Molecular, Genetic, and Biochemical Nutrition Commons^™

Programming Heart Disease: Does Poor Maternal Nutrition Alter Expression Of Cardiac Markers Of Proliferation, Hypertrophy, And Fibrosis In Offspring?, Cathy Chun

Honors Scholar Theses

Maternal malnutrition can affect fetal organogenesis, metabolic processes, and factors involved in developmental regulation. Of the many physiological effects poor maternal nutrition can induce in offspring, one of the most important organs affected is the heart. Cardiovascular disease has been associated with poor maternal diet. It also been suggested that hypertension can originate during impaired intrauterine growth and development. Hypertension can trigger hypertensive heart disease and is associated with numerous heart complications. We hypothesized that poor maternal nutrition would alter critical growth factors associated with normal heart development, specifically, insulin-like growth factor (IGF)-1, IGF-2, transforming growth factor (TGF)β, and connective …

Examining Maternal Obesity Effects On Oogenesis, Follicular Development, And Embryonic Myogenesis, Chris Lindeman, Jennifer Wood

UCARE: Research Products

The CDC estimates that more than one-third of U.S. adults (approximately 78.6 million) are obese. Despite national efforts to combat this with diet and exercise, the number of obese adults and children continues to climb. It is critical to emphasize that obesity can lead to lifelong, chronic complications and health risks including hypertension, heart disease, and diabetes.

Diet and obesity also have important impacts on the reproductive health of female including the ability to become pregnant (fertility) and risk for complications during pregnancy. Furthermore, for women who do become pregnant, obesity can affect the development of the embryo and fetus, …

Current And Past Menstrual Status Is An Important Determinant Of Femoral Neck Geometry In Exercising Women, Rebecca J. Mallinson, Nancy I. Williams, Jenna C. Gibbs, Karsten Koehler, Heather C.M. Allaway, Emily Southmayd, M. J. De Souza

Department of Nutrition and Health Sciences: Faculty Publications

Menstrual status, both past and current, has been established as an important determinant of bone mineral density (BMD) in young exercising women. However, little is known regarding the association between the cumulative effect of menstrual status and indices of bone health beyond BMD, such as bone geometry and estimated bone strength.

Purpose: This study explores the association between cumulative menstrual status and indices of bone health assessed using dualenergy x-ray absorptiometry (DXA), including femoral neck geometry and strength and areal BMD (aBMD), in exercising women.

Methods: 101 exercising women (22.0 ± 0.4 years, BMI 21.0 ± 0.2 kg/m2, 520±40 min/week …

Effect Of Green Tea On Interaction Of Lipid Oxidation Products With Sarcoplasmic And Myofibrillar Protein Homogenates Extracted From Bovine Top Round Muscle, Nahathai Stapornkul, Tatiana Prytkova, Lilian Were

Food Science Faculty Articles and Research

The interaction between lipid oxidation products and bovine sarcoplasmic (SP) and myofibrillar protein (MP) homogenates in the presence of green tea was investigated. To monitor the effect of green tea on lipid oxidation, aldehydes were measured while effect on protein was monitored via changes in myoglobin, thiols, and tryptophan fluorescence over nine days of refrigerated storage. The presence of SP and MP decreased free aldehydes in the buffers. The SP bound more aldehydes than MP. The tea compounds exhibited more favorable binding energies than aldehydes near histidine 64 close to the heme moiety of myoglobin. Addition of tea lowered tryptophan …

A Pilot Study For Plant The Seed: A Nutrition Education Program Using Local Food Environment To Put Theory Into Action, Yeon Bai, Shahla M. Wunderlich, Karen A. Lee

Department of Nutrition and Food Studies Scholarship and Creative Works

The purpose of this study is to implement Plant the Seed, a garden-based nutrition education program designed to reconnect children with locally grown food, food environments of the past and present, and the benefits of eating seasonal foods. The pilot study investigates the environmental context and theory variables known to influence healthy food choice behavior. Social Cognitive Theory (SCT) provided a framework for the program’s curriculum and evaluation. The target audience is middle school students. Plant the Seed is a two-part program. In Part 1 (classroom), students participate in practical, interactive activities based on specific educational objectives that target …

Food Labeling And Consumer Associations With Health, Safety, And Environment, Joanna K. Sax, Neal Doran

Faculty Scholarship

The food supply is complicated and consumers are increasingly calling for labeling on food to be more informative. In particular, consumers are asking for the labeling of genetically modified organisms (GMO) food based on health, safety and environmental concerns. At issue is whether the labels that are sought would accurately provide the information desired. The present study examined consumer (n = 181) perceptions of health, safety and the environment for foods labeled organic, natural, fat free or low fat, GMO, or non-GMO. Findings indicated that respondents consistently believed that foods labeled GMO are less healthy, safe and environmentally-friendly compared to …

Genotoxic Effects Of Magnesium Deficiency In The Cardiovascular System And Their Relationships To Cardiovascular Diseases And Atherogenesis, Burton M. Altura, Nilank C. Shah, Gatha J. Shah, Bella T. Altura

The School of Health Sciences Publications and Research

The authors present evidence for a novel, new hypothesis whereby magnesium deficiency (MgD) acts as a genotoxic agent which probably causes numerous, hertofore, unrecognized consequences, even over a short-term, on the physiological, molecular and biochemical machinery of cardiovascular tissues and cells. The end result of these genotoxic effects of MgD probably plays important roles in the etiology and generation of diverse cardiovascular diseases, atherosclerosis, inflammation, and strokes via alterations in the epigenome of cardiovascular tissues and cells. The importance of adequate water-borne and dietary levels of Mg is emphasized.

The Expression Of Platelet-Activating Factor Is Induced By Low Extracellular Mg2+ In Aortic, Cerebral And Neonatal Coronary Vascular Smooth Muscle; Cross Talk With Ceramide Production, Nf–Kb And Proto-Oncogenes: Possible Links To Atherogenesis And Sudden Cardiac Death In Children And Infants, And Aging: Hypothesis, Review And Viewpoint, Burton M. Altura, Wenyan Li, Aimin Zhang, Tao Zheng, Nilank C. Shah, Gatha J. Shah, Bella T. Altura

The School of Health Sciences Publications and Research

An attempt is made, herein, to reconcile, and integrate, various phenomena associated with magnesium deficiency (MgD) in cardiovascular health, disease, and aging as well as reasons for the high incidence of sudden cardiac death in infants and young adults. With new experiments, we demonstrate, for the first time, that very low concentrations of platelet-activating factor (PAF), when added to primary cultured cerebral, neonatal coronary, and aortic vascular smooth muscle (VSM) cells (from three different mammals) promote rapid rises in free intracellular Ca2+ ions and a significant, concomitant reduction in free intracellular Mg2+ ions; these actions of PAF being curtailed with …

Potential Roles Of Magnesium Deficiency In Inflammation And Atherogenesis: Importance And Cross-Talk Of Platelet-Activating Factor And Ceramide, Burton M. Altura, Asefa Gebrewold, Nilank C. Shah, Gatha J. Shah, Bella T. Altura

The School of Health Sciences Publications and Research

Epidemiologic studies in North America and Europe have shown that people consuming Western-type diets are low in magnesium (Mg) content (i.e., < 30 - 65% of the RDA for Mg); most such diets in the USA show that 60 - 80% of Americans are consuming only 185 - 235 mg/day of Mg. Low Mg content in areas of soft-water, and Mg-poor soil, is associated with high incidences of ischemic heart disease (IHD), coronary artery disease, hypertension, and sudden cardiac death (SCD). It is clear that the leading underlying cause of death worldwide is atherosclerosis. Importantly, both animal and human studies have shown an inverse relationship between dietary intake of Mg and atherosclerosis. The myocardial level of Mg has consistently been observed to be lower in subjects dying from IHD and SCD in soft-water areas than those in hard-water areas. Over the past 20 years, our laboratories, using several types of primary cultured vascular smooth muscle (VSM) cells, and myocardial cells, demonstrated that declining levels of extracellular Mg ([Mg2+]0) activated several enzymatic pathways to produce increases in cellular sphingolipids, particularly ceramides which are known to exert numerous types of cardiovascular manifestations including inflammatory effects; the latter play important roles in atherogenesis and cardiovascular diseases. Approximately 20 years ago, we reported that low [Mg2+]0 caused formation of platelet-activating factor (PAF) as well as other types of PAF-like molecules and suggested that these molecules might be causative agents in low Mg2+- induced IHD and SCD. Herein, we review results and data from our labs which strongly support roles for ceramides, PAF and PAF-like lipids in low [Mg2+]0-induced IHD and SCD.

Postprandial Paraoxonase 1 Activity Following Consumption Of Recommended Amounts Of Mixed Meals In Healthy Males, Noriko Kameyama, Chizuko Maruyama, Kazuhiko Kotani, Russell Caccavello, Alejandro Gugliucci, Sadako Matsui, Taro Maruyama

Faculty Publications & Research of the TUC College of Osteopathic Medicine

Aim: Postprandial lipid level increases induce oxidative stress, which is involved in atherogenesis. The antioxidant properties of paraoxonase 1 (PON1) have attracted attention. However, changes in postprandial PON1 levels differ across prior studies, and changes in PON1 lactonase activity, potentially relevant to PON1 physiology, after the consumption of ordinary meals are unknown. Herein we evaluated postprandial serum lipid levels and PON1 changes following mixed-meal consumption of the amounts recommended for ordinary meals.
Methods: Nine healthy male volunteers consumed three different meals in a randomized cross-over design. The test meals were as follows: S, white rice; SMF, S with …

The Role Of Pxr And Ikkβ Signaling In Cardiometabolic Disease, Robert N. Helsley

Theses and Dissertations--Pharmacology and Nutritional Sciences

Cardiovascular disease (CVD) is the leading cause of death worldwide and is partially attributed to perturbations in lipid metabolism. Xenobiotics, such as pharmaceutical drugs and environmental chemicals, have been associated with increased risk of CVD in multiple large-scale human population studies, but the underlying mechanisms remain poorly defined. We and others have identified several xenobiotics as potent agonists for the pregnane X receptor (PXR), a nuclear receptor that can be activated by numerous drugs as well as environmental and dietary chemicals. However, the role of PXR in mediating the pathophysiological effects of xenobiotic exposure in humans and animals remains elusive. …

Suppression Of Nlrp3 Inflammasome By Γ-Tocotrienol Ameliorates Type 2 Diabetes, Yongeun Kim, Wei Wang, Meshail Okla, Inhae Kang, Regis Moreau, Soonkyu Chung

Department of Nutrition and Health Sciences: Faculty Publications

The Nod-like receptor 3 (NLRP3) inflammasome is an intracellular sensor that sets off the innate immune system in response to microbial-derived and endogenous metabolic danger signals. We previously reported that γ-tocotrienol (γT3) attenuated adipose tissue inflammation and insulin resistance in diet-induced obesity, but the underlying mechanism remained elusive. Here, we investigated the effects of γT3 on NLRP3 inflammasome activation and attendant consequences on type 2 diabetes. γT3 repressed inflammasome activation, caspase-1 cleavage, and interleukin (IL) 1β secretion in murine macrophages, implicating the inhibition of NLRP3 inflammasome in the anti-inflammatory and antipyroptotic properties of γT3. Furthermore, supplementation of leptin-receptor KO mice …

Disparities In Access To Preventive Health Care Services Among Insured Children In A Cross Sectional Study, Christian King

Department of Nutrition and Health Sciences: Faculty Publications

Children with insurance have better access to care and health outcomes if their parents also have insurance. However, little is known about whether the type of parental insurance matters. This study attempts to determine whether the type of parental insurance affects the access to health care services of children. I used data from the 2009–2013 Medical Expenditure Panel Survey and estimated multivariate logistic regressions (N=26,152). I estimated how family insurance coverage affects the probability that children have a usual source of care, well-child visits in the past year, unmet medical and prescription needs, less than 1 dental visit per year, …

Magnesium Deficiency Results In Oxidation And Fragmentation Of Dna, Down Regulation Of Telomerase Activity, And Ceramide Release In Cardiovascular Tissues And Cells: Potential Relationship To Atherogenesis, Cardiovascular Diseases And Aging, Burton M. Altura, Nilank C. Shah, Gatha J. Shah, Jose Luis Perez-Albela, Bella T. Altura

The School of Health Sciences Publications and Research

The authors discuss the potential relationship between magnesium, cardiovascular diseases, and aging.

Sudden Cardiac Death In Infants, Children And Young Adults: Possible Roles Of Dietary Magnesium Intake And Generation Of Platelet-Activating Factor In Coronary Arteries, Burton M. Altura, Wenyan Li, Aimin Zhang, Tao Zheng, Nilank C. Shah, Gatha J. Shah, Bella T. Altura

The School of Health Sciences Publications and Research

Magnesium (Mg) is a co-factor for more than 500 enzymes, and is the second most abundant intracellular cation after potassium. It is vital in numerous physiological, cellular and biochemical functions and systems necessary for life. Approximately 35 years ago, our laboratory suggested that a progressive, dietary deficiency and/or metabolic induced loss of Mg from the body, beginning early in life, particularly during development of the coronary arteries, could lead to coronary arterial vasospasm, ischemic heart disease, and sudden-cardiac death (SCD). Herein, we review evidence for a brand-new, novel hypothesis which combines knowledge suggesting a combined role for hypomagnesemia and platelet-activating …

Insights Into The Possible Mechanisms By Which Platelet-Activating Factor And Paf-Receptors Function In Vascular Smooth Muscle In Magnesium Deficiency And Vascular Remodeling: Possible Links To Atherogenesis, Hypertension And Cardiac Failure, Burton M. Altura, Nilank C. Shah, Gatha J. Shah, Jose Luis Perez-Albela, Bella T. Altura

The School of Health Sciences Publications and Research

The authors discuss different studies concerning the relationship between platelet-activating factor (PAF) and PAF-receptors with atherosclerosis and hypertension.

Mechanisms By Which Dietary Ellagic Acid Attenuates Obesity And Obesity-Mediated Metabolic Complications, Inhae Kang

College of Education and Human Sciences: Dissertations, Theses, and Student Research

Ellagic acid (EA) is a polyphenol found in various fruits and plants, such as berries, pomegranates, muscadine grapes, nuts and bark of oak tree. EA has been known to exhibit anti-inflammatory and anti-proliferative effects in various types of cancer. However, little is known about the effects of EA on obesity. Herein, 1) the lipid-lowering role of EA was identified in primary human adipose stem cells (hASCs) and human hepatoma Huh7 cells; 2) the molecular mechanisms by which EA attenuates adipogenesis by epigenetic modification were identified; 3) the effects of EA on high fat and high sucrose-mediated obesity was …

Biofeedback Relaxation Techniques In Addressing Cortex-Hypothalamus Control Loop For Motivation Of Obesity Avoidance, Liljana Bozinovska, Ahmed Majekodunmi

Professional Agricultural Workers Journal

This research explores how the achievement motivation pathway in the cortex influences hypothalamic activity, which could influence appetite control and obesity avoidance. The objective was to examine the sympathetic/parasympathetic feedback loop, and the influence of various biofeedback relaxation techniques on lowering heart rate (HR) and electrodermal activity (EDA). The methodology used was a standard biofeedback mechanism with visual representation of the measured physiological parameters. The feedforward part of the said feedback loop is controlled by hypothalamus while the feedback part is evaluated by the cortex. The participants were young adults and the sample size was ten. The results revealed that …

The Role Of Exercise In Polychlorinated Biphenyl Induced Cardiovascular Disease, Margaret O'Bryan Murphy

Theses and Dissertations--Nutritional Sciences

Cardiovascular disease remains the leading cause of death in Western societies. Endothelial dysfunction is one of the initiating steps in the development of atherosclerosis. While there is a strong correlation with a person’s genetics, lifestyle factors including smoking, physical activity, and diet can significantly increase a person’s susceptibility to the development of atherosclerosis. In addition to these lifestyle factors, there is a strong body of evidence linking exposure to environmental pollutants including persistent organic pollutants such as polychlorinated biphenyls to increased cardiovascular disease and mortality. It has been well-established that exercise protects against cardiovascular disease, but whether exercise can modulate …

The Benefits Of Breastfeeding, Avery Kordus

Senior Honors Theses

Breastfeeding research is plentiful, and the majority of the literature shows that breast milk is the superior form of infant nutrition except in the rare circumstances of infant metabolic disorders, maternal drug use, or positive HIV status. In comparison to formula, breast milk provides improved cognition, development, behavior, bonding, nutrition, digestion, immunity, and long-term health with fewer diseases and conditions in infants. Mothers are benefited by breastfeeding through bonding, faster weight loss, and reduction in certain cancers and conditions. Breast milk contains the proper amount of carbohydrates, fats, proteins, vitamins, and minerals, and is also specialized for each infant and …

In Vitro Analysis Of Short Chain Fatty Acids And Human Fecal Microbiota Stimulated By Pectin Sources, Byungjick Min

Graduate Theses and Dissertations

As interest increases for colonic health, various studies have been conducted to investigate functional ingredients for host health and prevention of chronic disease in humans such as colon cancer and Type 2 diabetes. In particular dietary fiber has been reported to have beneficial effects on colonic health. More recently, dietary fiber has been categorized based on its characteristics and numerous studies have been conducted to determine correlations with chronic diseases. Pectin is a naturally occurring biopolymer that has been used in various applications for purposes of pharmaceutical and biotechnology. Pectin is a soluble dietary fiber and can be entirely fermented …

Effect Of Functional Starch In Brown Rice And Grain Sorghum On Plasma Glucose And Insulin Responses In Humans, Nicole Marie Poquette

Graduate Theses and Dissertations

Diabetes and obesity are chronic illnesses increasing at dramatic rates in the U.S. and around the world. Research has looked to prevent or control diabetes and obesity through functional ingredients such as healthy-dietary carbohydrates to control blood glucose levels. Starch is a principle carbohydrate, which influences blood glucose levels, and measuring starch digestibility fractions can help predict the glucose response in the body. The objectives of this study were to investigate the functional starch content of parboiled brown rice flour and grain sorghum flour, and measure the effects on postprandial plasma glucose and insulin levels of 14 and 10 healthy …

Lifestyle, Dietary Factors, And Antibody Levels To Oral Bacteria In Cancer-Free Participants Of A European Cohort Study, Dominique S. Michaud, Jacques Izard, Zachary Rubin, Ingegerd Johansson, Elisabete Weiderpass, Anne Tjønneland, Anja Olsen, Kim Overvad, Marie Christine Boutron-Ruault, Françoise Clavel-Chapelon, Laure Dossus, Rudolf Kaaks, Verena A. Katzke, Heiner Boeing, Jana Foerster, Antonia Trichopoulou, Androniki Naska, Giana Ziara, Paolo Vineis, Sara Grioni, Domenico Palli, Rosario Tumino, Amalia Mattiello, Petra Hm Peeters, Peter D. Siersema, Aurelio Barricarte, José-María Huerta, Esther Molina-Montes, Miren Dorronsoro, J. Ramón Quirós, Eric J. Duell, Bodil Ohlsson, Bengt Jeppsson, Anders Johansson, Pernilla Lif, Kay-Tee Khaw, Nick Wareham, Ruth C. Travis, Tim J. Key, Heinz Freisling, Talita Duarte-Salles, Magdalena Stepien, Elio Riboli, H. Bas Bueno-De- Mesquita

Department of Food Science and Technology: Faculty Publications

Background: Increasing evidence suggests that oral microbiota play a pivotal role in chronic diseases, in addition to the well-established role in periodontal disease. Moreover, recent studies suggest that oral bacteria may also be involved in carcinogenesis; periodontal disease has been linked several cancers. In this study, we examined whether lifestyle factors have an impact on antibody levels to oral bacteria.

Methods: Data on demographic characteristics, lifestyle factors, and medical conditions were obtained at the time of blood sample collection. For the current analysis, we measured antibody levels to 25 oral bacteria in 395 cancer-free individuals using an immunoblot …

Associations Between Alcohol Consumption And Fasting Blood Glucose In Young Adults, Julie Ann Lucca

Master's Theses

Current research shows moderate alcohol consumption is associated with decreased risk of diabetes and excessive consumption or binge drinking can cause insulin resistance and diabetes. In 2010, diabetes was the seventh leading cause of death in the United Statesand was responsible for significant health complications: blindness, kidney failure, and limb amputations, and is a large national economic burden. Fasting blood glucose (FBG) is a tool used to help diagnose diabetes. Abnormally high FBG, ≥100 mg/dl, is indicative of diabetes and pre-diabetes. Few studies have observed diabetic prevalence among young adults or college students. Studying young adults can help provide added …

Control Of Candida Albicans Metabolism And Biofilm Formation By Pseudomonas Aeruginosa Phenazines, Diana K. Morales, Nora Grahl, Chinweike Okegbe, Lars E. P. Dietrich, Nicholas J. Jacobs, Deborah A. Hogan

Dartmouth Scholarship

Candidaalbicanshasdevelopmentalprogramsthatgoverntransitionsbetweenyeastandfilamentousmorphologies and between unattached and biofilm lifestyles. Here, we report that filamentation, intercellular adherence, and biofilm develop- ment were inhibited during interactions between Candida albicans and Pseudomonas aeruginosa through the action of P. aeruginosa-produced phenazines. While phenazines are toxic to C. albicans at millimolar concentrations, we found that lower concentrations of any of three different phenazines (pyocyanin, phenazine methosulfate, and phenazine-1-carboxylate) allowed growth but affected the development of C. albicans wrinkled colony biofilms and inhibited the fungal yeast-to-filament transition. Phenazines impaired C. albicans growth on nonfermentable carbon sources and led to increased production of fer- mentation products (ethanol, glycerol, and …

Eating Behaviors Of Older Adults Participating In Government-Sponsored Programs With Different Demographic Backgrounds, Yeon Bai, Shahla M. Wunderlich, Joseph Brusca, Johnson-Austin Marti, Michelle O'Malley

Department of Nutrition and Food Studies Scholarship and Creative Works

The purpose of this study was to determine the food behaviors of nutritionally high-risk seniors as a function of their racial background, gender, marital status, and education level. A total of 69 seniors were identified to be at high nutritional risk using the Nutrition Screening Initiative (NSI) checklist. A supplemental questionnaire (SQ) was created to examine the risk factors in relation to the participant’s demographic background. Key results indicated that Asians practiced healthy food behaviors and women were more likely to eat alone (p≤0.05). Married participants (90.9%) were most likely to consume 2 meals or more each day. College educated …

Medical Nutrition Therapy Provided To Adult Hematopoietic Stem Cell Transplantation Patients, Mary G. Habschmidt, Cheryl A. Bacon, Mary B. Gregoire, Heather E. Rasmussen

Department of Nutrition and Health Sciences: Faculty Publications

This study explored the current medical nutrition therapy (MNT) provided to adult patients undergoing hematopoietic stem cell transplantation (HSCT) and examined the current and desired role of registered dietitians (RDs) in providing MNT. A total of 60 RDs (57% response rate) responded to an electronic questionnaire. Descriptive statistics and χ² analyses (SPSS, version 18) were used. Results revealed the primary form of diet was oral, and for patients on nutrition support, parenteral nutrition (PN) was used more frequently (16%–31%) than enteral nutrition (EN) (5%–9%; P ≤ .05). Nutrition support decisions were based on patients’ individualized needs rather than established …

Green Tea Extract Protects Against Fibrogenesis Associated With Nonalcoholic Fatty Liver Disease In Diet-Induced Obese Rats, Allyson M. Bower

Master's Theses

No abstract provided.

Microbial Co-Occurrence Relationships In The Human Microbiome, Karoline Faust, J. Fah Sathirapongsasuti, Jacques Izard, Dirk Gevers, Jeroen Raes, Curtis Huttenhower

Department of Food Science and Technology: Faculty Publications

The healthy microbiota show remarkable variability within and among individuals. In addition to external exposures, ecological relationships (both oppositional and symbiotic) between microbial inhabitants are important contributors to this variation. It is thus of interest to assess what relationships might exist among microbes and determine their underlying reasons. The initial Human Microbiome Project (HMP) cohort, comprising 239 individuals and 18 different microbial habitats, provides an unprecedented resource to detect, catalog, and analyze such relationships. Here, we applied an ensemble method based on multiple similarity measures in combination with generalized boosted linear models (GBLMs) to taxonomic marker (16S rRNA gene) profiles …

Structure, Function And Diversity Of The Healthy Human Microbiome, Curtis Huttenhower, Jacques Izard

Department of Food Science and Technology: Faculty Publications

Studies of the human microbiome have revealed that even healthy individuals differ remarkably in the microbes that occupy habitats such as the gut, skin and vagina. Much of this diversity remains unexplained, although diet, environment, host genetics and early microbial exposure have all been implicated. Accordingly, to characterize the ecology of human-associated microbial communities, the Human Microbiome Project has analysed the largest cohort and set of distinct, clinically relevant body habitats so far. We found the diversity and abundance of each habitat’s signature microbes to vary widely even among healthy subjects, with strong niche specialization both within and among individuals. …