Are your mouth and jaw getting the food workout they need? Here’s why we should eat – rather than drink – our food and chew it thoroughly.
Chewing Starts the Digestive Process
Digestion begins in the mouth. Saliva contains amylase and lipase, enzymes needed for starch and fat digestion.
Adequate chewing increases saliva to lubricate food, which eases its passage through the esophagus when we swallow.
Chewing signals the GI tract to prepare for food. The stomach makes gastric juice, which comprises enzymes, hydrochloric acid, and other substances. The pancreas prepares to secrete enzymes and bicarbonate into the small intestine. Extra saliva relaxes the pylorus so food can exit the stomach and move into the small intestine.
Enzymes and stomach acid work on the surface of food only. Chewing increases the surface area available for them to work. That’s especially important for the digestion of protein, which has many functions in the body.
But all foods need to be chewed small enough for stomach acid to further reduce them in size. That enhances bioavailability, the faster release and fuller absorption of nutrients and fluids into the GI tract.
In fact, most of the foods we don’t chew enough tend to be carbohydrates, such as bread and rice. They absolutely need amylase for digestion, but can be easy to swallow without adequate chewing.
Dogs eat carbs the right way. A dog will simply swallow meat; its digestive system can process meat in that whole state. Give a dog a piece of bread, though, and the chewing begins.
But back to humans…
Chewing Increases Satiety, the Had-Enough Feeling
Sensors throughout the GI tract monitor nutrient levels and the amount of chewing, tasting and swallowing involved in a meal. Giving your mouth and jaw a good food workout can bring on fullness signals sooner.
Foods with harder, crunchier textures – apples, raw broccoli, carrots, celery – require more chewing. They also provide more nutrients than semi-soft fats, or junk foods. So choosing foods that require lots of jaw action could lead to greater satiation – which ends the meal – and satiety, how soon we want our next meal.
Chewing longer helps to raise glucose levels. Those in turn raise insulin levels. Insulin is involved in satiety and feedback loops that end a meal, again marking chewing as a key satiety factor.
What About Hormones?
Chewing thoroughly helps to release higher levels of CCK (cholecystokinin). CCK is a powerful satiety hormone, so releasing more of it can decrease appetite for a longer time.
CCK is released primarily when we eat protein and fats, but its satiety function tends to be specific to carbs.
The chewing-and-CCK connection could help vegans, for example. They often have strong cravings for carbs generally and sugar in particular, due to their low protein intake and low levels of CCK. Chewing foods for a longer time could help vegans eliminate sugar cravings by increasing their CCK levels. (So could more protein, but that’s another article.)
Then there’s ghrelin, truly a monster hormone. It increases appetite and decreases energy expenditure. Yikes. More chewing increases satiety by decreasing levels of ghrelin.
In a country that produces 3950 calories per day for every man, woman and child, no one needs more ghrelin. So if simply chewing longer can reduce ghrelin levels, by all means chew longer.