Resistant Starch: are potatoes best eaten cold?

Starch is a form of carbohydrate found in foods like potatoes, rice, pasta, and bread.  It is easily digested in the small intestine and increases blood sugar levels.

On the other hand, current research indicates that resistant starches might be useful for not only managing blood sugar levels, but also for supporting gut health.

In my last Gut Health 101 post, we talked about how to keep your gut happy.  As noted, a major factor in maintaining gut health is consuming plenty of fiber.  Fiber is considered a prebiotic because it feeds beneficial microbes in the gut.  But, you don’t have to eat salads at every meal. An unexpected source of fiber can be found in starchy foods!

In this post, we’ll explain what resistant starch is, its benefits, and how to include it in your diet.  Read on to learn more!

What is Resistant Starch?

Resistant starch is a type of fiber that is found in starchy foods and the digestive enzymes in our bodies are unable to digest them.  They’re found in foods such as potatoes and grains. These undigested fibers make their way to the large intestine, where some of them are fermented by your gut microbes. 

There are 5 types of resistant starch currently recognized, 3 of which are found in natural, whole foods.  The other 2 types are added to processed foods to increase fiber content.  We will focus on the three found in whole foods here:(1)

  • Type 1 –starch granules are protected from digestive enzymes by an outer barrier.  Seeds, legumes, and whole grains are considered Type 1
  • Type 2 – these starch molecules are so tightly packed that enzymes are unable to break them up. Green bananas, raw potatoes, and legumes are considered Type 2
  • Type 3 – certain starches can become resistant when they are cooked then chilled.  Foods that can form Type 3 resistant starches include potatoes, rice, and corn tortillas

Benefits of Consuming Resistant Starch

One of the most common reasons people seek out resistant starch is for blood sugar management.  Because resistant starches are not digested in the small intestine, they do not increase blood sugar to the same extent or as quickly as other starches.  Blood sugar responses vary by individual and may be influenced by the types of microbes in the gut(2).

Another benefit of consuming resistant starches is that they move more slowly through the stomach, making you feel full for longer(1), thus, reducing your desire to snack throughout the day! 

Some resistant starches, particularly Type 2 and Type 3, can be fermented by gut bacteria to produce short chain fatty acids (SCFAs).  Among the many beneficial roles of SCFAs are reducing inflammation, protecting colon health, influencing brain function, and even playing a role in energy production(1).

Studies also suggest that including resistant starches in your diet may improve insulin resistance and lower LDL (“bad”) cholesterol(1).

What foods have resistant starch?

While potatoes (ideally cooked and chilled) are the most common source of resistant starch eaten in the U.S., below is a list of other foods with good amounts of resistant starch(1):

  • Uncooked Oats
  • Butter or Lima Beans
  • Kidney Beans
  • Potato Salad
  • Sweet Potatoes
  • Plantains, raw
  • Corn Tortillas, cooked then chilled 7-14 days
  • Corn Flakes
  • Barley
  • Green Bananas, raw
  • Rye Bread
  • Sourdough Bread
Graphic with five common starchy foods that contain resistant starch.

Recommendations

Studies have shown that consuming at least 15 grams of resistant starch daily is ideal(1).

Most Americans do not meet total recommended fiber intake of 21-25 grams per day for women and 30-38 grams per day for men.  The good news is that including resistant starches in your diet can help you meet those goals.

For my endurance athletes out there, resistant starch is a fiber so eating significant amounts of these foods before an intense and/or long workout or before a big race may cause GI distress. That said, hold off on consuming resistant starches until your rest & recovery periods – then you can chow down!

Summary

Resistant starches are not digested by human digestive enzymes, so they are considered a dietary fiber.  Including resistant starches in your diet can be a great way to increase fiber intake and support your gut!

Many common foods naturally contain good amounts of resistant starches.  Some foods, like potatoes, durum wheat pasta, and rice, can be cooked then chilled to increase the resistant starch content.

Aim to get at least 15 grams of resistant starch daily to improve overall fiber intake.  Take care not to eat a lot of it before a particularly long or intense workout in order to avoid uncomfortable GI issues, but otherwise eat up, buttercup!

Have you experimented with resistant starches in your diet?  What were your experiences?  Let me know in the comments or send me a message!

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