigned to one of two diet groups: a diet based on the 2010 DGA or a diet based on a Typical American Diet (TAD). The Perceived Stress Scale and allostatic load were used to assess stress load. Eight-week change in perceived stress did not significantly (p = 0.45) differ between the DGA (+0.53 ± 0.99) and TAD (-0.57 ± 0.99) groups. Likewise, 8-week change in allostatic load did not significantly (p = 0.79) differ between the two diet intervention groups (DGA: +0.001 ± 0.26 vs. TAD: +0.105 ± 0.28). However, we did find strong inverse associations between 8-week change in stress and intervention-based improvements in diet quality (lower sodium and higher vegetable consumption). When statistically accounting for these inverse associations, we found that perceived stress and allostatic load were higher (p < 0.04) in the DGA group. These findings suggest that improvements in dietary vegetable and sodium intake mediated effects of the diet intervention on psychological and physiological stress load. That is, adopting and adhering to a diet of higher quality (DGA) for 8 weeks may have been generally more stressful in the absence of improvements in vegetable or sodium consumption. This study provides further evidence for the mental health benefits of maximizing vegetable and minimizing sodium consumption.
                Cover page: Diet Quality for Sodium and Vegetables Mediate Effects of Whole Food Diets on 8-Week Changes in Stress LoadCreative Commons 'BY' version 4.0 license
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                • Peer Reviewed
                UC Davis Previously Published Works (2017)
                Docosahexaenoic acid (DHA) is a major constituent, and primary omega-3 fatty acid, in the brain. Evidence suggests that DHA consumption may promote cognitive functioning and prevent cognitive decline, and these effects may be particularly relevant in the context of fear or stress. However, the potency and efficacy of dietary DHA may depend on the form of DHA (e.g., phospholipid; PL vs. triglyceride; TG). In this study, we compared in mice the effects of consuming PL and TG forms of DHA on associative, avoidance (fear) based learning and memory. Diets consisted of either no DHA or 1%, 2%, and 4% PL- or TG-DHA. After 4 weeks on the test diets (n = 12/group), we used the 3-day passive avoidance (PA) and elevated plus maze (EPM) to examine fear and fear-associated learning and memory. We found a significant (p < 0.05) diet by time interaction in the PA and EPM. Compared to the control and the 1% TG-DHA group, mice consuming the diet supplemented with 1% PL-DHA displayed a significantly greater latency by test day 2 in the 3-day PA. No differences in latency between any of the groups were observed during trials 1 and 3. Mice consuming the 2% PL-DHA diet spent significantly more time frequenting the open arms during the first minute, but not the last 4 min, of the test. Compared to all other groups, mice fed the 4% TG-DHA diet had increased spleen, liver, and visceral fat weight. Consumption of the lower dose PL-DHA may confer enhanced efficacy, particularly on fear-based learning behavior.
                  Cover page: Emotion-Based Cognition in Mice Is Differentially Influenced by Dose and Chemical Form of Dietary Docosahexaenoic Acid
                  • Article
                  • Peer Reviewed
                  UC Davis Previously Published Works (2023)

                  Background

                  Progressive age-associated change in frequencies and functional capacities of immune cells is known as immunosenescence. Despite data linking chronic environmental, physiological, and psychosocial stressors with accelerated aging, how stress contributes to immunosenesence is not well characterized.

                  Objective

                  To help delineate the contribution of cumulative physiological stress on immunosensence we assessed relationships between a composite measurement of cumulative physiological stress, reflecting the functioning of the hypothalamic-pituitary-adrenal axis, sympathetic nervous system, cardiovascular system, and metabolic processes, and lymphocyte changes typically affiliated with aging in a cohort of healthy volunteers ranging from 18 to 66 y.

                  Results

                  Physiological stress load positively correlated with subject age in the study cohort and was significantly higher in adults 50-66 y compared to adults 18-33 y and 34-49 y. Using physiological stress load, we identified a significant age-dependent association between stress load and frequencies of circulating regulatory T lymphocytes (Tregs). Frequencies were higher in younger participants, but only in participants exhibiting low physiological stress load. As stress load increased, frequencies of Tregs decreased in young participants but were unchanged with increasing stress load in middle and older age individuals. Follow-up analysis of stress load components indicated lower circulating DHEA-S and higher urinary norepinephrine as the primary contributors to the effects of total stress load on Tregs. In addition, we identified age-independent inverse associations between stress load and frequencies of naïve Tregs and naïve CD4 T cells and positive associations between stress load and frequencies of memory Tregs and memory CD4 T cells. These associations were primarily driven by stress load components waist circumference, systolic and diastolic blood pressure, CRP, and HbA1c. In summary, our study results suggest that, in younger people, physiological stress load may diminish regulatory T cell frequencies to levels seen in older persons. Furthermore, independent of age, stress load may contribute to contraction of the naïve Treg pool and accumulation of memory Treg cells.

                  Clinical trial

                  Registered on ClincialTrials.gov (Identifier: NCT02367287).
                    Cover page: Cumulative physiological stress is associated with age-related changes to peripheral T lymphocyte subsets in healthy humans.
                    • Article
                    • Peer Reviewed
                    UC Davis Previously Published Works (2009)
                    The direct costs of paternal care are relatively well documented in primates, however little research has explored these effects in monogamous rodents. The present study examines the long-term effects that pairing and parenting have on male prairie voles. We hypothesized that there would be a significant weight loss over the course of pairing and parenting, presumably from the energetic demands that accompany these changes in social condition. In a longitudinal study, we followed ten male prairie voles through being housed with their brother; paired with a female; and caring for three consecutive litters. We found a significant drop in bodyweight across time, with maximum weight loss near the weaning of the first litter. At that same time, feeding increased, leading to possible recovery in weight; however, leptin levels dropped precipitously across time and did not recover. Corticosterone did not change significantly across time points, and overall activity levels also did not vary significantly over the course of the study. In addition, newly paired males showed a significant increase in preference for a 2% sucrose solution during a three-hour test, indicating a metabolic need for more calories. A cross-sectional study confirmed leptin and corticosterone findings, and showed significant loss of subcutaneous (inguinal) fat in males that had cared for a litter of pups, when compared to males housed with their brothers or newly paired males. These results suggest that cohabitation with a female, and caring for pups, all have costs for male prairie voles.
                      Creative Commons 'BY-NC-ND' version 4.0 license
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