Toasting bread has only a small impact on the nutritional value of bread. Toasting bread has both detriments and benefits, but the differences between toasted and non-toasted bread are minimal.
According to nutritionist Monica Reinagel of QuickAndDirtyTips.com, toasting bread can sometimes lower the glycemic impact of the bread. This means that it causes a lower rise in blood sugar than regular, non-toasted bread. On the other hand, toasting bread causes it to have a higher amount of acrylamide. According to Cancer.gov, acrylamide is found in certain foods when they are heated above 248 degrees Fahrenheit. Acrylamide has been linked to cancer; however, more research is needed on the subject.