White bread is one of the star foods of our gastronomy, since many people almost need it to have some lentils or in the morning. to make some toast. The ‘problem’ is that for many people it is a prohibited food due to its high glycemic index, which causes a very pronounced sugar spike after taking it. Although There are options to have less impact.
Your metabolism. Our body, due to the refined flours used, causes its carbohydrates to be digested quickly, causing a blood glucose spike. However, for some time now a ‘biohack’ has been circulating on the internet that promises to change this with a simple gesture: put the bread in the freezer and toast it before eating it. Something that can be ideal especially for diabetics.
Here the question is almost obligatory: is it an urban legend?
What happens to the bread? To understand why bread changes its properties when cooled or heated, we must look at its main component, which it’s starch. In these cases, when the bread is baked, the starch gelatinizes, becoming easily digestible for our enzymes, and this causes the sugar to quickly pass into the blood.
However, when we subject that bread to an extreme cooling process, such as freezing, and subsequently toast it, the molecular structure of the starch changes. What occurs here is a physical-chemical phenomenon known as retrogradation, which has as its final result the formation of type 3 resistant starch.
A new starch. Type 3 resistant starch lives up to its name, as it resists digestion in the small intestine. The result is that, instead of being broken down into glucose quickly, it passes intact to the large intestine, where it acts in a similar way to dietary fiber, serving as food for our intestinal microbiota.
What does science say? This mechanism is something that already It was tested in 2008 with the publication of an article that measured the glycemic response in healthy volunteers after consuming white bread subjected to different processes:
- Fresh white bread: 259 mmol min/l.
- Just toasted white bread: 193 mmol min/l.
- White bread frozen and then toasted: 157 mmol min/l.
The important thing here is that frozen and then toasted white bread shows a significant drop in the glycemic index. That is, the simple act of freezing the bread and putting it through the toaster reduced the glucose spike by almost 40%.
There is more evidence. In addition to this, there are other published studies that showed that frozen and reheated white bread generates a much lower glycemic response at all times measured after ingestion. In fact, already in 1988, another study showed that roasting reduces the degree of digestion, and subsequent work confirms that leave it frozen for a long time The amount of resistant starch progressively increases.
It’s not magic. Although science suggests that toasted and frozen bread is metabolically better at keeping glycemic spikes at bay, there is fine print to keep in mind. One of these important points is that, in healthy people, reducing the glycemic index is interesting on a physiological level, but its impact on general health or weight loss is minimal if it is not accompanied by a healthier diet.
Additionally, toasting bread increases its palatability. That is, it is richer, crunchier and not as filling as fresh bread, which can lead us to eat more, canceling out any benefits of resistant starch.
The alternatives. If you want to continue eating bread but with a lower impact on your health, one of the options is to opt for whole grain bread that is 100% whole grain or made with long-fermented sourdough, since they have an inherently lower glycemic index thanks to their high fiber content.
But we must also remember that the glycemic load of a meal does not depend on a single food. Combining bread with good sources of protein, healthy fats, such as extra virgin olive oil, and fiber flattens the glucose curve much more forcefully than the best toasted bread.
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