Short Chain Fatty Acids
Short-chain fatty acids are special molecules produced by the beneficial bacteria in the gut, which have the enzymes necessary to ferment and eat dietary fiber.
They are the main source of nutrition for the cells in the colon.
Short-chain fatty acids also play an important role in overall health and in preventing and fighting disease.
They can help reduce the risk of certain inflammatory diseases, including heart disease, obesity, diabetes type II, metabolic syndrome, and others.
Read on to find out everything you need to know about short-chain fatty acids.
What exactly are short-chain fatty acids?
They are fatty acids with less than 6 carbon atoms.
The short-chain fatty acids (SCFAs) are produced as the friendly bacteria in the gut ferments the fiber in the colon and are also the main energy source for the cells in the lining of the colon.
This is why they are known to play an essential role in colon health.
The leftover short-chain fatty acids are used for other body functions and provide about 10% of your daily calories.
They are vital for the metabolism of fat and carbohydrates as well.
The short-chain fatty acids are metabolites with a distinctive chemical structure, including a carboxylic acid head and a saturated hydrocarbon tail.
They are distinguished by the number of carbon atoms in their “tails.”
Approximately 95% of all of the short-chain fatty acids in the body are:
- Acetate C2 (2 carbons in the tail)
- Butyrate C4 (4 carbons in the tail)
- Propionate C3 (3 carbons in the tail)
Propionate is involved in the production of glucose by the liver, in which butyrate and acetate are transformed into cholesterol and other fatty acids.
There are various factors that affect how many short-chain fatty acids there are in the colon. These include the microorganisms which are present in the colon, the food source there, as well as the time it takes for the ingested food to travel through the digestive system.
The short-chain fatty acids are the so-called molecular messengers of the gut microbiota, which play an essential role in how dietary fiber affects human health.
These molecules, which are produced by the bacteria in the colon, can remain in the gut, while others travel through the body and take part in various interactions with various health effects.
Which foods are good sources of short-chain fatty acids
Foods that are rich in fiber like legumes, oats, vegetables, fruits, and others are linked to the increased production of short-chain fatty acids.
A study found a positive correlation between the intake of plant foods and the increased amounts of short-chain fatty acids in stools.
But the type and amount of fiber eaten also affects the composition of the gut bacteria in the gut, which too has an effect on the amount of short-chain fatty acids produced.
Studies have found that eating more fiber will increase the production of butyrate, and decreasing it leads to lesser production of these short-chain fatty acids.
Here are the best types of fiber that increase the production of short-chain fatty acids in the human colon:
- Inulin – this can be found in garlic, leeks, artichokes, wheat, onions, asparagus, and rye.
- Resistant starch – found in grains, rice, barley, beans, grains, legumes, green bananas, and cooked and then cooled potatoes.
- Pectin – found in apples, carrots, apricots, oranges, and others.
- Fructooligosaccharides – found in different fruits and vegetables, including asparagus, onions, garlic, and bananas.
- Arabinoxylan – found in cereal grains, such as wheat bran. Also, check our dedicated article for the most suitable wheat bran substitutes.
- Guar gum – found in guar beans.
- Certain types of cow’s milk, butter, and cheese also contain some butyrate.
Since the production of short-term fatty acids is closely linked to the food eaten, scientists believe that there is an important link between the diet and the gut flora as well as the overall health.
See also: Why do we need dietary fiber?
How do the short-chain fatty acids affect the human health
Short-chain fatty acids and digestive disorders
SCFAs have important effects on the GI tract and thus influence gut health.
They are the main source of energy for the friendly bacteria in the colon and for the cells in the lining in the colon.
They can help boost the mucous layer, which protects the gut, and also can influence the genes which control the cell cycle and proliferation.
They are also found to influence muscular contraction, which helps propel the intestinal content through the GI tract as well.
Short-chain fatty acids can be very beneficial against certain digestive disorders.
Butyrate is known to have an anti-inflammatory effect on the gut.
Eating foods rich in dietary fibers like pectin and resistant starch, which get converted into short-chain fatty acids, has been found to reduce diarrhea in children.
Inflammatory Bowel Disease (IBD)
Crohn’s disease and ulcerative colitis are the two most common types of inflammatory bowel disease. One symptom of both conditions is chronic bowel inflammation.
Due to the fact that butyrate is known to have an anti-inflammatory effect on the gut, it is used to treat these conditions.
Studies show that butyrate supplements can help reduce bowel inflammation and that lowered amounts of short-chain fatty acids are associated with the worsening of ulcerative colitis. It also helps reduce the leaky gut symptom, which is associated with ulcerative colitis.
Other studies have found that SCFAs and namely butyrate, can help improve the symptoms of both Crohn’s disease and ulcerative colitis.
A study with patients with ulcerative colitis who were asked to consume 60g of oat bran every day showed that their symptoms had improved after only 3 months of daily intake of oat bran.
Another study found that certain butyrate supplements help improve and caused remissions in over 50% of the Crohn’s disease patients involved in the experiment.
Other research found that enemas with short-chain fatty acids twice daily for 6 weeks helped reduced the symptoms of Crohn’s disease by 13%.
Short-chain fatty acids and their effect on colon cancer
SCFAs may play an essential role in the prevention as well as the treatment of some cancers, mainly colon cancer.
There are some lab studies that suggest that the butyrate can help keep the cells of the colon healthy and can prevent the growth of malignant tumor cells, and also helps the destruction of the cancerous cells in the colon as well.
But the actual mechanisms behind this correlation are not yet clear.
Some studies suggest that there is a link between eating high-fiber diets and a lowered risk of developing colon cancer. Many scientists suggest that it is the short-chain fatty acids that are responsible for this.
There are various studies on animals that report a positive link between the intake of high fiber foods and a reduced risk of colon cancer.
But then, only the high fiber diet without the bacteria which makes butyrate was not found to protect against the development of colon cancer.
Also, a low fiber diet including the butyrate-producing gut bacteria was also found to be ineffective for colon cancer prevention.
The studies involving humans too have mixed results, with some finding a link between high fiber diets and reduced colon cancer risk and others finding no correlation at all.
Still, these abovementioned studies did not actually explore gut bacteria, and as other studies suggest, the actual type of gut bacteria can also play a role in the prevention of colon cancer.
Short-chain fatty acids and their effect on diabetes
There has been reported scientific evidence that butyrate can have a positive effect on humans and animals with type II diabetes.
This same review of the different studies also highlighted the fact that people with this type of diabetes have an imbalance of gut bacteria and microorganisms too.
Short-chain fatty acids have been found to help increase the enzyme activity in the muscle tissue and the liver, which results in improved control of the blood sugar levels.
In some animal studies, the propionate and acetate supplements showed an improvement in the blood sugar levels in both diabetic and healthy rats.
But there are much fewer studies involving humans, and the results are still mixed.
A study found that a propionate supplement reduced blood glucose levels, but then another study didn’t find a significant effect of short-chain fatty acid supplements on the blood sugar levels in people without diabetes.
Other human studies have found associations between fermentable dietary fiber and improved insulin sensitivity and blood sugar control.
But this effect was found only in overweight people or those with insulin resistance, but not in healthy people.
Short-chain fatty acids and their effect on weight loss
Short-chain fatty acids have an impact on the way energy is metabolized by the body and thus have a possible protective effect against obesity and metabolic disease.
The composition of the gut microbiome affects the regulation of energy and the absorption of nutrients, so it can also affect the development of obesity or prevent it.
Still, the evidence of such a correlation is still not completely conclusive, because while some studies have found that short-chain fatty acids do help reduce glucose and cholesterol levels, which can help protect against obesity, they do provide a significant source of calories which on the other hand can contribute to obesity as well.
Some studies have found that short-chain fatty acids can help regulate the metabolism of fat by decreasing its storage and increasing its burning.
When this happens, the amount of free fatty acids in the blood is reduced, which too can help protect against excessive weight gain.
Some animal studies have also explored this matter. Mice that were given butyrate for 5 weeks, those who were obese lost 10.2% of their body weight, and the amount of body fat was reduced by 10%.
Acetate supplements reduced the storage of fats in rats as well.
Then again, the link between short-chain fatty acids and weight loss has been based on animal and laboratory studies rather than on actual humans.
Short-chain fatty acids and their effect on the immune system
Another known benefit of short-chain fatty acids is on the human immune system.
There is research that shows that the short-chain fatty acids and namely butyrate, can have an anti-inflammatory effect on the human organism.
Also, that they seem to play a part in the specialization of the immune cells, also known as T cells which are responsible for keeping the “peace” in the body.
Plus, some studies suggest that due to their effect on the gut environment, short-chain fatty acids can boost and actually modulate the immune system to allow it to protect the organism from developing cancer.
Overall, there is no doubt that short-chain fatty acids are incredibly important molecules, which allow for the diet and the gut microbiome to contribute to better overall health.
Because the production of short-chain fatty acids is directly connected to food intake, many scientists agree that there is a vital link between the diet and the gut microbiome and overall health.
Short-chain fatty acids and their effect on heart health
There are numerous observational studies that have linked eating high-fiber diets with a reduced risk of heart disease.
But this association often tends to depend on the actual type of fiber and the fiber source as well.
Fiber intake in humans has also been linked to a reduction of inflammation.
A possible reason why fiber helps reduce heart disease could be due to the production of short-chain fatty acids in the human colon.
Various studies involving animals and humans have concluded that short-chain fatty acids can help reduce cholesterol levels – including the total and LDL cholesterol in the blood.
One specific short-chain fatty acid – butyrate has been found to interact with the genes producing cholesterol, and possibly reducing its production in the body.
A study found that the production of cholesterol in the livers of rats that were given propionate supplements decreased. The same tendency was found in rats that were given acetic acid.
This same effect was observed in obese people who were given vinegar containing acetate, which caused a reduction of the excess cholesterol in the bloodstream.
Should you take short-chain fatty acids supplements?
Short-chain fatty acid supplements are commonly found in the form of butyric acid salts, and others.
They are usually referred to as potassium, sodium, calcium, or magnesium butyrate.
These supplements can easily be bought over the counter and even online.
But are they are actually beneficial?
The short-chain fatty acid supplements by themselves may not be the best way to boost the levels of fatty short-chain fatty acids in your colon.
Because the butyrate supplements are absorbed in the small intestine before they actually reach the colon, they may not have any beneficial qualities, since the short-chain fatty acids are produced by the fermenting in the colon by the friendly bacteria there.
Plus, there is very limited scientific evidence about the effectiveness of any of the short-chain fatty acid supplements offered on the market.
The butyrate which reaches the colon is best provided by the intake of fiber. So, increasing the high fiber foods in your diet is a much better idea if you want to benefit from the increased amount of short-chain fatty acids in your colon and your body.
There is no doubt that short-chain fatty acids have a variety of beneficial effects on the human body.
They help feed the good bacteria in the gut and help keep the microbiome healthy and balanced.
This is essential not only for the digestive system but for the immune system, heart health, blood sugar levels, as well as the metabolism and functioning of the body. They are even found to help prevent certain types of cancer as well.
It also seems to have an effect on better weight management and weight loss.
But supplements are less likely to improve the levels of short-chain fatty acids in your colon and body.
The best way to ensure that their levels are high enough to keep you healthy, fit, and well is to eat a high-fiber diet.
In order to increase the fiber intake, it is recommended that you start by introducing foods that are high in soluble fiber and insoluble fiber slowly, and by gradually increasing their quantities so that you can reach the recommended daily intake of 25-38 grams per day.