Bread may be a simple kitchen staple, but did you know that how you store it can actually impact its health benefits?
Maybe you store yours at room temperature in the pantry or toss it into the refrigerator (we beg you to stop doing that, because it only dries it out).
But if you store your bread in the freezer, you may be getting some additional benefits besides long-lasting storage — because freezing bread can also give a meaningful boost to your gut health, blood sugar and digestion, thanks to a natural change in the starches through a process called retrogradation, which forms resistant starch.
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Cooling is key to retrogradation, and storage temperature influences how much resistant starch forms.
The Science Behind Retrogradation
Starch is a type of carbohydrate found in foods like bread, potatoes and grains, and it absorbs moisture and gelatinizes when cooked with water. At a molecular level, starch is made up of two glucose polymers: amylose and amylopectin. In bread, for instance, registered dietitian Avery Zenker explains that the heat of baking disrupts the hydrogen bonds that normally keep starch molecules tightly packed in a crystalline structure, allowing amylose and amylopectin to become easier for digestive enzymes to access.
As the bread cools after baking, those starches begin to shift again. “During retrogradation, some of the starch molecules realign and form new crystalline structures that are more difficult for the body to digest and absorb, hence their name, ‘resistant starch,’” Zenker said. The amount of resistant starch that forms in bread can range significantly, depending on factors like the type of wheat, how the bread is processed, the ingredients used and the baking method. “Fresh-baked white bread contains about 0.5 to 1.7% resistant starch by weight. After cooling or freezing and thawing, this might increase to 1 to 3%” said Zenker, as a reference point.
What Refrigerating And Freezing Bread Really Does to It
Cooling is key to retrogradation, and storage temperature influences how much resistant starch forms.
Bread stored in the fridge actually develops more resistant starch than bread at room temperature or frozen, but the trade-off is that it goes stale faster. While freezing may cause slower formation of resistant starch, it’s typically recommended to preserve its quality.
Storage affects the texture, too. “For refrigeration, the texture ends up being drier as the cooler temperature and circulation of the fridge dehydrates the product unless tightly sealed when cooled,” said Brian Chau, principal food scientist at Chau Time. An easy fix is to add a bit of water when reheating, whether you’re toasting it or warming it in the oven or on the stovetop.
Freezing, on the other hand, makes bread more rigid. “When thawing frozen foods, the cell structures rupture from the ice formation,” Chau said. “This can further rearrange the starch alignment to create a different and possibly more resistant structure of starches in the food.” While freezing may alter the structure in this way, the total amount of resistant starch formed is generally higher in bread stored in the fridge.
The Health Benefits Of Resistant Starch
These temperature changes affect digestion — fresh bread produces a higher glycemic response than refrigerated or frozen. In fact, one study found that toasting bread after freezing and defrosting lowered glucose response even further, likely because the freeze–toast–cool cycle creates multiple heat-and-cool phases that favor resistant starch formation.
Because resistant starch isn’t absorbed into the bloodstream, it has little effect on blood sugar, making it helpful for people with insulin resistance, including Type 2 diabetes. “Resistant starch slows the absorption of other carbohydrates into the blood,” Zenker explained. “Because less of the carbohydrates in the food are absorbed, the impact on blood sugar is more blunted, reducing blood glucose and insulin spikes. This supports steady energy throughout the day, helps prevent sugar crashes and promotes feelings of fullness.
Beyond impacting blood sugar, resistant starch supports gut health, as it reaches the colon intact, where it feeds gut bacteria. “[Gut bacteria] consume resistant starch and release beneficial compounds called short-chain fatty acids (SCFAs) like butyrate,” Zenker said. Butyrate fuels healthy colon cells, reduces inflammation, and even influences brain health via the gut–brain axis. SCFAs also help maintain the intestinal lining, lowering the risk of what’s commonly referred to as “leaky gut.”
There’s also emerging evidence that resistant starch may aid feelings of fullness. “Indirectly, resistant starch may impact satiety and blood sugar by increasing GLP-1 production in the gut,” Zenker explained. SCFAs stimulate colon cells to produce GLP-1, a hormone that signals fullness to the brain. This is the same pathway targeted by popular GLP-1 medications such as Ozempic. While boosting GLP-1 naturally may help reduce hunger and cravings, Zenker notes that more research is needed to fully understand the impact of resistant starch on GLP-1 and satiety.
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Toasting your bread after freezing it can significantly lower glycemic responses.
This Starch Trick Works On More Than Just Bread
Beyond bread, starchy foods like rice, pasta and potatoes also gain resistant starch when cooked and cooled. One study found that cooled and reheated rice led to a 30% lower rise in blood glucose compared with freshly cooked rice. “It’s important to note that the benefit of resistant starch is small, so moderate portions still matter,” Zenker said.
Like bread, storage plays a role in balancing resistant starch formation and texture. “I typically recommend storing foods like potatoes in the fridge for up to three days because freezing can make them unpleasant,” said Sarah Glinski, a Canadian registered dietitian specializing in gut health. For rice and pasta, she advises choosing storage based on when you’ll eat them: refrigeration works for up to three days, while freezing is best for longer-term storage — up to three months — before texture starts to suffer.
How Meaningful Is The Difference?
A small 2008 study looked at how freezing and toasting white bread affects blood sugar. The study found that compared with fresh, homemade white bread, bread that had been frozen and then thawed (or toasted after freezing and thawing) triggered significantly lower glycemic responses, by up to 39%.
“For people with diabetes or prediabetes, this could help with blood sugar management,” Glinski said. “Many people with these conditions have been advised to avoid carbohydrates, but this is usually unnecessary. Eating foods high in fiber, like resistant starch, can be a way to enjoy carbohydrates without them impacting your blood sugars as much.”
How To Pick Bread That Supports Your Health
Beyond storage, the key to healthy bread is what’s inside the loaf and how much you eat. “I typically recommend people choose whole wheat bread or sprouted grain bread, which is naturally higher in fiber,” Glinski said. Breads with seeds like chia, flax and sunflower are also good sources, aiming for at least 3 grams per slice. “For healthy blood sugar levels, choose bread with less than 3 grams of sugar per slice, and check the ingredient list for cane sugar, honey, molasses or brown rice syrup,” Glinski added.
For those who need to limit fermentable carbs (FODMAPs), sourdough can be a good option, as it generally has lower FODMAP content and may be gentler on digestion. Ultimately, portion size and what’s in your bread still play a big role in making each slice healthier.