The Impact of Almond and Walnut Consumption on the Human Fecal Metabolome

Objectives Metabolomic studies can be utilized to generate biomarkers of food intake. Undigested food components affect the fecal microbiota and metabolome. Accordingly, we aimed to identify fecal metabolites unique to almond and walnut consumption. Methods Untargeted metabolomic analyses were completed on 66 endpoint fecal samples from two separate 3-week randomized, controlled-feeding, crossover studies examining almond (n = 30) and walnut (n = 36) consumption in adults (25–75 yr). Control diets, representative of the typical American diet, were fed at weight maintenance with 0 g/day of nuts. During the treatment arms, the base diet was scaled down to allow isocaloric inclusion of 42 g/day of almonds or walnuts. The Kruskal-Wallis H test was used to determine statistically significant metabolites between treatment and control groups with Benjamini-Hochberg false discovery rate adjustments (reported as q-values). Results Of the 318 quantifiable fecal metabolites, 42 were significantly different when comparing the treatment groups to their respective controls after adjustment (q < 0.05). Of these 42 metabolites, 9 were significantly different in both the almond and walnut treatment samples. Two metabolites, palmitoleic acid and p-cresol, were unique to almonds—the relative concentration of palmitoleic acid was higher in the almond group compared to control and p-cresol was lower in almond compared to control. Walnut treatment samples contained 31 unique metabolites, including 15 fatty acyls, the majority of which were higher in the walnut group compared to control. Conclusions Higher concentrations of fecal fatty acyls in the almond and walnut groups compared to their respective controls support previous findings that the plant cell walls of nuts reduce digestibility, therefore, limiting accessibility of intact lipids. Overall, these results reveal promise in identifying fecal biomarkers of food intake for eventual use in personalized dietary recommendations. Ongoing analyses include utilizing machine learning models to further biomarker panel development through incorporation of baseline data and metagenomic analyses. Funding Sources This research was funded by the Foundation for Food and Agriculture Research and the National Center for Supercomputing Applications Faculty Fellowship.

Changes in Serum Antioxidant Vitamin Levels After Consumption of Korean Diet and American Diet Among Korean Adults: A Randomized Controlled Trial

Objectives This study aimed to investigate changes in serum antioxidant vitamin levels after consumption of balanced Korean diet (BKD), recommended American diet (RAD), and typical American diet (TAD) among Korean adults from a randomized controlled trial. Methods Among 54 adults aged 25–65 years with body mass index ≥23 kg/m2 and blood LDL-cholesterol ≥120 mg/dL who finished a crossover feeding study conducted between 2015–2017, 16 subjects were selected for analyses of serum β-carotene, retinol, and α-tocopherol levels at baseline and after consumption of each diet for 4 weeks. Serum antioxidant vitamin levels were measured by high-performance liquid chromatography. Results Mean levels of serum β-carotene, retinol, and α-tocopherol at baseline were 0.37, 0.34, and 7.19 mg/L, respectively. After consumption of BKD, increase in serum β-carotene and retinol levels was observed compared to the baseline, whereas α-tocopherol level was decreased. After consumption of RAD, serum β-carotene, retinol, and α-tocopherol levels were increased. However, retinol level was reduced after consumption of TAD. Conclusions This study may provide evidences about effects of diets on antioxidant vitamin levels in human body. Funding Sources This work was carried out with the support of ‘Research Program for Agricultural Science and Technology Development’, National Institute of Agricultural Science, Rural Development Administration, Republic of Korea (Project No. PJ013475022018).

Influence of cooking skills and nutritional training on dietary choices of incoming chiropractic students

Objective We aimed to identify chiropractic students' cooking skills, perceptions of healthy eating, and influence of prior nutrition training on dietary intake. Methods Two cohorts of incoming graduate students were surveyed to assess nutritional training prior to matriculation, perceptions of healthy eating behaviors, cooking skills, current dietary intake, and barriers to healthy eating. Using independent t tests, correlations, and descriptive statistics, data from the cohorts were assessed. Results The response rate was 88.7% (n = 178). Nutritional training significantly increased perception of nutritional knowledge and confidence in giving nutrition advice. Completion of at least 1 college nutrition course was associated with nearly double students' weekly fatty fish intake. Males were more likely to eat animal protein, and females preferred desserts. Modeling a healthy diet for future patients was rated as being important, yet most students consumed diets consistent with the typical American diet. The leading barriers to healthy eating included lack of time and money. Conclusion Similar to students in other healthcare professions, incoming chiropractic students wish to model healthy behaviors but fail to apply their knowledge and attitudes to their own dietary intakes due to common barriers.

Abstract 51: Effects of Dietary Patterns on Subclinical Cardiac Damage: Results From the DASH Trial

Background: The Dietary Approaches to Stop Hypertension (DASH) diet (rich in fruit (F), vegetables (V), low-fat dairy, and fiber, and reduced in saturated fat and cholesterol) lowered blood pressure (BP) and low-density lipoprotein cholesterol after 8 weeks compared with a typical American diet. However, direct effects on cardiovascular damage are unknown. Hypothesis: The DASH diet reduces cardiac injury, strain, and inflammation compared to a typical American diet. Methods: The DASH feeding study was a 3-arm, parallel-design, randomized controlled trial of adults with systolic BP (SBP) <160 mm Hg and diastolic BP (DBP) of 80-95 mm Hg, without cardiovascular disease (CVD) and not taking BP medications. Participants were randomized to 8 weeks of monitored feeding with: a typical American diet with 3.6 servings of F/V per day (ref), a F/V-enriched diet (8.5 servings of F/V per day), or the DASH diet (9.6 servings of F/V per day). Calories were adjusted to keep weight constant throughout feeding. We compared the effects of these diets on 3 cardiac biomarkers: high-sensitivity cardiac troponin I (hs-cTnI), N-terminal b-type pro natriuretic peptide (NT-proBNP), and high-sensitivity C-reactive protein (hs-CRP), measured in stored serum collected at baseline and after feeding. Results: Of the 257 participants with available specimens, 33% were aged >50 yrs, 48% were women, and 56% were non-white. Mean baseline SBP/DBP was 131/85 mmHg. Compared to control, the F/V-enriched diet reduced hs-cTnI by 53% (95% CI: 18, 73; P = 0.008) and NT-proBNP by 24% (95% CI: 7, 38; P = 0.01) ( Figure ). Similarly, compared to control, DASH reduced hs-cTnI by 49% (95% CI: 11, 71; P = 0.02) and NT-proBNP by 20% (95% CI: 2, 35; P = 0.04). Hs-CRP did not differ between diets, and none of the markers differed between DASH and F/V-enriched diets. Conclusions: In adults with high BP but not CVD, both F/V-enriched and DASH diets lowered sensitive markers of cardiac injury and strain over 8 weeks. Our study demonstrates early, direct cardiovascular benefits from diets rich in F/V.

Challenges in Designing and Delivering Diets and Assessing Adherence: A Randomized Controlled Trial Evaluating the 2010 Dietary Guidelines for Americans

ABSTRACT Background Controlled-feeding trials are challenging to design and administer in a free-living setting. There is a need to share methods and best practices for diet design, delivery, and standard adherence metrics. Objectives This report describes menu planning, implementing, and monitoring of controlled diets for an 8-wk free-living trial comparing a diet pattern based on the Dietary Guidelines for Americans (DGA) and a more typical American diet (TAD) pattern based on NHANES 2009–2010. The objectives were to 1) provide meals that were acceptable, portable, and simple to assemble at home; 2) blind the intervention diets to the greatest extent possible; and 3) use tools measuring adherence to determine the success of the planned and implemented menu. Methods Menus were blinded by placing similar dishes on the 2 intervention diets but changing recipes. Adherence was monitored using daily food checklists, a real-time dashboard of scores from daily checklists, weigh-backs of containers returned, and 24-h urinary nitrogen recoveries. Proximate analyses of diet composites were used to compare the macronutrient composition of the composite and planned menu. Results Meeting nutrient intake recommendations while scaling menus for individual energy intake amounts and food portions was most challenging for vitamins D and E, the sodium-to-potassium ratio, dietary fiber, and fatty acid composition. Dietary adherence for provided foods was &gt;95%, with no differences between groups. Urinary nitrogen recoveries were ∼80% relative to nitrogen intake and not different between groups. Composite proximate analysis matched the plan for dietary fat, protein, and carbohydrates. Dietary fiber was ∼2.5 g higher in the TAD composite compared with the planned menu, but ∼7.4 g lower than the DGA composite. Conclusions Both DGA and TAD diets were acceptable to most participants. This conclusion was supported by self-reported consumption, quantitative weigh-backs of provided food, and urinary nitrogen recovery. Dietary adherence measures in controlled-feeding trials would benefit from standard protocols to promote uniformity across studies. The trial is registered at clinicaltrials.gov as NCT02298725.

Endotoxin May Not Be the Major Cause of Postprandial Inflammation in Adults Who Consume a Single High-Fat or Moderately High-Fat Meal

ABSTRACT Background Metabolic endotoxemia is considered a cause for high-fat diet (HFD)-induced inflammation. However, convincing experimental evidence in humans is scant. Objective We determined whether a HFD or moderately HFD increases LPS and LPS-mediated cytokine production in the postprandial blood (PPB). Methods Ninety-eight volunteers (age: 37.3 ± 1.5 y) from the cross-sectional phenotyping study (PS) and 62 volunteers (age: 26.8 ± 1.2 y) from the intervention study (IS) consumed a breakfast containing 60% kcal fat (HF) and 36% kcal fat (moderately HF), respectively. For the IS, only the results from the placebo group are presented. Blood samples were probed for LPS-mediated cytokine production by incubating them with LPS inhibitor polymyxin B (PMB) for 24 h at 37°C besides the Limulus amebocyte lysate (LAL) assay. Repeated-measures ANOVA was used to compare the temporal changes of metabolic profiles and treatment outcomes. Results At least 87.5% of the plasma LPS measurements in 32 PS volunteers from each time point were below the LAL assay sensitivity (0.002 EU/mL). PMB suppressed IL-1β (P = 0.035) and IL-6 (P = 0.0487) production in the 3 h PPB of the PS after 24 h incubation at 37°C compared to the vehicle control, suggesting the presence of LPS. However, the amount of LPS did not increase the cytokine concentrations in the 3 h PPB above the fasting concentrations. Such suppression was not detected in the PPB of the IS. Treating whole blood with lipoprotein lipase (LPL) significantly (P &lt; 0.05) increased FFA and cytokine (IL-1β, IL-6, TNF-α) concentrations in both studies. Conclusion LPS may not be the major cause of postprandial inflammation in healthy adults consuming a moderately HF meal (36% kcal fat, similar to the typical American diet) or a HF meal (60% kcal fat). Plasma FFAs may modulate postprandial inflammation. The prevailing concept of HFD-induced metabolic endotoxemia requires careful re-evaluation. The PS was registered at clinicaltrials.gov as NCT02367287 and the IS as NCT02472171.

Differential Effects of Typical Korean Versus American-Style Diets on Gut Microbial Composition and Metabolic Profile in Healthy Overweight Koreans: A Randomized Crossover Trial

The Westernized diet has been associated with the pathogenesis of metabolic diseases, whereas a Korean diet has been reported to exert beneficial effects on health in several studies. However, the effects of Western and Korean diets on the gut microbiome and host metabolome are unclear. To examine the diet-specific effects on microbiome and metabolome, we conducted a randomized crossover clinical trial of typical Korean diet (TKD), typical American diet (TAD), and recommended American diet (RAD). The trial involved a 4-week consumption of an experimental diet followed by a 2-week interval before diet crossover. 16S rRNA sequencing analysis identified 16, 10, and 14 differential bacteria genera specific to TKD, RAD, and TAD, respectively. The Firmucutes-Bacteroidetes ratio was increased by TKD. Nuclear magnetic resonance metabolome profiling revealed that TKD enriched branched chain amino acid metabolism, whereas ketone body metabolism was evident in RAD and TAD. Microbiome and metabolome responses to the experimental diets varied with individual enterotypes. These findings provide evidence that the gut microbiome and host metabolome rapidly respond to different cultural diets. The findings will inform clarification of the diet-related communication networks of the gut microbiome and host metabolome in humans.

An 8-week Controlled Feeding Trial Based on the 2010 Dietary Guidelines for Americans Has Minimal Effect on the Fecal Microbiota in Overweight and Obese Women (FS11-08-19)

Objectives To determine whether a high quality diet based on the 2010 Dietary Guidelines of America (DGA) alters the composition of the fecal microbiome in individuals at risk for cardiometabolic disease, compared to a diet based on a typical American diet (TAD). Methods A total of 52 overweight and obese women were enrolled in a randomized, double-blind, controlled feeding trial. Women were randomly assigned to the DGA or TAD group (n = 28 DGA and 24 TAD). Diets matched each participant's estimated energy requirement and subjects remained weight-stable. The DGA diet was based on the 2010 DGA food-group recommendations, whereas the TAD diet was based on the average adult intake patterns from the NHANES 2009–2010 survey. Participants provided a stool sample 1-week prior to intervention (W0), within the second week of diet intervention (W2), and at the final week of intervention (W8). Microbial profiles were assessed using 16S rRNA amplicon sequencing and expressed as median % relative abundance. Data analyses were performed using standardized pipelines (QIIME 1.9 and R packages). False Discovery Rate (FDR) was set at 0.2. Results No differences were found in α- and β-diversity indices at the operational taxomonic unit (OTU) level by diet assignment at W0, and no taxa were differentially abundant at FDR < 0.2. Similarly, α- and β-diversity indices (OTU level) were not altered by diet within W2 or W8. A single OTU within the Ruminococcus genera was higher in TAD at both W2 (TAD = 0.014%; DGA = 0.00%) and W8 (TAD = 0.017%; DGA = 0.00%; FDR < 0.05), and the Adlercreutzia genera from the Actinobacteria phyla was also higher in TAD at both W2 (TAD = 0.027%; DGA = 0.001%) and W8 (TAD = 0.022%; DGA = 0.002%). No within-diet differences between W0 and W2, and W0 and W8 were observed in any α- and β-diversity indices tested. When adjusting for W0 relative abundances, 10 OTUs were altered by diet at W2 and 39 OTUs were altered at W8. Conclusions A weight-maintaining diet based on the 2010 DGA minimally differed in the fecal microbiota compared to a weight-maintaining typical American diet. Results herein suggests differences in food-based dietary patterns does not have a large effect on the composition of the fecal microbiota in humans. Funding Sources Supported by National Dairy Council; Campbell Soup Co.; USDA-ARS Projects 2032-51530-022-00D and 6026-51000-010-05S.

An 8-week Controlled Feeding Trial Based on the 2010 Dietary Guidelines for Americans Has Minimal Effect on the Fecal Microbiota in Overweight and Obese Women (FS11-08-19)

Objectives To determine whether a high quality diet based on the 2010 Dietary Guidelines of America (DGA) alters the composition of the fecal microbiome in individuals at risk for cardiometabolic disease, compared to a diet based on a typical American diet (TAD). Methods A total of 52 overweight and obese women were enrolled in a randomized, double-blind, controlled feeding trial. Women were randomly assigned to the DGA or TAD group (n = 28 DGA and 24 TAD). Diets matched each participant's estimated energy requirement and subjects remained weight-stable. The DGA diet was based on the 2010 DGA food-group recommendations, whereas the TAD diet was based on the average adult intake patterns from the NHANES 2009–2010 survey. Participants provided a stool sample 1-week prior to intervention (W0), within the second week of diet intervention (W2), and at the final week of intervention (W8). Microbial profiles were assessed using 16S rRNA amplicon sequencing and expressed as median % relative abundance. Data analyses were performed using standardized pipelines (QIIME 1.9 and R packages). False Discovery Rate (FDR) was set at 0.2. Results No differences were found in α- and β-diversity indices at the operational taxomonic unit (OTU) level by diet assignment at W0, and no taxa were differentially abundant at FDR < 0.2. Similarly, α- and β-diversity indices (OTU level) were not altered by diet within W2 or W8. A single OTU within the Ruminococcus genera was higher in TAD at both W2 (TAD = 0.014%; DGA = 0.00%) and W8 (TAD = 0.017%; DGA = 0.00%; FDR < 0.05), and the Adlercreutzia genera from the Actinobacteria phyla was also higher in TAD at both W2 (TAD = 0.027%; DGA = 0.001%) and W8 (TAD = 0.022%; DGA = 0.002%). No within-diet differences between W0 and W2, and W0 and W8 were observed in any α- and β-diversity indices tested. When adjusting for W0 relative abundances, 10 OTUs were altered by diet at W2 and 39 OTUs were altered at W8. Conclusions A weight-maintaining diet based on the 2010 DGA minimally differed in the fecal microbiota compared to a weight-maintaining typical American diet. Results herein suggests differences in food-based dietary patterns does not have a large effect on the composition of the fecal microbiota in humans. Funding Sources Supported by National Dairy Council; Campbell Soup Co.; USDA-ARS Projects 2032-51530-022-00D and 6026-51000-010-05S.