Strawberries are one of the fruits highest in the anthocyanins antioxidants, which is what gives them their vibrant red color. But more than that, they contain polyphenols, a beneficial plant compound that also has antioxidant properties. A 2017 study observed a 6-week consumption of polyphenols from strawberries and cranberries that helped improve insulin sensitivity in overweight and obese adults who were yet to be diagnosed with diabetes. They are also a rich source of vitamin C while being low in sugar to help improve insulin resistance.