A simple processing technique could slow the digestion of starches in potatoes, making potato-based foods less likely to cause blood glucose spikes, according to a new study presented at Nutrition 2022 Live Online, the annual conference of the American Society for Nutrition, and described in a press release from the organization.
There has been some debate over the years about whether potatoes are a good food choice for people with diabetes. On the one hand, potatoes include a range of beneficial nutrients — including potassium, calcium, magnesium, and antioxidant substances like flavonoids and carotenoids. Depending on the preparation method, they can also contain varying amounts of resistant starch, which can aid in digestive health. But potatoes are also somewhat high in easily digested carbohydrate in the form of starch, which can lead to blood glucose spikes in people with diabetes. And some preparation methods for potatoes add potentially unhealthy forms of fat and excess calories. Surprisingly, there aren’t many studies looking specifically at potatoes and diabetes, but one study found that women who consumed more potatoes before pregnancy were more likely to develop gestational diabetes.
For the latest study, researchers aimed to modify potatoes to make their starch be absorbed more slowly in the digestive system. To do this, they cubed potatoes and blanched (partially cooked) them in a solution contains calcium at 70° C (158° F) for 30 minutes, before steaming them as the main cooking method. Then, they put both untreated and treated cooked potatoes through a simulated digestive process to look at how starched in the potatoes reacted.
Treated potatoes digested more slowly in simulated process
The processing technique that the researchers used caused a reaction with pectin, a form of fiber found in potatoes. This created a gel-like substance that acted as a barrier between starch in the potatoes and digestive enzymes that break down starch. As a result, the simulated digestive process showed that while 10.5% of starch in untreated potatoes was digested slowly, this number rose to 35.3% in treated potatoes — which would result in a slower, more sustained rise in blood glucose. The researchers noted that this effect could make people feel full for longer after eating treated potatoes, potentially leading to a lower total intake of calories as well.
“Without our treatment, enzymes move freely in and out of cells, and starch is […] rapidly converted to glucose,” emphasized study author Amy Lin, PhD, head of the Food Carbohydrate Program at the Singapore Institute of Food and Biotechnology Innovation, in the press release. “The treatment allows the starch to be slowly degraded to prevent a spike in [glucose] and then fully converted to glucose to meet our energy and nutritional needs.”
The next step, according to the researchers, is look at how treated potatoes affect blood glucose, hunger, and more in actual people in a clinical trial. If this process is shown to be safe and effective at improving health-related outcomes, it could be used for prepared and frozen potato-based foods like roasted potatoes, hash browns, or potato nuggets.