What Is Resistant Starch? Is It Good For You?
When is a carb not a carb?

(Approximate reading time 3 minutes)

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The word “starch” may stir up a little concern in some health-conscious people, especially for the low-carb advocators.  Doesn’t it jack up your blood sugar level the same way sugar does?  Shouldn’t we stay away from excessive starchy foods?

Let’s leave the debate between low carb and high carb for now, there is one type of starch whose benefits that both camps seem to agree on:

Resistant Starch

Resistant starch is the starch that your body cannot digest, hence the name “resistant”: it is resistant to digestion.  Usually, the digestive enzymes in your small intestines break down starches and turn them into glucose.  But because resistant starch cannot be digested by these enzymes, they go through the stomach and small intestines undigested, and arrive in the colon pretty much intact.

Here is where the party gets started.  The good bugs in your colon loooooove these starches and start their fiesta.  They feed on them and ferment them.  The process results in the production of short chain fatty acids including acetate, propionate, and butyrate.

There have been researches showing the various benefits of resistant starches.  For one, butyrate is the energy source for your enterocytes, those cells that line the GI tract. 

It has also been shown to help reduce insulin resistance.  This is easy to understand because it does not get digested and turned into glucose, therefore has minimal impact on blood sugar levels.

Resistant starch also provides more satiety, thus is helpful controlling calorie intake.  It could even help some people with constipation problems.

Colorectal cancer is the third most common cause of cancer death in the world.  A study published in the American Journal of Clinical Nutrition found that resistant starch changed the metabolism of certain bacteria in the colon that help with cancer prevention.  Another in vitro model conducted at Georgia Health Sciences University’s Department of Biochemistry showed that butyrate may help reduce inflammation in the colon and block cancer cells growth.  There are other studies showing resistant starch may not only help with colon and bowel cancer prevention, but also treatment.

By acting more like fiber and prebiotics (food for good bacteria) than the typical starch, resistant starch encourages the growth of good bacteria, thus improve digestion and nutrient absorption.

Kitavans are a small tribe of farmers living in Papua New Guinea.  Their diet seems to contradict both conventional nutrition theory and the popular low carb diet: 60% from carbohydrates, 30% from fat (mostly saturated fat), and 10% from protein.  A lot of them smoke, and they are not very physically active.  However, they are slim, and most of them live well into their nineties, without being bothered by most of the modern diseases, and they almost never have strokes or heart attacks.

Turns out, the fact that the carbs they are eating are mostly resistant starch can partially explain the mystery.  Kitavans don’t absorb the huge amount of carbs they eat as sugar.  Instead, these carbs are feeding the good bugs in the colon, providing fuel for energy and neurons.  

Native africans have substantial lower rate of colon cancer than African Americans.  It used to be attributed the high amount of fiber in their diet.  But modern day sub-Saharan Africans don’t eat that much fiber any more.  Instead a big part of their diet now is refined corn meal.  But they still rarely get colon cancer.  In addition to the fact that they eat very little animal products, resistant starch also played a part.  The way they cook the corn meal and then eat it like a porridge cold or reheated increases the content of resistant starch.  So instead of fibre, the good bacteria in the gut now feasts on these starches and still churn out huge amount of beneficial short chain fatty acids.

So where can we find these wonderful starches?

It’s actually not that difficult.  The easiest way is cooked and cooled rice. When cooked rice is cooled, it goes through a process called retrogradation that produces resistant starch.  So cook a bigger batch then usual next time and fridge the leftover.  Reheat it again will not destroy the resistant starch that gets formed during the cooling process.  The type of rice that has one of the highest content of resistant starch is basmati rice from India.

Cooked and cooled potato also has a lot of resistant starch, so does raw potato.  If you are really keen on adding a lot of resistant starch, try to add some raw potato starch into your smoothie.  Do not cook it.

Some other starchy root vegetable that have a lot of resistant starch are taro and purple sweet potato.  When I learned about this, it made me very happy, as both are my favorite foods, espeically for breakfast and snacks.

The coating of nuts, seeds, grains and beans contain resistant starch as well.  But it may not be a good idea to devour too much of these for the sole purpose of having more resistant starch.   Some people don’t respond well to grains and beans.  And it’s certainly not a good idea to consume too much nuts and seeds.

Unripe fruits such as green bananas, green mangos and green papayas are a good source of resistant starch as well, but it’s not easy to buy, and you may not like its taste. If you have easy access to it, blending some into a smoothie is a good idea.  You can also incorporate green banana flour in your baking.

As wonderful as resistant starch is, it is not a good idea to overdo it.  Too much of it can have similar effect to too much fibre: abdominal pain, excessive flatulence and bloating.  For people with sensitive bowels, this may be especially true.  If you already suffer from constant bloating and digestive discomfort, resistant starch my add to the problem because of the fermentation and production of gas.  So adding resistant starch slowly to the diet is key.  I’d not recommend completely avoiding it unless the symptoms are severe.

Now you have more excuses to enjoy that plate of fried rice from leftovers!

(For chronic digestive problems, avoiding certain foods during the healing process should be temporary, never a permanent solution.   The only permanent solution is to get to the root causes of the problem and address those root causes.  Otherwise, your “do-not-eat-list” will get longer and longer.  If you would like to know more about how I may help you overcome chronic digestive issues and finally start your healing journey, please reach out to our customer service to set up a free consultation.)


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  • American Chemical Society.  New low-calorie rice could help cut rising obesity rates

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