Potatoes contain a special type of fiber called resistant starch. Unlike normal starch, it isn’t digested in the small intestine but reaches the colon intact, where it acts as a prebiotic: feeding the beneficial bacteria in our gut microbiota.
A study published in the Journal of Nutrition (2015) showed that consuming potato resistant starch significantly increases short-chain fatty acid (butyrate) production, associated with reduced intestinal inflammation and lower colon cancer risk.
Researchers at the University of Murcia (2021) confirmed that resistant starch from cooked and cooled potatoes (like in potato salad) has a prebiotic effect comparable to oats or barley.
The trick is in the preparation: when you cook potatoes and cool them (24h in the fridge), the starch recrystallizes into a form more resistant to digestion. You can reheat them without losing this effect. That’s why potato salad or day-old boiled potatoes are especially beneficial.