About resistant starch

Potatoes grown in compost

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

This page was last updated by Bernard Preston on 24th August, 2019.

By Bernard Preston

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 is known as a polysaccharide; the number of sugar units varies from hundreds and can be several thousand, depending on the source of the starch.

In amylose, this long chain has a twisted or helical configuration that makes it difficult for enzymes to reach the glucose units; it is less digestible and more of the food 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 mouth and 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 an athlete, 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, french fries and short-grained, precooked rice; they have a strongly glycemic effect, read a very high GI; they are rich in amylopectin; they spike your blood glucose.

About 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 foods which are then absorbed more slowly in the large intestine, not as glucose but as healthy short chain fatty acids.

These bacteria and yeasts 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.

In order for this to happen normally, a healthy microflora is necessary. In fact researchers are finding that many of the diseases of our modern world have their origin in a deficiency of these supportive bugs in the colon. One can take tablets called probiotics, but it's very easy to get them from your food. Just five minutes work every morning, easily done by one child, will provide your family with what's needed; read more about kefir benefits.

Oddly, one friend who started enjoying kefir daily reported much less gas passed; I can't explain that.

About resistant starch

100 percent wholemeal

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

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 this substance 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 carbohydrate, much of which is fibre, reaches the colon where it is known as 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 which stores that glucose as adipose.

That's what happens to rapidly digested starch.

Interesting research shows that soluble fibre found in rolled oats, for example, has a greater effect on the insulin spike, whereas resistant starch reduces the glucose; they work together producing a wonderful beneficial effect. 1

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 percent or less, and is rapidly absorbed, spiking the blood sugar.

My own experimentation shows that even wholesome 100% full grain bread still gives a surge in my blood glucose to unacceptably high levels, even with just butter; with a salad is another matter; it's much less. But this sharp rise can also be completely countered by a short ten minute walk after lunch.

That's because 86% of the starch even in wholemeal bread is still made up of unresistant carbohydrate; it turns to sugar so you must burn it, or you'll finds pounds being layered in the wrong places.

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 carbohydrate 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 for tomorrow's dinner.

Cooling is the other way to reduce the rapidly absorbed fraction; boiled potato is very quickly 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 fermentation; 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.

Rolled oats

Unprocessed rolled oats is one of the best examples describing about resistant starch; the finest remedy for high cholesterol, it's also an excellent solution to insulin resistance; it hardly affects the postprandial blood glucose, especially if you take a short walk after breakfast.

These Quaker oats recipes should be a basic in everyone's diet. It's the kind of food that grandma would have offered, and it's still the best.

In short, large prospective studies prove that a higher whole grain consumption reduces the risk of death from chronic diseases such as type 2 diabetes and cardiovascular disease.2


Sprouting chickpeas inverter bottle

Legumes like chickpeas and beans have large amounts of resistant fibre, but they need to be soaked, rinsed several times and preferably sprouted and even fermented to remove so-called anti-nutrients.

As soon as you start investigating the subject about resistant starch, you begin to realise it's a profoundly complex. When you buy legumes like chickpeas in a can, you have no idea how they've been prepared; certainly they wouldn't have been sprouted and fermented, but probably not soaked and rinsed adequately? It's immensely important to get the lectins out.

Rinsing and soaking several takes one day, followed by another three sprouting chickpeas; the actual time taken is perhaps fifteen minutes to give you enough for homemade hummus for a month; not a lot.

Cooking chickpeas is not difficult, but it does take some time which is why we should prepare several pounds at a time and freeze 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

Did you find this page interesting? How about forwarding it to a friend, or book and food junkie. Or, better still, Face Book or Twitter it. 


56 Groenekloof Rd,

Hilton, KZN

South Africa