Soluble & Insoluble Fibre - What's the Difference?

Fibre is usually bundled into two broad categories, insoluble and soluble. Insoluble fibres got most of the attention, because it took on numerous different roles. Contrasting their sawdust-like cousins that carry food remnants through the colon in record time - soluble fibres swell with water and slows down the movement of food through the small intestine. As a result of this - the entrance of sugar into the blood is delayed. Soluble fibres also absorb bile acids, which are made from cholesterol by the liver.
Although there are beneficial bacteria all through the human digestive tract - food moves through too fast in the upper sections for the bacteria to make much use of prebiotics.
Therefore, it is in the colon where beneficial bacteria (probiotics) take advantage of the prebiotic energy – which is obtained from both your diet and naturally transpiring products of metabolism. The majority of the bacteria in the colon are anaerobe - which implies that they don't use oxygen during metabolism and rather derive energy from a process called fermentation.

The soluble fibres that provide good bacteria are carbohydrates that escape upper intestinal absorption or digestion. These include such delights as non-starch polysaccharides resistant starch; non-digestible oligosaccharides resistant dextrin, along with undigested portions of disaccharides and sugar alcohols.

What actually makes all these types of soluble fibre valuable are the products that result from their digestion through good bacteria, and the effects these products have on human’s health. The main products of fermentation are short chain fatty acids (SCFA), mainly acetate, butyrate and propionate. SCFA’s is inclined to acidify the colon - which quells the growth of pathogens. These fatty acids are rapidly absorbed by the cells lining the colon and contributes a little usable energy.

Acetate is metabolized in the kidneys, heart, muscles and brain. Propionate absorbed by the liver can be utilised to create new glucose and might inhibit cholesterol amalgamation. It may even play a role in how humans store fat. Butyrate is metabolized by the colon cells - which provides energy and acts as a regulator of cell growth and maturity, which in turn may reduce risk of colon cancer by promoting cell-death at a normal rate.

Obviously these types of soluble fibre can break down into a number of other metabolites, for example: lactate, ethanol, pyruvate and a few gases - Methane, hydrogen, carbon dioxide and hydrogen sulphide.

After soluble fibres digest, their fermentation products are in general beneficial to health as noted above - which is why we need to increase their role on our diets. The same cannot be said when it comes to feeding different bacteria the undigested portions of proteins. The building blocks of proteins are amino acids, and the breakdown products of their metabolism in the colon produce possibly toxic products such as ammonia and amines.

No matter how you get your fibre - straight from vegetables and fruits, beans, grains or hidden away in one of the mode
sources - invisible soluble fibres have proved to be a prebiotic godsend to our health.