Irritable bowel syndrome (IBS) is a "disorder of gut-brain interaction" characterized by a group of symptoms that commonly include abdominal pain, abdominal bloating and changes in the consistency of bowel movements. These symptoms may occur over a long time, sometimes for years. IBS can negatively affect quality of life and may result in missed school or work or reduced productivity at work. Disorders such as anxiety, major depression, and chronic fatigue syndrome are common among people with IBS.
Prebiotics are compounds in food that foster growth or activity of beneficial microorganisms such as bacteria and fungi. The most common environment considered is the gastrointestinal tract, where prebiotics can alter the composition of organisms in the gut microbiome.
The Clostridia are a highly polyphyletic class of Bacillota, including Clostridium and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the class Clostridia are often but not always Gram-positive and have the ability to form spores. Studies show they are not a monophyletic group, and their relationships are not entirely certain. Currently, most are placed in a single order called Clostridiales, but this is not a natural group and is likely to be redefined in the future.
A low-residue diet is a diet intended to reduce certain constituents of the bowel, often with consequence for functional behaviour of the bowel. It may be prescribed for patients with ailments or functional gastrointestinal disorders mitigated by fewer and smaller bowel movements each day.
Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the gut microbiota. The gut is the main location of the human microbiome. The gut microbiota has broad impacts, including effects on colonization, resistance to pathogens, maintaining the intestinal epithelium, metabolizing dietary and pharmaceutical compounds, controlling immune function, and even behavior through the gut–brain axis.
Dysbiosis is characterized by a disruption to the microbiome resulting in an imbalance in the microbiota, changes in their functional composition and metabolic activities, or a shift in their local distribution. For example, a part of the human microbiota such as the skin flora, gut flora, or vaginal flora, can become deranged, with normally dominating species underrepresented and normally outcompeted or contained species increasing to fill the void. Similar to the human gut microbiome, diverse microbes colonize the plant rhizosphere, and dysbiosis in the rhizosphere, can negatively impact plant health. Dysbiosis is most commonly reported as a condition in the gastrointestinal tract or plant rhizosphere.
Jeffrey Ivan Gordon is a biologist and the Dr. Robert J. Glaser Distinguished University Professor and Director of the Center for Genome Sciences and Systems Biology at Washington University in St. Louis. He is internationally known for his research on gastrointestinal development and how gut microbial communities affect normal intestinal function, shape various aspects of human physiology including our nutritional status, and affect predisposition to diseases. He is a member of the National Academy of Sciences, the American Academy of Arts and Sciences, the Institute of Medicine of the National Academies, and the American Philosophical Society.
John A. McDougall is an American physician and author. He has written a number of diet books advocating the consumption of a low-fat vegan diet based on starchy foods and vegetables.
Mark Adam Hyman is an American physician and author. He is the founder and medical director of The UltraWellness Center and was a columnist for The Huffington Post. Hyman was a regular contributor to the Katie Couric Show until the show's cancellation in 2013. He writes a blog called The Doctor’s Farmacy, which examines many topics related to human health and welfare. He is the author of several books on nutrition and longevity, including Food Fix, Eat Fat, Get Thin, and Young Forever.
David Perlmutter is an American celebrity doctor, author, low-carbohydrate diet advocate and promoter of functional medicine.
Emeran Anton Mayer is a gastroenterologist, lecturer, author, editor, neuroscientist, documentary filmmaker and a professor in the Departments of Medicine, Physiology and Psychiatry at the David Geffen School of Medicine at UCLA. He is a pioneer of medical research into brain gut interactions
Alessio Fasano is an Italian-born medical doctor, pediatric gastroenterologist and researcher. He currently holds many roles, including professor of pediatrics at Harvard Medical School and professor of nutrition at Harvard T.H. Chan School of Public Health, both in Boston. He serves as director of the Center for Celiac Research and Treatment at MassGeneral Hospital for Children (MGHfC) and co-director of the Harvard Medical School Celiac Research Program. In addition, he is director of the Mucosal Immunology and Biology Research Center at MGHfC, where he oversees a research program with approximately 50 scientists and staff researching a variety of acute and chronic inflammatory diseases, including cystic fibrosis, celiac disease, enteric infections and necrotizing enterocolitis. A common theme of these programs is the study of the emerging role of the gut microbiome in health and disease. Fasano is also the scientific director of the European Biomedical Research Institute of Salerno (EBRIS) in Italy. Along with these leadership positions, he is a practicing outpatient clinician in pediatric gastroenterology and nutrition and the division chief.
Steven R. Gundry is an American physician and low-carbohydrate diet author. He is a former cardiac surgeon and cardiac surgery researcher who runs an experimental clinic investigating the impact of diet on health. Gundry is the author of The Plant Paradox: The Hidden Dangers in "Healthy" Foods That Cause Disease and Weight Gain, which promotes the controversial lectin-free diet.
Timothy David Spector is a British epidemiologist, medical doctor, and science writer.
Eran Elinav is an Israeli immunologist and microbiota researcher at the Weizmann Institute of Science and the DKFZ.
Gemma Newman known as the Plant Power Doctor is a British medical doctor, nutritionist, author and advocate of whole food plant-based nutrition.
Alan Desmond is an Irish consultant gastroenterologist and writer known for his advocacy of plant-based nutrition.
Joel K. Kahn is an American cardiologist, integrative medicine practitioner and promoter of whole food plant-based nutrition. He has been criticized for promoting anti-vaccine and COVID-19 misinformation.
Megan Rossi is a dietitian, nutritionist and author specialising in the microbiome. Her PhD in gut health received the Dean's Award top 5% for Outstanding Research Higher Degree.
Palaniappan Manickam, better known as Dr. Pal, is a board-certified gastroenterologist, who is originally from India, and currently practices in California. He specializes in gut health, time-restricted eating, and a mostly plant-based diet. He is also a celebrity doctor who uses in-person and virtual stand-up comedy ("MedCom") to educate the general public on chronic illness intervention.
