An examination of relationships between vitamin B12 status and functional measures of peripheral neuropathy in young adult vegetarians

Introduction

Prevalence rates for vitamin B12 deficiency in U.S. adult vegetarians may exceed 30%, which is concerning given the role for this vitamin in numerous nervous system functions, including the synthesis of myelin sheaths. Defective myelin synthesis and repair are directly linked to peripheral neuropathy; yet, few investigations have examined how physical indicators of peripheral neuropathy (e.g., hand dexterity, vibration sensitivity and balance) are impacted in individuals adhering to vegetarian diets. This feasibility research explored the relationships between peripheral neuropathy and vitamin B12 status using a cross-sectional study design. In addition, a small pilot trial was conducted for limited-efficacy testing of vitamin B12 supplementation for reducing peripheral neuropathy.

Methods

Healthy, able-bodied adults (n = 38; 19-40 years of age) reported exclusive adherence to a vegetarian or vegan diet for 3 years. Peripheral neuropathy was measured using a force plate for assessing balance, and a vibration sensitivity tester and pegboard tests to assess hand dexterity. Serum vitamin B12 and folate were measured using standard radioimmunoassay techniques.

Results

Twenty-six percent of the sample displayed deficient or marginal vitamin B12 status (serum vitamin B12 <221 pmol/L). Participants with adequate vitamin B12 status scored 10% higher on the Purdue pegboard assembly test and 20% higher on the left hand adjusted functional dexterity test in comparison to participants with marginal-to-deficient vitamin B12 status (p < 0.05).

Discussion

These data provide preliminary evidence that peripheral neuropathy can be detected in individuals with marginal-to-deficient vitamin B12 status.

Nitrogen Balance at the Recommended Dietary Allowance for Protein in Minimally Active Male Vegans

Vegan diets have gained popularity in recent years for reasons including health benefits and concerns for animal welfare. Although these diets are considered to be nutritionally adequate, questions remain over whether the current protein recommendation (0.8 g/kg/d) is sufficient. Protein status is determined through a nitrogen balance analysis when the protein content of the diet is known. A negative balance indicates a catabolic state, and a positive nitrogen balance indicates an anabolic state. In healthy adults, nitrogen equilibrium is the expectation reflecting the net synthesis and breakdown of proteins. Currently, there are no known studies measuring nitrogen balance in strict vegan men fed the protein requirement. Eighteen minimally active vegan men received a 5-day eucaloric diet (protein content: 0.8 g/kg/d). On day five, 24 h urine was collected for nitrogen analysis. Both the mean absolute nitrogen balance (-1.38 ± 1.22 g/d) and the mean relative nitrogen balance (-18.60 ± 16.96 mg/kg/d) were significantly lower than zero (equilibrium) (p < 0.001). There were no correlations seen between nitrogen balance and age, years as vegan, or fat-free mass. Consuming 0.8 g/kg/d of protein is not adequate to produce nitrogen balance in men adhering to typical strict vegan diets for at least one year.

Curcumin Confers Anti-Inflammatory Effects in Adults Who Recovered from COVID-19 and Were Subsequently Vaccinated: A Randomized Controlled Trial

COVID-19 infection and vaccination offer disparate levels of defense against reinfection and breakthrough infection. This study was designed to examine the effects of curcumin supplementation, specifically HydroCurc (CURC), versus placebo (CON) on circulating inflammatory biomarkers in adults who had previously been diagnosed with COVID-19 and subsequently received a primary series of monovalent vaccine doses. This study was conducted between June 2021 and May 2022. Participants were randomized to receive CURC (500 mg) or CON capsules twice daily for four weeks. Blood sampling was completed at baseline and week-4 and analyzed for biomarkers. Linear regression was utilized to examine the between-group differences in post-trial inflammatory biomarker levels, adjusting for baseline and covariates including age, sex, race/ethnicity, and interval between COVID-19 diagnosis and trial enrollment. The sample (n = 31) was 71% female (Age 27.6 ± 10.4 y). The CURC group exhibited significantly lower post-trial concentrations of proinflammatory IL-6 (β = -0.52, 95%CI: -1.03, -0.014, p = 0.046) and MCP-1 (β = -0.12, 95%CI: -0.23, -0.015, p = 0.027) compared to CON, adjusting for baseline and covariates. Curcumin intake confers anti-inflammatory activity and may be a promising prophylactic nutraceutical strategy for COVID-19. These results suggest that 4 weeks of curcumin supplementation resulted in significantly lower concentrations of proinflammatory cytokines in adults who recovered from COVID-19 infection and were subsequently vaccinated.

Associations Between Food Skills and Resilience in Adults Ages 18 to 45 in the USA During the COVID-19 Pandemic (2020 April-June): A Brief Report

Early in the COVID-19 pandemic, there were limited options for eating away from home, obligating many US adults to prepare foods at home, a situation that provided an opportunity to examine relationships between food skills, resilience, and coping in the initial months of the pandemic. This research surveyed a convenience sample of adults (n = 134; 18-45 years of age) from the Phoenix Metropolitan area when a "stay at home" pandemic directive was mandated in the state of AZ. The study objective was to explore how food skills correlated to resilience and whether resilience directly related to the ability to manage oneself during this time. Previously validated measures for food skills and resiliency were utilized for the online questionnaire, which also included the question, "I was able to manage myself during the Coronavirus Pandemic." The Spearman's rank order correlation test and a linear, stepwise regression analysis were used to examine relationships between scores. Participants scored at the 77% percentile for total food skill proficiency, and at the 84th percentile for resilience. Both total food skills and resilience were correlated to the ability to self-manage during COVID-19 (r = 0.246 and r = 0.444, respectively; p ≤ 0.004). The stepwise linear regression model retained only the food skill domain "food selection and planning" as a significant predictor of resilience (standardized coefficient, 0.278; 99% CI [- 0.056, 0.414]; p < 0.05). These data suggest that resilience and food skills factored into participants' ability to self-manage during the COVID-19 mandate, "stay at home."

Early time-restricted eating may favorably impact cognitive acuity in university students: a randomized pilot study

Cognitive acuity is important for academic success. The preliminary efficacy of early time-restricted eating (eTRE) on cognitive acuity was examined in a sample of university students attending a large southwestern university. It was hypothesized that adherence to eTRE would result in improved cognitive acuity as assessed by the Trail Making Tests (i.e., TMT-A and TMT-B) and the Stroop Color and Word Test. Participants were randomized to an intervention group (eTRE) with a daily 6-hour eating window or a control group (CON) with a daily 16-hour eating window; 24 participants initiated the study (13 eTRE and 11 CON). Blood ketones (i.e., β-hydroxybutyrate [BHB]) and brain-derived neurotrophic factor were also assessed. The 8-week intervention was forestalled by COVID-19 laboratory closures beginning in March 2020, and only data obtained at week 0 (baseline) and week 4 were viable for statistical analyses. Study attrition was high (50% for eTRE and 23% for CON). At week 4, there was a 27% and 6% decrease in TMT-B response time for the eTRE and CON groups, respectively (P = .02). TMT-B response time was inversely correlated to plasma BHB among participants (r = -0.633; P = .008). Considering the inverse relationship between TMT-B response time and plasma BHB, these preliminary data suggest that eTRE may improve some aspects of cognitive acuity in this population. Future investigations are needed to confirm these findings and should accommodate individual preferences regarding the initiation time of the eating window while also considering the impact on social influences and exercise engagement.

Palmitoylethanolamide Reduces Proinflammatory Markers in Unvaccinated Adults Recently Diagnosed with COVID-19: A Randomized Controlled Trial

BACKGROUND

Inflammation is at the core of many chronic conditions and exacerbates infectious conditions, including the severity of coronavirus disease 2019 (COVID-19) infections.

OBJECTIVES

This study aimed to examine the effects of a novel food supplement, palmitoylethanolamide (PEA), specifically Levagen+, as compared with a placebo on proinflammatory biomarkers in adults recently diagnosed with COVID-19 who were unvaccinated and nonhospitalized.

METHODS

This study was a double-blind randomized placebo-controlled trial conducted October 2020-March 2021 (clinicaltrials.gov: NCT04912921). Participants aged 19-53 y were unvaccinated and recently infected with COVID-19 as indicated by a positive test result per RT-PCR or antigen test, and they reported to the test site following diagnosis as allowed by the CDC's return-to-work policy. Participants were stratified by age, sex, and BMI and randomly assigned by coin toss to receive 600 mg Levagen+ twice daily (LEV) or placebo tablets twice daily (CON) for 4 wk. At baseline and week 4, participants completed health histories, 24-h dietary recalls, anthropometrics, and nonfasting blood sampling. The primary outcomes were the 4-wk change between groups for IL-6, C-reactive protein, ferritin, intercellular adhesion molecule 1, soluble P-selectin (sP-selectin), and neutrophil/lymphocyte ratio. Multiple linear regression models were utilized to assess treatment effects on outcomes, adjusting for covariates.

RESULTS

A total of 60 participants completed the study (LEV: n = 30; CON: n = 30). After 4 wk of supplementation, sP-selectin (β = -11.5; 95% CI: -19.8, -3.15; P = 0.0078), IL-1β (β = -22.9; 95% CI: -42.4, -3.40; P = 0.0222), and IL-2 (β = -1.73; 95% CI: -3.45, -0.065; P = 0.0492) concentrations were significantly reduced in the LEV group compared with the CON group.

CONCLUSIONS

Inflammatory mechanisms are crucial to optimal resolution of infectious conditions, yet unchecked secretion of inflammatory mediators can promote the dysregulated immune response implicated in COVID-19 complications. Overall, PEA supplementation produced anti-inflammatory effects in individuals recently diagnosed with COVID-19 who were nonhospitalized.

Serum creatinine as an indicator of lean body mass in vegetarians and omnivores

Growing numbers of Americans are adopting vegetarian or vegan diets. While risk for some chronic conditions may be lower when following these diets, concern remains over the ability to consume adequate amounts of various nutrients, notably, protein. Knowing that serum creatinine is a reliable marker of muscle mass, this study examined the relationships between serum creatinine, lean body mass (LBM), handgrip strength, and protein intake in healthy vegetarian (n = 55) and omnivorous (n = 27) adults. Significantly higher protein intakes (+31%), LBM (+7%), serum creatinine (+12%) and handgrip strength (+14%) were observed for the omnivore participants compared to vegetarian participants. Positive correlations (p < 0.001) were noted between creatinine and LBM (R² = 0.42), creatinine and handgrip strength (R² = 0.41), protein intake and LBM (R² = 0.29), and handgrip strength and LBM (R² = 0.69). These data show that serum creatinine concentrations were lower in vegetarian women and men in comparison to their omnivorous counterparts and that serum creatinine concentrations correlate with LBM and strength in healthy adults, regardless of diet.

Erythrocyte osmotic fragility is not linked to vitamin C nutriture in adults with well-controlled type 2 diabetes

Erythrocyte fragility is amplified by oxidative stress and linked to diabetes-specific microvascular disease. Vitamin C supplementation improves glycemic indices in adults with type 2 diabetes (T2D) by improving antioxidant status. This cross-sectional study examined the relationships between vitamin C status and erythrocyte osmotic fragility in adults with or without T2D. Participants provided a fasting blood sample for erythrocyte osmotic fragility testing as a function of hypotonic NaCl concentrations. Additionally, plasma was stabilized with metaphosphoric acid prior to vitamin C analysis using isocratic reverse-phase UV-HPLC separation. Participants were grouped as diagnosed T2D (n = 14; 36% female; 55.5 ± 8.2 y; 31.5 ± 9.0 kg/m²; HbA1c: 7.4 ± 1.9%; plasma vitamin C: 36.0 ± 12.2 μM) or no diabetes (n = 16; 69% female; 38.7 ± 13.5 y; 26.8 ± 6.6 kg/m²; HbA1c: 5.4 ± 0.3%; plasma vitamin C: 34.8 ± 10.9 μM). Participant characteristics differed between groups only for age and hemoglobin A1c (HbA1c; p < 0.05). All hemolysis parameters were in normal ranges for the participants with T2D, and no significant differences in hemolysis parameters were noted between those with or without T2D. However, among participants with T2D, the NaCl concentration eliciting 50% hemolysis was higher for those with low (<7%) vs. high (>7%) HbA1c values (p = 0.037) indicating a slightly higher erythrocyte fragility in the former group. Vitamin C status did not impact any of the hemolysis parameters in adults with or without T2D. Thus, erythrocyte fragility was not elevated in T2D, and vitamin C nutriture was not related to erythrocyte fragility in adults with well-controlled T2D.

Establishing 24-Hour Urinary Sucrose Plus Fructose as a Predictive Biomarker for Total Sugars Intake

BACKGROUND

Twenty-four-hour urinary sucrose and fructose (24uSF) has been studied as a biomarker of total sugars intake in two feeding studies conducted in the United Kingdom (UK) and Arizona (AZ). We compare the biomarker performance in these populations, testing whether it meets the criteria for a predictive biomarker.

METHODS

The UK and AZ feeding studies included 13 and 98 participants, respectively, aged 18 to 70 years, consuming their usual diet under controlled conditions. Linear mixed models relating 24uSF to total sugars and personal characteristics were developed in each study and compared. The AZ calibrated biomarker equation was applied to generate biomarker-estimated total sugars intake in UK participants. Stability of the model across AZ study subpopulations was also examined.

RESULTS

Model coefficients were similar between the two studies [e.g., log(total sugars): UK 0.99, AZ 1.03, P = 0.67], as was the ratio of calibrated biomarker person-specific bias to between-person variance (UK 0.32, AZ 0.25, P = 0.68). The AZ equation estimated UK log(total sugar intakes) with mean squared prediction error of 0.27, similar to the AZ study estimate (0.28). Within the AZ study, the regression coefficients of log(total sugars) were similar across age, gender, and body mass index subpopulations.

CONCLUSIONS

Similar model coefficients in the two studies and good prediction of UK sugar intakes by the AZ equation suggest that 24uSF meets the criteria for a predictive biomarker. Testing the biomarker performance in other populations is advisable.

IMPACT

Applications of the 24uSF biomarker will enable improved assessment of the role of sugars intake in risk of chronic disease, including cancer. See related commentary by Prentice, p. 1151.

Using Nutrition Knowledge and Diet Quality Questionnaires as Screening Tools to Identify Female Collegiate Athletes in Need of Dietitian Referral

The purpose of this study was to evaluate nutrition knowledge and diet quality in collegiate athletes to determine if referral to a sports registered dietitian (RD) is warranted. This cross-sectional study analyzed four sections of the Nutrition for Sport Knowledge Questionnaire and the Rapid Eating Assessment for Patients Questionnaire, both validated in athletic populations. The relationship between nutrition knowledge and diet quality was evaluated. Significance was set at P ≤ 0.05. One hundred and twenty athletes reported a median nutrition score of 52 (45-61), and a dietary quality score of 53 (46-58), with a weak, positive association between both (r = 0.28 (95% CI: 0.11-0.44), P < 0.01). Fifty-four percent were categorized as needing a referral to a sports RD. Diet quality scores differed between dietitian referral group with 49 (43-54) versus 58 (52-62) for the nonreferral group, respectively (P < 0.01, V = 0.71), with no difference in nutrition knowledge observed, P = 0.73. Overall, nutrition knowledge and diet quality in our sample of collegiate athletes was poor. College athletic departments with limited access to sports RD should use these questionnaires to evaluate knowledge and the need of dietitian referral separately.

Vitamin B6 Supplementation Reduces Symptoms of Depression in College Women Taking Oral Contraceptives: A Randomized, Double-Blind Crossover Trial

Oral contraceptive (OC) users have a heightened risk of low plasma concentrations of vitamin B6, a cofactor in the tryptophan-serotonin pathway critical to mood regulation. The purpose of this crossover study was to determine whether vitamin B6 supplementation reduced symptoms of depression and improved mood states in college women using OC. Participants were healthy (aged 18-25 yrs), did not take dietary supplements, and used OC (estrogen with progestin) consistently for at least 1 year. During the 12-week, randomized, double-blind crossover trial (4-week treatment periods [100 mg vitamin B6 daily or placebo] separated by a 4-week washout) participants (n = 8) maintained normal exercise and eating patterns and recorded tablet consumption daily. The Beck Depression Inventory-II (BDI-II) and Profile of Mood States (POMS) were used to assess mental health before and after each 4-week treatment period. Average dietary vitamin B6 intakes did not vary during the trial (1.2-1.4 mg/d), whereas vitamin B6 status rose significantly following the B6 supplementation period compared to the other three time points. BDI-II scores were reduced 20% by vitamin B6 supplementation in comparison to an 11% rise with placebo ingestion (p = 0.046). POMS scores were not significantly impacted by vitamin B6 supplementation. These preliminary data support a growing literature suggesting the benefits of B6 supplementation for reducing symptoms of depression in young women using OC.

An evaluation of the serum carbon isotope ratio as a candidate predictive biomarker of the dietary animal protein ratio (animal protein/total protein) in a 15-day controlled feeding study of US adults

BACKGROUND

The serum natural abundance carbon isotope ratio (CIR) was recently identified as a candidate biomarker of animal protein intake in postmenopausal women. Such a biomarker would help clarify the relation between dietary protein source (plant or animal) and chronic disease risk.

OBJECTIVES

We aimed to evaluate the performance of the serum CIR as a biomarker of dietary protein source in a controlled feeding study of men and women of diverse age and BMI.

METHODS

We conducted a 15-d feeding study of 100 adults (age: 18-70 y, 55% women) in Phoenix, AZ. Participants were provided individualized diets that approximated habitual food intakes. Serum was collected at the end of the feeding period for biomarker measurements.

RESULTS

Median [IQR] animal protein intake was 67 g/d [55-88 g/d], which was 64% of total protein. The serum CIR was positively correlated with animal protein and inversely correlated with plant protein intake, leading to a strong correlation (r2 = 0.76) with the dietary animal protein ratio (APR; animal/total protein). Regressing serum CIR on the APR, serum nitrogen isotope ratio (NIR), gender, age, and body weight generated an R2 of 0.78. Following the measurement error model for predictive biomarkers, the resulting regression equation was then inverted to develop a calibrated biomarker equation for APR. Added sugars ratio (added/total sugars intake) and corn intakes also influenced the serum CIR but to a much lesser degree than the APR; variations in these intakes had only small effects on biomarker-estimated APR.

CONCLUSIONS

Based on our findings in this US cohort of mixed sex and age, we propose the serum CIR alongside NIR as a predictive dietary biomarker of the APR. We anticipate using this biomarker to generate calibrated estimates based on self-reported intake and ultimately to obtain more precise disease risk estimates according to dietary protein source.

Daily Vinegar Ingestion Improves Depression Scores and Alters the Metabolome in Healthy Adults: A Randomized Controlled Trial

Daily vinegar ingestion has been linked to improved glycemic control, but recent data suggest a separate unexplored role for vinegar in mental health. Utilizing a placebo-controlled, parallel arm study design, this 4-week trial examined the impact of daily vinegar ingestion on mood states and urinary metabolites in healthy college students. Participants were randomized to the vinegar group (VIN: n = 14; 1.5 g acetic acid/day as liquid vinegar) or the control group (CON: n = 11; 0.015 g acetic acid/day as a pill) with no change to customary diet or physical activity. At baseline and at study week four, participants completed the Profile of Mood States (POMS) and the Center for Epidemiological Studies-Depression (CES-D) questionnaires and provided a first-morning urine sample for targeted metabolomics analyses. The change in both POMS depression scores and CES-D scores differed significantly between groups favoring improved affect in the VIN versus CON participants after four weeks. Metabolomics analyses pre and post-intervention suggested metabolite alterations associated with vinegar ingestion that are consistent for improved mood, including enzymatic dysfunction in the hexosamine pathway as well as significant increases in glycine, serine, and threonine metabolism. These data warrant continued investigation of vinegar as a possible agent to improve mood state.

Investigating the performance of 24-h urinary sucrose and fructose as a biomarker of total sugars intake in US participants - a controlled feeding study

BACKGROUND

Developing approaches for the objective assessment of sugars intake in population research is crucial for generating reliable disease risk estimates, and evidence-based dietary guidelines. Twenty-four-hour urinary sucrose and fructose (24uSF) was developed as a predictive biomarker of total sugars intake based on 3 UK feeding studies, yet its performance as a biomarker of total sugars among US participants is unknown.

OBJECTIVES

To investigate the performance of 24uSF as a biomarker of sugars intake among US participants, and to characterize its use.

METHODS

Ninety-eight participants, aged 18-70 y, consumed their usual diet under controlled conditions of a feeding study for 15 d, and collected 8 nonconsecutive 24-h urines measured for sucrose and fructose.

RESULTS

A linear mixed model regressing log 24uSF biomarker on log total sugars intake along with other covariates explained 56% of the biomarker variance. Total sugars intake was the strongest predictor in the model (Marginal R2 = 0.52; P <0.0001), followed by sex (P = 0.0002) and log age (P = 0.002). The equation was then inverted to solve for total sugars intake, thus generating a calibrated biomarker equation. Calibration of the biomarker produced mean biomarker-based log total sugars of 4.79 (SD = 0.59), which was similar to the observed log 15-d mean total sugars intake of 4.69 (0.35). The correlation between calibrated biomarker and usual total sugars intake was 0.59 for the calibrated biomarker based on a single biomarker measurement, and 0.76 based on 4 biomarker repeats spaced far apart.

CONCLUSIONS

In this controlled feeding study, total sugars intake was the main determinant of 24uSF confirming its utility as a biomarker of total sugars in this population. Next steps will include validation of stability assumptions of the biomarker calibration equation proposed here, which will allow its use as an instrument for dietary validation and measurement error correction in diet-disease association studies.

A Novel Mobile App (Heali) for Disease Treatment in Participants With Irritable Bowel Syndrome: Randomized Controlled Pilot Trial

BACKGROUND

A diet high in fermentable, oligo-, di-, monosaccharides and polyols (FODMAPs) has been shown to exacerbate symptoms of irritable bowel syndrome (IBS). Previous literature reports significant improvement in IBS symptoms with initiation of a low FODMAP diet (LFD) and monitored reintroduction. However, dietary adherence to the LFD is difficult, with patients stating that the information given by health care providers is often generalized and nonspecific, requiring them to search for supplementary information to fit their needs.

OBJECTIVE

The aim of our study was to determine whether Heali, a novel artificial intelligence dietary mobile app can improve adherence to the LFD, IBS symptom severity, and quality of life outcomes in adults with IBS or IBS-like symptoms over a 4-week period.

METHODS

Participants were randomized into 2 groups: the control group (CON), in which participants received educational materials, and the experimental group (APP), in which participants received access to the mobile app and educational materials. Over the course of this unblinded online trial, all participants completed a battery of 5 questionnaires at baseline and at the end of the trial to document IBS symptoms, quality of life, LFD knowledge, and LFD adherence.

RESULTS

We enrolled 58 participants in the study (29 in each group), and 25 participants completed the study in its entirety (11 and 14 for the CON and APP groups, respectively). Final, per-protocol analyses showed greater improvement in quality of life score for the APP group compared to the CON group (31.1 and 11.8, respectively; P=.04). Reduction in total IBS symptom severity score was 24% greater for the APP group versus the CON group. Although this did not achieve significance (-170 vs -138 respectively; P=.37), the reduction in the subscore for bowel habit dissatisfaction was 2-fold greater for the APP group than for the CON group (P=.05).

CONCLUSIONS

This initial study provides preliminary evidence that Heali may provide therapeutic benefit to its users, specifically improvements in quality of life and bowel habits. Although this study was underpowered, findings from this study warrant further research in a larger sample of participants to test the efficacy of Heali app use to improve outcomes for patients with IBS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04256551; https://clinicaltrials.gov/ct2/show/NCT04256551.

Evidence That Daily Vinegar Ingestion May Contribute to Erosive Tooth Wear in Adults

Vinegar ingestion at mealtime is gaining popularity for its antiglycemic effects; however, it is among the most acidic consumable substances. This study examined tooth wear in healthy adults participating in an 8-week randomized trial examining the effect of daily vinegar ingestion on insulin sensitivity and visceral fat reduction. Twice daily participants consumed a vinegar drink (two tablespoons vinegar in a cup of water; 3.6 g acetic acid) or a commercial vinegar pill (control, 0.045 g acetic acid) at mealtime. Participants were screened for dental erosion using the basic erosive wear examination (BEWE) by a blinded registered dental hygienist at trial baseline and week 8. Mean BEWE scores did not change in the control group but increased 18% in the vinegar group over the 8-week study (P = .038). Given the current popularity of vinegar as a medicinal agent, practitioners should caution patients who utilize this strategy on the possibility of erosive tooth wear. Trial registration: This trial was registered at ClinicalTrials.gov (NCT03577834) on July 5, 2018 and the institutional review board at Arizona State University provided ethical approval (STUDY00005418).

No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial

There are conflicting reports regarding the efficacy of plant versus animal-derived protein to support muscle and strength development with resistance training. The purpose of this study was to determine whether soy and whey protein supplements matched for leucine would comparably support strength increases and muscle growth following 12 weeks of resistance training. Sixty-one untrained young men (n = 19) and women (n = 42) (18–35 year) enrolled in this study, and 48 completed the trial (17 men, 31 women). All participants engaged in supervised resistance training 3×/week and consumed 19 grams of whey protein isolate or 26 grams of soy protein isolate, both containing 2 g (grams) of leucine. Multi-level modeling indicated that total body mass (0.68 kg; 95% CI: 0.08, 1.29 kg; p < 0.001), lean body mass (1.54 kg; 95% CI: 0.94, 2.15 kg; p < 0.001), and peak torque of leg extensors (40.27 Nm; 95% CI: 28.98, 51.57 Nm, p < 0.001) and flexors (20.44 Nm; 95% CI: 12.10, 28.79 Nm; p < 0.001) increased in both groups. Vastus lateralis muscle thickness tended to increase, but this did not reach statistical significance (0.12 cm; 95% CI: −0.01, 0.26 cm; p = 0.08). No differences between groups were observed (p > 0.05). These data indicate that increases in lean mass and strength in untrained participants are comparable when strength training and supplementing with soy or whey matched for leucine.

Mung Bean Protein Supplement Improves Muscular Strength in Healthy, Underactive Vegetarian Adults

Although vegetarian diets are considered generally protective against chronic disease, nutrient deficiencies, including protein, are possible due to low bioavailability from plant-based sources. The consequences of inadequate dietary protein include reduced lean body mass (LBM) and muscle weakness. This study examined relationships between protein intake, strength, and LBM in 37 underactive vegetarians and recorded the impact of protein supplementation (18 g/day mung bean protein) on these indices utilizing an eight-week, randomized, controlled, feeding trial. Both handgrip and knee flexor and extensor strength were measured at baseline and week eight. At baseline, LBM was significantly related to grams of protein consumed daily. LBM was also correlated to grip strength (r = 0.569, p < 0.001) and lower body strength (r = 0.763 to 0.784; p < 0.001). Twenty-five vegetarians completed the feeding trial, including 11 in the protein supplementation group (PRO) and 14 in the control group (CON). At the end of the trial, LBM and strength did not differ significantly between groups. However, the average percent change for grip, flexor, and extensor strength did differ between PRO and CON participants (+2.9 ± 7.2% and −2.6 ± 7.3% respectively, p = 0.05). Thus, there were strong associations between dietary protein, LBM, and strength in vegetarians and an indication that supplementary vegetarian protein increased strength in the absence of exercise and independent of LBM.

Health Biomarkers in Adults Are More Closely Linked to Diet Quality Attributes Than to Plant-Based Diet Categorization

Although plant-based diets are promoted for healthy outcomes, these diets are not synonymous with high-quality diets. Plant-based diets can include highly processed, less healthful foods, including savory snacks, pastries, and sugary fruit drinks. This cross-sectional study examined the diet quality of vegetarian and omnivorous adults, matched for gender, age, and adiposity, and related diet quality to standard health biomarkers. Diet quality was assessed using the Rapid Eating and Activity Assessment for Participants Short Version questionnaire. Participants (17 vegetarians and 16 omnivores; 28.2 ± 8.9 years; 22.5 ± 2.7 kg/m²) were non-smokers and healthy by self-report. The median duration of adherence to the vegetarian diet was 27 months. Physical activity level and diet quality did not differ significantly between diet groups. Moreover, health biomarkers did not differ by diet groups. When participants were regrouped by low versus high diet quality, health biomarkers differed significantly between groups for fasting insulin, HOMA-IR, triglyceride (TG)/HDL ratio, and blood folate, with more favorable levels in the group with high diet quality. These data suggest that health biomarkers more closely align with diet quality attributes than with plant-based diet categorization. Thus, messaging focused on healthy diet attributes may lead to better health outcomes than the simple promotion of plant-based diets.

High-nitrate salad increased plasma nitrates/nitrites and brachial artery flow-mediated dilation in postmenopausal women: A pilot study

Cardiovascular disease risk is elevated in postmenopausal women relative to men of the same age or to younger, premenopausal women. This elevated risk is closely linked to the loss of estrogen, which is a potent stimulator of the vasodilator nitric oxide. While studies have largely supported dietary nitrate supplementation (typically concentrated beetroot juice) to augment plasma nitric oxide, these studies focused mainly on improving vascular fitness of athletes or patient populations. The purpose of this controlled crossover trial was to assess the feasibility of consuming a high-nitrate, leafy green salad twice daily for 10 consecutive days versus a low-nitrate, canned vegetable control (beans, corn, or peas) on plasma nitrate/nitrite concentration and measures of cardiovascular health in postmenopausal women. We hypothesized that plasma nitrate/nitrite concentration and flow-mediated dilation would improve following the leafy green salad treatment. Ten women (52.6 ± 4.9 y; 26.4 ± 6.4 kg/m²) completed the two 10-day treatment periods separated by 2-3 weeks washout. The mean fasting plasma nitrate/nitrite concentration was significantly increased following the high-nitrate salad treatment compared to the control (+156% and+ 16% respectively; P = .002, effect size = 0.661). Flow-mediated dilation responded favorably to the high nitrate salad in comparison to the canned vegetable condition (+17% versus -8% respectively; P = .047, effect size = 0.407); however, there were no treatment effects on peripheral or derived central-aortic blood pressure. These data suggest that daily ingestion of nitrate-rich, leafy green salads may prove a useful strategy for improving cardiovascular health in postmenopausal women.

Daily red wine vinegar ingestion for eight weeks improves glucose homeostasis and affects the metabolome but does not reduce adiposity in adults

This is the first study to investigate the effects of vinegar on adiposity and glycemia using both anthropometrics and metabolomics.

Rapid Eating Assessment for Participants [shortened version] scores are associated with Healthy Eating Index-2010 scores and other indices of diet quality in healthy adult omnivores and vegetarians

The Healthy Eating Index-2010 is a measure of diet quality as portrayed by the Dietary Guidelines for Americans; however, computing the Healthy Eating Index score is time consuming and requires trained personnel. The Rapid Eating Assessment for Participants [shortened version] is a simple measure that quickly, in less than 10 min, assesses diet quality in a clinical or research setting. This research evaluated the degree of correlation between these two methods of scoring diet quality, as well as between these methods and other indicators of diet quality, including the nutrient density of the diet, the dietary potential renal acid load, urine pH, and plasma vitamin C concentrations. The research design was a secondary data analysis, and participants were healthy adults (n = 81) self-classified as omnivorous, vegetarian, or vegan. Confounding variables were identified and controlled using partial correlations. The two methods of scoring diet quality were significantly correlated (r = 0.227, p = 0.047). Both the Healthy Eating Index and the Rapid Eating Assessment for Participants scoring methods were correlated to nutrient density of the diets (r = 0.474 and r = 0.472 respectively, p < 0.001) as well as to the dietary potential renal acid load and urinary pH (r ranging from 0.304-0.341, p ≤ 0.002). The Rapid Eating Assessment for Participants, but not the Healthy Eating Index, was significantly correlated to plasma vitamin C concentrations (r = 0.500, p < 0.001 and 0.192, p = 0.095 respectively). These results in combination with ease of use and low cost suggest that the Rapid Eating Assessment for Participants measure is a useful tool for assessing diet quality.

Use of Novel High-Protein Functional Food Products as Part of a Calorie-Restricted Diet to Reduce Insulin Resistance and Increase Lean Body Mass in Adults: A Randomized Controlled Trial

Significant reductions in insulin resistance (IR) can be achieved by either calorie restriction or by the increase of lean mass. However, calorie restriction usually results in significant loss of lean mass. A 6-week randomized controlled feeding trial was conducted to determine if a calorie-restricted, high-protein diet (~125 g protein/day consumed evenly throughout the day) using novel functional foods would be more successful for reducing IR in comparison to a conventional diet (~80 g protein/day) with a similar level of calorie restriction. Healthy adults (age 20-75 years; body mass index, 20-42 kg/m²) with raised triglyceride/high-density lipoprotein ratios were randomly assigned to the control group (CON: test foods prepared using gluten-free commercial pasta and cereal) or to the high-protein group (HPR: test foods prepared using novel high-protein pasta and cereal both rich in wheat gluten). Mean weight loss did not differ between groups (-2.7 ± 2.6 and -3.2 ± 3.0 kg for CON (n = 11) and HPR (n = 10) respectively, p = 0.801); however, the 6-week change in fat-free mass (FFM) differed significantly between groups (-0.5 ± 1.5 and +1.5 ± 3.8 kg for CON and HPR respectively, p = 0.008). IR improved in HPR vs. CON participants (homeostasis model assessment-estimated insulin resistance [HOMAIR] change: -1.7 ± 1.4 and -0.7 ± 0.7 respectively; p = 0.020). The change in HOMA-IR was related to the change in FFM among participants (r = -0.511, p = 0.021). Thus, a high-protein diet using novel functional foods combined with modest calorie restriction was 140% more effective for reducing HOMA-IR in healthy adults compared to a lower protein, standard diet with an equal level of calorie restriction.

Examining the Impact of Adherence to a Vegan Diet on Acid-Base Balance in Healthy Adults

Acidogenic diets, commonly measured by the potential renal acid load (PRAL), have been linked with metabolic diseases including insulin resistance, hepatic dysfunction, and cardiometabolic risk. Vegan diets are linked to low dietary acid loads, but the degree of adherence to a vegan diet to demonstrate this benefit is unknown. This study compared the change in PRAL and urine pH of omnivores who followed a vegan diet for either 2, 3, or 7 days over one week. Healthy adults were recruited from a campus population and randomly assigned to one of the three groups: VEG7 (vegan diet followed for seven consecutive days); VEG3 (vegan diet followed for three evenly spaced days over one week); or VEG2 (vegan diet followed for two evenly spaced days over one week). Gender, age, and body mass index did not differ between groups (overall: 21.8 ± 2.4 y and 24.4 ± 5.6 kg/m²). Following the one week intervention, outcome measures did not vary between the VEG2 and VEG3 groups, and these groups were collapsed for the final analyses. The 24-h urine pH was raised after seven consistent days of vegan diet adherence and was unchanged after 2-3 days of vegan diet adherence over the course of a week (+0.52 ± 0.69 and -0.02 ± 0.56 respectively, p = 0.048). However, dietary PRAL scores fell significantly in both dietary groups during the 7-day trial. Since low dietary PRAL scores have been related to improve metabolic parameters, adoption of a vegan diets for several days per week should be explored as a diet strategy to lower disease risk.

Vitamin D Supplementation Appears to Increase Plasma Aβ40 in Vitamin D Insufficient Older Adults: A Pilot Randomized Controlled Trial

Low plasma amyloid-β (Aβ) is linked to Alzheimer's disease. Since vitamin D cleared brain Aβ in vitro, this 8-week trial examined whether vitamin D increased plasma Aβ40. Vitamin D insufficient adults (6/18 M/F; 64.3 ± 10.9 y) were randomized to placebo or vitamin (50,000 IU/week) treatments. The vitamin group experienced greater plasma Aβ40 change than controls, +14.9 ± 12.0 and +12.8 ± 12.8 pg/mL (p = 0.045; effect size, 0.228). Change in Aβ40 for older participants (≥60 y) was +18.3 ± 33.6 and -3.2 ± 44.5 pg/mL for vitamin (n = 4) and placebo (n = 4) groups (effect size, 0.295). Thus, vitamin D may increase plasma Aβ, particularly in older adults, suggesting decreased brain Aβ.

Cardiorespiratory Fitness and Peak Torque Differences between Vegetarian and Omnivore Endurance Athletes: A Cross-Sectional Study

In spite of well-documented health benefits of vegetarian diets, less is known regarding the effects of these diets on athletic performance. In this cross-sectional study, we compared elite vegetarian and omnivore adult endurance athletes for maximal oxygen uptake (VO2 max) and strength. Twenty-seven vegetarian (VEG) and 43 omnivore (OMN) athletes were evaluated using VO2 max testing on the treadmill, and strength assessment using a dynamometer to determine peak torque for leg extensions. Dietary data were assessed using detailed seven-day food logs. Although total protein intake was lower among vegetarians in comparison to omnivores, protein intake as a function of body mass did not differ by group (1.2 ± 0.3 and 1.4 ± 0.5 g/kg body mass for VEG and OMN respectively, p = 0.220). VO2 max differed for females by diet group (53.0 ± 6.9 and 47.1 ± 8.6 mL/kg/min for VEG and OMN respectively, p < 0.05) but not for males (62.6 ± 15.4 and 55.7 ± 8.4 mL/kg/min respectively). Peak torque did not differ significantly between diet groups. Results from this study indicate that vegetarian endurance athletes’ cardiorespiratory fitness was greater than that for their omnivorous counterparts, but that peak torque did not differ between diet groups. These data suggest that vegetarian diets do not compromise performance outcomes and may facilitate aerobic capacity in athletes.

Plant-Based Nutraceutical Increases Plasma Catalase Activity in Healthy Participants: A Small Double-Blind, Randomized, Placebo-Controlled, Proof of Concept Trial

Oxidative stress resulting from dietary, lifestyle and environmental factors is strongly associated with tissue damage and aging. It occurs when there is either an overproduction of reactive oxygen species (i.e., oxidants) or decreased bioavailability of antioxidants that can scavenge them. The objective of this 12-week double-blind placebo-controlled study was to assess the efficacy of a nutraceutical at augmenting antioxidant status. Healthy adults (25-45 y) were randomized to either a treatment group (Product B, n = 23) or a placebo group (control, n = 20). No significant effect of Product B was observed for anthropometric variables or markers of glucose and lipid regulation. Biomarkers of oxidative stress were likewise not altered following the 12-week intervention. Plasma catalase concentrations were significantly elevated following 12 weeks of Product B as compared to the control group (+6.1 vs. -10.3 nmol/min/mL, p = 0.038), whereas other measures of antioxidant capacity were not significantly different between the groups. Product B effectively augmented concentrations of the anti-aging antioxidant catalase in healthy adults.

Examining the utility of a laser device for measuring height in free-living adults and children

Background

Height is an important health assessment measure with many applications. In the medical practice and in research settings, height is typically measured with a stadiometer. Although lasers are commonly used by health professionals for measurement including facial imaging, corneal thickness, and limb length, it has not been utilized for measuring height. The purpose of this feasibility study was to examine the ease and accuracy of a laser device for measuring height in children and adults.

Findings

In immediate succession, participant height was measured in triplicate using a stadiometer followed by the laser device. Measurement error for the laser device was significantly higher than that for the stadiometer (0.35 and 0.20 cm respectively). However, the measurement techniques were highly correlated (r² = 0.998 and 0.990 for the younger [<12 y, n = 25] and older [≥12 y, n = 100] participants respectively), and the estimated reliability between measurement techniques was 0.999 (ICC; 95 % CI: 0.998,1.000) and 0.995 (ICC; 95 % CI: 0.993,0.997) for the younger and older groups respectively. The average differences between the two styles of measurement (e.g., stadiometer minus laser) were significantly different from zero: +0.93 and +0.45 cm for the younger and older groups respectively.

Conclusions

These data demonstrate that laser technology can be adapted to measure height in children and adults. Although refinement is needed, the laser device for measuring height merits further development.

Eating in the absence of hunger in college students

Nearly one-third of college students are overweight or obese. Disinhibited eating, a phenomenon defined as the lack of self-restraint over food consumption prompted by emotional or external factors, is prevalent among college students and may be a target for intervention in this population. Eating in the absence of hunger (EAH) is a form of disinhibited eating that has been studied extensively in children and adolescents, but there is little investigation of EAH among college students. In this research, a validated measure for assessing continual and beginning EAH in children and adolescents was modified and assessed in a free-living college population (n = 457; 84% F; 24.5 ± 7.6 years; 23.4 ± 4.8 kg/m(2)). Nine subscales grouped into three latent factors (emotion, external, and physical) accounted for 68% of the variance in continual EAH, and a separate set of nine subscales grouped into the same latent factors accounted for 71% of the variance in beginning EAH (Cronbach's alpha: 0.82 for continual EAH and 0.81 for beginning EAH). Female sex and sedentary behavior were significantly related to continual EAH, relationships driven by scores for the emotion factor, and to beginning EAH, relationships driven by scores for the physical factor. BMI was weakly related to the emotion factor (p = 0.06) for continuing EAH only. The observation that a sedentary lifestyle was associated to EAH (both continuing and beginning EAH) in a college population is a novel finding and reveals a possible strategy to moderate EAH.

Comparison of correlates of bone mineral density in individuals adhering to lacto-ovo, vegan, or omnivore diets: a cross-sectional investigation

Vegetarian diets are associated with factors that may not support bone health, such as low body mass and low intakes of protein; yet, these diets are alkaline, a factor that favors bone mineral density (BMD). This study compared the correlates of BMD in young, non-obese adults consuming meat-based (n = 27), lacto-ovo vegetarian (n = 27), or vegan (n = 28) diets for ≥1 year. A 24 h diet recall, whole body DXA scan, 24 h urine specimen, and fasting blood sample were collected from participants. BMD did not differ significantly between groups. Protein intake was reduced ~30% in individuals consuming lacto-ovo and vegan diets as compared to those consuming meat-based diets (68 ± 24, 69 ± 29, and 97 ± 47 g/day respectively, p = 0.006); yet dietary protein was only associated with BMD for those following vegan diets. Urinary pH was more alkaline in the lacto-ovo and vegan groups versus omnivores (6.5 ± 0.4, 6.7 ± 0.4, and 6.2 ± 0.4 respectively, p = 0.003); yet urinary pH was associated with BMD in omnivores only. These data suggest that plant-based diets are not detrimental to bone in young adults. Moreover, diet prescriptions for bone health may vary among diet groups: increased fruit and vegetable intake for individuals with high meat intakes and increased plant protein intake for individuals who follow a vegetarian diet plan.

Dietary self-monitoring, but not dietary quality, improves with use of smartphone app technology in an 8-week weight loss trial

OBJECTIVE

Dietary self-monitoring is linked to improved weight loss success. Mobile technologies, such as smartphone applications (apps), might allow for improved dietary tracking adherence. The authors assessed the use of a popular smartphone app for dietary self-monitoring and weight loss by comparing it with traditional diet counseling and entry methods.

METHODS

Diet tracking and weight loss were compared across participants during an 8-week weight loss trial. Participants tracked intake using 1 of 3 methods: the mobile app "Lose It!", the memo feature on a smartphone, or a traditional paper-and-pencil method.

RESULTS

App users (n = 19) recorded dietary data more consistently compared with the paper-and-pencil group (n = 15; P = .042) but not the memo group (n = 13). All groups lost weight over the course of the study (P = .001), and no difference in weight loss was noted between groups.

CONCLUSIONS AND IMPLICATIONS

Smartphone apps could represent a novel and feasible dietary self-monitoring method for individuals.

Vitamin C supplementation slightly improves physical activity levels and reduces cold incidence in men with marginal vitamin C status: a randomized controlled trial

The early indications of vitamin C deficiency are unremarkable (fatigue, malaise, depression) and may manifest as a reduced desire to be physically active; moreover, hypovitaminosis C may be associated with increased cold duration and severity. This study examined the impact of vitamin C on physical activity and respiratory tract infections during the peak of the cold season. Healthy non-smoking adult men (18–35 years; BMI < 34 kg/m²; plasma vitamin C < 45 µmol/L) received either 1000 mg of vitamin C daily (n = 15) or placebo (n = 13) in a randomized, double-blind, eight-week trial. All participants completed the Wisconsin Upper Respiratory Symptom Survey-21 daily and the Godin Leisure-Time Exercise Questionnaire weekly. In the final two weeks of the trial, the physical activity score rose modestly for the vitamin C group vs. placebo after adjusting for baseline values: +39.6% (95% CI [−4.5,83.7]; p = 0.10). The number of participants reporting cold episodes was 7 and 11 for the vitamin C and placebo groups respectively during the eight-week trial (RR = 0.55; 95% CI [0.33,0.94]; p = 0.04) and cold duration was reduced 59% in the vitamin C versus placebo groups (−3.2 days; 95% CI [−7.0,0.6]; p = 0.06). These data suggest measurable health advantages associated with vitamin C supplementation in a population with adequate-to-low vitamin C status.

Sodium benzoate-rich beverage consumption is associated with increased reporting of ADHD symptoms in college students: a pilot investigation

OBJECTIVE

Sodium benzoate, a common additive in popular beverages, has recently been linked to ADHD. This research examined the relationship between sodium benzoate-rich beverage ingestion and symptoms related to ADHD in college students.

METHOD

College students (N = 475) completed an anonymous survey in class in fall 2010. The survey assessed recent intake of a noninclusive list of sodium benzoate-rich beverages and ADHD-related symptoms using a validated screener.

RESULTS

Sodium benzoate-rich beverage intake was significantly associated with ADHD-related symptoms (p = .001), and significance was retained after controlling for covariates. Students scoring ≥4 on the screener (scores that may be consistent with ADHD; n = 67) reported higher intakes (34.9 ± 4.4 servings/month) than the remainder of the sample (16.7 ± 1.1 servings/month).

CONCLUSION

These data suggest that a high intake of sodium benzoate-rich beverages may contribute to ADHD-related symptoms in college students and warrants further investigation.

The effect of peanut and grain bar preloads on postmeal satiety, glycemia, and weight loss in healthy individuals: an acute and a chronic randomized intervention trial

BACKGROUND

Peanut consumption favorably influences satiety. This study examined the acute effect of peanut versus grain bar preloads on postmeal satiety and glycemia in healthy adults and the long-term effect of these meal preloads on body mass in healthy overweight adults.

METHODS

In the acute crossover trial (n = 15; 28.4 ± 2.9 y; 23.1 ± 0.9 kg/m2), the preload (isoenergetic peanut or grain bar with water, or water alone) was followed after 60 min with ingestion of a standardized glycemic test meal. Satiety and blood glucose were assessed immediately prior to the preload and to the test meal, and for two hours postmeal at 30-min intervals. In the parallel-arm, randomized trial (n = 44; 40.5 ± 1.6 y, 31.8 ± 0.9 kg/m2), the peanut or grain bar preload was consumed one hour prior to the evening meal for eight weeks. Body mass was measured at 2-week intervals, and secondary endpoints included blood hemoglobin A1c and energy intake as assessed by 3-d diet records collected at pre-trial and trial weeks 1 and 8.

RESULTS

Satiety was elevated in the postprandial period following grain bar ingestion in comparison to peanut or water ingestion (p = 0.001, repeated-measures ANOVA). Blood glucose was elevated one hour after ingestion of the grain bar as compared to the peanut or water treatments; yet, total glycemia did not vary between treatments in the two hour postprandial period. In the 8-week trial, body mass was reduced for the grain bar versus peanut groups after eight weeks (-1.3 ± 0.4 kg versus -0.2 ± 0.3 kg, p = 0.033, analysis of covariance). Energy intake was reduced by 458 kcal/d in the first week of the trial for the grain bar group as compared to the peanut group (p = 0.118). Hemoglobin A1c changed significantly between groups during the trial (-0.25 ± 0.07% and -0.18 ± 0.12% for the grain bar and peanut groups respectively, p = 0.001).

CONCLUSIONS

Compared to an isoenergetic peanut preload, consumption of a grain bar preload one hour prior to a standardized meal significantly raised postmeal satiety. Moreover, consumption of the grain bar prior to the evening meal was associated with significant weight loss over time suggesting that glycemic carbohydrate ingestion prior to meals may be a weight management strategy.