Short-chain fatty acids are produced by the friendly bacteria in your gut.

In fact, they are the main source of nutrition for the cells in your colon.

Short-chain fatty acids may also play an important role in health and disease.

They may reduce the risk of inflammatory diseases, type 2 diabetes, obesity, heart disease and other conditions (1Trusted Source).

This article explores how short-chain fatty acids affect health.

What Are Short-Chain Fatty Acids?

Short-chain fatty acids are fatty acids with fewer than 6 carbon (C) atoms (2Trusted Source).

They are produced when the friendly gut bacteria ferment fiber in your colon, and are the main source of energy for the cells lining your colon.

For this reason, they play an important role in colon health (1Trusted Source).

Excess short-chain fatty acids are used for other functions in the body. For example, they may provide roughly 10% of your daily calorie needs (2Trusted Source).

Short-chain fatty acids are also involved in the metabolism of important nutrients like carbs and fat (3Trusted Source).

About 95% of the short-chain fatty acids in your body are:

  • Acetate (C2).
  • Propionate (C3).
  • Butyrate (C4).

Propionate is mainly involved in producing glucose in the liver, while acetate and butyrate are incorporated into other fatty acids and cholesterol (4Trusted Source).

Many factors affect the amount of short-chain fatty acids in your colon, including how many microorganisms are present, the food source and the time it takes food to travel through your digestive system (5Trusted Source).

BOTTOM LINE:Short-chain fatty acids are produced when fiber is fermented in the colon. They act as a source of energy for the cells lining the colon.

Food Sources of Short-Chain Fatty Acids

Eating a lot of fiber-rich foods, such as fruits, vegetables and legumes, is linked to an increase in short-chain fatty acids (6Trusted Source).

One study of 153 individuals found positive associations between a higher intake of plant foods and increased levels of short-chain fatty acids in stools (7).

However, the amount and type of fiber you eat affects the composition of bacteria in your gut, which affects what short-chain fatty acids are produced (8Trusted Source).

For example, studies have shown that eating more fiber increases butyrate production, while decreasing your fiber intake reduces production (9Trusted Source).

The following types of fiber are best for the production of short-chain fatty acids in the colon (10Trusted Source, 11Trusted Source):

  • Inulin: You can get inulin from artichokes, garlic, leeks, onions, wheat, rye and asparagus.
  • Fructooligosaccharides (FOS): FOS are found in various fruits and vegetables, including bananas, onions, garlic and asparagus.
  • Resistant starch: You can get resistant starch from grains, barley, rice, beans, green bananas, legumes and potatoes that have been cooked and then cooled.
  • Pectin: Good sources of pectin include apples, apricots, carrots, oranges and others.
  • Arabinoxylan: Arabinoxylan is found in cereal grains. For example, it is the most common fiber in wheat bran, making up about 70% of the total fiber content.
  • Guar gum: Guar gum can be extracted from guar beans, which are legumes.

Some types of cheese, butter and cow’s milk also contain small amounts of butyrate.

BOTTOM LINE:High-fiber foods, such as fruits, veggies, legumes and whole grains, encourage the production of short-chain fatty acids.

Short-Chain Fatty Acids and Digestive Disorders

Short-chain fatty acids may be beneficial against some digestive disorders.

For example, butyrate has anti-inflammatory effects in the gut (12Trusted Source).

Diarrhea

Your gut bacteria convert resistant starch and pectin to short-chain fatty acids, and eating them has been shown to reduce diarrhea in children (13Trusted Source, 14Trusted Source).

Inflammatory Bowel Disease

Ulcerative colitis and Crohn’s disease are the two main types of inflammatory bowel disease (IBD). Both are characterized by chronic bowel inflammation.

Because of its anti-inflammatory properties, butyrate has been used to treat both of these conditions.

Studies in mice have shown that butyrate supplements reduce bowel inflammation, and acetate supplements had similar benefits. Additionally, lower levels of short-chain fatty acids were linked to worsened ulcerative colitis (15Trusted Source, 16Trusted Source).

Human studies also suggest that short-chain fatty acids, especially butyrate, can improve symptoms of ulcerative colitis and Crohn’s disease (17Trusted Source, 18Trusted Source, 19Trusted Source, 20Trusted Source).

A study involving 22 patients with ulcerative colitis found that consuming 60 grams of oat bran every day for 3 months improved symptoms (17Trusted Source).

Another small study found that butyrate supplements resulted in clinical improvements and remission in 53% of Crohn’s disease patients (18Trusted Source).

For ulcerative colitis patients, an enema of short-chain fatty acids, twice per day for 6 weeks, helped reduce symptoms by 13% (21Trusted Source).

BOTTOM LINE:Short-chain fatty acids may reduce diarrhea and help treat inflammatory bowel diseases.

Short-Chain Fatty Acids and Colon Cancer

Short-chain fatty acids may play a key role in the prevention and treatment of certain cancers, mainly colon cancer (22Trusted Source, 23Trusted Source, 24Trusted Source).

Lab studies show that butyrate helps keep colon cells healthy, prevents the growth of tumor cells and encourages cancer cell destruction in the colon (24Trusted Source, 25Trusted Source, 26Trusted Source, 27Trusted Source).

However, the mechanism behind this is not well-understood (28Trusted Source, 29Trusted Source, 30Trusted Source).

Several observational studies suggest a link between high-fiber diets and a reduced risk of colon cancer. Many experts suggest the production of short-chain fatty acids may be partly responsible for this (28Trusted Source, 30Trusted Source).

Some animal studies also report a positive link between high-fiber diets and a reduced risk of colon cancer (31Trusted Source, 32Trusted Source).

In one study, mice on a high-fiber diet, whose guts contained butyrate-producing bacteria, got 75% fewer tumors than the mice who did not have the bacteria (33Trusted Source).

Interestingly, the high-fiber diet alone — without the bacteria to make butyrate — did not have protective effects against colon cancer. A low-fiber diet — even with the butyrate-producing bacteria — was also ineffective (33Trusted Source).

This suggests that the anti-cancer benefits only exist when a high-fiber diet is combined with the correct bacteria in the gut.

However, human studies provide mixed results. Some indicate a connection between high-fiber diets and reduced cancer risk, while others find no link (34Trusted Source, 35Trusted Source, 36Trusted Source, 37Trusted Source).

Yet these studies did not look into the gut bacteria, and individual differences in gut bacteria may play a role.

BOTTOM LINE:Short-chain fatty acids have been shown to protect against colon cancer in animal and lab studies. However, more research is required.

Short-Chain Fatty Acids and Diabetes

A review of the evidence reported that butyrate can have positive effects in both animals and humans with type 2 diabetes (38Trusted Source).

The same review also highlighted that there appears to be an imbalance in gut microorganisms in people with diabetes (38Trusted Source, 39Trusted Source).

Short-chain fatty acids have been shown to increase enzyme activity in the liver and muscle tissue, resulting in better blood sugar control (40Trusted Source, 41Trusted Source, 42Trusted Source).

In animal studies, acetate and propionate supplements improved blood sugar levels in diabetic mice and normal rats (43Trusted Source, 44Trusted Source, 45Trusted Source).

Yet there are fewer studies involving people, and the results are mixed.

One study found that propionate supplements reduced blood sugar levels, but another study found that short-chain fatty acid supplements did not significantly affect blood sugar control in healthy people (46Trusted Source, 47Trusted Source).

A number of human studies have also reported associations between fermentable fiber and improved blood sugar control and insulin sensitivity (48Trusted Source, 49Trusted Source).

Yet this effect is generally only seen in individuals who are overweight or insulin resistant, and not in healthy individuals (46Trusted Source, 47Trusted Source, 50Trusted Source).

BOTTOM LINE:Short-chain fatty acids seem to help regulate blood sugar levels, especially for people who are diabetic or insulin resistant.

Short-Chain Fatty Acids and Weight Loss

The composition of microorganisms in the gut can affect nutrient absorption and energy regulation, thus influencing the development of obesity (51Trusted Source, 52Trusted Source).

Studies have shown that short-chain fatty acids also regulate fat metabolism by increasing fat burning and decreasing fat storage (8Trusted Source).

When this occurs, the quantity of free fatty acids in the blood is reduced, and it may also help protect against weight gain (40Trusted Source, 53Trusted Source, 54Trusted Source, 55Trusted Source).

Several animal studies have examined this effect. After a 5-week treatment with butyrate, obese mice lost 10.2% of their original body weight, and body fat was reduced by 10%. In rats, acetate supplements reduced fat storage (40Trusted Source, 56Trusted Source).

However, the evidence linking short-chain fatty acids to weight loss is based mainly on animal and test-tube studies.

BOTTOM LINE:Animal and test-tube studies indicate that short-chain fatty acids may help prevent and treat obesity. However, human studies are needed.

Short-Chain Fatty Acids and Heart Health

Many observational studies have linked high-fiber diets to a reduced risk of heart disease.

However, the strength of this association often depends on the fiber type and source (57Trusted Source).

In humans, fiber intake has also been linked to reduced inflammation (58Trusted Source).

One of the reasons fiber reduces heart disease risk may be due to the production of short-chain fatty acids in the colon (59Trusted Source, 60Trusted Source, 61Trusted Source).

Studies in both animals and humans have reported that short-chain fatty acids reduced cholesterol levels (28Trusted Source, 62Trusted Source, 63Trusted Source, 64Trusted Source, 65Trusted Source).

Butyrate is thought to interact with key genes that make cholesterol, possibly reducing cholesterol production (66Trusted Source).

For example, cholesterol production decreased in the livers of rats given propionate supplements. Acetic acid also reduced cholesterol levels in rats (62Trusted Source, 67Trusted Source, 68Trusted Source).

This same effect was seen in obese humans, as acetate in vinegar decreased the amount of excess cholesterol in the bloodstream (64Trusted Source).

BOTTOM LINE:Short-chain fatty acids may decrease the risk of heart disease by reducing inflammation and blocking cholesterol production.

Should You Take a Supplement?

Short-chain fatty acid supplements are most commonly found as butyric acid salts.

These are generally referred to as sodium, potassium, calcium or magnesium butyrate. They are easily available online or over-the-counter.

However, supplements may not be the best way to increase your levels of short-chain fatty acids. Butyrate supplements are absorbed before they reach the colon, usually in the small intestine, which means all of the benefits for colon cells will be lost.

Additionally, there is very little scientific evidence about the effectiveness of short-chain fatty acid supplements.

Butyrate reaches the colon best when it’s fermented from fiber. Therefore, increasing the amount of high-fiber foods in your diet is probably a much better way to improve your short-chain fatty acid levels.

BOTTOM LINE:Eating high-fiber foods is the best way to increase short-chain fatty acid levels, as supplements are absorbed before reaching the colon.

Take Home Message

Due to their anti-inflammatory and anti-cancer properties, it is likely that short-chain fatty acids have a wide range of beneficial effects on your body.

One thing is for certain: looking after your friendly gut bacteria can lead to a whole host of health benefits.

The best way to feed the good bacteria in your gut is to eat plenty of foods high in fermentable fiber.