Resistant starch is an extremely important component of a healthy diet. Starches normally pass through the stomach, into the small intestine where they are broken down into smaller units and finally into glucose molecules where they are absorbed as a source of energy. Until recently it was thought that all carbohydrates were broken down in this manner and only fibre made it through to the large intestine. In recent years better technology has emerged that has shown that this is not the case, some starch actually make it right through to the large intestine before it is broken down. This starch is called resistant starch, and it's importance has only recently been recognised, resistant starch along with soluble fibre encourage the growth of very beneficial bacteria.
Some grains have now been bred to contain more resistant starch, and they have been incorporated into bread, breakfast cereal to give similar value as dietary fibre.
Depending on what you eat, there may be more resistant starch in the large intestine than dietary fibre. The way the food is cooked and processed also influences the amount of resistant starch that it contains. Studies in the United Kingdom have shown that the typical British diet only supplies 12-15 grams of dietary fibre per day, whereas the starch reaching the bowel is typically 5-40 grams.
This research has been supported by observational studies in Japan and other Asian countries where they have found low levels of fibre in the diet, but the stool weights are high.
Cooking and cooling can alter the way starch granules line up so some foods will contain more resistant starch when cool to when it is served hot, potatoes are an example of this.The fibre content remains the same whether potatoes are hot or cold. Why does this happen? Starch is made up of glucose molecules linked together to form amylose and amylopectin. Amylose has a linear molecular structure and can stack to form very tightly packed granules which is insoluble and hard to digest whereas amylopectin has a branched structure and thus cannot form tightly packed granules and is thus easier to digest. Most plants contain some amylose, about 20-25% while peas contain 60% and certain species of maize contain 80% (Hi -Maize) so these plants contain a lot of resistant starch. Green bananas also contain a lot of resistant starch, and only cooking pasta to el dente (still chewy) produces a lot of resistant starch. Cooking rice the Asian way so it absorbs most of the water also produces a lot of resistant starch.
The downside of this is the bacterial fermentation of fibre,resistant starch and any carbohydrate not digested in the small intestine produces large quantities of gas in the large intestine. The more fibre and complex carbohydrate eaten, the more bacteria and the larger the volume of gas produced.
Better to burp and bear the shame,
Than squelch the burp and bear the pain ( original author unknown)
Cheers
