A recent study examined the use of antibacterial mouthwash and its ability to inhibit the blood pressure-lowering effect of exercise.

I’ll wait while you read that sentence again.

How in the world is blood pressure affected by mouthwash?

When we eat foods with nitrates in them there are bacteria in our mouth that convert the nitrate to nitrite. Nitrite can be converted to nitric oxide in the body. Nitric oxide in the bloodstream lowers blood pressure. We also know that exercising lowers blood pressure by a sustained production of nitric oxide. The waste product of nitric oxide utilization is nitrate. The saliva glands can dispose of nitrate from the blood by excreting it in saliva. Once in the mouth it can be converted back into nitrite by bacteria. These facts led researchers to wonder if killing the friendly bacteria in the mouth would have an effect on blood pressure and would it reduce the effect of exercise on blood pressure?

A few years earlier a small Swedish study had healthy patients rinse with antibacterial mouthwash twice a day. After one week they found that the study patients had an increase of blood pressure by two to four points. Their blood nitrite levels dropped by 25%. This doesn’t sound like a lot, but cardiovascular risk is directly related to blood pressure, point by point. This increases the risk of cardiovascular disease by 7 percent.

The exercise study had patients exercise on two different occasions. One exercise period they rinsed with mouthwash, on the other they rinsed with a minty placebo (the patients and doctors were blinded as to what they received). The exercisers that used mouthwash had a higher systolic blood pressure on average just over 3 points.

In both studies the researchers administered a mouthwash that had chlorhexidine in it, a potent bactericidal solution, that is prescription only in the United States. This same mouthwash is used frequently by patients before surgery because its use has been proven to decrease the incidence of postoperative wound infections and pneumonia. The study needs to be repeated with alcohol-based mouthwashes.

During the last few years there has been intense study of the bacteria that live within us and how they affect our health. A study earlier this year found that the presence of a certain oral bacteria was directly related to the aggressiveness of colorectal cancer via a different protein that promotes tumor growth.

Another study in the last year linked gum disease to Alzheimer’s disease. The bacteria most commonly responsible for chronic gum disease produces an enzyme that was present in higher levels in brain tissue of patients who suffered Alzheimer’s compared to normal brains of the same age. A second study showed that the bacteria can increase the production of amyloid beta, a major component of the amyloid plaques in Alzheimer’s. These studies don’t prove direct causation and more needs to be done.

Gum disease also has implications during pregnancy. Women with periodontitis are more likely to give birth early or to lower weight babies. In the case of diabetes, out of control blood sugar increases the risk for gum disease. And, gum infections are proven to make it harder to control blood sugar levels.

It is a vicious circle.

Good oral hygiene is so much more than just the care of your teeth. The best recommendations are to brush your teeth at least twice a day and to floss at least once a day. Rinse your mouth out after meals if you don’t brush just to wash away food and sugars. Don’t forget to go to the dentist.

Lastly, if you are going to use mouthwash, consider one that freshens breath more than kills bacteria.

Dr. Salvatore Iaquinta is a head and neck surgeon at Kaiser Permanente San Rafael and the author of “The Year They Tried To Kill Me.” He takes you on the Highway to Health every fourth Monday.