Short-chain fatty acids (SCFAs) are
fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...
s with fewer than six
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
atom
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons.
Every solid, liquid, gas, and ...
s.
Derived from
intestinal
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans ...
microbial
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
fermentation
Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...
of indigestible foods, SCFAs are the main energy source of
colonocytes, making them crucial to
gastrointestinal
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...
health.
SCFAs all possess varying degrees of water solubility, which distinguishes them from longer chain fatty acids that are immiscible.
List of SCFAs
Functions
SCFAs are produced when dietary fiber
Dietary fiber (in British English fibre) or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition, and can be grouped generally by the ...
is fermented in the colon. Macronutrient composition (carbohydrate, protein, or fat) of diets affects circulating SCFAs.
Acetate, propionate, and butyrate are the three most common SCFAs.
SCFAs and medium-chain fatty acid
Medium-chain triglycerides (MCTs) are triglycerides with two or three fatty acids having an aliphatic tail of 6–12 carbon atoms, i.e. medium-chain fatty acids (MCFAs). Rich food sources for commercial extraction of MCTs include palm kernel oil a ...
s are primarily absorbed through the portal vein
The portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approxima ...
during lipid digestion
Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...
, while long-chain fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...
s are packed into chylomicrons
Chylomicrons (from the Greek χυλός, chylos, meaning ''juice'' (of plants or animals), and micron, meaning ''small particle''), also known as ultra low-density lipoproteins (ULDL), are lipoprotein particles that consist of triglycerides (85 ...
, enter lymphatic capillaries
Lymph capillaries or lymphatic capillaries are tiny, thin-walled microvessels located in the spaces between cells (except in the central nervous system and non-vascular tissues) which serve to drain and process extracellular fluid. Upon enterin ...
, then transfer to the blood at the subclavian vein
The subclavian vein is a paired large vein, one on either side of the body, that is responsible for draining blood from the upper extremities, allowing this blood to return to the heart. The left subclavian vein plays a key role in the absorption ...
.[
SCFAs have diverse ]physiological
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
roles in body functions.[ They can affect the production of lipids, energy and vitamins. They can also affect appetite and cardiometabolic health.] Additionally they may have an impact on mental health and mood. The three main SCFAs, acetate, propionate and butyrate, were shown to lower blood pressure
Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure" r ...
in experimental models, and clinical trials to determine their effect on hypertensive patients are underway. Butyrate
The conjugate acids are in :Carboxylic acids.
{{Commons category, Carboxylate ions, Carboxylate anions
Carbon compounds
Oxyanions ...
is particularly important for colon health because it is the primary energy source for colonocytes (the epithelial cells of the colon).[ The liver can use acetate for energy.]
See also
* List of carboxylic acids
Carboxylic acids are organic acids characterized by a carboxyl (-COOH) functional group. The naming of these compounds is governed by IUPAC nomenclature, which ensures systematic and consistent naming of chemicals. Numerous organic compounds have o ...
* Medium-chain fatty acid
Medium-chain triglycerides (MCTs) are triglycerides with two or three fatty acids having an aliphatic tail of 6–12 carbon atoms, i.e. medium-chain fatty acids (MCFAs). Rich food sources for commercial extraction of MCTs include palm kernel oil a ...
(MCFA), fatty acid with aliphatic tails of 6 to 12 carbons, which can form medium-chain triglycerides
* Long-chain fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...
(LCFA), fatty acid with aliphatic tails of 13 to 21 carbons
* Very long chain fatty acid A very-long-chain fatty acid (VLCFA) is a fatty acid with 22 or more carbons. Their biosynthesis occurs in the endoplasmic reticulum. VLCFA's can represent up to a few percent of the total fatty acid content of a cell.
Unlike most fatty acids, V ...
(VLCFA), fatty acid with aliphatic tails of 22 or more carbons
References
Further reading
A review of the biological properties of SCFA from the Danone Institute
via archive.org
The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge". It provides free public access to collections of digitized materials, including websites, software applications/games, music, ...
{{Fatty acids, state=collapsed
Fatty acids