S C a N ' S Pulse

SCAN’SPulse Spring 2019, Vol. 38, No. 2 CONTENTS Exercise and the Human Gut Microbiome 1 Exercise and the Human Gut by Michael Crosier, PhD, RD Microbiome 3 The human microbiome is an excit- may contribute to the health effects From the Editor ing area of research. Although this of regular, moderate exercise. 6 field is in its infancy, scientists are Cellular Senescence-Associated rapidly gaining an understanding of Gut Bacteria Functions Arterial Dysfunction with Advancing the interactions between our cells Age: Translational Potential of and the microbes living in and on our Many aspects of health are linked Nutraceuticals as Senolytics body. We are inhabited with trillions with gut physiology, and our gut bac- 10 of microbes, the largest concentra- teria are important contributors to Implications of Higher-Risk Dietary tion residing in our distal gastroin- this interaction. For example, normal Supplements and Factors Predicting testinal (GI) tract, where the digestion and motility through the GI Their Use in Collegiate Athletes microorganism genome (gut micro- tract is dependent on gut bacteria.2 biome) is about 150 times greater Gut bacteria have the ability to pro- 14 than our own.1 While there is great duce a variety of vitamins, such as fo- From the Chair interindividual variation in bacterial late, vitamin K, and biotin, and are composition, the primary bacterial able to carry out biotransformations 15 phyla found in our guts are Bac- of bile acids, phytonutrients, and Conference Highlights teroidetes and Fermicutes.1 Within other xenobiotics.3 The fermentation 17 these phyla and others, thousands of of resistant carbohydrate in the distal Reviews different bacterial species, mostly GI tract results in the production of anaerobic, inhabit the GI tract.2 the short-chained fatty acids (SCFAs) 17 butyrate, propionate, and acetate. In Research Digest Research is showing a strong connec- addition to contributing to energy tion between our gut bacteria and metabolism,4 these SCFAs serve as 19 host physiology and is demonstrat- ligands for receptors that can activate Of Further Interest ing how this connection relates to various signaling pathways.5 The role risk of disease and overall health. In of SCFAs as signaling molecules influ- 21 Upcoming Events addition, researchers are learning ence physiologic processes such as more about the environmental influ- intestinal secretion of peptides in- ences shaping our microbiome, such volved in satiety and hepatic gluco- as changes throughout the lifecycle neogenesis.6,7 and diet. Although less is known about the effects of exercise on the Our immune system is also intimately human gut microbiome, studies have associated with our gut bacteria. Gut revealed positive changes in our gut bacteria enhance the barrier function bacteria in response to exercise. of the intestine.7 They can also stimu- These exercise-induced changes late the innate immune system and protect against pathogens through chronic diseases, including heart dis- Academy of Nutrition and Dietetics the production of bacteriocides and ease, diabetes, musculoskeletal ail- Dietetic Practice Group of Sports, competition with pathogenic bacte- ments, and potentially mental health Cardiovascular, and Wellness ria.3 conditions.15-17 In the gut, regular Nutrition (SCAN) moderate-intensity exercise has been Although the ideal bacterial compo- shown to reduce the occurrence of SCAN Website: www.scandpg.org sition to maximize health is not colorectal cancer and inflammatory known, high microbial diversity is as- bowel diseases.18-20 However, exercise sociated with improvements in can also lead to GI distress. It has SCAN Office health status, whereas decreased mi- been reported that between 30% to 120 S. Riverside Plaza, Suite 2190 crobial diversity is associated with an 90% of distance runners have experi- Chicago, IL 60606 Phone: 312/899-1775 increased risk for metabolic disease enced exercise-related intestinal [email protected] such as obesity and type 2 diabetes.2 problems.21 Running at high intensity Interim Executive Director: Adriana Legreid often produces GI upset such as Determinants of the Gut bloating, diarrhea, stomach pain, and SCAN Executive Committee Microbiome bleeding.22 High-intensity training Chair Lindzi Torres, MS, MPH, RDN, CSSD has been associated with reduced GI Microbial colonization begins imme- blood flow and hypoxia, potentially Chair-Elect diately at birth and fluctuates leading to mucosal injury and in- Jennifer Ketterly, MS, RD, CSSD throughout the lifecycle. The initial creased intestinal permeability.23,24 bacterial composition is influenced The integrity of intestinal tight junc- Past Chair Cheryl Toner, MS, RDN by mode of delivery, with infants de- tions can be disrupted by the physi- livered vaginally having a greater cal stress of exercise, potentially Treasurer concentration of Bacteriodetes than leading to systemic inflammation.25 Lynn Cialdella Kam, PhD, MA, MBA, RDN Firmicutes compared with infants de- Although an individual bout of in- livered via cesarean section.9 Bacteria tense exercise may increase inflam- Secretary Sherri Stastny, PhD, RD, CSSD diversity increases as solid food is in- mation, habitual exercise and fitness troduced.10 The microbiome typically leads to suppression of basal inflam- Director, Sports Dietetics—USA Subunit continues to change between adult- matory cytokines,26 and has been as- Elizabeth Abbey, PhD, RDN, CDN hood and elderly years. After age 65, sociated with preservation of a more the number of microbial species robust mucosal lining and lesser de- Director, Wellness/Cardiovascular 11 27 RDs Subunit tends to decrease. Changes in GI gree of intestinal permeability. In Mark Hoesten, RD physiology, such as changes in sali- type 2 diabetics, combined aerobic vary function and gut motility, affect and resistance training led to a de- Director of Events gut microbiota as we age.12 crease in several pro-inflammatory Enette Larson-Meyer, PhD, RD, CSSD, FACSM cytokines and an increase in the anti- Director of Communications In adults, diet is a major determinant inflammatory modulators inter- Cara Harbstreet, MS, RD of microbial composition. A high- leukins 4 (IL-4) and 10 (IL-10).28 fiber diet rich in fruits, vegetables, Director of Member Services legumes, and whole-wheat grain Intestinal and systemic effects of ex- Karen Reznik Dolins, EdD, RD, CSSD, CDN products has been shown to increase ercise may be related to changes in 2 SCAN Delegate to House of Delegates microbial diversity. The fecal micro- the gut microbiome. Research shows Jean Storlie, MS, RD biota of vegetarian and vegan sub- that exercise and fitness are associ- jects versus omnivores have lower ated with an increase in the microbial ____________________________ stool pH, likely due to a greater pro- diversity and increases in health-production of SCFA.13 Overall, a more moting bacterial populations.2 On Editor-in-Chief, SCAN’S PULSE Mark Kern, PhD, RD complex and diverse diet is associ- the other hand, frailty and poor exer- ated with a more diverse micro- cise capacity in the elderly is associ- To contact an individual listed above, go to biome.12 While less is known about ated with low fecal microbial www.scandpg.org/executive-committee/ how exercise affects our gut micro- diversity.29 Exercise-induced alter- biome, research has shown that phys- ations in gut bacteria may play a role ical stress alters the composition of in intestinal immune function and the gut microbiome.14 overall GI physiology. Fit individuals have been shown to have a micro- Effect of Exercise on the Gut biome enriched in butyrate-produc- and Gut Bacteria ing bacteria such as Clostridiales, Roseburia, and Lachnospiraceae,30 Regular moderate exercise provides and increased production of the protection against a number of SCFA butyrate is associated with in- 2 | SCAN’S PULSE Spring 2019, Vol. 38, No. 2 From The Editor Keep Calm and Read PULSE by Mark Kern, PhD, RD, Editor-in-Chief There are plenty of reasons to be stressed out with work and life, but reading a new issue of SCAN’s PULSE is not one of them. I’m hopeful that you can find a few precious moments to relax and read through the pages of this issue. If you do, you will come away with a little more knowledge and perhaps even a sense of relief that you’ve made progress in understanding a few of the complexities of our field. In our previous (Winter) issue, we provided an article regarding diet and the gut microbiome. As a complement to that piece, our cover article by Michael Crosier, PhD, RD discusses the latest research on the role that exercise plays in determining the microbiome. After that, Zachary Clayton, PhD offers his insight into processes of cellular ageing and describes possible ways that what we ingest may intervene to counter it. In our final feature article, you’ll learn from John Sassone, MS, RD and Michelle Bar- rack, PhD, RD, CSSD about the use of dietary supplements that could jeopardize the health or athletic eligibility of competitors and the issues that professionals working with those athletes should consider. You should also spend some time reading through the other informative departments that we provide including “Reviews,” “Conference Highlights,” “Of Further Interest,” “From the Chair,” and “Research Digest.” And don’t fret when you’ve finished, because we’ll have another issue in your inbox for you to enjoy this summer. testinal health.4 Other exercise-in- shown to alter the gut microbiome in Conclusion duced changes in the gut micro- humans.37 Professional rugby players biome that have been associated had a higher fecal microbiome diver- Along with diet, exercise is an easily with health benefits include im- sity compared with controls matched accessible tool that may contribute to proved insulin sensitivity,31 increased for body size, age, and gender. The gut microbiome diversity. Increased satiety,32 and improved mental higher diversity correlated to greater gut bacterial diversity and richness is health.33 exercise intensity and also greater associated with health benefits.4 Posi- protein intake.

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