Answer : Both rye bread and pumpernickel bread are typically made with a mix of rye flour and wheat flour. Brands vary widely as a source of whole grains, so check the ingredients list on the label for whole rye flour and whole wheat flour. Besides being a whole grain-just like whole wheat-rye is a good choice for people watching their glycemic index (a measure of how rapidly the body converts food to sugars), such as diabetics. Rye has an unusually high level of fiber in its endosperm, the inner part that serves as a seedlings food supply. (When grains are processed rather than whole, the outer bran and germ are stripped away and the endosperm is all that remains.) This fiber-rich endosperm generally gives rye products-including rye bread and pumpernickel bread-a lower glycemic index than products made from wheat. On most other measures of nutritional value, rye and pumpernickel bread are not significantly different from regular whole-wheat bread. Both are richer sources of folate and folic acid and, depending on the brand, may be marginally lower in saturated fat. Whole-wheat bread is higher in protein and magnesium while typically lower in sodium per slice. All three types of bread contain about the same amount of calories per serving.