10/23/2026
RETROGRADATION...ever heard of it?
How Yesterday's Potatoes, Rice, and Pasta May Be Better for Your Gut!
A little nutritional science that might make you look at your leftovers differently!
What if I told you that you could increase the resistant starch content of certain foods?
No powders, no expensive supplements, and no fancy kitchen gadgets.
Just your refrigerator!
It's a fascinating process called RETROGRADATION, and it involves something as simple as cooking, cooling, and reheating your food.
SO LET ME BREAK DOWN WHAT RETROGRADATION IS?
When we cook starchy foods like potatoes, rice, and pasta, heat and moisture cause the starch granules to swell and their molecular structure to loosen.
This process is called gelatinization.
It makes starch easier for our digestive enzymes to break down into glucose, which can contribute to a rise in blood sugar after eating.
When those cooked foods are cooled, in the refrigerator, some of those starch molecules begin reorganizing themselves into a more tightly packed structure.
This is called starch retrogradation.
And the result?
Some of that previously digestible starch becomes resistant starch, specifically resistant starch type 3 (RS3).
In other words, we've changed how some of that starch behaves in the digestive tract simply by changing its temperature history!
WHY DOES YOUR GUT CARE?
Unlike ordinary digestible starch, resistant starch isn't completely broken down in the small intestine.
Instead, a portion travels into the colon, where beneficial gut microorganisms can ferment it.
For some peeps it shows up as bloating/gas after eating it.
During fermentation, these microorganisms produce substances called short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate.
Now, if you've followed my nutritional teachings for any length of time, you know how much I emphasize the importance of a healthy intestinal environment.
Butyrate is interesting because it:
Serves as an important energy source for cells lining the colon.
Helps maintain intestinal barrier integrity.
Participates in regulating intestinal immune and inflammatory responses.
Supports normal colon function.
And while resistant starch can encourage butyrate production, the amount produced is gonna depend on your individual microbiome and the other foods in your diet.
Remember, we're not just feeding ourselves. We're also feeding the trillions of microorganisms sharing our digestive real estate!
LET'S LOOK AT THE RESEARCH
RICE — Sonia et al., 2015
Researchers examined how cooling and reheating white rice affected its resistant starch content.
Here's what they found:
Freshly cooked rice: 0.64 grams of resistant starch per 100 grams.
Cooked rice cooled at room temperature for 10 hours: 1.30 grams.I dont recommend cooling 10 hrs at room temp. (Bacteria)
Cooked rice refrigerated at 4°C for 24 hours and then reheated: 1.65 grams.
That's more than DOUBLE the resistant starch in the refrigerated-and-reheated rice!
The researchers also studied 15 healthy adults and found that the cooled-and-reheated rice produced a lower post-meal blood glucose response compared with freshly cooked rice.
Same rice. Different preparation. Different metabolic response.
POTATOES — Larder et al., 2018
Researchers found that boiled potatoes refrigerated for 24 hours could develop more resistant starch than potatoes cooled for just one hour at room temperature.
In some comparisons, the increase reached approximately 114%.
Of course, potato variety, cooking technique, and storage conditions all influence the outcome.
PASTA — Hodges et al., 2019
Researchers compared freshly cooked pasta with pasta that had been cooled or cooled and reheated.
Their findings suggested that reheated pasta could produce a more favorable post-meal glucose response than freshly cooked pasta.
Now, remember that portion sizes and the overall composition of your meal still matter!
DOES REHEATING DESTROY THE BENEFITS?
Not necessarily!
Some retrograded starch remains resistant even after ordinary reheating.
You can prepare rice, potatoes, or pasta ahead of time, refrigerate them, and enjoy them reheated the following day.
You don't have to eat cold mashed potatoes unless that's your idea of a good time, BUT
MY PRACTICAL KITCHEN ADVICE is
If you're preparing these foods anyway, consider cooking enough for another meal.
Refrigerate promptly in shallow containers, keep at 40°F (4°C) or below, and reheat thoroughly when ready to eat.
For food safety, don't leave cooked rice sitting on the counter for hours to increase resistant starch. Certain bacteria, including Bacillus cereus, can grow when cooked rice is improperly stored.
And one more important point: Resistant starch does not make carbohydrates disappear.
These foods still contain digestible carbohydrates and calories. The amount of resistant starch formed varies, and individuals managing diabetes should still consider portions and monitor their glucose responses.
I frequently remind people that nutrition isn't simply about WHAT we eat.
It's also about how we prepare our foods, how we digest them, and how our individual microbiomes respond.
Something as ordinary as refrigerating yesterday's potatoes can change their starch structure and influence both digestion and post-meal blood sugar.
Does that mean every leftover potato becomes a nutritional powerhouse overnight?
No, so don't come at me with those comments. Use common sense!
But it does give us another simple, inexpensive way to support our digestive health.
Sometimes better nutrition isn't about buying something new. It's about understanding what we already have in our kitchens.
Rooted in nature, backed by knowledge.
Dr. Jodi Barnett, N.D. 🫶
---
RESEARCH REFERENCES
Sonia, S., Witjaksono, F., & Ridwan, R. (2015). Effect of cooling of cooked white rice on resistant starch content and glycemic response. Asia Pacific Journal of Clinical Nutrition, 24(4), 620–625.
Larder et al. (2018). Research on potato preparation, cooling conditions, and resistant starch. Food Research International.
Hodges et al. (2019). Research examining cooking, cooling, and reheating pasta and postprandial glycemic response. Foods.
Birt, D. F., et al. (2013). Resistant starch: Promise for improving human health. Advances in Nutrition, 4(6), 587–601. https://doi.org/10.3945/an.113.004325
A little food science can go a long way toward better everyday choices!