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What is the resistant starch in cooled pasta?

When cooked pasta, rice, or potatoes cool down, part of their starch recrystallizes and the small intestine can no longer cut it into sugar. This "resistant starch" reaches the colon intact, where bacteria ferment it. Legumes already provide some, without any cooling.

Cold, legumes, then a meal's journey hour by hour: change the step, choose a dish, drag the slider.

What does cold do to the starch in pasta and rice?

Starch is made of long chains of glucose. Cooking unfolds them, and amylase, the enzyme of the small intestine, cuts them into sugar. In the cold, some of the chains stick back together into crystals it can no longer cut.

straight chain (amylose)branched chain (amylopectin)amylase, the enzyme that cutsglucose going into the blood
    With care: this page explains what happens in the body; it does not recommend any food. The effect of cold on blood sugar is real but modest, measured in small groups. Bloating, irritable bowel, diabetes: medical advice helps adapt the diet.

    Frequently asked questions about resistant starch

    What is resistant starch?

    The part of starch that is not cut into glucose in the small intestine and reaches the colon intact. There are several kinds: locked in (legumes, whole grains), raw and compact (green banana, raw potato), recrystallized after cooking and cooling (pasta, rice, potatoes). In a Western diet, about 10% of the starch eaten resists this way (Cummings and Englyst, 1991).

    Should pasta be eaten cold, or can it be reheated?

    Reheating undoes part of it, not all. In people who had intestinal surgery, the share of carbohydrates reaching the end of the small intestine went from 9% (fresh potatoes) to 18% (cooled) then 14% (reheated) (Englyst and Cummings, 1987). Rice kept 24 h at 4 °C (39 °F) then reheated contained 1.65 g of resistant starch per 100 g, versus 0.64 g for fresh rice (Sonia, 2015). This page explains what happens; it does not say how to eat.

    How long in the fridge to form resistant starch?

    Studies most often test 24 h at 4 °C (39 °F): on rice (Sonia, 2015), pasta (Hodges, 2020), and mung beans, where this setting gave the most (Chauhan, 2024).

    How much resistant starch do people eat per day?

    In the United States, about 1.9 g per 1,000 kcal eaten (Miketinas, 2020). In Italy, about 8.5 g per day (Brighenti, 1998). With up to 60 g per day of crystal-type resistant starch, volunteers had no more digestive symptoms (Storey, 2007).

    Why do lentils cause gas?

    Their resistant starch and their sugars raffinose and stachyose reach the colon: humans lack the enzyme that cuts them, so bacteria ferment them and release hydrogen and carbon dioxide (Elango, 2022; Di Stefano, 2007).

    See also

    What happens in the body after a meal? How long to recover gut flora after antibiotics? How does the stomach digest protein? Where do the fats we eat go?

    Sources

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    True or false?

    Reheating cooled pasta cancels the effect of the cold.

    False. The crystals of cooled starch melt between 120 and 177 °C (248 and 351 °F) (Sievert and Pomeranz, 1990): reheating undoes only part of them. Rice that was cooled then reheated kept 2.5 times more resistant starch than fresh rice (Sonia, 2015).

    Starch is digested in the stomach.

    False. Salivary amylase starts the work, stomach acid stops it; most of it is cut in the small intestine by pancreatic amylase (Peyrot des Gachons and Breslin, 2016).

    Colon cells feed partly on what bacteria make.

    True. In human colonocytes, the butyrate supplied by bacteria accounts for 73 to 75% of the oxygen consumed (Roediger, 1980).

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    Metabolive. "What is the resistant starch in cooled pasta?" Updated November 3, 2026. https://metabolive.com/en/everyday/resistant-starch.