Same answer as your question about wine.
Only bread made from pure wheat and flour (and leavening) is valid matter for the Eucharist. In the West, unleavened bread is used. In the East, leavened. Both are valid matter.
If there’s no wheat bread, then there’s no Eucharist. It’s that simple.
If by “normal loaf of bread” you mean the typical bread that takes up most of the space in a typical grocery store (like “sandwich white” or “butter top wheat” etc. etc.) the answer is no. Those are not valid matter for the Eucharist because they contain too many other ingredients beyond just wheat-flour and water. They have milk, oils, sugars, high fructose corn syrup, and all kinds of other ingredients added to them. They are not valid matter for the Eucharist.
On the other hand, if one were to go to some kind of specialty bread (maybe from a specialty bakery) that makes a bread from pure wheat flour and water (again, some leavening) without adding anything else, then that would be valid matter.
For example:
The popular “Wonder Bread”
Wheat Flour Enriched ( Flour , Barley Malt , Ferrous Sulfate Iron ] , Vitamin B Niacin Vitamin B3 , Thiamine Mononitrate Vitamin B1 { Thiamin Vitamin B1 } , Riboflavin Vitamin B2 { Riboflavin Vitamin B2 } , Folic Acid Vitamin B9 ] ) , Water , Corn Syrup High Fructose , Contains 22% or less , Wheat Gluten , Salt , Soybeans Oil , Yeast , Calcium Sulphate , Vinegar , Monoglyceride , Dough Conditioners ( Sodium Stearoyl Lactylate , Calcium Dioxide ) , Soy Flour , Diammonium Phosphate , Dicalcium Phosphate , Monocalcium Phosphate , Yeast Nutrients ( Ammonium Sulfate ) , Calcium Propionate , To Retain Freshness
source:
foodfacts.com/ci/nutritionfacts/Bread-and-Flour-Products/Wonder-Classic-White-Bread–oz/30443