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Taking care of oral health is good and necessary but, if using mouthwash twice or more often daily can be a matter of concern.

A recent study reveals people who use mouthwash twice a day to keep their mouth clean may end up with diabetes. A Harvard study shows using it more than once a day can increase the risk of obesity and type-2 diabetes.

Researchers from the Harvard School of Public Health have claimed that anti-bacterial mouthwash could kill beneficial microbes living in our mouth that protect us against diabetes and obesity.

"People using the product twice a day were around 55 percent more likely to develop diabetes or dangerous blood sugar spikes – known as pre-diabetes – within three years," said the study, according to a Daily Mail report.

The study authors explained their findings saying nearly all popular mouthwash solutions include ingredients that kill both the good and bad bacteria.

KJ Joshipura, Professor of epidemiology at the Harvard School of Public Health, said: "Most of these antibacterial ingredients in mouthwash are not selective. In other words, they do not target specific oral bacteria. Instead, these ingredients can act on a broad range of bacteria."

The research team came to the conclusion after looking looked at 1,206 overweight people aged 40 to 65 without the prevalence of any major cardiovascular diseases or diabetes.

Over the study period, around 17 percent of the people surveyed developed diabetes or pre-diabetes, but that rose to 20 percent for those using mouthwash once a day, and 30 percent for those using it in the morning and evening, the Daily Mail reported.

Good bacteria in the mouth can protect us against obesity and diabetes, as it helps the body produce nitric oxide.

The researchers also warned that killing off good helpful bacteria may make room for harmful bacteria to thrive, and therefore rinsing once a day may be advisable.

The research was published in the journal Nitric Oxide.