About resistant starch

About resistant starch explains where they are found and why it is so good for you.

Plant starches are found in many foods like potatoes and grains like wheat. They contain two different compounds; amylose makes up about a quarter, and amylopectin three quarters. 

They are quite different; amylose is long chain of glucose molecules linked together in what's known as a polysaccharide; the number of sugar units varies from hundreds and can be several thousand, depending on the starch source.




In amylose, this long chain has a twisted or helical configuration that makes it difficult for enzymes to reach the glucose units; it's less digestible and tends to reach the large intestine for break down by the normal flora instead.  

Amylopectin, the three-quarters fraction of starch, is soluble in water; it, on the other hand, consists of short, highly branched chains, which are readily digested by enzymes in the small intestine; then the many thousands of glucose molecules are ready for immediate absorption, and cause a rapid rise in blood sugar; excellent if you are a sprinter, but not if you sit behind a computer for most of the day.

This is complex stuff, but bear with me if you want to be able to enjoy better health, and in particular if you are obese and tired of the loss of well-being that goes with it.

  • Rapidly digested starch
  • Slowly digested starch
  • Resistant starch

The colossal problem with the modern Western diet is that it consists in the main of rapidly digested starch; an example would be boiled potato and short-grained, precooked rice; they have a strongly glycemic effect, read have a very high GI; they are high in amylopectin.

Resistant starch on the other hand is not absorbed in the small intestine as it is high in the helical amylose, which enzymes find more difficult to digest. It reaches the colon where it is fermented by the microflora which are able to break down these starches which are then absorbed more slowly in the large intestine, not as glucose but as short chain fatty acids.

These bacteria also produce various gases which cause flatulence which is quite normal, and to be expected; to put it crudely, people on a healthy diet fart more!


About resistant starch

About resistant starch describes how some starches are broken down in the small intestine giving an immediate and unwelcome surge in blood glucose, but others pass through to the colon for digestion.

In the colon, often called the large intestine, they are acted upon by the healthy bacteria, or normal flora, that live there specifically to digest this resistant starch and turn it into various fatty acids like butyrate; google it as it acts as a very important anti inflammatory in the body.

Those healthy bugs that live in your colon incidentally are called probiotics; in order to flourish they need plenty of resistant starch that has escaped the attention of the enzymes in the small intestine. In modern lingo, that starch which reaches the colon is called a prebiotic; there it's fed upon and turned not into glucose but short chain fatty acids.



The beauty of resistant starch is that it reduces the risk of getting type 2 diabetes, and in fact ameliorates the effect of the disease. This is because it does not cause the surge in blood sugar, demanding an immediate spurt of insulin, storing the glucose as adipose, that rapidly digested starch produces.

It's also because of that butyrate which has an anti inflammatory effect on your pancreas too, helping to prevent autoimmune diseases like diabetes. Don't take it in tabulate form but rather let your food be your medicine. If you know about resistant starch, the healthy bugs in your colon will produce plenty of it for free.

So, how do we get more resistant starch into our diets?

It comes as no surprise that the more food manufacturers process our grains and potatoes the greater the amount of rapidly digested starch it will contain.

Whole grain, unprocessed wheat contains 14% of resistant starch that will reach the colon, whilst refined cake flour has 2% or less, and is rapidly absorbed, spiking the blood sugar.

Over and above whole grains, legumes like peas and beans, and seeds such sunflower and flax have a large amount of resistant starch; the enzymes in the small intestine have greater difficulty getting to the starch in unrefined foods. These are what as known as prebiotics; don't be dumb  and spend a fortune buying them in capsules; just eat more unrefined foods; and let them cool first, preferably overnight in the fridge.



Cooling is the other way to reduce the rapidly absorbed fraction; boiled potato is very rapidly digested in the small intestine, spiking blood sugar and demanding a spurt of insulin, immediately depositing the glucose in all the wrong places; it makes us fat.

But take that boiled potato, cool it over night and then enjoy it, hot or cold, and far more of it reaches the colon for digestion; knowing about resistant starch has profound implications for the good housewife.

Add some vinegar or lemon juice and you make your chilled potato salad even more resistant to digestion in the small intestine.

A cup of rolled, raw oats has 17.6g of resistant starch; grind it finely and precook it and it reduces that whole grain into porridge containing only 0.5g.

Look out for the cooking time on the package. A pasta, oats or rice that requires long cooking will have far more resistant starch in it. Avoid the precooked stuff; it makes you fat because it's easily acted on by enzymes in the small intestine and rapidly absorbed into the blood stream.

Elsewhere we'll look at new potatoes that have far more resistant starch in them.

Short cuts

There are no short cuts much to our dismay, to better health. What is astonishing that so desperate are some to shed unwanted pounds, but equally determined not to change their diet, that they would risk the serious side effects of sibutramine, for example, in some diet products rather than change to finding out about resistant starch.

Worse, these products are very expensive. Dieter beware if you value your life.


  1. Bernard Preston
  2. Meaning of starch
  3. About resistant starch



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