A Cross-Sectional Study on the Association of Walnut Consumption with Obesity and Relative Fat Mass among United States Adolescents and Young Adults in NHANES (2003-2020).

Background: Walnuts contain nutrients and phytochemicals that can promote metabolic health. However, the high energy content of walnuts along with other nuts raises the concern that consuming nuts promotes obesity. Objectives: We sought to investigate the associations between consumption of walnuts as well as other nuts and measures of obesity in adolescents and young adults. Methods: This study included 8874 adolescents (12-19 y) and 10,323 young adults (20-39 y) from 8 waves of National Health and Nutrition Examination Survey data (2003-2020). The associations of consumption of 1) walnuts only (WO); 2) walnuts with other nuts (WON); 3) other nuts (ON); and 4) no nuts (NN) with obesity status and relative fat mass (RFM) were assessed using logistic and linear regressions stratified by age group and sex. Sample weights were used in all statistical analyses. Results: The mean daily intake of walnuts was not different between the 2 walnut consumption groups within each age group (adolescents: 2.18 [standard error (SE) 0.14] g; P = 0.917; young adults: 4.23 [0.37] g; P = 0.682). The WON group had the lowest prevalence of obesity (adolescents: 8.3%; young adults: 21.1%) while the NN group had the highest prevalence (adolescents: 24.1%; young adults: 35.4%). The models indicated lower odds of obesity in adolescent girls (odds ratio [OR]: 0.27; P < 0.05) and young adult women (OR: 0.58; P < 0.05) who consumed WON than in those who consumed NN. In both young women and girls, RFM was significantly lower in the WON and ON groups than the NN group (P < 0.001). In young men, WON consumption was also associated with a lower RFM (OR: -1.24; 95% confidence interval: -2.21, -0.28) compared with NN consumption. Conclusions: For adolescents girls and young women, dietary intake of walnuts combined with other nuts has the strongest inverse association with measures of obesity.

Secondary Analysis of Sweetness Liking from Pilot Study Replacing Sugar Sweetened Soda with Flavored, Unsweetened Sparkling Water.

OBJECTIVE: This study aimed to evaluate changes in sensory ratings (liking, sweetness intensity, "just about right" (JAR) level of sweetness) of 0-10.7% w/w sugar in soda after 1 and 2 wk of replacing sugar-sweetened soda consumption with unsweetened, flavored, sparkling water. METHODS: Consumers of sugar-sweetened sodas (17 men and women, average age 28 years) replaced their sodas with unsweetened, flavored sparkling waters for 2 wk. Changes in sensory ratings were evaluated for sodas ranging from 0-10.7% w/w added sugar. In a secondary analysis, cluster analysis identified "Sweet Likers" (liking increased with sugar concentration) and "Sweet Moderates" (liking peaked in the middle of the concentration range) in the baseline ratings, and models for changes in sensory ratings were reevaluated by sweet-liking group. RESULTS: The primary analyses showed no significant effects of the intervention on sweetness intensity or liking ratings. However, the secondary analysis showed that Sweet Likers reduced liking ratings for all sodas, but particularly for the highest concentration (p = 0.0021) after the intervention. Sweet Moderates, however, increased liking ratings after the intervention, driven by an increase in liking for the lower concentrations of sugar (p = 0.0058). Additionally, Sweet Moderates increased their overall ratings for sweetness intensity in sodas (p = 0.00074). CONCLUSION: These results suggest that the intervention may have been more successful in shifting sensory perception and acceptance of less-sweet sodas for Sweet Moderates than for Sweet Likers. These results should be verified in a larger sample that intentionally recruits by sweet liker status, to see if initial liking for sweetness may be a critical factor in interventions aiming to improve liking of less sweet beverages.

Consumers of sugary soda replaced their sodas with unsweetened, flavored sparkling water for 2 weeks, rating a range of sugar in soda in terms of sweetness intensity and liking for sweetness before, during, and after the intervention.No changes were significant in the sensory ratings for the whole group, but if the subjects are separated by baseline "sweet-liking," the "Sweet Likers" reduced liking for the highest concentration of sugar in soda, while the "Sweet Moderates" increased liking ratings for the lowest and zero concentrations of sugar in soda.

Obesity modifies the association between diabetes and iron biomarkers and red cell indices in reproductive-aged women in the United States.

Obesity and diabetes are associated with impaired iron metabolism. We aimed to examine the independent relationship between diabetes and iron after controlling for body weight (or obesity) in women aged 20-49 years. The National Health and Nutrition Examination Survey data from 2015 to 2018 were used in this investigation. Body composition data, HbAc1, iron biomarkers (serum ferritin (SF), soluble transferrin receptor (sTfR), and body iron index (BII)), mean corpuscular volume (MCV), mean hemoglobin concentration (MCH), red cell distribution width (RDW), and hemoglobin were used. Linear regression models were used to examine how and to what extent body mass index (BMI) modified the relationship between diabetes and iron status biomarkers. A total of 1834 women aged 20-49 were included in the analysis with a mean (SD) age of 32 .2 ± 6.1 years and BMI of 29.5 ± 6.9 kg/m2. The mean SF (p = 0.014) and BII (p < 0.001) were lower, while sTfR (p < 0.001) was higher in women with diabetes than those with no diabetes. Mean estimates for MCV and MCH were lower, while RDW (p = 0.001) was higher in diabetes patients (all p < 0.001). Women with diabetes were more likely to have iron deficiency, anemia, and iron deficiency anemia than those without diabetes (18.1% vs 8.6%, p < 0.001), (24.4% vs 8.4%, p < 0.001), and (14.8% vs 5.2%, p < 0.001), respectively. Among women with obesity, those with diabetes had lower predicted ferritin (ß = -0.19, p = 0.016), BII (ß = -0.99, p = 0.016), and hemoglobin (ß = -0.27, p = 0.042) than those without diabetes. The study shows that diabetes is linked to lower iron stores; this is exacerbated in those with obesity.

Impact on oxidative stress of oral, high-dose, iron supplementation for management of iron deficiency after bariatric surgery, a preliminary study.

OBJECTIVES: High-dose oral iron supplementation for patients who develop iron deficiency after bariatric surgery may induce oxidative stress in the gastrointestine. The study's objective was to test this hypothesis by determining the impact of high-dose oral iron on systemic oxidative stress. METHODS: We used archived plasma samples from a randomized controlled clinical trial (NCT02404012) comparing FeSO4 (195 mg/day, NatureMade®, West Hills, CA) with a heme iron polypeptide (HIP, 60.4 mg/day, Proferrin®, Colorado Biolabs, Lafayette, CO) for 8 weeks. Systemic oxidative stress was measured using malondialdehyde and total antioxidant capacity (MDA, Abcam, ab238537 and TAC, Abcam, ab65329 Cambridge, UK) assays. Data was log-transformed and presented as means and standard deviations; a mixed model was used to determine the effects of time (0, 2, 4, and 8 weeks) and treatment (FeSO4 versus HIP) on oxidative stress. RESULTS: The FeSO4 (N = 8) and HIP (N = 5) participants were balanced in body mass index (35.0 ± 5.5 kg/m2), race (93 % White), time post-surgery (7.3 ± 3.3 years), as well as serum concentrations of iron (P > 0.05). The FeSO4 group tended to be older (44.3 ± 4.5 years) and they had lower concentrations of serum ferritin (6.5 ± 2.7 µg/mL) than the HIP (38.2 ± 9.3 years, and 12.9 ± 16.8 µg/mL) group (P = 0.080, and P = 0.017 respectively). We observed a larger increase in serum iron in the FeSO4 group during the 8 weeks of Fe supplementation, compared to that in the HIP group (p = 0.004). We observed a decreasing trend in MDA over the 8 weeks (p = 0.080) in the FeSO4 treatment group. There were no significant differences in TAC between and within FeSO4 and HIP groups over the 8 week supplementation period. CONCLUSIONS: This preliminary study suggests that high-dose oral iron supplementation for iron deficiency does not adversely impact systemic oxidative stress in patients undergoing bariatric surgery.

Systematic Review and Meta-Analysis to Estimate a Reference Range for Circulating Ionized Magnesium Concentrations in Adult Populations.

BACKGROUND: There is a lack of consensus on a reference range for ionized magnesium (iMg2+) in blood as a measure of the status of circulating iMg2+ for the screening of populations. OBJECTIVES: We estimated the reference range of iMg2+ levels for healthy adult populations and the ranges for populations with cardiovascular disease (CVD), type 2 diabetes, hypertension, and renal disease. We also estimated 95% ranges for circulating magnesium (Mg) in healthy and those with cardiometabolic diseases. METHODS: We searched Ovid MEDLINE, Cochrane Central Register of Controlled Trials, and Embase through 24 July, 2020 to identify articles. We included English, peer-reviewed, randomized controlled trials, prospective and retrospective cohort studies, case-control studies, and cross-sectional studies that measured iMg2+ in blood or circulating Mg at baseline. The protocol was registered on PROSPERO (CRD42020216100). Estimated ranges were calculated by employing a frequentist random-effects model using extracted (or calculated) means and SDs from each included study. We determined the 95% confidence interval of the pooled mean. RESULTS: A total of 95 articles were included with 53 studies having data for healthy participants and 42 studies having data for participants with cardiometabolic diseases. The estimated reference range for iMg2+ for healthy populations was 0.40-0.68 mmol/L, 0.38-0.64 mmol/L for CVD, 0.34-0.66 mmol/L for type 2 diabetes, 0.39-1.04 mmol/L for hypertension, and 0.40-0.76 mmol/L for renal disease. For circulating Mg, the estimated range was 0.72-1.0 mmol/L for healthy adults, 0.56-1.05 mmol/L for CVD, 0.58-1.14 mmol/L for type 2 diabetes, 0.60-1.08 mmol/L for hypertension, and 0.59-1.26 mmol/L for renal disease. CONCLUSIONS: Estimated reference ranges for cardiometabolic disease states for both iMg2+ and circulating Mg were broad and overlapped with the estimated range for healthy populations (0.40-0.68 mmol/L). Further studies should evaluate whether iMg2+ can be used as a biomarker of cardiometabolic disease.

Sexual Function and Satisfaction in the Context of Obesity.

PURPOSE OF REVIEW: Sexual dysfunction is commonly associated with overweight/obesity, but the underlying physiological and psychosocial mechanisms are not fully understood. This review contextualizes the obesity-sexual (dys)function relationship, describes recent insights from the medical and social science literature, and suggests opportunities for continued research. RECENT FINDINGS: Although sexual dysfunction has been historically evaluated as a consequence/outcome of obesity, it is increasingly considered as a harbinger of future metabolic comorbidities, including type 2 diabetes and cardiovascular disease. Body image dissatisfaction is a consistent predictor for lower sexual satisfaction across BMI categories, likely mediated by cognitive distraction during partnered sex. To fully capture the relationship between obesity and sexual dysfunction, multidisciplinary research approaches are warranted. While clinically significant weight loss tends to improve sexual functioning for women and men, higher body image satisfaction may independently promote sexual function and satisfaction without concomitant weight loss.

Evaluation of Unintended Consequences of COVID-19 Pandemic Restrictions and Obesity Prevalence Among Youths.

This cohort study examines the association between COVID-19 pandemic restrictions and obesity prevalence among youths aged 2 to 19 years in Monroe County, Indiana.

Relationship between short-term self-reported dietary magnesium intake and whole blood ionized magnesium (iMg2+) or serum magnesium (s-Mg) concentrations.

OBJECTIVE: Since we and others have shown that supplemental magnesium raises whole blood ionized magnesium (iMg2+) we investigated the relationships between self-reported dietary magnesium intake and concentrations of whole blood iMg2+ and serum magnesium (s-Mg). METHODS: We obtained whole blood iMg2+ concentrations, as well as s-Mg concentrations, from a pilot, three-arm, randomized, controlled, crossover bioavailability study of magnesium supplements (n = 23; 105 measures). Dietary magnesium intake was assessed using three-day food records and the Nutrition Data System for Research (NDSR, University of Minnesota, MN, USA). Whole blood iMg2+ was measured with an electrode analyser (NOVA Biochemical, Waltham, MA, USA), whereas s-Mg was measured using atomic absorption spectroscopy. A linear mixed-effects model was employed with dietary magnesium as the outcome variable and iMg2+, s-Mg, study treatment and study visit as fixed effects. We adjusted age, gender, race and body mass index covariates. RESULTS: Values for dietary magnesium, iMg2+ and s-Mg were 303.8 ± 118.9 mg/day, 1.3 ± 0.1 mg/dL and 2.2 ± 4.1 mg/dL, respectively. No association was found between dietary magnesium intake and iMg2+ -125 ± 176.95 (p = .49) or s-Mg -9.33 ± 5.04 (p = .08). CONCLUSIONS: Whole blood iMg2+ and s-Mg concentrations do not reflect short-term self-reported dietary intake in adults. Further research is needed to determine whether blood biomarkers of magnesium may reflect dietary magnesium intake.Key messagesDietary intake of magnesium, a shortfall nutrient, may be objectively measured using blood biomarkers of magnesium.Serum magnesium and whole blood iMg2+ were not associated with short-term dietary intake of magnesium.

Just noticeable difference in sweetness perception of cola: Small changes in sugar are noticeable.

Sugar-sweetened beverage consumption contributes to obesity and related diseases. Fortunately, beverages with reduced sweetness are a growing category in the beverage industry. These lower sweetness products could be useful for reducing the total dietary intake of sugar, but publicly available data are sparse on how much sweetness can be reduced without the change becoming noticeable to consumers. We investigated the just noticeable difference (JND) in sweetness of a cola-flavored carbonated beverage. Two sensory tests were conducted to detect the JND from 12.00% w/w sucrose. In each test, we used cola-flavored seltzer water with five decreasing sucrose concentrations (test 1:8.02-12.00% w/w; test 2:10.21-12.00% w/w). In both tests, samples were paired with the 12.00% reference, and participants were instructed to identify the sweeter sample. Participants correctly identified the reference sample at 10.21% in test one (p = .0039) and at 10.89% (p = .014) in test two. The data indicate that in a cola beverage, sucrose can be reduced by ~9.25% of the original concentration (12.00-10.89% w/w) before the sweetness becomes apparent to consumers. However, further work should consider whether sugar reductions greater than 9.25% would be acceptable, even if the difference in sweetness is apparent. Practical Applications: These data could help researchers and industry product developers know how much sugar can be reduced from a cola-flavored beverage before the change is apparent to consumers.

Risk of Type 2 Diabetes Among Individuals with Excess Weight: Weight Trajectory Effects.

PURPOSE OF REVIEW: Increased risk of type 2 diabetes mellitus (T2D) among individuals with overweight or obesity is well-established; however, questions remain about the temporal dynamics of weight change (gain or loss) on the natural course of T2D in this at-risk population. Existing epidemiologic evidence is limited to studies that discretely sample and assess excess weight and T2D risk at different ages with limited follow-up, yet changes in weight may have time-varying and possibly non-linear effects on T2D risk. Predicting the impact of weight change on the risk of T2D is key to informing primary prevention. We critically review the relationship between weight change, trajectory groups (i.e., distinct weight change patterns), and T2D risk among individuals with excess weight in recently published T2D prevention randomized controlled trials (RCTs) and longitudinal cohort studies. RECENT FINDINGS: Overall, weight trajectory groups have been shown to differ by age of onset, sex, and patterns of insulin resistance or beta-cell function biomarkers. Lifestyle (diet and physical activity), pharmacological, and surgical interventions can modify an individual's weight trajectory. Adolescence is a critical etiologically relevant window during which onset of excess weight may be associated with higher risk of T2D. Changes in insulin resistance and beta-cell function biomarkers are distinct but related correlates of weight trajectory groups that evolve contemporaneously over time. These multi-trajectory markers are differentially associated with T2D risk. T2D risk may differ by the age of onset and duration of excess body weight, and the type of weight loss intervention. A better understanding of the changes in weight, insulin sensitivity, and beta-cell function as distinct but related correlates of T2D risk that evolve contemporaneously over time has important implications for designing and targeting primary prevention efforts.

Recommendation on an updated standardization of serum magnesium reference ranges.

PURPOSE: Serum magnesium is the most frequently used laboratory test for evaluating clinical magnesium status. Hypomagnesemia (low magnesium status), which is associated with many chronic diseases, is diagnosed using the serum magnesium reference range. Currently, no international consensus for a magnesemia normal range exists. Two independent groups designated 0.85 mmol/L (2.07 mg/dL; 1.7 mEq/L) as the low cut-off point defining hypomagnesemia. MaGNet discussions revealed differences in serum magnesium reference ranges used by members' hospitals and laboratories, presenting an urgent need for standardization. METHODS: We gathered and compared serum magnesium reference range values from our institutions, hospitals, and colleagues worldwide. RESULTS: Serum magnesium levels designating "hypomagnesemia" differ widely. Of 43 collected values, only 2 met 0.85 mmol/L as the low cut-off point to define hypomagnesemia. The remainder had lower cut-off values, which may underestimate hypomagnesemia diagnosis in hospital, clinical, and research assessments. Current serum magnesium reference ranges stem from "normal" populations, which unknowingly include persons with chronic latent magnesium deficit (CLMD). Serum magnesium levels of patients with CLMD fall within widely used "normal" ranges, but their magnesium status is too low for long-term health. The lower serum magnesium reference (0.85 mmol/L) proposed specifically prevents the inclusion of patients with CLMD. CONCLUSIONS: Widely varying serum magnesium reference ranges render our use of this important medical tool imprecise, minimizing impacts of low magnesium status or hypomagnesemia as a marker of disease risk. To appropriately diagnose, increase awareness of, and manage magnesium status, it is critical to standardize lower reference values for serum magnesium at 0.85 mmol/L (2.07 mg/dL; 1.7 mEq/L).

Assessment of baseline rates of functional and absolute iron deficiency in bariatric surgery candidates: a retrospective study.

BACKGROUND: Preoperative optimization of iron status is a priority in candidates for bariatric surgery. Inflammation is strongly associated with obesity, and as a consequence, functional iron deficiency (ID) is potentially an underreported issue in surgical candidates. OBJECTIVES: In light of updated practice guidelines, to retrospectively review preoperative iron status in an Irish cohort of bariatric surgery candidates, taking account of the relative incidence rate of functional ID. SETTING: A tertiary care obesity service with bariatric surgery referral in Ireland. METHODS: Baseline nutritional biochemistry records were reviewed between February 2017 and February 2020 in a hospital, Dublin, Ireland. Absolute ID was defined as serum ferritin <30 µg/L; functional ID was defined as ferritin, 30 to 100 µg/L, in the presence of C-reactive protein >5 mg/L. Anemia was indexed with reference to hemoglobin and qualified by vitamin B12 and folate status to rule out anemia unrelated to primary ID. RESULTS: The analysis included 120 patients, 68% female, 49.6 ± 9.3 years, and body mass index, 52.0 ± 9.6 kg/m2. The prevalence of absolute and functional ID was 11.7% and 30.8%, respectively (P = .0003). Anemia was associated with absolute ID and functional ID in 14.3% and 10.8% of patients (P = .29). Folate and vitamin B12 deficiency occurred in <5% of patients. CONCLUSION: In patients seeking bariatric surgery for severe obesity, the prevalence of baseline functional ID is substantial and can be associated with anemia. These findings raise queries with regard to how best to optimize preoperative iron status in the context of ongoing inflammation.

Roux-en-Y gastric bypass-induced bacterial perturbation contributes to altered host-bacterial co-metabolic phenotype.

BACKGROUND: Bariatric surgery, used to achieve effective weight loss in individuals with severe obesity, modifies the gut microbiota and systemic metabolism in both humans and animal models. The aim of the current study was to understand better the metabolic functions of the altered gut microbiome by conducting deep phenotyping of bariatric surgery patients and bacterial culturing to investigate causality of the metabolic observations. METHODS: Three bariatric cohorts (n = 84, n = 14 and n = 9) with patients who had undergone Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG) or laparoscopic gastric banding (LGB), respectively, were enrolled. Metabolic and 16S rRNA bacterial profiles were compared between pre- and post-surgery. Faeces from RYGB patients and bacterial isolates were cultured to experimentally associate the observed metabolic changes in biofluids with the altered gut microbiome. RESULTS: Compared to SG and LGB, RYGB induced the greatest weight loss and most profound metabolic and bacterial changes. RYGB patients showed increased aromatic amino acids-based host-bacterial co-metabolism, resulting in increased urinary excretion of 4-hydroxyphenylacetate, phenylacetylglutamine, 4-cresyl sulphate and indoxyl sulphate, and increased faecal excretion of tyramine and phenylacetate. Bacterial degradation of choline was increased as evidenced by altered urinary trimethylamine-N-oxide and dimethylamine excretion and faecal concentrations of dimethylamine. RYGB patients' bacteria had a greater capacity to produce tyramine from tyrosine, phenylalanine to phenylacetate and tryptophan to indole and tryptamine, compared to the microbiota from non-surgery, normal weight individuals. 3-Hydroxydicarboxylic acid metabolism and urinary excretion of primary bile acids, serum BCAAs and dimethyl sulfone were also perturbed following bariatric surgery. CONCLUSION: Altered bacterial composition and metabolism contribute to metabolic observations in biofluids of patients following RYGB surgery. The impact of these changes on the functional clinical outcomes requires further investigation. Video abstract.

Nutrition care practice patterns for patients with COVID-19-A preliminary report.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 is a respiratory virus that poses risks to the nutrition status and survival of infected patients, yet there is paucity of data to inform evidence-based quality care. METHODS: We collected data on the nutrition care provided to patients with coronavirus disease 2019 (COVID-19) by registered dietitian nutritionists (RDNs). RESULTS: Hospitalized COVID-19 patients (N = 101) in this cohort were older adults and had elevated body mass index. The most frequent nutrition problems were inadequate oral intake (46.7%), inadequate energy intake (18.9%), and malnutrition (18.4%). These problems were managed predominantly with enteral nutrition, food supplements, and multivitamin-multimineral supplement therapy. Over 90% of documented problems required a follow-up. CONCLUSION: This data set is the first of its kind to report on the types of nutrition diagnoses and interventions for COVID-19 cases used by RDNs and highlights the need for increased and continued nutrition care.

Feasibility of Mass-Spectrometry to Lower Cost and Blood Volume Requirements for Assessment of B Vitamins in Patients Undergoing Bariatric Surgery.

Bariatric surgery induces deficiencies in a combination of B vitamins. However, high costs and a large blood volume requirement are barriers to routine screening. We adapted and validated a method coupling tandem mass spectrometry (MS/MS) with high-performance liquid chromatography (HPLC) to facilitate cost-effective analysis for simultaneous detection of B vitamins in low volumes of plasma. Based on existing methods, pooled plasma was extracted using hexane and acetonitrile and seven B vitamin analytes were separated using HPLC. Detection was performed with an Agilent 6460 triple quadrupole tandem mass spectrometer (MS/MS) using electrospray ionization in the positive ion mode. We evaluated linearity, recovery, precision, and limit of detection, as well as costs of the assay. We evaluated seven B vitamins from plasma; five (riboflavin, nicotinamide, pantothenic acid, pyridoxine, and biotin) were detected and quantified with precision and linearity. Recovery ranged from 63 to 81% for each of the vitamins, except for nicotinamide-the recovery of which was suppressed to 40%, due to plasma matrix effects. We demonstrated the feasibility of the HPLC-MS/MS method for use in patients who undergo bariatric surgery by analyzing pooled plasma from patients with a lower cost and blood volume than had we sent the samples to a commercial laboratory. It is advantageous and feasible, in terms of low cost and blood volume requirement, to simultaneously measure plasma concentrations of B vitamins using HPLC-MS/MS. With further improvements, the method may enable personalized nutritional assessment for the nutritionally compromised, bariatric surgery population.

Circulating Ionized Magnesium as a Measure of Supplement Bioavailability: Results from a Pilot Study for Randomized Clinical Trial.

Oral supplementation may improve the dietary intake of magnesium, which has been identified as a shortfall nutrient. We conducted a pilot study to evaluate appropriate methods for assessing responses to the ingestion of oral magnesium supplements, including ionized magnesium in whole blood (iMg2+) concentration, serum total magnesium concentration, and total urinary magnesium content. In a single-blinded crossover study, 17 healthy adults were randomly assigned to consume 300 mg of magnesium from MgCl2 (ReMag®, a picosized magnesium formulation) or placebo, while having a low-magnesium breakfast. Blood and urine samples were obtained for the measurement of iMg2+, serum total magnesium, and total urine magnesium, during 24 h following the magnesium supplement or placebo dosing. Bioavailability was assessed using area-under-the-curve (AUC) as well as maximum (Cmax) and time-to-maximum (Tmax) concentration. Depending on normality, data were expressed as the mean ± standard deviation or median (range), and differences between responses to MgCl2 or placebo were measured using the paired t-test or Wilcoxon signed-rank test. Following MgCl2 administration versus placebo administration, we observed significantly greater increases in iMg2+ concentrations (AUC = 1.51 ± 0.96 vs. 0.84 ± 0.82 mg/dL·24h; Cmax = 1.38 ± 0.13 vs. 1.32 ± 0.07 mg/dL, respectively; both p < 0.05) but not in serum total magnesium (AUC = 27.00 [0, 172.93] vs. 14.55 [0, 91.18] mg/dL·24h; Cmax = 2.38 [1.97, 4.01] vs. 2.24 [1.98, 4.31] mg/dL) or in urinary magnesium (AUC = 201.74 ± 161.63 vs. 139.30 ± 92.84 mg·24h; Cmax = 26.12 [12.91, 88.63] vs. 24.38 [13.51, 81.51] mg/dL; p > 0.05). Whole blood iMg2+ may be a more sensitive measure of acute oral intake of magnesium compared to serum and urinary magnesium and may be preferred for assessing supplement bioavailability.

A multidimensional analysis of the longitudinal effects of roux en y gastric bypass on fatigue: An association with visceral obesity.

BACKGROUND AND OBJECTIVES: Severe obesity is associated with fatigue, however, the effects of weight loss after bariatric surgery on particular dimensions of fatigue are unknown. In a secondary analysis of a prospective cohort study of women undergoing roux-en-y gastric bypass (RYGB) we explored relationships among multiple dimensions of fatigue and improving adiposity, insulin resistance and inflammation. METHODS: Before, and 1 and 6 months after RYBG, dimensions of fatigue were assessed using the validated, self-report, Multidimensional Fatigue Inventory. Total, abdominal visceral (VAT) and subcutaneous (SAT) adiposity, insulin sensitivity (Si and HOMA) and plasma concentrations of leptin, C-reactive protein (CRP) and interleukin-6 (Il-6) were measured using air displacement plethysmography, computed tomography, glucose tolerance testing and enzyme-linked immunoassay. Associations were assessed using Spearman correlations and linear regression. RESULTS: At baseline, the majority of our female participants (N = 19, body mass index, 46.5 kg/m2, age 37.2 years) were experiencing elevated levels of fatigue. By 6 months, dimensions of physical (-43%), reduced activity (-43%), reduced motivation (-38%), general (-31%; all p < .005), and mental (-18%, p < .05) fatigue improved, concomitant with decreases in markers of adiposity, inflammation and insulin resistance. The decrease in VAT was associated with improvement in mental fatigue (beta, 0.447 ±â€¯0.203, p = .045), independent of other indices of adiposity, IL-6 concentrations, or Si. CONCLUSIONS: In the 6 months after RYGB, fatigue improved, especially physical fatigue. Decreases in mental fatigue were strongly associated with decreases in visceral adiposity. Nevertheless, the biologic mechanisms underlying changes in these specific fatigue dimensions remain undetermined.