Saliva

According to researchers, hundreds or even millions of bacterial colonies move from one mouth to another during a kiss, and allergens can linger in the saliva for nearly a day after ingestion, regardless of brushing, rinsing or other interventions.

Allergists have linked kissing to swelling of the lips or tongue, sneezing, itching and rashes in the throat in people who are prone to allergic reactions from food and medicines.

An individual’s preference for food is shaped by the variability in the activity of an oral enzyme known as salivary amylase.

"Differences in starch perception likely affect people's nutritional status by influencing their liking for and intake of starchy and starch-thickened foods," said lead author Abigail Mandel.

Saliva secretes amylase enzyme which helps in breaking down the starch into simpler sugar molecules.

These molecules are ultimately absorbed into the bloodstream and thus influence blood glucose levels.