Have you heard of short-chain fatty acids? In this article you’re going to become familiar with these incredible substances.
Despite being little known outside of scientific literature, short-chain fatty acids (SCFAs) not only play a crucial role in the health of your digestive system, but are also involved in energy production, the control of inflammation, weight management and even cholesterol regulation.
What are short-chain fatty acids?
Fatty acids are the building blocks of fat. Chemically speaking, they’re straight chains of carbon atoms, along with hydrogen atoms and a group called a carboxyl group on the end – which is what makes them an acid.
A fat is formed when molecules of a fatty acid combine. There are many types of fatty acids, some of which we’re quite familiar with – you may have heard of alpha-linolenic acid (ALA), which is an omega-3 fatty acid found in many seeds such as flax seeds.
Some of the carbon chains of fatty acids are really long – DHA, which is another omega-3 fat found in fish, has 22 carbon atoms.
SCFAs are specific types of fatty acids which contain less than six carbon atoms in their tails. The most commonly encountered SCFAs are butyric acid, acetic acid and, propionic acid.
How do you obtain SCFAs?
One SCFA – butyric acid – is found in dairy products, especially butter, ghee and some cheeses such as parmesan cheese. In fact its name means ‘butter’ in Greek.
However, a major source of SCFAs is from the fibre in food. Scientists have known for years that fibre is beneficial for our health, but until recently, it hasn’t been clear exactly how it works to benefit the body.
Fibre is any type of carbohydrate which you can’t digest. However, fibre doesn’t simply pass out of your body unaltered and an important, but previously overlooked, role of fibre is to act as a food source for the bacteria living in your gut.
Fibre and bacteria – a healthy combination
Science is starting to recognise what many naturopathic practitioners have believed for years – the bacteria residing in your digestive system have far reaching effects on your general health. These bacteria, collectively known as the microbiome, can broadly be classified as beneficial and not so beneficial as far as health is concerned.
Most of the time you’re relatively unaware of these trillions of bacteria hitching a ride along life with us, until something goes wrong. When the non-beneficial or pathogenic bacteria take over, the first symptoms tend to be digestive, such as IBS and food sensitivities.
Fascinating research into the microbiome is revealing how the makeup of bacteria you play host to can affect the health of the whole body in previously unsuspected ways.
The question is, if the bacteria live in the digestive system, how do they influence general health? The answer may lie in SCFAs.
Bacteria, like us, need food to survive. When you eat foods containing fibre you not only encourage the growth of the beneficial types of bacteria by providing them with a food source, but as the fibre is fermented by the bacteria, SCFAs are produced.
So-called friendly bacteria include those belonging to the species Lactobacillus and Bifidobacteria – these types of bacteria produce large quantities of SCFAs.
The process happens in the large intestine or colon – the SCFAs in turn increase the acidity in the intestines which is an environment pathogenic bacteria don’t like, so they don’t grow as well (1). In other words the production of SCFAs involves a cycle in which bacteria feed on fibre, then produce the acids which contribute to the environment they prefer to live in, so they can produce more SCFAs.
The amount and types of bacteria in the colon, the food source they are feasting on and how long it takes food to travel through the intestines all influence the amount and proportions of SCFAs produced.
The process of creating SCFAs needs the bacteria in the microbiome to work together, almost like a complex community.
Benefits of SCFAs
Gut bacteria living in harmony and producing plenty of SCFAs result in wide-ranging health benefits.
- SCFAs and digestive health
SCFAs provide fuel for the cells of the intestines, and good levels of SCFAs have been linked to a healthy intestinal mucus lining. In fact, studies have shown when no bacteria are present in the gut, the cells lining the colon were able to produce less energy (2).
Research suggests SCFAs can influence the genes which regulate the process of cell division and renewal in the gut, which may have implications for the prevention of colon cancer (3).
Other researchers have noted however that simply eating a high fibre diet, without the bacteria which produce SCFAs, was ineffective at protecting against colon cancer. Having a great population of bacteria in combination with a low fibre diet was equally ineffective. It seems therefore it’s the combination of the fibre and the right type of bacteria which offers the protection.
Finally, SCFAs appear to control the muscular contractions which move food through the intestines during the process of digestion (4). All this is good news for your digestive system, but science is now discovering SCFAs are also transported into the bloodstream where they are carried around the entire body. There they act as signalling molecules and have been shown to have many beneficial effects on overall health.
- SCFAs and intestinal permeability
Research has linked low levels of SCFA production with increased intestinal permeability, otherwise known as leaky gut.
Low levels of butyrate have been found in studies to cause tiny gaps in the walls lining the small intestines to become larger, letting molecules through which shouldn’t gain access to the body (5).
Increased intestinal permeability has been linked to a range of health issues including food sensitivities, auto-immune diseases, skin problems and even mood disorders. Because the health of the intestinal lining is crucial to the proper functioning of the immune system, it follows SCFAs also play a role in immune function.
- SCFAs and obesity
Research has discovered SCFAs affect specific receptors involved in fat and glucose metabolism. They seem to help to improve the body’s sensitivity to insulin, therefore helping us to regulate blood sugar.
SCFAs can also inhibit fat storage and increase the amount of fat burned and so reduce body weight (6). SCFAs also appear to encourage the release of a hormone called leptin, which regulates appetite and body weight over the long term (7).
- SCFAs and Type 2 diabetes
Research concentrating on butyric acid concluded this SCFA has beneficial effects on blood sugar control with relation to Type 2 diabetes (8). The specific types of bacteria which produce butyric acid were found to be low in people suffering from Type 2 diabetes (9).
- SCFAs and inflammation
We know eating more fibre is linked to lower levels of chronic inflammation in the body, and evidence suggests butyric acid may inhibit the production of certain inflammatory molecules (10). Inflammation is at the heart of many diseases. Butyric acid has been used with success to reduce the inflammation in cases of Crohn’s disease and ulcerative colitis.
- SCFAs and cholesterol
The SCFA propionic acid is metabolised by the liver. It’s thought it may reduce the liver’s production of cholesterol. In fact, SCFAs have been shown to reduce blood levels of cholesterol (11).
How can you boost your production of SCFAs?
Certain types of fibre have been found to significantly boost the production of SCFAs.
These include:
- Inulin – found in Jerusalem artichokes, chicory root, dandelion greens, onions, garlic, leeks and asparagus.
- FOS – short for fructo-oligosaccharides. This is a type of fibre found in plant foods especially garlic, onions, artichoke and banana.
- Pectin – good sources are apples, pears, apricots, carrots, guava and oranges.
- Resistant starch – in seeds, legumes, and unripe bananas – it is formed when starchy foods such as potatoes and rice are cooked and then cooled.
These types of fibre are often known as prebiotics because they serve as such good food sources for your gut bacteria.
Some people find they experience gas and bloating when they consume foods high in prebiotics. This can be due to a medical condition called small intestinal bacterial overgrowth, (SIBO) whereby the bacteria which should be in the colon migrate to the small intestine, where they aren’t usually found.
If this is the case for you, it’s best to introduce these foods very gradually, and to work with a therapist to correct the balance of bacteria throughout your digestive tract.
Test, don’t guess
One of the most exciting aspects about our emerging knowledge of SCFAs are the clues they can give us about what is happening in the body. If you know how efficiently your bacteria are producing SCFAs, you can discover the state of health of your personal microbiome.
We know our individual genetic makeup exerts an influence over the precise ratio of the bacterial species in the microbiome, so we each play host to a different population with a different capacity to produce SCFAs.
The ability of your microbiome to produce SCFAs can be assessed by a test which examines your stool. Analysis of the levels of the different types of SCFAs can tell us how effectively they’re being produced by your gut bacteria.
On the other hand, a urine test known as the OAT test – which stands for organic acids test – analyses your urine to detect the levels of other substances produced by your digestive bacteria, providing a good picture of the makeup of your microbiome.
Takeaway
We now understand that SCFAs have profound effects on your body, and we also know their levels are affected by what you eat. Research is ongoing, but SCFAs may hold one key to the huge rise in inflammatory diseases seen in the modern Western world. All this goes to show looking after your gut bacteria can have many benefits for your overall health.
A consultation with an experienced Amchara Personalised Health practitioner, with testing where appropriate, can recommend a lifestyle and nutritional plan to maximise the health of your microbiome and improve your production of these wonderful SCFAs.
We’re dedicated to providing you with both insightful information and evidence-based content, all orientated towards the Personalised Health approach.
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