Yeong Rhee

Background: Oxidative stress, the imbalance of prooxidants and antioxidants, has been recognized as a contributor in the development of age-related cognitive decline and Alzheimer's disease and Alzheimer's disease related dementias (AD/ADRD). Exogenous antioxidant intake may play a role in maintaining cognitive health during aging; however, few studies have examined cognitive status in relation to established antioxidant intake recommendations in older adults. Objective: This cross-sectional study investigated cognitive status differences among older adults based on adequacy of dietary antioxidant intake. Methods: Participants (n = 50, 71.5 ± 5.1 years old, 66% female) completed three-day food logs. Recommended Daily Allowance (RDA) defined antioxidant adequacy for vitamin C, vitamin E, selenium (Se), while Adequate Intake determined antioxidant adequacy for manganese (Mn). The Saint Louis University Mental Status (SLUMS) examination categorized normal cognition, mild neurocognitive disorder, or dementia via 30-point scale. Results: No significant differences in mean SLUMS scores were observed between participants with adequate versus inadequate antioxidant intake; however, there were significant differences in cognitive status distribution by adequacy of vitamin C (p = 0.001), vitamin E (p = 0.024), Se (p = 0.018), Mn (p = 0.001), and all four combined (p = 0.002). A higher proportion of participants with inadequate intake had cognitive impairment. Conclusions: Antioxidant adequacy may be associated with clinically meaningful cognitive classification thresholds.

Background: The Mediterranean Diet (MD) is well-studied for slowing cognitive declines. Few studies have examined how a Western MD (wMD) may impact cognitive function. Objective: This study examined whether a wMD predicted less cognitive decline over 9 years in a national sample of American adults. The measures were episodic memory (EM) and executive functioning (EF) at baseline and 9 years follow-up. Methods: This is a secondary analysis of the Midlife in the United States Study (MIDUS), using a longitudinal cohort design with cross-sectional dietary data. Participants in this study had data from Waves 2 and 3 of MIDUS ( n  = 833, 46 ± 12 years; 45% male). Regression analyses tested whether wMD adherence predicted 9-year changes in EM and EF. Moderator analyses determined whether the relationship between wMD, EM, and EF differed across sociodemographic characteristics. Results: wMD score at Wave 2 predicted attenuated declines in EM 9 years later (β = 0.06, p  = 0.04). The association between wMD and EM was not moderated by age, sex, race, education, or income and thus is consistent across sociodemographic subpopulations. wMD did not predict EF (fully adjusted wMD β = 0.00, p  = 0.86). Contextualized effect sizes showed that individuals who strongly adhered to the wMD (+1 SD) experienced ∼50–60% less decline in 9-year EM when compared to those with average adherence. Conclusions: A wMD was related to slowed EM declines across sociodemographic populations in a national U.S. sample. Education is needed about healthful dietary habits, including increased fruit and vegetable intake.

The purpose of this study was to evaluate the associations of (1) individual absolute and body size normalized weakness cut-points, and (2) the collective weakness classifications on time to diabetes in Americans. We analyzed data from 9577 adults aged at least 50-years from the Health and Retirement Study. Diabetes diagnosis was self-reported. A handgrip dynamometer measured handgrip strength (HGS). Males with HGS 2 (normalized to BMI) were categorized as weak. Females were classified as weak if their HGS was 2. Compounding weakness included falling below 1, 2, or all 3 cut-points. Persons below the body weight normalized weakness cut-points had a 1.29 (95% confidence interval (CI): 1.15–1.47) higher hazard for incident diabetes, while those below the BMI normalized cut-points had a 1.30 (CI: 1.13–1.51) higher hazard. The association between absolute weakness and incident diabetes was insignificant (hazard ratio: 1.06; CI: 0.91–1.24). Americans below 1, 2, or all 3 collective weakness categories had a 1.28 (CI: 1.10–1.50), 1.29 (CI: 1.08–1.52), and 1.33 (CI: 1.09–1.63) higher hazard for the incidence of diabetes, respectively. Our findings indicate that while absolute weakness, which is confounded by body size, was not associated with time to diabetes, adjusting for the influence of body size by normalizing HGS to body weight and BMI was significantly associated with time to diabetes. This suggests that muscle strength, not body size, may be driving such associations with time to diabetes.

Background: Population-level surveillance of the prevalence and trends of basic self-care limitations will help to identify the magnitude of physical disablement in the rapidly growing older American demographic. We sought to evaluate the prevalence and trends of activities of daily living (ADL) limitations in the United States. Methods: The analytic sample included 30,418 Americans aged ≥50 years from the 2006–2018 waves of the Health and Retirement Study. ADLs were self-reported. Weighted prevalence estimates were presented, and trends analyses were performed. Results: Although overall ADL disability prevalence was 16.5% (95% confidence interval: 15.8–17.2) in 2018, there were no changes in limitations during the study period (p = 0.52). Older adults had a greater ADL disability prevalence than middle-aged adults (p < 0.001). While older persons experienced a declining trend of ADL limitations (p < 0.001), middle-aged persons had an increasing trend (p < 0.001). Males had a lower ADL limitation prevalence than females (p < 0.001). Hispanic and non-Hispanic Black had a higher ADL disability prevalence than non-Hispanic White (p < 0.001). Conclusions: This investigation revealed that while the estimated prevalence of ADL limitations in the United States was substantial, changes in such limitations were not observed. Our findings can help guide ADL screening, target sub-populations with an elevated ADL limitation prevalence, and inform interventions.

Obesity is known to be partially influenced by low-grade inflammation caused by pro-inflammatory cytokines and excess adipose tissue. Flaxseed contains secoisolariciresinol diglucoside (SDG) and α-linolenic acid (ALA) that have been shown to prevent pro-inflammatory cytokine production and secretion. This study determined flaxseed effects on inflammation regulatory gene expressions and their relationships with weight gain in an obese animal model. C57BL/6J mice were fed with whole flaxseed, defatted flaxseed, or flaxseed oil supplemented high-fat diet for eight weeks. After eight weeks of dietary treatment, NF-κB, IκBα, IKKβ, IL-6, TNF-α, Akt2, and adiponectin gene expressions were measured. The result shows how health-promoting compounds in flaxseed assist in alleviating and preventing obesity-induced low-grade inflammation by actively working against IKKβ/NF-κB pathway.

Diet-induced obesity (DIO) has been shown to increase DNA methyltransferases (DNMTs) expression and DNMTs binding at obesity-associated genes. Natural compounds have the potential to reverse obesity-associated gene expression via the regulation of DNA methylation. The objective of this study was to determine the effect of health promoting compounds of flaxseed on DNMTs and obesity-associated gene expression and weight gain. Sixty C57BL/6J male mice were randomly assigned into one of the following diet groups and fed for eight weeks: 45% kcal fat; 45% kcal fat+10% whole flaxseed; 45% kcal fat+6% defatted flaxseed; 45% kcal fat+4% flaxseed oil; and 16% kcal fat. DNMT1, DNMT3a, DNMT3b, leptin, and peroxisome proliferator-activated receptor (PPAR)-α expressions in adipose and muscle tissues were determined by real-time PCR. The health promoting compounds of flaxseed affected selected gene expression and attenuated weight gain. Further research is needed to identify the specific mechanisms modulating leptin or PPAR-α expression during DIO development.

Objectives: The prevalence of overweight and obesity continue to increase among adults in the United States, which warrants an increased need for research on factors impacting lifestyle behaviors. This study examines the relationships between socioeconomic status, health status, attitude about overall eating habits, retail food environment and healthy and unhealthy dietary behaviors. Methods: We conducted a cross-sectional study of 125 adults living in the Midwest metropolitan area comprising Fargo (North Dakota) and Moorhead (Minnesota) of the United States. Chi-square, t-tests and binomial logistic regressions were used for the statistical analyses. Results: The results from this study represent that low household incomes, poor health status, single status were associated with unhealthy dietary behaviors such as eating while watching TV/reading and using food as a punishment, while neighborhood grocery store having a wide selection of fruits and vegetables decreased the odds of using food as a punishment. Furthermore, eating healthy snacks, eating dinner with family, and having scheduled meals were associated with good eating habit, consuming a diet medium in fat compared to high in fat, and high household income, respectively. Conclusions: The findings from this study can be used in developing effective public health strategies and interventions aimed at improving overall health status of adults.

Dietary intake may cause variable bacterial prevalence in the gastrointestinal tract. The objective of this research was to determine the prevalence of Enterobacteriaceae in the cecum and feces and its relationship to weight changes following flaxseed-, health-promoting compounds of flaxseed-, or buckwheat-supplemented diets. Seventy-two C57BL/6J male mice were randomly assigned to a diet group and fed for 8 weeks: high fat (45% kcal fat); 10% whole flaxseed (45% kcal fat); 6% defatted flaxseed (45% kcal fat); 4% flaxseed oil (45% kcal fat); 10% buckwheat (45% kcal fat); and low fat (16% kcal fat) diet groups. Significant differences in the prevalence of Enterobacteriaceae in the cecum (p < .0348) and feces at posttreatment (p < .0033) were observed. The prevalence of Enterobacteriaceae affected posttreatment weight (p < .0001). Our results indicate that there may be a relationship between an increase in Enterobacteriaceae prevalence and weight gain.