Antioxidants are molecules that fight free radicals in your body. Free radicals are compounds that can cause harm if their levels become too high in our body. They’re linked to multiple illnesses, including diabetes, heart disease, and cancer. Our bodies have their antioxidant defenses to keep free radicals in check.

However, antioxidants are also found in food, especially in fruits, vegetables, and other plant-based, whole foods. Several vitamins, such as vitamins E and C, are effective antioxidants. Hundreds of thousands of substances act as antioxidants. The most familiar ones are vitamin C, vitamin E, beta-carotene, and other related carotenoids, along with the minerals selenium and manganese. They’re joined by glutathione, coenzyme Q10, lipoic acid, flavonoids, phenols, polyphenols, phytoestrogens, and many more. Most are naturally occurring, and their presence in food is likely to prevent oxidation or to serve as a natural defense against the local environment.

Bacteria are a large group of prokaryotic microorganisms (cells lacking a nucleus, as opposed to eukaryotic ones, that have a nucleus, and that form the human body) that were among the first life forms to appear on Earth. They are commonly found in most of the planet’s habitats and live in symbiotic (mutually beneficial), commensal (eating from the same dish) or parasitic (living in or on another organism and benefiting from it) relationships with plants, animals and humans. Many people believe that all bacteria are pathogens. Although some of them can be harmful, most of them are beneficial and necessary for remaining in good health.

Bacteria are 10 to 50 times smaller than human cells. In the human body, there are an estimated 40 trillion microorganisms, including at least 1000 different known species of bacteria with more than 3 million genes—that is, 150 times more genes than humans have. Large bacterial communities live on the skin and in our bodily cavities. The largest community lives in our guts: the gut microbiota.

A genus of bacterial species naturally present in a mammal’s gut. You can also find these bacteria in fermented foods (such as dairy products) or dietary supplements.

Abdominal bloating is a condition in which the abdomen swells and gets tight. More common in women, it can cause belly pain that varies from mild to intense. It is provoked by excess gas, when said gas does not pass through belching or flatulence and therefore builds up in the stomach and intestines, or by an excessive reaction to normal gas production e.g. hypersensitivity of the bowel. In general, people suffering from bloating have flatter bellies in the morning that progressively become more distended over the day.

Gut bacteria produce butyrate, an important short-chain fatty acid that supports digestive health, helps control inflammation, and even aids in preventing disease. Gut bacteria transform dietary fibres found in whole, plant foods called “prebiotics” because they nourish and encourage the health-promoting activities of beneficial bacteria in the gut microbiome.

Your body produces less butyrate than other short-chain fatty acids, but it has many health benefits. It is needed for your overall gut health, as well as helping to make energy for some gut cells

The colon, also known as the large intestine, is the last part of the digestive tract. It allows the absorption of water and essential vitamins produced by gut bacteria and the transformation of non-digested residues, which is the origin of faeces. Shorter in length than the small intestine, with a longer transit time, the colon is considerably thicker in diameter and harbours the vast majority of the gut microbiota.

The term commensalism refers to a type of relationship between two different organisms that “eat from the same dish”. In this kind of relationship, neither benefits from the other or provokes any harm. It is, therefore, a neutral relationship. Other classes of relationships between organisms include mutualism, in which both organisms obtain benefits, or parasitism, where one profits from the other by harming it. Although “friendly” bacteria inhabiting our organism are usually referred to as commensal, research in this field suggests that the relationship between our gut microbiota and us is not merely commensal, but rather mutualistic.

This is a type of Inflammatory Bowel Disease (IBD) that can affect any part of the digestive system, from the mouth to the back passage, although it mostly occurs in the last section of the small intestine, the ileum, or the large intestine, the colon. Its most usual symptoms include diarrhoea, abdominal pain and extreme tiredness, as well as bloody stools and weight loss on occasion.

This disorder often begins gradually and becomes worse over time. People with Crohn’s disease sometimes go for long periods without any symptoms or very mild ones, known as remission periods. These phases can be followed by very troublesome periods during which the disease flares up. The exact cause of this disorder is unknown, although researchers point out some factors like genetics, and immune system anomaly that causes it to attack healthy bacteria in the gut, smoking or environmental factors (curiously, the disease is more common in Western countries than in the world’s developing areas).

Also called dysbacteriosis, it refers to an imbalance of microbial colonies, either in number or type, that have colonized the human body. This is most common in the digestive tract, but it can happen in any exposed surface or mucous membrane. Dysbiosis can affect digestion, absorption of nutrients, production of vitamins and controlling the growth of harmful microorganisms. A wide range of factors, such as changes in dietary habits or antibiotic use, can influence the delicate microbial balance and thus, lead to dysbiosis. Researchers believe that it may have a role in disorders such as Inflammatory Bowel Disease (IBD), chronic fatigue, obesity or even certain cancers.

Fermentation is a chemical process by which an organism converts sugars and carbohydrates present in food into an acid or an alcohol. Humans have used it for centuries to turn raw materials into assimilable final products, in food such as yoghurt, kefir, cheese, bread, wine and beer, or even chocolate.

This is the name given to the community of microorganisms inhabiting the length and breadth of the mammalian gastrointestinal tract. The composition of this microbial community is host-specific. Each individual’s gut microbiota can undergo endogenous and exogenous alterations. It is sometimes called human flora, microflora or gut flora. These terms, however, are less used by scientists as it leads to the incorrect idea that tiny plants colonise us, while the microorganisms making up our microbiota are different kinds of microbes

Human Microbiome Project. Launched in 2008, it was a five-year US National Institutes of Health (NIH) project that had the aim of identifying and characterising microbial communities found at multiple human body cavities and looking for correlations between changes in the microbiome and human health and diseases.

See gut flora/gut microbiota.

This term refers to the biological community of microorganisms living in the environment of the human gut. Although the bacteria belong to different groups and are present in our digestive systems in different quantities, they work as a team, playing an essential role in helping digest food, boosting the immune system, preventing infections and even influencing mood and behaviour.

The immune system is generally known as the body’s defence system against infectious organisms and other invaders. It is made up of a network of cells, tissues and specialized organs that communicate with each other and act through a cascade of biological reactions that involve cytokines. The immune response acts to destroy and eliminate the detected agent to prevent it from causing any harm to the host.

Inflammation is the body’s biological response as it aims to fight against an aggression. It can be characterized by specific symptoms such as redness, swelling, a feeling of heat or pain, or altered functions of the involved organ. Infection is caused by bacteria, viruses or fungi, whereas inflammation is part of our innate immunity and does not necessarily imply an infection.

Inflammatory Bowel Disease (or IBD) covers Crohn’s disease and ulcerative colitis. Both disorders are characterized by an excessive swelling of the wall of one section of the digestive tract.

Irritable Bowel Syndrome (IBS) is a common functional disorder of the gut affecting 15% to 20% of people worldwide (with a higher prevalence in women). Irritable Bowel Syndrome is the main motivation behind gastroenterology consultations. Researchers believe it may originate from an unbalanced gut microbiota.

Lactobacillus is a type of rod-shaped bacteria that normally inhabits our oral, digestive and genital cavities. It is also present in some fermented foods like yoghurts or dietary supplements. Its name comes from its ability to convert lactose and other sugars into lactic acid. Due to their effectiveness, lactobacilli are normally used for treating and preventing diarrhoea, including some infectious types such as rotavirus diarrhoea in children or traveller’s diarrhoea.

The term metagenome refers to the entire collection of microbial genes found in a particular environment (or ecosystem). Metagenomics is the method used to analyze this metagenome. It reflects the potential capacity of a specific ecosystem, what action their gens can implement. It also reflects which microorganisms are present.

The term ‘microbial ecology’ is used to refer to the study of microbes and their interactions with the environment, as well as with plants, animals and each other. Although they are the tiniest creatures on Earth, they have a deep impact on humans and the planet. That is why scientists believe the study of microbial ecology can lead us to find better solutions to environmental restoration, food production and bioengineering, for instance.

Researchers usually refer to the human microbiome when talking about the entire collection of genes found in all of the microbial cells living in the human body. It is sometimes confused with microbiota, the word used to define the hundreds of trillions of microorganisms living in the human body.

It is the name given to the community of microorganisms that reside either on the surface or in different cavities of the body: the skin, the mouth, the ears, the vagina or the gastrointestinal tract, among others. (See gut microbiota)

Often wrongly used as a synonym of the word “microbe”, microorganisms are single- or multiple-cell organisms, so tiny that they cannot be seen with the naked eye (microscopic). Microorganisms are diverse and include parasites, bacteria, archaea, fungi and viruses. Microorganisms are the oldest form of life on Earth. The study of microorganisms is called microbiology.

A pathogen is an infectious biological agent that can produce a disease in its host. The term is mostly used to describe microorganisms like virus, bacteria or fungi, among others. These agents can disrupt the normal physiology of plants, animals and humans.

Policosanol is a chemical most often obtained from sugar cane. It can also be made from other plants, such as wheat.

Policosanol is most commonly used for leg pain due to poor blood circulation (intermittent claudication). It is also used for high cholesterol and clogged arteries.

Policosanol seems to decrease cholesterol production in the liver and to increase the breakdown of LDL (low-density lipoprotein or “bad”) cholesterol. It also decreases the stickiness of particles in the blood known as platelets.

Postbiotics are functional bioactive compounds, generated in a matrix during fermentation, which may be used to promote health. Postbiotics is used as an umbrella term for all synonyms and related terms of these microbial fermentation components. Therefore, postbiotics can include many different constituents including metabolites, short-chain fatty acids (SCFAs), microbial cell fractions, functional proteins, extracellular polysaccharides (EPS), cell lysates, teichoic acid, peptidoglycan-derived muropeptides and pili-type structures.

Feeding and supporting commensal gut microbes through a diverse, plant-based diet of prebiotic fibre foods may ensure abundance of not only beneficial bacteria, but also those fermentation by-products, or postbiotics, that demonstrate nutritional, metabolic, and immune health benefits.

Prebiotics are functional non-digestible food components (such as certain kinds of fibre) that stimulate the activity or the growth of some specific groups of bacteria, e.g. bifidobacteria and lactic acid bacteria. Scientific studies have proved that both prebiotics and probiotics have several beneficial effects on the host’s health, especially in terms of digestive and immune functions.

According to the 2001 WHO/FAO definition, probiotics are “live microorganisms which, when administered in adequate amount, confer a health benefit on the host”. They are commonly consumed as part of fermented food, e.g. yoghurt, or as dietary supplements.

The relationship established between two organisms that need each other to survive is called symbiosis. Bacteria have a long history of symbiotic interactions with humans, and they have even evolved in symbiosis with other microbes and with their hosts. Humans have trillions of bacteria living in their digestive tracts, and these bacteria have found a suitable ecosystem for their development. As they break down the food that humans can’t digest by themselves, they produce energy and the vitamins we need.

Superfood is a term attributed to a food or foods that confer health benefits based on the exceptional nutrient density of that food. Superfoods are rich in compounds such as antioxidants, fibre, fatty acids and phytonutrients, all considered beneficial for good health.