Many on the Atkins diet are eating high amounts of iron in thier diet from meats. Too much iron can build up in the system and become toxic. For me, I was only getting around 50-60% RDA of iron each day, so my multis have added iron. Fitday can be good for checking things like that.

The one a day vitamin "other ingredients"
Calcium Carbonate, Cellulose, Magnesium Oxide, Green Tea Extract, Ascorbic Acid, Ferrous Fumarate, Acacia, Dl Alpha Tocopheryl Acetate, Niacinamide, Croscarmellose Sodium, Zinc Oxide, Dextrin, D-Calcium Panthothenate, Dicalcium Phosophate, Caffeine Powder , Silicon Dioxide, Hypromellose, Magnesium Stearate, Titanium Dioxide, Gelatin, Corn Starch, Crospovidone, Glucose, Manganese Sulfate, Calcium Silicate, Cupric Sulfate, Polyethylene Glycol, Pyridoxine, Hydrochloride, Riboflavin, Dextrose, Thiamine Mononitrate, Lecithin, Beta Carotene, Chromium Chloride, Resin, FD&C Blue #1 Lake, Folic Acid, Sodium Selenate, Phytonadione, Tricalcium Phosphate, Cholecalciferol, Cyanocobalamin

There is both gluclose and dextrose listed as ingredients. Those are both sugars. There is also corn starch used as a filler.