The nutritional content of whole wheat breads also varies among recipes, but an average slice of whole wheat bread derives 69 % of its calories from carbohydrates and 15 % from fat because of the oil found in wheat germ. The nutrient profile of whole wheat bread is also excellent. It has 2 grams of fibre, primarily insoluble, which has been shown to help prevent colon cancer and possible breast cancer. With almost a gram of iron, a substantial amount of folacin (15.6 micrograms), vitamin E, copper, vitamin B6 and the three major B vitamins per slice, whole wheat breads is nutrient dense food. Not all brown breads are whole wheat; bakers do play tricks. Read about the nutritional facts about white bread here.