The Effect of Berry Consumption on Oxidative Stress Biomarkers: A Systematic Review of Randomized Controlled Trials in Humans.

Bioactive compounds in berries may scavenge reactive oxygen and nitrogen species by donating electrons to free radicals, thereby protecting DNA, proteins, and lipids from oxidative damage. Evidence shows that berry consumption has beneficial health effects, though it remains unclear whether berries exert a significant impact on oxidative stress in humans. Thus, we performed a systematic review of randomized controlled trials (RCT) to examine the effects of non-acute (more than a single dose and ≥7 days) berry consumption on biomarkers of oxidative stress. Searches were conducted in PubMed, Cochrane Library, and Scopus; results were imported into Covidence for screening and data extraction. The literature search identified 622 studies that were screened, and 131 full-text studies assessed for eligibility. Ultimately, 28 RCTs met the eligibility criteria. Common biomarkers of oxidative stress (antioxidants, DNA damage, isoprostanes, malondialdehyde, and oxidized LDL) were systematically reviewed, and results were reported narratively. Of the approximate 56 oxidative stress biomarkers evaluated in the 28 RCTs, 32% of the biomarkers were reported to have statistically significant beneficial results and 68% of the biomarkers were reported as having no statistically significant differences. More well-designed and longer-term berry RCTs are needed to evaluate biomarkers of oxidative stress.

Distance Education in Nutrition and Dietetics Education over the Past 30 Years: A Narrative Review.

The coronavirus disease 2019 pandemic necessitated the use of distance education, which sparked a technological transformation that was long overdue in higher education. The purpose of this narrative review is two-fold: to summarize the state of knowledge regarding distance education in nutrition and dietetics education over the past 30 years to inform recommendations for future education/research and implications for practice and to determine the influence that distance education has had on the knowledge, skills, and attitudes of both nutrition and dietetics educators and their students. A narrative review of 822 publications yielded 25 that met the search criteria. In the scope of 30 years, the literature shows that attitudes and perceptions of distance education have changed as barriers to online access have diminished and the availability of online nutrition and dietetics courses and Accreditation Council for Education in Nutrition and Dietetics-accredited distance education programs has expanded. However, whereas the limited results are promising, the paucity of large-sample research about the use of distance education in nutrition and dietetics education restricts educators' knowledge of and ability to evaluate the learning outcomes of distance programs and courses. Moreover, differences in how accreditors, government agencies, and institutions define distance education could have significant influence on funding and financial aid benefits for students and research. Recommendations for future research and implications for practice are provided given the relevance and importance of distance education to nutrition and dietetics education.

Flavan-3-ols and Cardiometabolic Health: First Ever Dietary Bioactive Guideline.

Guideline recommendation for a plant bioactive such as flavan-3-ols is a departure from previous recommendations because it is not based on deficiencies but rather improvement in health outcomes. Nevertheless, there is a rapidly growing body of clinical data reflecting benefits of flavan-3-ol intake that outweigh potential harms. Thus, the objective of the Expert Panel was to develop an intake recommendation for flavan-3-ols and cardiometabolic outcomes to inform multiple stakeholders including clinicians, policymakers, public health entities, and consumers. Guideline development followed the process set forth by the Academy of Nutrition and Dietetics, which includes use of the Evidence to Decision Framework. Studies informing this guideline (157 randomized controlled trials and 15 cohort studies) were previously reviewed in a recently published systematic review and meta-analysis. Quality and strength-of-evidence along with risk-of-bias in reporting was reviewed. In drafting the guideline, data assessments and opinions by authoritative scientific bodies providing guidance on the safety of flavan-3-ols were considered. Moderate evidence supporting cardiometabolic protection resulting from flavan-3-ol intake in the range of 400-600 mg/d was supported in the literature. Further, increasing consumption of dietary flavan-3-ols can help improve blood pressure, cholesterol concentrations, and blood sugar. Strength of evidence was strongest for some biomarkers (i.e., systolic blood pressure, total cholesterol, HDL cholesterol, and insulin/glucose dynamics). It should be noted that this is a food-based guideline and not a recommendation for flavan-3-ol supplements. This guideline was based on beneficial effects observed across a range of disease biomarkers and endpoints. Although a comprehensive assessment of available data has been reviewed, evidence gaps identified herein can inform scientists in guiding future randomized clinical trials.

The Effects of Berry Polyphenols on the Gut Microbiota and Blood Pressure: A Systematic Review of Randomized Clinical Trials in Humans.

Berry consumption has beneficial effects on blood pressure. Intestinal microbiota transform berry phytochemicals into more bioactive forms. Thus, we performed a systematic review of randomized clinical trials to determine whether berry polyphenols in foods, extracts or supplements have effects on both the profile of gut microbiota and systolic and diastolic blood pressure in humans. PubMed, Cochrane Library, Scopus, and CAB Abstracts (EBSCOhost) were searched for randomized clinical trials in humans published from 1 January 2011 to 29 October 2021. Search results were imported into Covidence for screening and data extraction by two blinded reviewers, who also performed bias assessment independently. The literature search identified 216 publications; after duplicates were removed, 168 publications were screened with 12 full-text publications assessed for eligibility. Ultimately three randomized clinical trials in humans met the eligibility criteria. One randomized clinical trial showed a low risk of bias while the other two randomized clinical trials included low, high or unclear risk of bias. Together the randomized clinical trials showed that berry consumption (Aronia berry, strawberries, raspberries, cloudberries and bilberries) for 8-12 weeks had no significant effect on both blood pressure and the gut microbiota. More randomized clinical trials are needed to determine the effects of berry consumption on the profile of gut microbiota and blood pressure in humans.

Effect of Blueberry Consumption on Cardiometabolic Health Parameters in Men with Type 2 Diabetes: An 8-Week, Double-Blind, Randomized, Placebo-Controlled Trial.

BACKGROUND: Blueberries are dietary sources of polyphenols, specifically anthocyanins. Anthocyanins have been identified as having a strong association with type 2 diabetes risk reduction; however, to date few human clinical trials have evaluated the potential beneficial health effects of blueberries in populations with type 2 diabetes. OBJECTIVES: We investigated the effects of blueberry consumption for 8 wk on cardiometabolic parameters in men with type 2 diabetes. METHODS: In a double-blind, parallel-arm, randomized controlled trial, 52 men who are US veterans [mean baseline characteristics: age, 67 y (range: 51-75 y); weight, 102 kg (range: 80-130 kg); BMI (in kg/m2), 34 (range: 26-45)] were randomly assigned to 1 of 2 intervention groups. The interventions were either 22 g freeze-dried blueberries or 22 g placebo. The study participants were asked to consume 11 g freeze-dried blueberries or placebo with each of their morning and evening meals along with their typical diet. RESULTS: Mean ± SE hemoglobin A1c (7.1% ± 0.1% compared with 7.5% ± 0.2%; P = 0.03), fructosamine (275.5 ± 4.1 compared with 292.4 ± 7.9 µmol/L; P = 0.04), triglycerides (179.6 ± 10.1 compared with 199.6 ± 19.9 mg/dL; P = 0.03), aspartate transaminase (23.2 ± 1.4 compared with 30.5 ± 2.7 units/L; P = 0.02), and alanine transaminase (35.6 ± 1.5 compared with 48.3 ± 2.9 units/L; P = 0.0003) were significantly lower for those consuming blueberries for 8 wk than for those consuming the placebo. Fasting plasma glucose concentrations; serum insulin, total cholesterol, LDL-cholesterol, HDL-cholesterol, and C-reactive protein concentrations; blood pressure; and body weight were not significantly different after 8 wk consumption of blueberries compared with the placebo. CONCLUSIONS: Consumption of 22 g freeze-dried blueberries for 8 wk may beneficially affect cardiometabolic health parameters in men with type 2 diabetes.This trial was registered at clinicaltrials.gov as NCT02972996.

Postprandial Effects of Blueberry (Vaccinium angustifolium) Consumption on Glucose Metabolism, Gastrointestinal Hormone Response, and Perceived Appetite in Healthy Adults: A Randomized, Placebo-Controlled Crossover Trial.

The consumption of blueberries, as well as the phenolic compounds they contain, may alter metabolic processes related to type 2 diabetes. The study investigated the effects of adding 140 g of blueberries to a higher-carbohydrate breakfast meal on postprandial glucose metabolism, gastrointestinal hormone response, and perceived appetite. As part of a randomized crossover design study, 17 healthy adults consumed a standardized higher-carbohydrate breakfast along with 2 treatments: (1) 140 g (1 cup) of whole blueberries and (2) a placebo gel (matched for calories, sugars, and fiber of the whole blueberries). Each subject participated in two 2-h meal tests on separate visits ≥8 days apart. Venous blood samples and perceived appetite ratings using visual analog scales were obtained prior to and at 30, 60, 90, and 120 min after consuming the breakfast meals. Results show that glucose metabolism, several gastrointestinal hormones, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), peptide YY (PYY) concentrations and perceived appetite did not change significantly with blueberry consumption. However, pancreatic polypeptide (PP) concentrations were statistically significantly higher (p = 0.0367), and the concentrations were higher during 30, 60, 90, and 120 min after consumption of the blueberry breakfast meal than the placebo breakfast meal. Additional research is needed to determine whether blueberries and other flavonoid-rich foods reduce type 2 diabetes risk by modifying gastrointestinal hormones and perceived appetite.

The My Body Knows When Program Increased Intuitive Eating Characteristics in a Military Population.

INTRODUCTION: The purpose of this pilot study was to assess the effectiveness of the revised My Body Knows When (MBKW) program to promote intuitive eating behaviors within a sample of a military population through an online or in-person delivery mode. MATERIALS AND METHODS: Fifty-six overweight or obese adults (70% female); military service members (20%), retirees (38%) and family (42%) participated in the 10-week MBKW program at two military installations from 2012 to 2014. Body Mass Index, Intuitive Eating Scale-2 (IES-2; 23-item) and Motivation for Eating scale (MFES; 43-item) were collected at baseline and 10-weeks. Data were stratified by sex. Descriptive data were reported as mean ± standard deviation (SD), frequency, or percentage. A paired t-test was conducted with data at baseline and 10 weeks (α = 0.05, 80% power). RESULTS: Participants were predominantly female (70%); mean age of 51 ± 13 years; and BMI of 34.1 ± 5.5 kg/m2. There were no demographic, MFES, or IES-2 baseline differences between groups (in-person vs. online) or location. All subjects were collapsed into one group for a pre-post MBKW implementation assessment due to small sample size despite the original intent to stratify by online and in-person grouping. At 10 weeks, the remaining 26 participants exhibited a significant improvement (mean ± SD) in BMI (-0.4 ± 0.6 kg/m2; p = 0.012), environmental/social eating score (2.7 ± 0.4 points [pts]; -0.5 pt change; p < 0.001), emotional eating score (2.2 ± 0.5 pts; -0.6 pt change; p = 0.001), unconditional permission to eat score (3.4 ± 0.4 pts; +0.3 pt change; p = 0.017), eating for physical rather than emotional eating score (3.7 ± 0.8 pts; +1.0 pt change; p < 0.001), and reliance on hunger and satiety cues score (3.6 ± 0.5 pts; +0.8 pt change; p = 0.001). High attrition rates at the 10-week follow-up assessment precluded accurate assessment of long-term intervention effects. CONCLUSIONS: The MBKW program was associated with improved intuitive eating behaviors and with less external eating influence on behavior; however, a larger sample is required to assess the effectiveness of MBKW delivery mode. Modest weight loss was attained but testing the efficacy of the MBKW program in a large diverse sample with alternate scenarios may be worthwhile (e.g., primary prevention against weight gain, or during weight maintenance to prevent weight regain).

Utility of DXA screening for diagnosis of osteoporosis in US veterans aged 70 years and older.

Dual energy X-ray absorptiometry (DXA) is recommended for osteoporosis screening in men aged 70 years and older but supportive data is limited. The aim of this study was to determine the efficacy of DXA for the diagnosis of increased fragility in this group of subjects. We retrospectively identified men aged 70 years and older without prior history of fracture and/or conditions predisposing to low bone mineral density (BMD) who attended the VA endocrinology clinic and performed DXA for osteoporosis screening. We analyzed the relationship between BMD and demographic, anthropometric data and biochemical parameters using linear regression models. Out of 55 subjects identified, 13 (24%) men had normal BMD, 30 (54%) had osteopenia and 12 (22%) had a diagnosis of osteoporosis based on the femoral neck (FN) T-score. Lumbar spine T-scores were normal in all three groups. Weight and body mass index (BMI) were significantly higher in the normal BMD group compared with the osteopenia and osteoporosis groups (p<0.001). After adjustments for age, weight, BMI, vitamin D concentrations, and diabetes status, differences in the FN BMD among the groups remained significant (p<0.001). Based on the Fracture Risk Assessment Tool (FRAX) score calculations in 43 non-osteoporotic patients, 15 patients with osteopenia had a 10-year hip fracture probability ≥3%. Screening with DXA in male US veterans aged 70 years and older without known osteoporosis risk factors revealed that up to 50% of men may qualify for diagnostic workup to determine the etiology of low BMD and/or to meet criteria to initiate pharmacological therapy to reduce future fracture risk.

Diet Quality Is Lower and Energy Intake Is Higher on Weekends Compared with Weekdays in Midlife Women: A 1-Year Cohort Study.

BACKGROUND: Differences in energy and macronutrient intakes by weekday and weekend have been reported, but there are few data on differences in food group consumption and indices of diet quality. OBJECTIVE: The aim of this study was to describe dietary intake by day and on weekends compared with weekdays. DESIGN: This study utilized a longitudinal cohort design with self-reported dietary intake collected using the Automated Self-Administered 24-Hour Dietary Assessment Tool. PARTICIPANTS/SETTING: Participants were ambulatory women with access to high-speed internet, body mass index between 18 and 35, and aged 40 to 60 years from the Life in All Seasons study (n=52) conducted in Grand Forks, ND, between July 2012 and July 2014. Each woman completed an Automated Self-Administered 24-Hour Dietary Assessment Tool diet recall every 10 days for 1 year. MAIN OUTCOME MEASURES: Primary outcome measures were total and energy intake from macronutrients, food groups (per 1,000 kcal), and Healthy Eating Index-2010 (HEI-2010) scores from 1,866 24-hour recalls. STATISTICAL ANALYSES PERFORMED: Effects of weekend on energy and macronutrient intake, energy-adjusted food groups, and HEI-2010 scores and component scores were tested using mixed linear models. RESULTS: Participants (n=52) completed 1,080 recalls on weekdays and 786 on weekends. Seventy-five percent of women reported consuming more energy on weekends than on weekdays, with a higher mean intake of 158 kcal on weekends (P<0.01). The percentage of energy from carbohydrate (P<0.01) and protein (P<0.01) were both lower on weekends, and percentage of energy from alcohol higher (P<0.01). There was no difference in the percentage of energy from fat (P=0.07). Reported energy intake was greatest on Saturdays and lowest on Tuesdays. On weekends, women had reduced diet quality with more alcoholic beverages, solid fat, and potatoes, and less yogurt, whole fruits, dark green and orange vegetables, poultry, nuts and seeds, and whole grains per 1,000 kcal than on weekdays. HEI-2010 scores were lower on weekends than weekdays (P<0.01). Component scores were lower for whole fruits (P<0.01), greens and beans (P=0.02), whole grains (P<0.01), and dairy (P<0.01). CONCLUSIONS: Midlife women should be encouraged to maintain diet quality during weekends to improve overall diet quality scores.

Metabolic impact of 100% fruit juice consumption on antioxidant/oxidant status and lipid profiles of adults: An Evidence-Based review.

One hundred percent fruit juice (FJ) contains bioactive compounds with antioxidant activity. As such, this fruit form has the potential to improve antioxidant status and mediate outcomes influenced by redox status. A systematic review of the literature published between 1995 and 2013 was conducted using PubMed database to evaluate associations between intake of 100% FJ and markers of antioxidant/oxidant status and blood lipid levels in healthy, free-living adults ≥18 years. Data extraction and analysis was conducted according to the Academy of Nutrition and Dietetics Evidence Analysis Process. Limited evidence from ten clinical trials meeting inclusion/exclusion criteria suggests potential improvements in a variety of antioxidant or oxidants biomarkers postconsumption of 100% FJ. Weak evidence from five studies suggests that one or more blood lipid measures may be positively influenced by consumption of 100% FJ. Heterogeneity in study methodology including biomarkers, 100% FJ type, dosage, and intervention duration precludes the ability to make evidence-based recommendations regarding a specific dose-duration-juice effect. Key characteristics in study designs were identified which must either be controlled or statistically adjusted for in future investigations in order to obtain a more accurate understanding of the complex relationship between metabolic outcomes and consumption of 100% FJ in context of a healthy dietary pattern.

Measures of Diet Quality across Calendar and Winter Holiday Seasons among Midlife Women: A 1-Year Longitudinal Study Using the Automated Self-Administered 24-Hour Recall.

BACKGROUND: Systematic seasonal bias may confound efforts to estimate usual dietary intake and diet quality. Little is known about dietary quality over the winter holiday season. OBJECTIVES: The aims of this study were to test for differences in intakes of energy, percentage of energy from macronutrients, fruits and vegetables, and diet quality measured using the Healthy Eating Index 2010 (HEI-2010) by calendar and winter holiday seasons. DESIGN: Longitudinal cohort design. PARTICIPANTS/SETTING: Data were derived from the Life in All Seasons study. Two cohorts of women aged 40 to 60 years (N=52) from the greater Grand Forks, ND, area were followed for 1 year each between July 2012 and July 2014. Each woman completed an online diet recall using the Automated Self-Administered 24-Hour Recall every 10 days during the year, with a 92% response rate. STATISTICAL ANALYSES: Effects of calendar and winter holiday seasons on intakes of energy, percent energy from macronutrients, HEI-2010 total and component scores, and grams per day of individual fruits and vegetables were tested using mixed linear models. RESULTS: The mean total HEI-2010 score was 60.1±1.4. There were seasonal differences in some HEI-2010 component scores, but not in total scores. More lettuce or mixed lettuce salad was consumed during summer than during winter (P=0.034), and more fresh tomatoes were consumed during summer and fall compared with winter (P=0.001). More corn, berries, peaches and nectarines, and melons (P<0.001) were consumed during summer. There was no seasonal difference in reported intakes of energy (P=0.793). The total HEI-2010 score for dietary intake observed over the winter holiday season was lower than the rest of the year (P<0.001). Reported energy intake was not different (P=0.228). CONCLUSIONS: In this population, diet quality is significantly lower during the winter holiday period, but mostly consistent by season. Multiple recalls in any season can give a reasonable representation of usual overall diet quality throughout the year.

Phosphate homeostasis, parathyroid hormone, and fibroblast growth factor 23 in stages 3 and 4 chronic kidney disease.

AIMS: Increased concentrations of parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) often coincide with normal serum phosphorus ([P]s) in chronic kidney disease (CKD). We hypothesized that the phosphate concentration ([P]f) in the cortical distal nephron (CDN) determines [PTH] and [FGF23] in this circumstance. METHODS: We studied 29 patients with CKD at 4 visits and 28 controls at 1 visit. Assuming GFR = creatinine clearance (Ccr), we examined the following regressions: [P]s on its determinants, EP/Ccr and TRP/Ccr (P excretion and reabsorption per volume of filtrate); [PTH] and [FGF23] on [P]s and EP/Ccr; and TRP/Ccr on [PTH] and [FGF23]. We assumed that EP/Ccr is proportional to [P]f in the CDN. RESULTS: In controls, [P]s correlated with TRP/Ccr but not EP/Ccr. [PTH] and [FGF23] were unrelated to [P]s, EP/Ccr, and TRP/Ccr. In CKD, [P]s correlated with EP/Ccr and TRP/Ccr. [PTH] correlated with [P]s at 2 visits and with EP/Ccr at 4; [FGF23] correlated with [P]s and EP/Ccr at all visits. TRP/Ccr correlated with [FGF23] and [PTH] at one visit each. CONCLUSIONS: [P]f in the CDN, not [P]s, determined [PTH] in CKD. Because [FGF23] was consistently associated with only one determinant of [P]s, EP/Ccr, we infer that [P]f also determined [FGF23]. In patients with CKD, we speculate that [P]f in the CDN regulates FGF23 synthesis at that site.

Impact of 100% Fruit Juice Consumption on Diet and Weight Status of Children: An Evidence-based Review.

Consumption of 100% fruit juice remains controversial for its potential adverse impact on weight and displacement of essential foods in the diets of children. A systematic review of the literature published from 1995-2013 was conducted using the PubMed database to evaluate associations between intake of 100% fruit juice and weight/adiposity and nutrient intake/adequacy among children of 1 to 18 years of age. Weight status outcome measures included body mass index (BMI), BMI z-score, ponderal index, obesity, weight gain, adiposity measures, and body composition. Nutrient outcome measures included intake and adequacy of shortfall nutrients. Data extraction and analysis was conducted according to the Academy of Nutrition and Dietetics Evidence Analysis Process. Twenty-two studies on weight status provided evidence that did not support an association between 100% fruit juice consumption and weight/adiposity in children after controlling for energy intake. Limited evidence from eight studies suggests that children consuming 100% fruit juice have higher intake and adequacy of dietary fiber, vitamin C, magnesium, and potassium. Differences in methodology and study designs preclude causal determination of 100% fruit juice as sole influencer of weight status or nutrient intake/adequacy of shortfall nutrients. In context of a healthy dietary pattern, evidence suggests that consumption of 100% fruit juice may provide beneficial nutrients without contributing to pediatric obesity.

Parameters of phosphorus homeostasis at normal and reduced GFR: empiric observations.

AIMS: Influx (IP) determines urinary excretion of phosphorus (EP). Contributions of IP and reabsorption (TRP) to serum phosphorus ([P]s) can be depicted by normalization to creatinine clearance (EP/Ccr and TRP/Ccr) or by calculation of fractional excretion and reabsorption (FEP and FTRP). We analyzed these parameters at normal and reduced GFR. METHODS: We studied 29 patients with chronic kidney disease (CKD) and 28 controls. From [cr] and [P] in serumand urine we calculated [P]u/[cr]u, EP/Ccr, TRP/Ccr, (TRP/Ccr)/(EP/Ccr), FEP, and FTRP. We compared means between groups and examined pertinent linear regressions. RESULTS: [P]s was not different in CKD and controls. [Cr]s, EP/Ccr, and FEP were higher and TRP/Ccr, (TRP/Ccr)/(EP/Ccr), and FTRP were lower in CKD. [P]u/[cr]u, a surrogate for IP, was similar in both groups. In CKD, [P]s correlated with EP/Ccr and TRP/Ccr; EP/Ccr with [P]u/[cr]u and [cr]s; and FEP with EP/Ccr, TRP/Ccr, [P]u/[cr]u, and [cr]s. In controls, [P]s correlated with TRP/Ccr; EP/Ccr with [P]u/[cr]u; and FEP with EP/Ccr and [P]u/[cr]u. In both groups, FEP was a precise inverse function of (TRP/Ccr)/(EP/Ccr). Despite wide variation in TRP/Ccr, FEP was < 20% in 26/28 controls and > 20% in 27/29 patients with CKD. CONCLUSIONS: GFR affected determinants of [P]s, EP/Ccr, and FEP. FTRP was often dissociated from TRP/Ccr at normal or reduced GFR.

Determinants of Variance in the Habitual Physical Activity of Overweight Adults.

BACKGROUND: The number of days of data and number of subjects necessary to estimate total physical activity (TPA) and moderate-to-vigorous physical activity (MVPA) requires an understanding of within- and between-subject variances, and the influence of sex, body composition, and age. METHODS: Seventy-one adults wore accelerometers for 7-day intervals over 6 consecutive months. RESULTS: Body fat and sex influenced TPA and MVPA. The sources of subject-related variation for TPA and MVPA were within-subject (48.4% and 54.3%), between-subject (34.3% and 31.8%), and calendar effects (17.3% and 13.9%). Based on within-subject variances, the error associated with estimating TPA and MVPA by collecting 1 to 7 days of data ranged from 28.2% to 13.3% for TPA and 62.0% to 28.6% for MVPA. Based on between-subject variances, detecting a 10% difference between 2 groups at a power of 90% requires approximately 200 and 725 subjects per group for TPA and MVPA, respectively. CONCLUSIONS: Estimates of MVPA are more variable than TPA in overweight adults, therefore more days of data are required to estimate MVPA and larger sample sizes to detect treatment differences for MVPA. Log-transforming data reduces the need for additional days of data collection, thereby improving chances of detecting treatment effects.

Use of sevelamer to examine the role of intraluminal phosphate in the pathogenesis of secondary hyperparathyroidism.

AIMS: Parathyroid hormone (PTH) promotes calcium reabsorption in the cortical distal nephron (CDN). The phosphate concentration ([P]f) rises in that segment in chronic kidney disease (CKD); in theory, high [P]f could reduce availability of calcium for reabsorption and necessitate a compensatory rise in [PTH]. With assumptions, [P]f is proportional to phosphate excreted/volume of filtrate (EP/GFR). We therefore hypothesized that [PTH] would correlate with EP/GFR in CKD, and ΔPTH] would correlate with ΔEP/GFR after sevelamer therapy. METHODS: We conducted a 4-week, placebo-controlled trial of sevelamer carbonate in patients with CKD. [PTH]1-84 and parameters of phosphate homeostasis were measured before and after treatment. GFR was assumed to equal creatinine clearance (Ccr). Pertinent linear regressions were performed. RESULTS: Phosphate excretion fell in the sevelamer group only. Decrements in [PTH] with sevelamer differed from increments with placebo. With either treatment, [PTH] correlated with EP/Ccr and ΔPTH] correlated with ΔEP/Ccr. Changes in [PTH] were minimal in some sevelamer recipients despite reductions in EP/Ccr; calcium excreted/volume of filtrate was low in these subjects. CONCLUSIONS: Phosphate influx affected [PTH] in CKD by determining [P]f in the CDN. In some patients, low calcium influx may have blunted the effect of sevelamer on [PTH].

Tubular calcium reabsorption and other aspects of calcium homeostasis in primary and secondary hyperparathyroidism.

AIMS: Primary hyperparathyroidism (PHPT) causes hypercalcemia by increasing tubular calcium reabsorption. Because chronic kidney disease (CKD) is associated with normocalcemia, we inferred that calcium reabsorption is also normal, and hypothesized that normal reabsorption requires excessive parathyroid hormone (PTH) in CKD. METHODS: The following were obtained in controls and patients with CKD or PHPT: estimated GFR (eGFR); concentrations of PTH 1-84, 1,25-dihydroxyvitamin D, and ultrafilterable and ionized calcium ([PTH], [1,25(OH)2D], [Ca]uf, [Ca]i); and ratios of calcium excreted or reabsorbed per volume of filtrate (ECa/Ccr, TRCa/Ccr). Pertinent linear regressions were examined. RESULTS: In CKD, [PTH] was increased, but ECa/Ccr, TRCa/Ccr, [Ca]uf, and [Ca]i equaled control values. [PTH] was inversely related to eGFR but unrelated to [1,25(OH)2D]. TRCa/Ccr was constant at all [PTH]. In PHPT, [PTH] was no higher than in CKD, but TRCa/Ccr, [Ca]uf, and [Ca]i were increased. [1,25(OH)2D] correlated with [PTH]. In controls, TRCa/Ccr varied directly with [1,25(OH)2D] and inversely with [PTH]. CONCLUSIONS: In controls, calcium reabsorption rose with [1,25(OH)2D], and [PTH] fell in response. In PHPT, [PTH] determined [1,25(OH)2D]; together, the hormones increased calcium reabsorption and caused hypercalcemia. In CKD, normal calcium reabsorption required high [PTH].

The metabolizable energy of dietary resistant maltodextrin is variable and alters fecal microbiota composition in adult men.

Resistant maltodextrin (RM) is a novel soluble, nonviscous dietary fiber. Its metabolizable energy (ME) and net energy (NE) values derived from nutrient balance studies are unknown, as is the effect of RM on fecal microbiota. A randomized, placebo-controlled, double-blind crossover study was conducted (n = 14 men) to determine the ME and NE of RM and its influence on fecal excretion of macronutrients and microbiota. Participants were assigned to a sequence consisting of 3 treatment periods [24 d each: 0 g/d RM + 50 g/d maltodextrin and 2 amounts of dietary RM (25 g/d RM + 25 g of maltodextrin/d and 50 g/d RM + 0 g/d maltodextrin)] and were provided all the foods they were to consume to maintain their body weight. After an adaptation period, excreta were collected during a 7-d period. After the collection period, 24-h energy expenditure was measured. Fluorescence in situ hybridization, quantitative polymerase chain reaction, and 454 titanium technology-based 16S rRNA sequencing were used to analyze fecal microbiota composition. Fecal amounts of energy (544, 662, 737 kJ/d), nitrogen (1.5, 1.8, 2.1 g/d), RM (0.3, 0.6, 1.2 g/d), and total carbohydrate (11.1, 14.2, 16.2 g/d) increased with increasing dose (0, 25, 50 g) of RM (P < 0.0001). Fat excretion did not differ among treatments. The ME value of RM was 8.2 and 10.4 kJ/g, and the NE value of RM was -8.2 and 2.0 kJ/g for the 25 and 50 g/d RM doses, respectively. Both doses of RM increased fecal wet weight (118, 148, 161 g/d; P < 0.0001) and fecal dry weight (26.5, 32.0, 35.8 g/d; P < 0.0001) compared with the maltodextrin placebo. Total counts of fecal bacteria increased by 12% for the 25 g/d RM dose (P = 0.17) and 18% for the 50 g/d RM dose (P = 0.019). RM intake was associated with statistically significant increases (P < 0.001) in various operational taxonomic units matching closest to ruminococcus, eubacterium, lachnospiraceae, bacteroides, holdemania, and faecalibacterium, implicating RM in their growth in the gut. Our findings provide empirical data important for food labeling regulations related to the energy value of RM and suggest that RM increases fecal bulk by enhancing the excretion of nitrogen and carbohydrate and the growth of specific microbial populations.

Whey protein but not soy protein supplementation alters body weight and composition in free-living overweight and obese adults.

A double-blind, randomized clinical trial was conducted to determine the effect of consumption of supplemental whey protein (WP), soy protein (SP), and an isoenergetic amount of carbohydrate (CHO) on body weight and composition in free-living overweight and obese but otherwise healthy participants. Ninety overweight and obese participants were randomly assigned to 1 of 3 treatment groups for 23 wk: 1) WP; 2) SP (each providing ~56 g/d of protein and 1670 kJ/d); or 3) an isoenergetic amount of CHO. Supplements were consumed as a beverage twice daily. Participants were provided no dietary advice and continued to consume their free-choice diets. Participants' body weight and composition data were obtained monthly. Dietary intake was determined by 24-h dietary recalls collected every 10 d. After 23 wk, body weight and composition did not differ between the groups consuming the SP and WP or between SP and CHO; however, body weight and fat mass of the group consuming the WP were lower by 1.8 kg (P < 0.006) and 2.3 kg (P < 0.005), respectively, than the group consuming CHO. Lean body mass did not differ among any of the groups. Waist circumference was smaller in the participants consuming WP than in the other groups (P < 0.05). Fasting ghrelin was lower in participants consuming WP compared with SP or CHO. Through yet-unknown mechanisms, different sources of dietary protein may differentially facilitate weight loss and affect body composition. Dietary recommendations, especially those that emphasize the role of dietary protein in facilitating weight change, should also address the demonstrated clinical potential of supplemental WP.

Controlled meal frequency without caloric restriction alters peripheral blood mononuclear cell cytokine production.

BACKGROUND: Intermittent fasting (IF) improves healthy lifespan in animals by a mechanism involving reduced oxidative damage and increased resistance to stress. However, no studies have evaluated the impact of controlled meal frequency on immune responses in human subjects. OBJECTIVE: A study was conducted to establish the effects of controlled diets with different meal frequencies, but similar daily energy intakes, on cytokine production in healthy male and female subjects. DESIGN: In a crossover study design with an intervening washout period, healthy normal weight middle-age male and female subjects (n = 15) were maintained for 2 months on controlled on-site one meal per day (OMD) or three meals per day (TMD) isocaloric diets. Serum samples and peripheral blood mononuclear cells (PBMCs) culture supernatants from subjects were analyzed for the presence of inflammatory markers using a multiplex assay. RESULTS: There were no significant differences in the inflammatory markers in the serum of subjects on the OMD or TMD diets. There was an increase in the capacity of PBMCs to produce cytokines in subjects during the first month on the OMD or TMD diets.Lower levels of TNF-α, IL-17, MCP-1 and MIP-1ß were produced by PBMCs from subjects on the OMD versus TMD diet. CONCLUSIONS: PBMCs of subjects on controlled diets exhibit hypersensitivities to cellular stimulation suggesting that stress associated with altered eating behavior might affect cytokine production by immune cells upon stimulation. Moreover, stimulated PBMCs derived from healthy individuals on a reduced meal frequency diet respond with a reduced capability to produce cytokines.