One of the unfortunate things about bad breath is that we may not know we have bad breath until we speak. By this stage, we will have engaged in a social or business situation where we may cause people to recoil from us - even if subconsciously - at the very moment when we are trying to improve our relationship with them. If this group knows us well, this is less of a problem. Friends are more likely to be forgiving of the little things about us that perhaps jar them. But if we don't know these people well, we may have just sullied the all important first impressions that are the crucial beginning of any relationship - social, intimate, or business.
Bad breath is undoubtably a problem - frustrating, and usually recurring. Perhaps it gets covered up by mints and candy, but there are situations when we cannot always be chewing on gum. Its unprofessional in a business meeting, impractical when we're having lunch, and impossible when we're intimate with someone.
Bad breath is caused by bacteria. More specifically, the volatile sulfur compounds that are the result of the breakdown of two sulfur containing amino acids, methionine and cysteine. These bacteria live in the mouth and throat, and because they are anaerobic bacteria, they do not live on the surface of the tongue. They actually exist in the fibers which the tongue is made up of.
The bad news is that you cannot get rid of these bacteria permanently, despite the promise of some bad breath treatments. And you actually wouldn't want to, despite the inconvenience they cause when they are working overtime to produce bitter tasting and bad smelling metabolic byproducts. These bacteria are actually part of the digestive process, which begins in the mouth. You need them, and they need you!
There are things that make this normal aspect of digestion worse, however. Foods like dairy products and eating too much protein. That's why one very common side effect of the high protein Atkins diet is bad breath. The proteins in these foods gives these bacteria more 'fuel' to create even more volatile sulfur compounds. They are just doing their job, with very unpleasant after effects. And coffee contains acids which allow the bacteria to multiply. So for the social situations where you want to minimize bad breath, its a simple thing to avoid these foods and drinks.
Tea, on the other hand, can stop the growth of these bacteria. Researchers in Chicago at the University of Illinois have found that the polyphenols in tea can not only reduce the output of the volatile sulfur compounds by 30%, but they make it harder for the bacteria to multiply. The polyphenols active in this bad breath remedy are catechins and theaflavins. Catchetins are found in both green and black tea, and theaflavins are only found in black tea. So a strategy to prevent bad breath might be to avoid the alcohol at important lunches and dinners, and drink black tea instead! Alcohol, because it dries your mouth out, will aggravate bad breath.
References:
1. www.therabreath.com

2. www.nutraingredients.com/news/ng.asp?id=37915