The large intestine or colon is the last section of the digestive system and is about 1.5 metres (4.9 ft) long, which is about one-fifth of the whole length of the gastrointestinal tract.
The main functions of the large intestine is to:
- Extract water and salt from solid wastes before they are eliminated from the body through the rectum
- Provide a site for bacterial fermentation of unabsorbed food material
The large intestine does not play a role in the absorption of foods and nutrients, which is the role of the small intestine.
In order to maintain the overall health of the large intestine, there are three very important substances that need to be supplied or produced endogenously by the large intestine. These three substances include:
- Short Chain Fatty Acids
- Beneficial Bacteria
Glutamine is an α-amino acid that is used in the biosynthesis of proteins. In human blood, glutamine is the most abundant free amino acid, with a concentration of about 500–900 µmol/l.
Glutamine is essential for the health of the cells that line the wall of the large intestine. Glutamine also increases blood circulation to the large intestine.
The dietary sources of glutamine include:
- Brussels Sprouts
- Dandelion Greens
Short-chain fatty acids (SCFAs)
Short-chain fatty acids (SCFAs), also referred to as volatile fatty acids (VFAs), are fatty acids with less than six carbon atoms. They are normally manufactured endogenously when dietary fiber is fermented in the large intestine. Some SCFA’s can be consumed by diet.
The three most important SCFA’s for the large intestine include:
- Acetate (50% to 60% of the total SCFA’s)
- Butyrate (15% to 20% of the total SCFA’s)
- Propionate (20% to 25% of the total SCFA’s)
SCFA’s are produced when dietary fiber and resistant starch are fermented in the large intestine. The rate and amount of SCFA production depends on the species and amounts of microflora present in the large intestine.
Acetate enters the peripheral circulation to be metabolized by peripheral tissues. Acetate is the principal SCFA in the colon, and after absorption it has been shown to increase cholesterol synthesis.
The following foods/substances enhance the production of Acetate in the large intestine:
- Pectins (Apple and/or Grapefruit Pectin)
- Oat Bran
Propionate is largely taken up by the liver. Propionate, a gluconeogenerator, has been shown to inhibit cholesterol synthesis.
The following foods/substances enhance the production of Propionate in the large intestine:
- Larch Arabinogalactan
Dietary Butyrate is the major energy source for colonocytes. Butyrate has been studied for its role in nourishing the colonic mucosa and in the prevention of cancer of the colon, by promoting cell differentiation, cell-cycle arrest and apoptosis of transformed colonocytes; inhibiting the enzyme histone deacetylase and decreasing the transformation of primary to secondary bile acids as a result of colonic acidification. Without butyrates for energy, colon cells undergo autophagy (self digestion) and die. 1
The following foods/substances enhance the production of Butyrate in the large intestine:
- Resistant Starch (Amylose) (Banana Flour is superior form of resistant starch) 2
- Fructooligosaccharides (FOS)
- Larch Arabinogalactan
- Wheat Bran
Butyrate can also be taken as a supplement in the following forms:
- Calcium/Magnesium Butyrate
- Sodium Butyrate
Specific SCFA may reduce the risk of developing gastrointestinal disorders, cancer, and cardiovascular disease. Therefore, a greater increase in SCFA production and potentially a greater delivery of SCFA, specifically butyrate, to the distal colon may result in a protective effect. 3 4 5
The beneficial bacterial of the glut flora is health-enhancing and serves to prevent the overgrowth of potentially harmful bacteria in the gut. There is always a competition for resources (space and food) in the large intestine between beneficial and detrimental bacteria. A ratio of 80-85% beneficial to 15–20% potentially detrimental bacteria generally is considered normal within the intestines.
Beneficial bacteria (there are are a wide selection)