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What You Should Know about Resistant Starch

By Becca Hurt

Not everything you know about starch is necessarily correct.

With regard to starch, our minds tend to wander to blood sugar spikes, insulin overload, and inevitable energy crashes – not to mention their ability to stop efficient fat loss dead in its tracks.

For starchy carbs, these associations would be mostly correct – albeit incomplete. There’s more to the story, it seems.

Consider for a moment that one kind of starch may be a boon to your gut health and perhaps even an aid to your weight loss endeavors.

Enter the concept of resistant starch. What is it, how does it work, and what could it offer you? Read on to find out more.

What Is It?

Resistant starch is a type of starch that the stomach and small intestine are unable to break down and digest. As a result, it travels to the large intestine (colon) intact. In other words, it’s a starch that is resistant to digestion, hence “resistant starch.”

This is opposed to other starches, which we can digest, absorb in the small intestine, and metabolize as glucose (i.e. sugar).

There are 4 types of resistant starch, which I will briefly touch on for the purpose of categorizing food sources in each group.

  • RS Type 1: Beans, grains, seeds (starch bound by non-digestible plant cell walls)
  • RS Type 2: Green bananas, potatoes, plantains (starch that is non-digestible in its raw state due to its high amylase content – RS becomes accessible upon heating).
  • RS Type 3: Cooked and cooled potatoes, grains, and beans (retrograded starch – the cooking and cooling changes the chemical structure and makes it more resistant to digestion).
  • RS Type 4: supplemental resistant starch like raw potato starch (manufactured; doesn’t occur naturally).

Although there are different types of resistant starch, in general all types act fairly similarly in the body. That said, they may have slightly different effects on gut flora.

Why It’s Beneficial

Think lower blood sugar, improved digestion, enhanced sleep and better glucose tolerance?

Since resistant starch doesn’t break down in the small intestine, it reaches the colon intact. There bacteria feed on it, and eventually it is broken down.

In a sense, resistant starch is food for the good bacteria in the gut and serves as a prebiotic. As a result of beneficial bacteria digesting resistant starches, compounds called short-chain fatty acids are formed (specifically butyrate). Why is that beneficial? Butyrate indirectly feeds the cells that line the colon, which may support improvements in digestive system functionality.

Resistant starch has also been shown to reduce inflammation in the colon, which helps benefit digestive disorders (e.g. constipation, ulcerative colitis, Crohn’s disease, etc.).

Most starches are broken down in the small intestine and immediately impact our blood sugar and insulin levels (both increase). In the case of resistant starch, the only way the starch is broken down is by bacteria consuming it. As a result, our bodies do not experience a spike in blood sugar or insulin.

In fact, resistant starch has been shown to improve insulin sensitivity, reduce fasting blood sugar[i] and improve satiety!

Is Resistant Starch a Good Choice for You?

If you’re struggling with high blood sugars or with managing your blood sugars, have diagnosed insulin resistance or digestion problems, and/or have hit a weight loss plateau, adding in resistant starch (appropriately) could be a worthy experiment.

As with most experiments, in order to know the true outcome and results, assessing beforehand is critical. Obtaining lab values (e.g. blood sugar, A1C, body fat %, etc.) before starting this new diet and/or protocol and again after a minimum of 6 weeks, will help you know for certain if incorporating resistant starch into your diet is valuable for you personally.

After learning a bit about resistant starch, you may be thinking, “I’m on board! Let’s start today!” But before we have a heyday with resistant starch, let’s consider the bigger picture on these “RS” foods. Yams, brown rice, quinoa, white potatoes, peas, beans, and green bananas all contain resistant starch. However, what does your intuition tell you about these same foods? They’re higher in overall carbohydrate content in comparison to other foods that are classified as “carbs” (i.e. non-starchy vegetables).

Resistant starch is also very similar to fiber in that too much at once may lead to gas, bloating, cramping, diarrhea or constipation, and other unpleasant digestive effects. When adding these foods to your diet for the purpose of increasing your resistant starch intake, do so with slight caution.

Particularly if your resistant starch and/or fiber intake is minimal, start slowly! The potential effects that you might feel are not the “fault” of RS. They’re indication that your gut needs work, which is even more reason to continue with this implementation.

How Can I Get Resistant Starch in My Diet?

Since there are various forms of resistant starch, there are various ways to incorporate it into your diet as well. A helpful practice to consider in conjunction with adding RS foods is a quality daily probiotic.

Whole Foods 

Think green, unripe banana…. A typical large banana has approximately 30 grams of carbohydrate. However, if it’s green and totally unripe (probably unappealing to many people), the majority of that carbohydrate will be resistant starch that your body does not digest into glucose. Similar to cooked and then cooled resistant starch foods, your body doesn’t digest the carbohydrate in the green banana as it would a fully ripe, yellow banana. Instead, your gut flora digest it.

Cooked, Then Cooled Foods

The prospect of rice and potatoes appropriately raise concern for some people who cannot tolerate their carb load. One way to help combat the glucose response and improve insulin sensitivity, studies find, is to eat these foods by first cooking and then cooling them. By doing this, the typical “negative impacts” are mitigated by the resistant starch.

Resistant Starch Supplement

You can always consider supplementing with resistant starch rather than obtaining it in whole-food form. One benefit: it may be easier!

Much like supplemental protein, resistant starch supplement commonly comes in powder form as raw potato starch (others include plantain flour or green banana flour). With about 8 grams of resistant starch per 1 tablespoon, you can incorporate it into a smoothie or add it into sparkling water.

Another great option, especially for endurance athletes looking for a great addition to their training plan, is UCAN. This super-starch is broken down slowly as well, allowing for continued performance and improved fat burning for fuel.

If you choose to incorporate resistant starch into your diet (whatever the form), gradually work your way up to 30-40 grams of RS per day. Some people need to start with just a teaspoon or so (from supplement form), or half a whole-food source (e.g. half a green banana) per day. Keep in mind, too, that most people tolerate RS best when consumed in solid food form (rather than liquid) and as part of a full meal rather than alone.

Are you interested in learning more about the role resistant starch can – or should – play in your diet? Schedule a consultation with a club dietitian today!

Thanks for reading.

[i] Park, O.J., et al. “Resistant starch supplementation influences blood lipid concentrations and glucose control in overweight subjects,” J Nutr Sci Vitaminol. 2004 50(2):93-9.


The posts on this blog are not intended to suggest or recommend the diagnosis, treatment, cure, or prevention of any disease, nor to substitute for medical treatment, nor to be an alternative to medical advice. The use of the suggestions and recommendations on this blog post is at the choice and risk of the reader.
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