 A major bakery chain is being challenged by regulators over the inclusion of ingredients in its products that are not actually there. Bimbo Bakeries, whose products include Sara Lee, Thomas Inglis muffins, and Andamans, being warned by the U.S. Food and Drug Administration, some items that listed ingredients like sesame seeds or tree nuts contain none of those things. FDA officials say that food labels must be truthful. They say including such things is not a substitute for preventing cross-contamination in products.