Here's the easiest way yet to avoid pneumonia: brush your teeth.

Simple enough, I know, but too many people skip out on oral hygiene -- and that's especially true when they're sick.

Big mistake -- because that's exactly when you don't want to let your guard down: A small study of 37 patients on ventilators found that pneumonia often begins with a dramatic shift in oral bacteria.

And that's a shift that can be prevented with a toothbrush.

The study didn't look at how this change in oral bacteria leads to the misery of pneumonia, but other studies have already mapped out the route: Nasty little critters build up in the mouth... and then drip right into your lungs, where they can wreck havoc.

Some studies have even shown that people with deep pockets in their gums are more likely to die of pneumonia -- and that's another sign of the role these bacteria play, since they just love to hide in those pockets.

In fact, gum pockets are about as cozy a home as a germ could ask for: warm, wet and sheltered.

The Yale University researchers behind the new study say you can minimize your own risk by brushing twice a day with a fluoride toothpaste -- and I'd say they got that half right.

Brush twice a day -- but skip the fluoride.

Despite what you've heard, fluoride isn't all that great for your teeth. And along with not doing much to prevent cavities, this toxic substance can actually damage your brain and weaken your bones.

Try an all-natural fluoride-free toothpaste instead -- and don't forget to floss, because there's a lot more than gum disease and pneumonia on the line here.

Just last month, I told you how gum infections can raise your risk of heart attack and stroke. Poor periodontal health has also been linked to everything from obesity to dementia to pre-term births and underweight babies.

Along with brushing and flossing, there's another simple way to keep your mouth clean and protect your heart at the same time: give up sugar.

Sugar serves as fuel for the bacteria that can damage your teeth and boost your risk of disease. Take away their fuel, and they die.

One more note here: If you do get sick, throw away your toothbrush once you recover. The same bacteria that caused your illness can hide in your toothbrush -- getting a free ride back into your body, twice each day.