However, functional ingredients may not produce the same effects when delivered outside a whole food matrix. Further, delivery of health benefits based on antioxidant capacity has come under intense scrutiny in recent years.Therefore, we studied the effects of beans on postprandial metabolic, oxidative stress, and inflammatory responses with the focus of understanding the contribution of food matrix and two specific properties: fiber and antioxidant capacity on biological responses in adults with MetS. We hypothesized that meals with whole black beans would produce greater benefits on postprandial responses than meals with added fiber or added antioxidant capacity.The study was conducted at the Ragle Human Nutrition Research Center on the UC Davis campus. Participants were recruited from the greater Sacramento area via flyers and websites. Interested participants were screened by phone for inclusionary and exclusionary criteria. Eligible participants were required to be adults ages 18 and older and meet criteria for MetS. Exclusionary criteria included diagnosis of a chronic disease , known allergies/intolerances to study foods, dieting, unusual dietary habits , pregnancy or lactation, smokers, drug or alcohol addiction and in recovery <1 year, excessively exercising,greenhouse pot on medications that interfered with outcome measurements as assessed by the study physician, or reported difficulty with phlebotomy or an indwelling catheter.
Participants who qualified after the phone screening were invited for in-person screening to provide written informed consent and confirm MetS with a fasting blood draw and anthropometric measurements. The study design of this pilot study was a randomized, controlled, crossover trial. There were a total of three study days, each separated by a one week washout period. Consistent with suggested postprandial methods, participants were instructed to consume the same meals, refrain from alcohol consumption, and avoid excessive exercise on the day before each study day. After a 12 hour overnight fast, participants arrived at the research center. The study registered nurse inserted an indwelling catheter into the antecubital vein and blood draws were obtained at baseline and post prandially every hour for five hours for a total of six blood draws per study day. Five hours was chosen to extend the findings of previous bean trials that assessed postprandial metabolic and inflammation markers after three hours and represent the usual amount of time between meals. After the baseline blood draw, a moderate-fat breakfast was provided to participants, which included one of three experimental soups to create the black bean meal, fiber matched meal, or antioxidant capacity matched meal. Meal consumption occurred within 20 min and was monitored to ensure compliance. Thereafter, bottled water was provided to the participants ad libitum.The moderate-fat breakfast consisted of commercially available foods typical of a Western-style breakfast and these foods were prepared as previously described.
Soups were provided as part of the meal and a Registered Dietitian matched for macronutrients using nutrition software and nutrition facts labels and for antioxidant capacity using the oxygen radical absorbance capacity method. The BB meal consisted of the moderate-fat meal and a soup made from dried black beans that was prepared according to the package instructions and carried dietary fiber and antioxidant capacity. The FM and AM meals comprised of the moderate-fat meal and soups that were couscous-based and supplemented with Instantized BiPro, a whey protein isolate , to match the protein level of the BB soup. Additionally, the FM soup was supplemented with Unifiber, an insoluble fiber supplement made mostly of powdered cellulose, but also included some maltodextrin and xanthan gum , and a 100% pure psyllium fiber supplement , to match the soluble and insoluble fiber content of the BB soup, but lack the antioxidant capacity. Specifically, the FM soup was matched for the soluble and insoluble dietary fiber of black beans, as the detailed chemical composition of black bean cell walls is currently unknown and, if it were known, it would be difficult to extract. The AM soup was supplemented with 300 mg grape seed extract that was added prior to consumption to match the antioxidant capacity of the BB soup, but lack the fiber content. Each moderate-fat breakfast and soup provided an average amount of fat in a typical meal and the soups alone comprised 30% of the calories of the entire breakfast . On each study day 90 mL of blood was drawn into EDTA blood collection tubes and immediately placed onto ice.
After 30 min, blood samples were centrifuged at 1800 X g for 15 min at 4 ˝C to obtain plasma and frozen at ´80 ˝C until lab analyses were performed in-batch. Biochemical measurements were performed according to manufacturers’ instructions, including appropriate quality controls. Triglyceride and glucose concentrations were analyzed by enzymatic colorimetric assays using a clinical autoanalyzer . High sensitivity C-reactive protein was analyzed by a chemiluminescent immunometric assay. Pro-inflammatory cytokines, interleukin -6 and IL-1β, and biomarkers of vascular endothelial activation, soluble intercellular adhesion molecule1 and soluble vascular cell adhesion molecule1 , were measured by ELISA . Insulin was analyzed by an AlphaLISA assay.Insulin resistance and sensitivity were calculated using homeostasis model assessment -insulin resistance, HOMA-β cell function, quantitative insulin sensitivity check index, and fasting glucose:insulin. Oxidized LDL was also analyzed by ELISA . Intra- and inter-variability for IL-6 were 5.7% and 16.4%, sICAM1 7.4% and 9.5%, sVCAM1 3.3% and 10.1%, and OxLDL 4.5% and 5.4%, respectively. Curve-fitting and interpolation of ELISA values were obtained by Graphpad 4.03 . Plasma hydrophilic and lipophilic Oxygen radical absorbance capacity values were measured according to Prior et al. with minor modifications.Outcome measurements were postprandial lipemia, inflammatory biomarkers, oxidative status, and glycemic control responses.Variables not meeting normality and/or homogeneity of variances assumptions were transformed using a log transformation.Data were analyzed by analysis of variance using a mixed model.Baseline concentrations of biochemical measurements were included in the model as a covariate when significantly different at baseline. Main effects were analyzed as meal, time, and meal ˆ time interactions. Random effects included participants and meal order. Post-hoc comparisons used the Bonferroni adjustment to correct for multiple comparisons. Statistical significance was considered at p < 0.006 and data was presented as least squares means as an estimate of the five hour postprandial response after the BB, FM, and AM meals or mean ˘ SD.In the current study, inclusion of black beans into a typical Western meal favorably modified the postprandial insulin response in adults with MetS. Black bean in the meal resulted in an attenuated postprandial insulin response compared to meals controlling for the fiber fraction or the antioxidant capacity of black beans. These results did not directly translate to improvements in endothelial function markers or appear to influence or be due to changes in markers of inflammation or oxidative damage in this study. Overall,30 plant pot the inclusion of black beans in a meal improved postprandial metabolic responses as indicated by postprandial insulin that could not be explained by either the fiber or antioxidant fractions alone. Few studies have investigated the postprandial response to beans. Thompsonet al., evaluated three bean and rice meals during a three hour postprandial period in adults with diabetes mellitus. The bean meals attenuated postprandial glucose, compared to the rice control meal. Further, the two hour postprandial glucose response was < 140 mg/dL after the bean meals, which is consistent with diabetic glycemic control goals. Other postprandial bean studies, investigating brown, white, and cream beans, and black bean extract, have also shown reduced glucose and insulin within a three hour postprandial period, compared to a reference food. In addition, white beans reduced postprandial lipemia, a result likely due to their different non-nutrient content compared to cream beans. Nilssonet al., tested brown beans consumed as an evening test meal and measured two inflammatory biomarkers the next morning.
IL-6 and IL-18 were reduced, which was explained, at least in part, by the actions of colonic fermentation. In the current study, these effects on inflammatory biomarkers would not have occurred, as the meals would not have reached the colon in the postprandial period of five hours. In contrast to the aforementioned postprandial bean studies, others have not shown differences on postprandial glucose or insulin responses after consumption of pinto beans, navy beans, black-eyed peas. The findings from the current study do not support these findings directly, since time and meal ˆ time interactions were not observed. A recent review found that adhesion molecules are not consistently altered postprandially, yet leukocyte bound markers are readily detected, which may be a better indicator of postprandial inflammation after high fat meals. IL-6 concentrations increased after all meals, which aligns with some but not all studies: four out of eight studies have demonstrated an elevated postprandial IL-6 response to meals. Postprandial inflammation is known to be sensitive to study design details, including length of postprandial assessments, meal challenge, or participants. The current study collected blood samples out to five hours, whereas longer assessment periods of six or more hours may be necessary to measure intervention associated differences. A high fat meal increased postprandial IL-18 and a high carbohydrate and high fiber meal decreased the postprandial IL-18 response. IL-18 is a relatively novel pro-inflammatory cytokine and recently associated with MetS with an independent but modest relationship to cardiovascular disease. Future studies will indeed want to expand inflammatory biomarkers to better understand postprandial inflammatory responses to dietary composition. Several studies using different foods, including walnuts, pecans, antioxidant spice blend, mixed grape powder, mint herbs, blueberries, orange juice, orange flavonoids, kiwifruit, and cherries, have demonstrated that these additions to a typical meal enhance antioxidant defense, as measured by ORAC. Further, meals without these antioxidants have been shown to decline postprandial antioxidant capacity. The results from the current study showed that the AM meal produced the highest ORAC value five hours post prandially, followed by the BB meal and then the FM meal. There was no significant influence of this enhanced antioxidant capacity on the endpoints measured. However, the last blood draw was obtained at five hours, which may have been too early to detect meal related differences in OxLDL. Examining the meal ˆ time interaction curves of OxLDL clearly showed a declining trajectory of OxLDL after the AM and BB meals between four and five hours post prandially. Previous work has shown that differences in OxLDL between treatments may not be apparent until six hours post prandially. Future research is needed to understanding the temporaldynamics of oxidative stress and damage to better discern the impact of dietary factors and to provide insight for developing dietary guidance. This pilot study had limitations worth noting. First, the study did not include a negative control that contained no fiber and antioxidant capacity to fully evaluate the impact of the black beans or to show the potential benefits imparted by the individual dietary components. The AM provided 1259 µmol/L trolox equivalents more antioxidant capacity than the BB meal. However, the postprandial total ORAC response between the BB and AM meals was not significantly different and both were significantly elevated compared to the FM meal, so the overall difference likely did not favor the AM meal over the BB meal remarkably. Another limitation was that MetS has inherent heterogeneity in its definition. However, MetS is increasing in incidence, so studying this at risk population provides potential applicability to a large portion of the population. Lastly, as a pilot study, enrolling one sex or increasing the sample size to circumvent potential sex differences was not feasible. Some sex differences in adults with MetS have been reported in postprandial metabolic indices, such as women with lower triglycerides, men with more delayed triglyceride clearance, and women with elevated IL-6. In order to ask whether the CO2-avoidance pathway has been adapted to suit the D. suzukii change in behavior, we first investigated their ability to detect CO2. The CO2 receptor is comprised of two 7-transmembrane proteins Gr21a and Gr63a, which are housed in the ab1C neuron on the D. melanogaster antenna. We found that the amino acid sequences of both Gr21a and Gr63a are extremely well conserved in the D. suzukii genome . In order to test whether the functional expression of the receptors occurs, we used single sensillum electrophysiology on the D. suzukii antenna . Our results indicate that an ab1C-like neuron in D. suzukii is present and is in fact more sensitive to CO2 than D. melanogaster across different concentrations . We next tested D. suzukii preference for CO2 in a T-maze Assay.