The original paleo dieters Og and Thag probably slew their mastodons with clubs and rocks rather than sneaking up on the beasts to fell them with bad breath. And if you happen to have breath that could knock over an elephant on a modern diet, switching to the paleo diet plan may be just what you need to get the most persistent halitosis under control.

Bad breath is only transiently a problem caused by what we eat. Little bits of onion and garlic and stinky cheese can indeed cause halitosis, but only as long as they remain in the mouth. Simply drinking a beverage with your meal will reduce your bad breath. Brushing your teeth will largely eliminate it.  Brushing your teeth and gargling, with mouthwash or with plain water, will knock out bad breath so that garlic breath is largely undetectable in just six hours.

Morning breath tends to be a little trickier, but the principle for dealing with honey-it's-halitosis breath in the morning is not especially difficult, either. Just make sure you don't have bacteria growing on your tongue. You can brush your tongue at the same time you brush your teeth, or use a metal or plastic tongue scraper (be gentle, the idea isn't to scrape your tongue raw), and with time, you will get your morning breath under control, too.

But what can you do about the really awful breath that smells like flatulence in reverse? Actually, this problem usually is flatulence in reverse. Unfriendly bacteria accumulate in your small intestine and build up so much gas pressure that the stinky byproducts of their digestive process percolate up from your small bowel into your stomach and into your throat, with or without upchucks of a burning stomach acid. The secret to controlling these bacteria is to stop feeding them. And that's where the paleo diet comes in.

The bad breath bacteria that live in your bowel feed on non-digestible, “resistant” starches and sugars. A single gram of undigested starch or sugar can result in the creation of 1/3 of a liter of gas. Or in non-metric units, an ounce of undigested starch or sugar can result in the creation of 8 gallons of gas, some of which is going to be released from one end of the digestive tract, and some of which is going to be released from the other. Foods that provide the stinky bacteria with resistant starches and sugars include:

Dairy products. Even if your body makes the lactase enzyme needed to digest the lactose sugar in milk, this particular sugar feeds gas-producing bacteria.
Fruit, especially dried fruit (and more especially prunes and dried apricots). The fructose in fruit is more slowly absorbed than other sugars, and lingers in the bowel where it can feed bacteria.
High-fructose corn syrup. This product is not 100% fructose. It is only “high” in fructose. But it presents the same problems as fruit, only more so because we tend to consume more sugar in soft drinks and baked goods than in fruit.
Resistant starch. This indigestible carbohydrate is found in beans, peas, legumes, corn, unripe bananas, plantains, sweet potatoes, yams, and most kinds of rice and pasta. All of these foods are restricted on the paleo diet, but if you have to indulge in a carbohydrate food, it should be a food that has relatively little resistant starch, such as sushi rice, sticky rice (but not arborio or basmati rice), or well-cooked Pontiac or Russett potatoes, served warm. Allowing a starchy food to cool off gelatinizes the carbohydrate so it can feed bacteria but can't feed you.
Sugar alcohols. These “zero-calorie” sweeteners such as maltitol, xylitol, erythritol, and isomalt are fermented by bacteria in the small intestine. They are added to stevia to make it pourable and they are added to many products sweetened with Nutrasweet to cancel out its after-taste.

Meat, fish, poultry, eggs, and green leafy vegetables don't feed the bacteria that cause halitosis, although high-fiber vegetables do feed the bacteria in the large bowel that can cause flatulence.

A combination of good oral hygiene—including tongue care—and the paleo diet can be just what you need to get rid of persistent halitosis. If you still can't get bad breath under control after making these changes, see your dentist about possible problems with your teeth or gums.