It's amazing how big an effect one small change in your diet can have on your health. If you're having trouble with your blood sugar and showing the signs of prediabetes and would like to avoid blood sugar spikes, you can help keep your blood sugar lower simply by eating lentils instead of rice or potatoes.

Lentils are a lot like beans. In fact beans, lentils and peas are often grouped together and collectively called pulses. They all grow in a pod and are similar nutritionally. While pulses do contain a lot of carbohydrates, they are largely the kind of complex carbohydrates that raise blood sugar slowly. And their high fiber content also helps slow the rise in blood sugar that comes from eating other starchy foods such as rice and potatoes.

Replacing half a serving of rice with lentils caused blood glucose to drop by up to 20 percent. Replacing potatoes with lentils led to a 35 percent drop.

“Pulses are extremely nutrient-dense food that have the potential to reduce chronic diseases associated with mismanaged glucose levels,” explained the study's co-author, Alison Duncan, in a statement.

The University of Guelph researchers looked at the effect three different types lentils — split red, small green and large green — had on blood sugar. All three prevented the steep rise in blood sugar from eating rice or potatoes.

In the study, people ate a portion of either rice or potatoes that contained roughly 50 grams of carbohydrate. That's a little more than what you'd find in a typical medium-sized baked potato or a cup of cooked white rice. They had their blood sugar measured before eating and two hours afterward. At other times, they ate 50:50 mixes of either rice or potatoes with each of the three types of lentils to see how that affected their blood sugar. Replacing half a serving of rice with lentils caused blood glucose to drop by up to 20 percent. Replacing potatoes with lentils led to a 35 percent drop.

All three types of lentils reduced the blood sugar increase that occurred two hours after eating rice or potatoes alone.

“This slower absorption means you don't experience a spike in glucose,” said Duncan. “Having high levels over a period of time can lead to mismanagement of blood glucose, which is the hallmark of Type 2 diabetes. Essentially, eating lentils can lower that risk.”

The researchers mixed in the lentils rather than giving them separately because people usually mix them into some other food.

The study appears in the Journal of Nutrition.