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 >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.

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Objectives Chardonnay grape marc (CM) is the remaining skins and seeds from winemaking that offers a rich source of phytonutrients. The objective was to evaluate glucose metabolism following the addition of CM to the diet. Methods Overweight or obese men and women with mild hyperlipidemia between 35–65 y were recruited for this double-blinded 16-week crossover study. Subjects consumed 1500mg of 1) microcrystalline cellulose (MCC), 2) high chardonnay seed extract/WellVine™ marc blend (HE) or 3) high WellVine™ chardonnay marc/seed extract blend (HM) in a randomized order. Each intervention arm lasted 3 weeks and included two 3-week washout periods. Following each intervention, fasting blood was drawn and assayed for glucose and insulin. Indexes of insulin resistance (HOMA-IR, McAuley) and insulin sensitivity (QUICKI) were calculated. Data were transformed before conducting analyses, when appropriate. Analyses were conducted with 24 completed subjects and intention to treat (ITT) with 3 subjects who withdrew using linear mixed model ANOVA. Results In the ITT analysis, fasting glucose and insulin showed a significant main effect of intervention (P = 0.04 and P = 0.03, respectively). For both glucose and insulin, pairwise comparisons showed a significant difference between HM and MCC (P = 0.03 and P = 0.03, respectively). The indexes, HOMA-IR and QUICKI showed a significant main effect of intervention (P = 0.04 and P = 0.03, respectively), whereas there was no effect with the McAuley index. For HOMA-IR and QUICKI, pairwise comparisons showed a significant difference between HM and MCC (P = 0.04 and P = 0.03, respectively). Conclusions There was an increase in QUICKI, indicating an increase in insulin sensitivity following the HM arm compared to MCC. This has important implications if it is followed up in a larger cohort. Following the HM arm there was also a decrease in fasting insulin and decrease in HOMA-IR compared to the MCC arm; in this case, the magnitude of these changes are not sufficient to suggest improvement in insulin resistance by clinical definitions. This was a proof of concept study, thus future studies should further explore these findings. Funding Sources NIFA Phase II Small Business Innovation Research Grant awarded to Sonomaceuticals, LLC, USDA CRIS 2032–51,530-025–00D.

ObjectiveDietary intake of added sugars in the United States is significantly higher than what is recommended by the Dietary Guidelines for Americans (DGA) and by other health organizations. There is limited research on how reducing the intake of added sugars would affect or change taste perception related to sugar. Our objective was to determine if sweet taste threshold and sweet preference changes in response to a diet intervention based on the recommendations in the 2010 DGA compared to an intervention based on the typical American diet (TAD) as described by recent surveys of U.S. adults.MethodsData for this report is from an eight‐week controlled feeding trial. Overweight or obese women, with insulin resistance and/or dyslipidemia, aged 20–65 years were randomized into one of two diet groups: the DGA diet or the TAD. Detection taste threshold was determined using a three‐alternative‐forced choice method and sweet preference was measured using the Monell forced‐choice, paired‐comparison tracking procedure. Measurements were obtained prior to the dietary intervention at baseline (BL), and after the diet intervention (ADI) to evaluate changes in taste acuity and hedonic preference. Data were log transformed, and analysis of covariance was used to identify differences between the two diet groups. In addition, the change in acuity and hedonic preference was calculated as ADI‐BL. Wilcoxon's rank test was used to identify differences in these parameters between the two groups. This is an on‐going study, with more participant cohorts being added to reach n = 44.ResultsPreliminary results were generated for the first 16 women (Age: DGA ‐ 45.0, TAD‐42.5 y; BMI: DGA – 30.4, TAD – 33.0 kg/m2) who have completed the study. Usual energy intake (kcals), and percent‐added sugars or sweet‐food intake were not different at BL between DGA and TAD (p = 0.92, 0.63, 0.92, respectively). There was no significant difference (p > 0.05) between diets in the change in sweet threshold or sweet preference. The DGA intervention, however, resulted in a larger reduction in the level of preferred sweetness compared to the TAD diet, when controlling for BL preference (p = 0.03).ConclusionsConsuming a diet following the DGA may possibly lower preference for sweet foods when compared to a TAD. Further, data from the complete cohort will be used to add to this report upon study completion.Support or Funding InformationFunded by National Dairy Council and USDA, ARS CRIS project #2032 51530 022 00D