The Weird Health Benefit Of Eating Leftover Sweet Potatoes, From A Cardiologist

Here at mindbodygreen, we're big fans of the mighty sweet potato. In addition to its candy-like taste, this nutrient-packed vegetable boasts a multitude of health benefits, including gut health1 and memory support2. So when Steven Gundry, M.D., shared a simple trick that can make them even healthier on the mindbodygreen podcast, we took notes.

While sweet potatoes have a variety of star characteristics (vitamins A and C, potassium, and a host of other minerals you can read about here), we're going to focus on one aspect: Sweet potatoes are high in resistant starch, a type of carbohydrate that's particularly beneficial for gut health.

This all sounds well and good, but what happens when you leave them in the fridge overnight? Well, says Gundry, "The process of cooling and then reheating actually makes much more of the starch resistant." The theory is that while those starches lose some of their structure during the cooking process, they form a brand-new structure once they cool. Research backs it up, showing that foods high in resistant starch have increased amounts after reheating them from cooled4.

You can apply the same science to any food high in resistant starches (plantains, legumes, rice, etc.), but Gundry's favorite source is a purple sweet potato. This tuber, a staple in the Okinawan diet (which is categorized as a Blue Zone), is remarkably high in resistant starch—and if you let it cool, the number may even skyrocket. "Roast your purple sweet potato, throw it in the refrigerator, reheat it, and you will turn almost 50% of that sweet potato into resistant starch," says Gundry. Simple as that.