Biology subjects

Gardner, C. D.

Publications and source records attributed to Gardner, C. D..

6 recordsLinked to original sources

bioRxiv2026

The Burger Battle: The Future is Blended

Texture is one of the major barriers to acceptance of sustainable protein products, yet the relationship between instrumental texture and consumer perception remains poorly understood. Here we combined consumer sensory evaluation and texture profile analysis to identify the factors that drive burger acceptance across blended, animal-based, and plant-based formulations. A total of 472 diners evaluated beef-mushroom (n = 171), turkey (n = 100), bean (n = 100), and pea (n = 101) burgers served in Stanford University dining halls, while texture profile analysis quantified physical texture (n = 10 per product). The beef-mushroom burger achieved the highest ratings for meatiness (77.0/100), tastiness (69.4/100), and moistness (61.8/100), and 78% of consumers rated its moistness as just-about-right. Although the pea burger exhibited mechanical properties similar to the beef-mushroom burger, including indistinguishable cohesiveness values (0.53 vs. 0.53), it received substantially lower ratings for meatiness (56.1 vs. 77.0), indicating that mechanical similarity alone does not ensure consumer acceptance. Across products, moistness emerged as the primary sensory limitation, with 58% of turkey consumers and 46% of bean consumers reporting insufficient moisture. Cohesiveness showed the strongest association with perceived meatiness (r = 0.82). These findings demonstrate that successful burger reformulation requires more than mechanical matching; products must reproduce the moisture, flavor, and eating experience associated with meat. Blended burgers may represent the most practical near-term strategy for reducing meat consumption without compromising eating quality.

bioengineering↗

bioRxiv2024

A secondary β-hydroxybutyrate metabolic pathway linked to energy balance

{beta}-hydroxybutyrate (BHB) is an abundant ketone body. To date, all known pathways of BHB metabolism involve interconversion of BHB and primary energy intermediates. Here we show that CNDP2 controls a previously undescribed secondary BHB metabolic pathway via enzymatic conjugation of BHB and free amino acids. This BHB-ylation reaction produces a family of endogenous ketone metabolites, the BHB-amino acids. Genetic ablation of CNDP2 in mice eliminates tissue amino acid BHB-ylation activity and reduces BHB-amino acid levels. Administration of BHB-Phe, the most abundant BHB-amino acid, to obese mice activates neural populations in the hypothalamus and brainstem and suppresses feeding and body weight. Conversely, CNDP2-KO mice exhibit increased food intake and body weight upon ketosis stimuli. CNDP2-dependent amino acid BHB-ylation and BHB-amino acid metabolites are also conserved in humans. Therefore, the metabolic pathways of BHB extend beyond primary metabolism and include secondary ketone metabolites linked to energy balance.

biochemistry↗

bioRxiv2020

Gut Microbiota-Targeted Diets Modulate Human Immune Status

Diet modulates the gut microbiome, and gut microbes, in turn, can impact the immune system. Here, we used two gut microbiota-targeted dietary interventions, plant-based fiber or fermented foods, to determine how each influences the human microbiome and immune system in healthy adults. Using a 17-week randomized, prospective study design combined with -omics measurements of microbiome and host, including extensive immune profiling, we found distinct effects of each diet. High-fiber consumers showed increased gut microbiome-encoded glycan-degrading CAZymes despite stable community diversity. Three distinct immunological trajectories in high fiber-consumers corresponded to baseline microbiota diversity. Alternatively, the high-fermented food diet steadily increased microbiota diversity and decreased inflammatory markers. The data highlight how coupling dietary interventions to deep and longitudinal immune and microbiome profiling can provide individualized and population-wide insight. Our results indicate that fermented foods may be valuable in countering the decreased microbiome diversity and increased inflammation pervasive in the industrialized society.

microbiology↗

bioRxiv2020

High-Throughput Stool Metaproteomics: Method and Application to Human Specimens

Stool-based proteomics is capable of significantly augmenting our understanding of host-gut microbe interactions. However, in comparison to competing technologies such as metagenomics and 16S rRNA sequencing, it is under-utilized due to its low throughput and the negative impact sample contaminants can have on highly sensitive mass spectrometry equipment. Here, we present a new stool proteomic processing pipeline that addresses these shortcomings in a highly reproducible and quantitative manner. Using this method, 290 samples from a dietary intervention study were processed in approximately 1.5 weeks, largely done by a single researcher. These data indicated a subtle but distinct monotonic increase in the number of significantly altered proteins between study participants on fiber- or fermented food-enriched diets. Lastly, we were able to classify study participants based on their diet-altered proteomic profiles, and demonstrated that classification accuracies of up to 89% could be achieved by increasing the number of subjects considered. Taken together, this study represents the first high throughout proteomic method for processing stool samples in a technically reproducible manner, and has the potential to elevate stool-based proteomics as an essential tool for profiling host-gut microbiome interactions in a clinical setting. ImportanceWidely available technologies based on DNA sequencing have been used to describe the kinds of microbes that might correlate with health and disease. However, mechanistic insight might be best achieved through careful study of the dynamic proteins at the interface between the foods we eat, our microbes, and ourselves. Mass-spectrometry-based proteomics has the potential to revolutionize our understanding of this complex system but its application to clinical studies has been hampered by low-throughput and laborious experimentation pipelines. In response, we developed SHT-Pro, the first high-throughput pipeline designed to rapidly handle large stool sample sets. With it, a single researcher can process over one hundred stool samples per week for mass spectrometry analysis, roughly 10 times faster than previous methods. Since SHT-Pro is fairly simple to implement using commercially available reagents, it should be easily adaptable to large-scale clinical studies.

systems biology↗

bioRxiv2019

Long-term dietary intervention reveals resilience of the gut microbiota despite changes in diet and weight

With the rising rates of obesity and associated metabolic disorders, there is a growing need for effective long-term weight loss strategies, coupled with an understanding of how they interface with host physiology. While diet is a critical and promising area of focus, it has been difficult to identify diets that are broadly effective in long-term weight management. To explore the interaction between specific diets and bacteria within the gut, we tracked microbiota composition over a 12-month period as part of a larger dietary intervention study of participants consuming either a low-carbohydrate or low-fat diet. While baseline microbiota composition was not predictive of weight loss, each diet resulted in substantial changes in the microbiota three months after the start of the intervention; some of these changes were diet-specific and others tracked with weight loss. After these initial shifts, the microbiota returned near its original baseline state for the remainder of the intervention, despite participants maintaining their diet and weight loss for the entire study. These results suggest a resilience to perturbation of the microbiomes starting state. When considering the established contribution of obese-associated microbiotas to weight gain in animal models, microbiota resilience may need to be overcome for long-term alterations to host physiology.

microbiology↗

bioRxiv2019

Gut microbiota plasticity is correlated with sustained weight loss on a low-carb or low-fat dietary intervention

BackgroundObesity is a complex global health challenge. Although both low-carbohydrate (low-carb) and low-fat diets can lead to weight loss, there is typically substantial variability in weight and related outcomes for both diet approaches among obese but otherwise healthy adults. Elucidating individual characteristics that might contribute to sustained weight loss is critical to developing effective dietary intervention strategies. We hypothesized that structural differences in the gut microbiota explained some portion of the weight loss variability among people randomized to either a low-carb or low-fat diet, possibly related to its effects on dietary compliance.\n\nResultsOur study included two staggered cohorts of obese adults enrolled in the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) study - a randomized clinical trial of either a low-fat or low-carb diet. In the discovery cohort (n=66), 161 pre-diet fecal samples were sequenced in addition to 157 samples collected after 10-weeks of dietary intervention. In the validation cohort (n = 56), 106 pre-diet fecal samples were sequenced. Pre-diet taxonomic features, such as the Prevotella/Bacteroides ratio, correlated to weight loss in the discovery cohort were not confirmed in the validation cohort. The most robust finding in the discovery cohort indicated that gut microbiota plasticity was linked to 12-month weight loss in a diet-dependent manner; subjects with higher sustained weight loss on a low-fat diet had higher pre-diet daily plasticity, whereas those most successful on the low-carb diet had greater microbiota plasticity over 10 weeks of dietary intervention. Unfortunately, because sample frequency and timing was quite different in the validation cohort, the relationship between plasticity and weight loss could not be studied in this group.\n\nConclusionsThese findings suggest the potential importance of gut microbiota plasticity in sustained weight loss. We highlight the importance of evaluating kinetic trends and in assessing reproducibility in studies of the gut microbiota.

microbiology↗