Glossary (A-Z) of all things related to SIBO symptoms,
causes, effects, treatment, relapse, reoccurrence and die-off.




Take in or soak up (energy or a liquid or other substance) by chemical or physical action.

A skin condition characterized by red pimples on the skin, especially on the face, due to inflamed or infected sebaceous glands.
A substance that causes an allergic reaction.

definition 1 – An emotional disorder characterized by an obsessive desire to lose weight by not eating enough to sustain oneself;

definition 2 – Lack or loss of appetite for food (as a medical condition).

A medicine (such as penicillin or its derivatives) that inhibits the growth of or destroys microorganisms.
A blood protein produced in response to and counteracting a specific antigen. Antibodies combine chemically with substances which the body recognizes as alien, such as bacteria, viruses, and foreign substances in the blood.
An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals are used against fungi.
Intense, excessive and persistent worry and fear about everyday situations. Fast heart rate, rapid breathing, sweating and feeling tired may occur.
Archaea constitute a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria, but this term has fallen out of use.


Bacteria are small single-celled organisms.
A bitter greenish-brown alkaline fluid which aids digestion and is secreted by the liver and stored in the gall bladder.
A swollen state caused by retention of fluid or gas.
Brain fog
Brain fog is not a medical or scientific term; it is used by individuals to describe how they feel when their thinking is sluggish, fuzzy, and not sharp.
Brain gut axis
The brain gut axis refers to the physical and chemical connections between your gut and brain. Millions of nerves and neurons run between your gut and brain. Neurotransmitters and other chemicals produced in your gut also affect your brain.
A serious eating disorder marked by bingeing, followed by methods to avoid weight gain.


Any of a large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose. They contain hydrogen and oxygen in the same ratio as water (2:1) and typically can be broken down to release energy in the animal body.
Carbohydrate digestion
The goal of carbohydrate digestion is to break down all disaccharides and complex carbohydrates into monosaccharides for absorption, although not all are completely absorbed in the small intestine (e.g., fibre). Digestion begins in the mouth with salivary amylase released during the process of chewing.
Cytolethal distending toxins (CDT) constitute a family of genetically related bacterial protein toxins able to stop the proliferation of numerous cell lines.
Celiac disease
Celiac disease, sometimes called celiac sprue or gluten-sensitive enteropathy, is an immune reaction to eating gluten, a protein found in wheat, barley and rye. If you have celiac disease, eating gluten triggers an immune response in your small intestine.
An insoluble substance which is the main constituent of plant cell walls and of vegetable fibres such as cotton. It is a polysaccharide consisting of chains of glucose monomers.
Chronic inflammation
Chronic inflammation is also referred to as slow, long-term inflammation lasting for prolonged periods of several months to years. Generally, the extent and effects of chronic inflammation vary with the cause of the injury and the ability of the body to repair and overcome the damage.
The pulpy acidic fluid which passes from the stomach to the small intestine, consisting of gastric juices and partly digested food.
A procedure in which a flexible fibre-optic instrument is inserted through the anus in order to examine the colon.
A condition in which there is difficulty in emptying the bowels, usually associated with hardened faeces.


Dao Enzyme
Diamine oxidase (DAO) is an enzyme that your body makes to break down histamine from foods. If your body doesn’t produce enough DAO, you may have diamine oxidase deficiency. Without enough of this enzyme, you can experience histamine intolerance, also called food histaminosis or enteral histaminosis.
Depression is a constant feeling of sadness and loss of interest, which stops you doing your normal activities. Different types of depression exist, with symptoms ranging from relatively minor to severe. Generally, depression does not result from a single event, but from a mix of events and factors.
A disease in which the body’s ability to produce or respond to the hormone insulin is impaired, resulting in abnormal metabolism of carbohydrates and elevated levels of glucose in the blood.
The identification of the nature of an illness or other problem by examination of the symptoms.
Diamine oxidase
Diamine oxidase (DAO) is an important digestive enzyme in your body. Some people take diamine oxidase supplements to help with histamine intolerance, which can cause migraines and headaches, gut issues, and skin conditions.
A condition in which faeces are discharged from the bowels frequently and in a liquid form.
Die off
A sudden collapse of a species or of a population or community of organisms, as from disease or environmental disruption.
Diet culture
Diet culture refers to a rigid set of expectations about valuing thinness and attractiveness over physical health and emotional well-being. Diet culture often emphasizes “good” versus “bad” foods, focuses on calorie restriction, and normalizes self-deprecating talk.
Dietary fibre
Dietary fibre, also known as roughage or bulk, includes the parts of plant foods your body can’t digest or absorb. Unlike other food components, such as fats, proteins or carbohydrates – which your body breaks down and absorbs – fibre isn’t digested by your body.
Sequence by which food is broken down and chemically converted so that it can be absorbed by the cells of an organism and used to maintain vital bodily functions.
Digestive enzymes
Digestive enzymes are substances that help you digest your food. They are secreted (released) by the salivary glands and cells lining the stomach, pancreas, and small intestine.
Any of a class of sugars whose molecules contain two monosaccharide residues.
The first part of the small intestine immediately beyond the stomach, leading to the jejunum.


Eating disorders
Any of a range of psychological disorders characterized by abnormal or disturbed eating habits.
A medical condition in which patches of skin become rough and inflamed with blisters which cause itching and bleeding.
A procedure in which an instrument is introduced into the body to give a view of its internal parts.
The strength and vitality required for sustained physical or mental activity.
A cell of the intestinal lining.
A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.


Facial swelling
Facial swelling is the build-up of fluid in the tissues of the face.
Fat is a term used to describe a class of macro nutrients used in metabolism called triglycerides. These make up one of three classes of macronutrients including proteins and carbohydrates. Fats provide a means of storing energy for most eukaryotes, as well as act as a food source.
Extreme tiredness resulting from mental or physical exertion or illness.
Fermentation is the process in which a substance breaks down into a simpler substance. Microorganisms like yeast and bacteria usually play a role in the fermentation process, creating beer, wine, bread, kimchi, yogurt and other foods.
Ferritin or hemosiderin. Ferritin is a protein with a capacity of about 4500 iron (III) ions per protein molecule. This is the major form of iron storage.
Fight or flight response
The fight-or-flight-or-freeze or the fight-flight response is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival.
The accumulation of gas in the alimentary canal.
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols, which are short-chain carbohydrates (sugars) that the small intestine absorbs poorly. Some people experience digestive distress after eating them.
Food intolerance
A food intolerance is difficulty digesting certain foods and having an unpleasant physical reaction to them. It causes symptoms, such as bloating and tummy pain, which usually happen a few hours after eating the food.
Food poisoning
Illness caused by bacteria or other toxins in food, typically with vomiting and diarrhoea.
A sugar of the hexose class found especially in honey and fruit.
Fructose intolerance
Fructose is a sugar that occurs naturally in fruits, vegetables, and honey. When a person is unable to digest or absorb fructose, they may have fructose intolerance. When a person has an intolerance to fructose, they may experience bloating, abdominal pain, and diarrhea.


A sugar of the hexose class which is a constituent of lactose and many polysaccharides.
Gall bladder
The small sac-shaped organ beneath the liver, in which bile is stored after secretion by the liver and before release into the intestine.
A substance or matter in a state in which it will expand freely to fill the whole of a container, having no fixed shape (unlike a solid) and no fixed volume (unlike a liquid).
Gastric acid
Gastric acid, gastric juice, or stomach acid, is a digestive fluid formed within the stomach lining. With a pH between 1 and 3, gastric acid plays a key role in digestion of proteins by activating digestive enzymes, which together break down the long chains of amino acids of proteins.
Blood sugar, or glucose, is the main sugar found in your blood. It comes from the food you eat and is your body’s main source of energy. Your blood carries glucose to all of your body’s cells to use for energy.
Glucose intolerance
Glucose intolerance (GI) can be defined as dysglycemia that comprises both prediabetes and diabetes. It includes the conditions of impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) and diabetes mellitus (DM).
Glycocalyx is a highly charged layer of membrane-bound biological macromolecules attached to a cell membrane. This layer functions as a barrier between a cell and its surrounding.
Any of a class of proteins which have carbohydrate groups attached to the polypeptide chain.
Your gut is part of your digestive system – it’s where food goes after you eat it, to get broken down into nutrients and waste. Your gut is quite literally your intestines, although the word is frequently used for any part of your digestive system, especially your stomach.
Gut health
Gut health refers to the balance of microorganisms that live in the digestive tract. Looking after the health of the gut and maintaining the right balance of these microorganisms is vital for physical and mental health, immunity, and more.
Gut microbiota / gut flora / microbiome
Gut microbiota are the microorganisms including bacteria, archaea and microscopic eukaryotes that live in the digestive tracts of humans and other animals including insects. Alternative terms include gut flora and microbiome. The gastrointestinal metagenome is the aggregate of all the genomes of gut microbiota.
Gut motility
Gastric motility (or gastrointestinal motility) is the process by which food travels through the digestive tract via a series of muscular contractions called peristalsis. When someone has a gastric motility disorder, these contractions do not occur normally, and food is not able to pass through the intestines properly.


Herbal antimicrobials
Anti-microbials are herbs that help the body to destroy or resist pathogenic microorganisms. Many of these herbs are also anti-inflammatory and can be divided into those that are anti-bacterial, anti-viral, anti-fungal, anti-parasitic etc.
Histamine intolerance
Histamine intolerance, also referred to as enteral histaminosis or sensitivity to dietary histamine, is a disorder associated with an impaired ability to metabolize ingested histamine that was described at the beginning of the 21st century.
A rash of round, red welts on the skin that itch intensely, sometimes with dangerous swelling, caused by an allergic reaction, typically to specific foods.
A colourless, odourless, highly flammable gas, the chemical element of atomic number 1.
Hydrogen SIBO
Hydrogen dominant SIBO is most associated with diarrhea, while methane dominant is most associated with constipation. It has been shown that methanobacterium archaea actually slows motility, which can explain this phenomenon.
Hydrogen sulphide
A colourless poisonous gas with a smell of bad eggs, made by the action of acids on sulphides.
Hydrogen sulfide SIBO
Hydrogen Sulfide SIBO is the term used when someones SIBO breath test results come back with extremely low levels of both hydrogen and methane gas, throughout the three hours of the test.
Hydrolonic acid
A polysaccharide molecule which is one of the chief components of connective tissue, forming a gelatinous matrix that surrounds cells.


Short for irritable bowel syndrome.
IBS-C is a type of IBS in which the abdominal discomfort or bloating happens with constipation. Generally, constipation is when stools don’t pass often enough (less than three times per week). Having hard stools that are difficult to pass or the feeling of an incomplete bowel movement are signs of constipation.
IBS-D is a type of IBS in which abdominal pain or bloating symptoms happen along with stools that are often loose or more frequent than usual.
IBS with both diarrhoea and constipation (mixed).
IgG antibodies
If IgG antibodies are detected in someone’s blood, there’s likely to be some level of immunity.
Ileocecal valve
The ileocecal valve is a sphincter muscle situated at the junction of the ileum (last portion of your small intestine) and the colon (first portion of your large intestine). Its function is to allow digested food materials to pass from the small intestine into your large intestine.
Immune reaction
A bodily response to an antigen that occurs when lymphocytes identify the antigenic molecule as foreign and induce the formation of antibodies and lymphocytes capable of reacting with it and rendering it harmless.
Immune response
The reaction of the cells and fluids of the body to the presence of a substance which is not recognized as a constituent of the body itself.
Immune system
A complex network of cells, tissues, organs, and the substances they make that helps the body fight infections and other diseases. The immune system includes white blood cells and organs and tissues of the lymph system, such as the thymus, spleen, tonsils, lymph nodes, lymph vessels, and bone marrow.
Any of a class of proteins present in the serum and cells of the immune system, which function as antibodies.
The process of infecting or the state of being infected.
Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.
A hormone made by the islet cells of the pancreas. Insulin controls the amount of sugar in the blood by moving it into the cells, where it can be used by the body for energy.
Insulin resistance
Insulin resistance is when cells in your muscles, fat, and liver don’t respond well to insulin and can’t easily take up glucose from your blood. As a result, your pancreas makes more insulin to help glucose enter your cells.
Intestinal permeability
Intestinal permeability is a recently observed condition where the junctions in the gut epithelial wall lose their integrity, allowing material from the lumen to translocate into the bloodstream, other organs, or the adipose tissue.

Intestinal permeability refers to how easily substances pass through the intestinal wall. When the tight junctions of intestinal walls become loose, the gut becomes more permeable, which may allow bacteria and toxins to pass from the gut into the bloodstream.

Iron is a mineral that is naturally present in many foods, added to some food products, and available as a dietary supplement. Iron is an essential component of hemoglobin, an erythrocyte (red blood cell) protein that transfers oxygen from the lungs to the tissues.
Irritable bowel syndrome
Irritable bowel syndrome (IBS) is a group of symptoms that occur together, including repeated pain in your abdomen and changes in your bowel movements, which may be diarrhea, constipation, or both. With IBS, you have these symptoms without any visible signs of damage or disease in your digestive tract.




A sugar present in milk. It is a disaccharide containing glucose and galactose units.
Lactose intolerance
Partial or total inability to digest lactose, which may result in abdominal pain, bloating, and diarrhoea after consuming milk and other dairy products and is caused by deficiency of the enzyme lactase.
Lactulose breath testing
The Lactulose breath test is an indirect method of measuring bacteria in the digestive tract. It can indicate the approximate population, location, and some information about the type of bacteria. It is used to diagnose Small Intestine Bacteria Overgrowth (SIBO).
Large intestine
The long, tube-like organ that is connected to the small intestine at one end and the anus at the other. The large intestine has four parts: cecum, colon, rectum, and anal canal. Partly digested food moves through the cecum into the colon, where water and some nutrients and electrolytes are removed.
Leaky gut
Leaky gut, or increased intestinal permeability (IP), is a condition that creates gaps in the lining of the intestinal walls. These gaps allow food particles, bacteria, and waste products to seep directly into the bloodstream.
A protein produced by fat cells that is a hormone acting mainly in the regulation of appetite and fat storage.
A complex molecule containing both lipid and polysaccharide parts.
Low iron
Low levels of ferritin less than 15 μg/ml are diagnostic of iron deficiency. Levels higher than 40 μg/ml in a healthy person are considered optimal.


Lack of proper nutrition, caused by not having enough to eat, not eating enough of the right things, or being unable to use the food that one does eat.
Membranous phase of digestions
Membranous-phase digestion occurs within the microenvironment of the unstirred water layer, intestinal mucus, and glycocalyx. As previously described, the unstirred water layer, mucus, and glycocalyx form a diffuse zone separating the mucosal surface from the lumen of the intestine.
Mental health
A person’s condition with regard to their psychological and emotional well-being.
A colourless, odourless flammable gas which is the main constituent of natural gas. It is the simplest member of the alkane series of hydrocarbons.
Methane SIBO
Methane SIBO is a term used when elevated levels of methane gas have been found on a hydrogen breath test for small intestine bacterial overgrowth. A more appropriate team is IMO – intestinal methanogenic overgrowth.
Methanobrevibacter smithii
Methanobrevibacter smithii is the predominant archaeon in the microbiota of the human gut. M. smithii has a coccobacillus shape. It plays an important role in the efficient digestion of polysaccharides by consuming the end products of bacterial fermentation.
The microbiome is the genetic material of all the microbes – bacteria, fungi, protozoa and viruses – that live on and inside the human body. The number of genes in all the microbes in one person’s microbiome is 200 times the number of genes in the human genome. The microbiome may weigh as much as five pounds.
A microscopic projection of a tissue, cell, or cell organelle especially any of the finger like outward projections of some cell surfaces.
Migrating motor complex (MMC)
Migrating motor complex, also known as migrating myoelectric complex, migratory motor complex, migratory myoelectric complex and MMC, is a pattern of electrical activity observed in the gastrointestinal tract in a regular cycle during fasting. The migrating motor complex (MMC) serves the role of housekeeper of the small intestine by propelling undigested food residue and sloughed enterocytes.
Any of the class of sugars (e.g., glucose) that cannot be hydrolysed to give a simpler sugar.
The ability of the muscles of the digestive tract to undergo contraction.


A substance that provides nourishment essential for the maintenance of life and for growth.


A form of life considered as an entity; an animal, plant, fungus, protistan, or moneran. any organized body or system conceived of as analogous to a living being: the governmental organism.
Excessive growth or increase in numbers an overgrowth of bacteria … may achieve pathogenic proportions.


Panic attacks
A sudden overwhelming feeling of acute and disabling anxiety.
Polycystic ovary syndrome is a disorder involving infrequent, irregular or prolonged menstrual periods, and often excess male hormone (androgen) levels. The ovaries develop numerous small collections of fluid – called follicles – and may fail to regularly release eggs.
The involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wave-like movements that push the contents of the canal forward.
A substance which has a molecular structure built up chiefly or completely from a large number of similar units bonded together.
Polyphenols are micronutrients that naturally occur in plants. They’re included in many supplements, though they’re also easy to get in your diet from foods like fruits, vegetables, teas, and spices. There are more than 8,000 types of polyphenols, which include: flavonoids like quercetin and catechins in fruits.
A carbohydrate (e.g. starch, cellulose, or glycogen) whose molecules consist of a number of sugar molecules bonded together.
Prebiotic was described as “a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improves host health”.
Probiotics are a combination of live beneficial bacteria and/or yeasts that naturally live in your body. Bacteria is usually viewed in a negative light as something that makes you sick. However, you have two kinds of bacteria constantly in and on your body — good bacteria and bad bacteria.

Probiotics are live bacteria and yeasts that are good for you, especially your digestive system. We usually think of these as germs that cause diseases. But your body is full of bacteria, both good and bad. Probiotics are often called “good” or “helpful” bacteria because they help keep your gut healthy.

A microscopic single-celled organism which has neither a distinct nucleus with a membrane nor other specialized organelles, including the bacteria and cyanobacteria.
Any of a class of nitrogenous organic compounds which have large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms, especially as structural components of body tissues such as muscle, hair, etc., and as enzymes and antibodies.
A skin disease marked by red, itchy, scaly patches.
Psychological distress
Psychological distress refers to non-specific symptoms of stress, anxiety and depression. High levels of psychological distress are indicative of impaired mental health and may reflect common mental disorders, like depressive and anxiety disorders.
Pyloric sphincter
The pyloric sphincter is a band of smooth muscle that controls the movement of partially digested food and juices from the pylorus into the duodenum.
Pyloric valve
The sphincter muscle of the pylorus that separates the stomach from the duodenum. Synonyms: musculus sphincter pylori, pyloric sphincter. Type of anatomical sphincter, sphincter, sphincter muscle. A ring of muscle that contracts to close an opening.



Rest and digest
The parasympathetic nervous system is one of three divisions of the autonomic nervous system. Sometimes called the rest and digest system, the parasympathetic system conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.
A sugar of the pentose class which occurs widely in nature as a constituent of nucleosides and several vitamins and enzymes.


Secondary fructose intolerance
Fructose is a sugar that occurs naturally in fruits, vegetables, and honey. When a person is unable to digest or absorb fructose, they may have fructose intolerance. When a person has an intolerance to fructose, they may experience bloating, abdominal pain, and diarrhea. In SIBO this can be result as a secondary effect.
Secondary lactose intolerance
Secondary lactose intolerance occurs when the gut lining (where lactase is produced) is damaged. This can occur due to a bout of gastroenteritis or due to chronic irritation (such as that due to food allergy or food intolerance), among other reasons.
Production and release of a useful substance by a gland or cell; also, the substance produced. In addition to the enzymes and hormones that facilitate and regulate complex biochemical processes, body tissues also secrete a variety of substances that provide lubrication and moisture.
A pouch that forms the first part of the large intestine. It connects the small intestine to the colon, which is part of the large intestine. Enlarge. The cecum connects the small intestine to the colon.
A compound present in blood platelets and serum, which constricts the blood vessels and acts as a neurotransmitter. Serotonin is the key hormone that stabilizes our mood, feelings of well-being, and happiness. This hormone impacts your entire body. It enables brain cells and other nervous system cells to communicate with each other. Serotonin also helps with sleeping, eating, and digestion.
Short chain fatty acids
Short-chain fatty acids (SCFAs) are the main metabolites produced by the microbiota in the large intestine through the anaerobic fermentation of indigestible polysaccharides such as dietary fibre and resistant starch. SCFAs might influence gut-brain communication and brain function directly or indirectly.
Small intestinal bacterial overgrowth (SIBO) occurs when there is an abnormal increase in the overall bacterial population in the small intestine – particularly types of bacteria not commonly found in that part of the digestive tract. This condition is sometimes called blind loop syndrome.
A mixture of polydimethylsiloxanes with antifoaming and anti-bloating effects. Simethicone reduces the surface tension of gas bubbles causing them to coalesce into larger bubbles that can be passed more easily by belching or flatulence.
Small intestine
A long tube-like organ that connects the stomach and the large intestine. It helps to further digest food coming from the stomach. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body. The small intestine is part of the digestive system.
An odourless, tasteless white substance occurring widely in plant tissue and obtained chiefly from cereals and potatoes. It is a polysaccharide which functions as a carbohydrate store and is an important constituent of the human diet.
The internal organ in which is a major part of the digestion of food occurs, being (in humans and many mammals) a pear-shaped enlargement of the alimentary canal linking the oesophagus to the small intestine.
Stomach acid
Stomach acid, or gastric acid, is a watery, colourless fluid that’s produced by your stomach’s lining. It’s highly acidic and helps break down food for easier digestion. This helps your body absorb nutrients more easily as food moves through your digestive tract.
Your stool passes out of your body through the rectum and anus. Another name for stool is faeces. It is made of what is left after your digestive system (stomach, small intestine, and colon) absorbs nutrients and fluids from what you eat and drink. Sometimes a bowel movement isn’t normal.
Sugar is a monosaccharide or a disaccharide. Sugars are mostly known commercially as any sweet crystalline solid disaccharide (sucrose) or monosaccharide (glucose) used as a sweetener or a preservative. Biologically, sugars are used especially by organisms as a source of metabolic energy.
A nutrient-rich food considered to be especially beneficial for health and well-being. Often overly hyped.
Sympathetic nervous system
The part of the nervous system that increases heart rate, blood pressure, breathing rate, and pupil size. It also causes blood vessels to narrow and decreases digestive juices.
A physical or mental feature, which is regarded as indicating a condition of disease, particularly such a feature that is apparent to the patient.


Total daily energy expenditure
TDEE stands for Total Daily Energy Expenditure. It is the total number of calories you burn in a given day. Your TDEE is determined by four key factors: Basal Metabolic Rate and Thermic Effect of Food.
A poison of plant or animal origin, especially one produced by or derived from microorganisms and acting as an antigen in the body.



A cytoplasmic actin-binding protein enriched in focal adhesions and adherens junctions that is essential for embryonic development.
Vitamin B
Any of a group of substances (the vitamin B complex) which are essential for the working of certain enzymes in the body and, although not chemically related, are generally found together in the same foods. They include thiamine (vitamin B1), riboflavin (vitamin B2), pyridoxine (vitamin B6), and cyanocobalamin (vitamin B12).
Vitamin D
Any of a group of vitamins found in liver and fish oils, essential for the absorption of calcium and the prevention of rickets in children and osteomalacia in adults. They include calciferol (vitamin D2) and cholecalciferol (vitamin D3).





Zonulin level
Zonulin is the only measurable blood protein that reflects the intestinal permeability, and increased zonulin levels are considered to be a marker of impaired intestinal barrier.