Bad breath most often starts at the back of the tongue and this huge accumulation of plague can affect the health of the gum tissues. Gum disease can also be a cause of bad breath. In minor cases, products such as mouthwash or toothpaste might help, but in most cases, this is not enough and can make the problem worse. Baking soda is not something I recommend in any oral product because it pushes the mouth into an alkaline pH which is the opposite direction one wants to put the pH to prevent halitosis or gum diseases which thrive in this basic and putrefactive environment. The mouth must be in a slightly acidic pH to prevent bad breath.
Peroxide is also ineffective in preventing halitosis.
Peroxides are oxygenating agents which can produce harmful free radicals and have been of concern to some health professionals when used for long periods of time in the presence of chronic inflamed tissue. Gum tissues are usually chronically inflamed and therefore are susceptible to negative effects of peroxides which can cause adverse cell changes to occur. Unfortunately, almost all major toothpaste and mouthwash makers are jumping on the misguided baking soda and peroxide band wagon. Alcohols can be harmful and I strongly urge consumers to stay away from them. Smoking too can make bad breath worse.