About

J. Bruce German is a professor associated with the Foods for Health Institute at UC Davis. His research focuses on the role of foods in health, particularly exploring how nutrition can influence health outcomes. His work includes studying the beneficial components of milk, such as complex sugars in breastmilk that protect infants against pathogens and support their microbiome. He has contributed to research demonstrating that these complex milk sugars can be obtained from cow's milk and have therapeutic potential for treating childhood malnutrition. His research is part of a broader effort to understand and develop nutritional strategies that promote health and prevent disease.

Research topics

• Biology
• Biochemistry
• Political Science
• Genetics
• Materials science
• Engineering ethics
• Evolutionary biology
• Public relations
• Engineering
• Chemistry

Selected publications

• Differential Psychopathology Associations Found for Docosahexaenoic Acid versus Arachidonic Acid Oxylipins of the Cytochrome P450 Pathway in Anorexia Nervosa

  medRxiv · 2025-03-03 · 1 citations

  preprintOpen access

  Abstract Anorexia nervosa (AN) is one of the deadliest disorders in psychiatry. AN patients tend to avoid high-fat and high-calorie foods to maintain a pathologically low body weight. High-fat foods are major sources of polyunsaturated fatty acids (PUFAs), lipids that are crucial for health and brain development. PUFAs can be categorized into different omega classes (n-3, n-6) or into essential (ALA, LA) versus nonessential PUFAs (EPA, DHA, ARA). PUFAs are metabolized by Cytochrome P450 (CYP450) enzymes into bioactive oxylipins with inflammation-resolving properties termed epoxy-fatty acids (EpFAs). EpFAs are further hydrolyzed into pro-inflammatory diol-fatty acids (DiHFAs) by soluble epoxide hydrolase (sEH), the protein product of an AN risk gene, EPHX2 . Using a meal challenge study protocol, EpFA and DiHFA oxylipins and sEH were analyzed in age-matched AN and healthy women to determine if sEH-associated oxylipins affect AN risk and psychopathology. At the fasting timepoint, half of the oxylipins were lower in AN compared to controls (all p<0.050). After eating, all but one EpFAs increased in AN (p=0.091 to 0.697) whereas all EpFAs decreased in controls (p=0.0008 to 0.462). By contrast, essential PUFA-derived DiHFAs significantly increased, whereas nonessential PUFA-derived DiHFAs significantly decreased in both groups. DiHFA oxylipins associated with AN psychopathology displayed a PUFA-dependent directionally opposite pattern: n-3 DHA-derived DiHFAs (DiHDPEs) were associated with lower severity in eating disorder risk, global psychological maladjustment, shape and restraint concerns, and global Eating Disorder Examination score. By contrast, n-6 ARA-derived DiHFAs (DiHETrEs) were associated with more severe emotional dysregulation, bulimia, interoceptive deficits, asceticism, and overcontrol scores. On the other hand, EpFA oxylipins were not significantly associated with AN psychopathology. This study confirms lipid metabolic dysregulation as a risk factor for AN. CYP450 oxylipins associated with AN risk and symptoms are sEH- and PUFA class-dependent. Our findings reveal that gene-diet interactions contribute to metabolic dysregulation in AN, highlighting a need for additional research to develop precision medicine for AN management.

  PublisherOA PDFDOI

• Development of a comprehensive food glycomic database and its application: Associations between dietary carbohydrates and insulin resistance

  Food Chemistry · 2025-01-20 · 4 citations

  articleOpen access

  Carbohydrates are an integral part of a healthy diet. The molecular compositions of carbohydrates encompass a very broad range of unique structures with many being ill-defined. This vast structural complexity is distilled into vague categories such as total carbohydrates, sugars, starches, and soluble/insoluble fibers. Structural elucidation of the food glycome is until recently extremely slow and immensely challenging. Dietary carbohydrates, including monosaccharides, oligosaccharides, glycosidic linkages, and polysaccharides were determined for the most consumed foods in the US consisting of 250 common foods using a multiglycomic platform. The food glycome was then correlated with clinical data from the National Health and Nutrition Examination Survey (NHANES) consisting of dietary recalls from 13,550 adults to determine associations between dietary carbohydrates, their structural features and insulin resistance. Several features were more powerful predictors compared to traditional measures indicating the need for molecular fine-scale food carbohydrate data in guiding precision nutrition initiatives and clinical studies. • Carbohydrates represent the most abundant biomolecules on Earth and are critical components of diet. • Despite their ubiquitous nature, they remain the “dark matter” of food. • We have constructed, for the first time, a comprehensive glycan database of food. • Access to quantitative and structural information of dietary glycans will aid clinical research into diet.

  PublisherDOI

• Generation of novel prebiotic oligosaccharide pools from fiber drives biological insight in bacterial glycan metabolism

  Applied and Environmental Microbiology · 2025-02-06 · 4 citations

  articleOpen access

  ABSTRACT Prebiotic oligosaccharides are dietary supplements that modulate the intestinal gut microbiome by selectively nourishing subsets of the microbial community with a goal to enhance host health. To date, the diversity of polysaccharide compositions in the fiber consumed by humans is not well represented by the limited scope of oligosaccharide compositions present in current commercial prebiotics. Recently, our UC Davis group developed a novel method to generate oligosaccharides from any polysaccharide fiber, termed F enton’s I nitiation T oward D efined O ligosaccharide G roups (FITDOG). Using this method, sugar beet pulp (SBP) was transformed into sugar beet oligosaccharides (SBOs) composed of arabinose- and galactose-containing oligosaccharides. Fecal fermentations of SBO and SBP produced similar shifts in donor-specific bacterial communities and acid metabolite profiles with a general enrichment of Bacteroides and Bifidobacterium . However, in vitro tests revealed more Bifidobacterium strains could consume SBO than sugar beet arabinan, and specific strains showed differential consumption of arabinofuranooligosaccharides or galactooligosaccharide (GOS) portions of the SBO pool. Genomic and glycomic comparisons suggest that previously characterized, arabinan-specific, extracellular arabinofuranosidases from Bifidobacterium are not necessary to metabolize the arabino-oligosaccharides within SBO. Synbiotic application of SBO with an SBO-consuming strain Bifidobacterium longum subsp. longum SC596 in serial fecal enrichments resulted in enhanced persistence among 9 of 10 donor feces. This work demonstrates a novel workflow whereby FITDOG creates novel oligosaccharide pools that can provide insight into how compositional differences in fiber drive differential gut fermentation behaviors as well as their downstream health impacts. Moreover, these oligosaccharides may be useful in new prebiotic and synbiotic applications. IMPORTANCE Prebiotics seek to selectively alter the host microbiome composition or function, resulting in a concurrent health benefit to the host. However, commercial prebiotics represent a small fraction of the diversity of food polysaccharide compositions. In this work a novel method, F enton’s I nitiation T oward D efined O ligosaccharide G roups (FITDOG) was used to generate an oligosaccharide pool from sugar beet pulp (SBP). Sugar beet oligosaccharides (SBOs) resulted in similar changes to SBP in fecal enrichments; however, SBO could be consumed by more beneficial bifidobacterial strains than the cognate polysaccharide. These results demonstrate how the details of glycan structure have a profound influence on how gut bacteria metabolize food carbohydrates. The implications of this work are relevant to understanding how different dietary sources influence the human microbiome and extend to developing novel oligosaccharide pools for prebiotic applications.

  PublisherDOI

• Exploring microRNAs in butter: identification and potential health impact

  HAL (Le Centre pour la Communication Scientifique Directe) · 2024-10-22

  article

  International audience

  Publisher

• A multi-glycomic platform for the analysis of food carbohydrates

  Nature Protocols · 2024-07-18 · 23 citations

  review
  PublisherDOI

• Genome-Wide Interactions with Dairy Intake for Body Mass Index in Adults of European Descent

  UNC Libraries · 2024-02-10

  articleOpen access

  Scope: Body weight responds variably to the intake of dairy foods. Genetic variation may contribute to inter-individual variability in associations between body weight and dairy consumption. Methods and results: A genome-wide interaction study to discover genetic variants that account for variation in BMI in the context of low-fat, high-fat and total dairy intake in cross-sectional analysis was conducted. Data from nine discovery studies (up to 25 513 European descent individuals) were meta-analyzed. Twenty-six genetic variants reached the selected significance threshold (p-interaction <10−7), and six independent variants (LINC01512-rs7751666, PALM2/AKAP2-rs914359, ACTA2-rs1388, PPP1R12A-rs7961195, LINC00333-rs9635058, AC098847.1-rs1791355) were evaluated meta-analytically for replication of interaction in up to 17 675 individuals. Variant rs9635058 (128 kb 3’ of LINC00333) was replicated (p-interaction = 0.004). In the discovery cohorts, rs9635058 interacted with dairy (p-interaction = 7.36 × 10−8) such that each serving of low-fat dairy was associated with 0.225 kg m−2 lower BMI per each additional copy of the effect allele (A). A second genetic variant (ACTA2-rs1388) approached interaction replication significance for low-fat dairy exposure. Conclusion: Body weight responses to dairy intake may be modified by genotype, in that greater dairy intake may protect a genetic subgroup from higher body weight.

  PublisherDOI

• A Glycome Encyclopedia of Commonly Consumed Foods and Their Fibers for Precision Nutrition

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access
  PublisherDOI

• Acid-active proteases to optimize dietary protein digestibility: a step towards sustainable nutrition

  Frontiers in Nutrition · 2024-02-08 · 9 citations

  articleOpen access

  Introduction: Historically, prioritizing abundant food production often resulted in overlooking nutrient quality and bioavailability, however, environmental concerns have now propelled sustainable nutrition and health efficacy to the forefront of global attention. In fact, increasing demand for protein is the major challenge facing the food system in the 21st century with an estimation that 70% more food is needed by 2050. This shift has spurred interest in plant-based proteins for their sustainability and health benefits, but most alternative sources of protein are poorly digestible. There are two approaches to solve digestibility: improve the digestibility of food proteins or improve the digestive capacity of consumers. Enhancing nutrient digestibility and bioavailability across diverse protein sources is crucial, with proteases presenting a promising avenue. Research, inspired by the proteases of human breast milk, has demonstrated that exogenous microbial proteases can activate within the human digestive tract and substantially increase the digestion of targeted proteins that are otherwise difficult to fully digest. Methods: Here, we introduce the use of an acid-active family of bacterial proteases (S53) to improve the digestibility and nutritional quality of a variety of protein sources, evaluated using the INFOGEST 2.0 protocol. Results: digestibility indicate that the most effective protease in the S53 family substantially improves the digestibility of an array of animal and plant-derived proteins-soy, pea, chickpea, rice, casein, and whey. On average, this protease elevated protein digestibility by 115% during the gastric phase and by 15% in the intestinal phase, based on the degree of hydrolysis. Discussion: The widespread adoption of these proteases has the potential to enhance nutritional value and contribute to food security and sustainability. This approach would complement ongoing efforts to improve proteins in the food supply, increase the quality of more sustainable protein sources and aid in the nourishment of patients with clinically compromised, fragile intestines and individuals like older adults and high-performance athletes who have elevated protein needs.

  PublisherOA PDFDOI

• Fatty Acids and Their Lipogenic Enzymes in Anorexia Nervosa Clinical Subtypes

  International Journal of Molecular Sciences · 2024-05-18 · 4 citations

  articleOpen access

  Disordered eating behavior differs between the restricting subtype (AN-R) and the binging and purging subtype (AN-BP) of anorexia nervosa (AN). Yet, little is known about how these differences impact fatty acid (FA) dysregulation in AN. To address this question, we analyzed 26 FAs and 7 FA lipogenic enzymes (4 desaturases and 3 elongases) in 96 women: 25 AN-R, 25 AN-BP, and 46 healthy control women. Our goal was to assess subtype-specific patterns. Lauric acid was significantly higher in AN-BP than in AN-R at the fasting timepoint (p = 0.038) and displayed significantly different postprandial changes 2 h after eating. AN-R displayed significantly higher levels of n-3 alpha-linolenic acid, stearidonic acid, eicosapentaenoic acid (EPA), docosapentaenoic acid, and n-6 linoleic acid and gamma-linolenic acid compared to controls. AN-BP showed elevated EPA and saturated lauric acid compared to controls. Higher EPA was associated with elevated anxiety in AN-R (p = 0.035) but was linked to lower anxiety in AN-BP (p = 0.043). These findings suggest distinct disordered eating behaviors in AN subtypes contribute to lipid dysregulation and eating disorder comorbidities. A personalized dietary intervention may improve lipid dysregulation and enhance treatment effectiveness for AN.

  PublisherOA PDFDOI

• Dietary fiber monosaccharide content alters gut microbiome composition and fermentation

  Applied and Environmental Microbiology · 2024-07-15 · 27 citations

  articleOpen access

  ABSTRACT Members of the mammalian gut microbiota metabolize diverse complex carbohydrates that are not digested by the host, which are collectively labeled “dietary fiber.” While the enzymes and transporters that each strain uses to establish a nutrient niche in the gut are often exquisitely specific, the relationship between carbohydrate structure and microbial ecology is imperfectly understood. The present study takes advantage of recent advances in complex carbohydrate structure determination to test the effects of fiber monosaccharide composition on microbial fermentation. Fifty-five fibers with varied monosaccharide composition were fermented by a pooled feline fecal inoculum in a modified MiniBioReactor array system over a period of 72 hours. The content of the monosaccharides glucose and xylose was significantly associated with the reduction of pH during fermentation, which was also predictable from the concentrations of the short-chain fatty acids lactic acid, propionic acid, and the signaling molecule indole-3-acetic acid. Microbiome diversity and composition were also predictable from monosaccharide content and SCFA concentration. In particular, the concentrations of lactic acid and propionic acid correlated with final alpha diversity and were significantly associated with the relative abundance of several of the genera, including Lactobacillus and Dubosiella . Our results suggest that monosaccharide composition offers a generalizable method to compare any dietary fiber of interest and uncover links between diet, gut microbiota, and metabolite production. IMPORTANCE The survival of a microbial species in the gut depends on the availability of the nutrients necessary for that species to survive. Carbohydrates in the form of non-host digestible fiber are of particular importance, and the set of genes possessed by each species for carbohydrate consumption can vary considerably. Here, differences in the monosaccharides that are the building blocks of fiber are considered for their impact on both the survival of different species of microbes and on the levels of microbial fermentation products produced. This work demonstrates that foods with similar monosaccharide content will have consistent effects on the survival of microbial species and on the production of microbial fermentation products.

  PublisherOA PDFDOI

Frequent coauthors

• Carlito B. Lebrilla

  University of California, Davis

  129 shared

• David A. Mills

  76 shared

• Jennifer T. Smilowitz

  74 shared

• Angela M. Zivkovic

  University of California, Davis

  59 shared

• E. N. Frankel

  46 shared

• Danielle G. Lemay

  Agricultural Research Service

  41 shared

• Ronald P. Mensink

  Maastricht University

  38 shared

• Frédéric Destaillats

  38 shared