Does chewing slowly really help with better digestion?

Chewing does one thing for certain: it physically breaks down food and mixes it with saliva into a smooth bolus that you can safely swallow. That is not a trivial point; without adequate chewing, people swallow larger pieces that are harder to digest. This mechanical effect is well described in the literature on chewing and swallowing physiology.

Saliva contains amylase, an enzyme that begins breaking down starch. More chewing means more saliva, and therefore more contact between amylase and your food. In theory that makes sense, but whether this leads to noticeably better digestion in healthy people in practice has not been demonstrated by the available research. The idea is biologically plausible, nothing more.

What is firmly established is that prolonged chewing produces significantly more saliva. That saliva is also less acidic, which is beneficial for your teeth and oral mucosa. For people with a dry mouth, such as older adults, chewing sugar-free gum can measurably improve saliva production. A systematic review found an average positive effect, although five of the included studies reported no improvement in the sensation of dry mouth. That review was partly funded by a chewing gum manufacturer, which is worth bearing in mind.

In people with Crohn's disease or ulcerative colitis who have intestinal narrowings, careful chewing is recommended as expert advice to help tolerate fibrous vegetables better. This is not the result of randomised research, but rather a practical line of reasoning.

Finally, a lesser-known point: chewing can temporarily introduce bacteria from the mouth into the bloodstream. For healthy people this is harmless, but people with a weakened immune system may be more affected by it.