Does the potency of resistant starch such as cooked and cooled potatoes, rice, etc., change with time? Does storing them longer in the fridge before eating them, for example, five days old versus three days, make them more potent? I have some patients who get mild gas, nothing life changing, when they eat older rice and potatoes. Just wondering what might cause this.

Kelsey Marksteiner:  Good question. I don’t think it makes a difference. At least the research I’ve seen on resistant starch, I actually haven’t seen any studies where they go for longer periods of time in the cooling period and then check on the amount of resistant starch. What I’ve seen is them just comparing different foods after a 24-hour cooling period. So I would say leave it in for a day to make sure that you’re getting maximum resistant starch, but beyond that I haven’t seen any evidence that there would be more resistant starch or the potency of resistant starch would change after more time in the refrigerator.

But to answer your other question about patients that get mild gas and the older rice and potatoes. I’m trying to think if there would be any real reason for that. And I don’t think so. I wonder if they’re equating the older … I guess I would really have to talk to the patients. But my guess would be maybe that they are either eating these things fresh or they’re eating them as leftovers and maybe the leftovers in general might be causing some of the mild gas versus the fresh. I’m not entirely sure that’s what you’re saying here. If they are indeed having trouble with five-day-old potatoes versus three-day-old potatoes, I honestly don’t know.

But my guess would be that they are kind of separating it into categories of fresh and leftover and they are noticing that they have problems with the leftovers, which would make sense given that there’s some resistant starch. And if their stomach, digestive tract is not used to having resistant starch very often, it definitely could cause a little bit of mild gas. Nothing to be worried about of course. It’s completely normal, and the more that they eat things like that, the less they’re going to have that gas production. But nothing to worry about. That would be my guess as to what’s going on here. But if it’s not, and if it is really the five days versus three days that they’re noticing it, I’m honestly not sure. So sorry I can’t be a little bit more helpful with that. But that’s my best guess and to answer the question about resistant starch over time, I’d leave it in the refrigerator for at least 24 hours but beyond that, I haven’t seen any evidence that resistant starch gets more potent or that there’s more of it.