Chewing ... a lost art
Our fast-paced Western culture does not put much emphasis on chewing. We have all seen the modern man and modern woman “I don’t have time to eat” running out the door commercials. The proffered responses are Eggo Waffles, Pop-Tarts, or a veritable infinite variety of breakfast bars. “Go for bars that have a real food — a nut, seed, fruit, or 100% whole grain as the first ingredient. The ultimate goal = a breakfast that's satisfying, filled with whole, real ingredients and clocks in around 400 calories to start your day,” says Jaclyn “Jackie” London, M.S., R.D., C.D.N., formerly nutrition editor at Good Housekeeping magazine. Are breakfast bars any more real food than Eggo Waffles or Pop-Tarts? The primary ingredient in breakfast bars, even the “natural” and “organic” ones, is (surprise, surprise) sugar. Of course, they are easy to eat on the run, and can be wolfed down to meet almost any schedule, theoretically leaving more time for productive activities. You really don’t have to laboriously chew them, just bite, chew once or twice, and swallow.
Of course, this behavior goes against your mother’s “chew your food” … and let’s not forget “take smaller bites,” “chew with your mouth closed,” and “wipe your mouth.” Emily Post may have written about etiquette, but mothers’ dicta are genetically passed from generation to generation. You know better than to ignore your mother … !!!
To get the nutrients and energy from the food we eat, it must be digested according to an established orderly sequence. The digestive process is the physical and chemical breakdown of the food, which takes places in our digestive tract. The adult digestive tract is approximately 30 feet long and comprises the mouth, esophagus, stomach, duodenum, small intestine and large intestine. Each part of the digestive tract has a particular function and specific acids, enzymes, and hormones for processing the food we eat.
The physical digestion begins in the mouth with mashing and mixing. Think “John Henry” or “Big Bad John.” Your lower jaw is the hammer and your upper teeth the anvil to break the food you intake into smaller pieces. Your objective is a smoothie, not chunky pico de gallo or salsa. The smaller the pieces the more efficient the total digestion will be. A common recommendation is to chew until the food in your mouth has lost all of its texture (really? Sounds a little extreme?) and becomes a smooth paste in your mouth (are we talking baby food consistency?). If you have to take a drink of water to swallow your food, you are probably not chewing enough. Cirino, E., “Chewing Your Food: Is 32 Really the Magic Number,” https://www.healthline.com/health/how-many-times-should-you-chew-your-food; Zink, K. and D. Lieberman, “Impact of meat and Lower Palaeolithic food processing techniques on chewing in humans,” Nature531(7595):500-3 (Mar. 24, 2016). https://doi.org/10.1038/nature16990
The chemical digestion also begins in the mouth. Even before you take your first bite, your nose smells the food you are about to consume, sends a message to your brain, which in turn sends a message to the nerves controlling your salivary glands to tell them to get to work, food is on the way.
Unfortunately, microwave cooking can reduce olfactory stimulation. The Maillard reaction is the source of many of the aromas that trigger salivation (think of bread baking in the oven or a steak on the grill); microwave cooking does not enable the Maillard reaction. Fine Dining Lovers, “Food Smells & Aromas: The Science of Smells” (May 29, 2015). https://www.finedininglovers.com/article/food-smells-aromas-science-smells; Tamanna, N., and N. Mahmood, “Food Processing and Maillard Reaction Products: Effect on Human Health and Nutrition,” Int. J. Food Sci. 2015:526762 (2015). https://doi.org/10.1155/2015/526762; Wangxin, Liu, et al., "Influence of cooking techniques on food quality, digestibility, and health risks regarding lipid oxidation," Food Res. Intl. 167 (2023). https://doi.org/10.1016/j.foodres.2023.112685
Olfactory message received, your salivary glands, all thousand or so of them in your mouth, produce saliva and deposit it into your mouth. Saliva softens food by making it moist. It also contains enzymes, specifically amylase, that helps break down carbohydrates into sugars, making them easier to be absorbed. Saliva also contains the enzyme lipase that helps break down triglycerides, a dietary fat, into glycerol and free fatty acids, which again helps the body absorb these fats. It also contains a number of compounds with antimicrobial properties that help protect against infection. Lai, W., et al., “Analysis of the Lipolytic Activity of Whole-Saliva and Site-Specific Secretions from the Oral Cavity of Healthy Adults,” Nutrients 11(1):191 (Jan 18, 2019). https://doi.org/10.3390/nu11010191; Vila, T., et al., “The power of saliva: Antimicrobial and beyond,” PLoS. Pathog. 15(11):e1008058 (Nov 14, 2019). https://doi.org/10.1371/journal.ppat.1008058
Physical and chemical digestion started; what about our neurological systems? As it turns out, chewing stimulates nerves to send alert signals to the stomach, pancreas, and gall bladder that food is on the way and for them to get ready to release the appropriate acids, enzymes, and bile. Mashing, salivating and mixing accomplished (or maybe not), a bolus, the mixture of food particles and saliva, is dispatched down your esophagus to your stomach. Once the bolus reaches the stomach and mixes with gastric juices, the food mass becomes known as chyme (we will get to this later).
While more mechanical digestion takes place in the stomach, the release of stomach acid, hydrochloric acid (HCl), stimulates pepsin to break down proteins. The hydrochloric acid also works to disinfect the swallowed food that then passes to the small intestine, where the majority of nutrients are absorbed into the body. Bicarbonates neutralize the acidic food, and bile emulsifies fats and carries toxins out of the body. We all have the experience of gastric distress when this process is out of balance (bloating, belching, releasing gas). More severe medical conditions such as leaky gut syndrome can result. Richardson, C. and M. Feldman, “Salivary response to food in humans and its effect on gastric acid secretion,” Am. J. Physiol. 250(1 Pt 1):G85-91 (Jan. 1986). https://doi.org10.1152/ajpgi.1986.250.1.G85; Ohta, M., et. al., “Effect of chewing or compressing food on autonomic nervous activity in older adults,” Gerodontology 34(4):434-440 (Dec. 2017). https://doi.org/10.1111/ger.12284; Izumi, K., et al., “Changes of bolus properties and the triggering of swallowing in healthy humans,” J. Oral Rehab. 48(5):592-600 (Jan. 22, 2021). https://doi.org/10.1111/joor.13151
What are the consequences of failing to chew properly? Fundamentally, your digestive system becomes confused and out of balance (some of us are more easily confused than others), which can result in acid reflux, bad breath, bloating, constipation, cramps, diarrhea, food poisoning, gas, gastroesophageal reflux disease (GERD), headaches, heartburn, indigestion, irritability, malnutrition, mood swings, nausea, over eating, skin problems, weight gain, to name a few conditions … gas perhaps the most public and embarrassing manifestation … list long enough to get your attention?
On the other hand, proper chewing leads to better digestion, enhanced nutrient absorption, and a stronger oral immune system. Interestingly, it also reduces your food intake by helping signal satiety to your brain. Over the longer-term proper chewing results in higher overall satisfaction from meals. Ly, T., et al., “Sequential appetite suppression by oral and visceral feedback to the brainstem,” Nature 624:130–137 (2023). https://doi.org/10.1038/s41586-023-06758-2
What does it take to “chew properly”? Start with a reasonable amount of food per bite; the bite should fit on your fork or spoon without it falling off. Augustus “Save Some Room for Later” Gloop from Willy Wonka & The Chocolate Factory is not your model.
Anticipation of what we are about to eat is a major factor in taste and satisfaction. “The French say that hunger is the best sauce. They're right. When you are hungry, everything tastes better. The very first bite of food has a much stronger taste and creates a stronger sensation than the one after that. And the more you eat, the less additional pleasure you get from each bite. … There's a reason we say "Good to the last bite" as a compliment.” Darling, N., “The First Bite Is the Best: Thoughts on Eating,” Psych. Today (Jan. 1, 2013). https://www.psychologytoday.com/us/blog/thinking-about-kids/201301/the-first-bite-is-the-best-thoughts-eating; Piqueras-Fiszman, B., “The Psychology of Food Choice: Anticipation and Mental Simulation,” in: Meiselman, H. (eds) Handbook of Eating and Drinking (Springer, Cham. 2020). https://doi.org/10.1007/978-3-030-14504-0_170; Skvortsova, A., et al., “Food anticipatory hormonal responses: A systematic review of animal and human studies,” Neuroscience & Biobehavioral Reviews 126:447-464 (2021). https://doi.org/10.1016/j.neubiorev.2021.03.030
With food in your mouth, close your lips and start chewing. Your tongue should move the food from side to side; you want to chew with both sides of your mouth. Your jaw should rotate slightly. Chew slowly. Eating slowly helps steady blood sugar, reduces blood pressure, leads to better hydration, may affect the risk of chronic disease, helps manage weight, and may improve mental health. Furthermore, you will experience more enjoyment from the simple act of eating. Angelopoulos, T, et al., “The effect of slow spaced eating on hunger and satiety in overweight and obese patients with type 2 diabetes mellitus,” BMJ Open Diabetes Res. Care 2(1):e000013 (Jul. 2, 2014). https://doi.org/10.1136/bmjdrc-2013-000013
How much chewing is enough? Ayurveda, the 7,000-year-old school of medicine considers slow and thorough chewing essential for strong digestive health.
One of Ayurveda’s core principles is prevention based on a delicate balance of body, mind and spirit. One of Ayurveda’s golden eating rules is to chew each bite of food 32 times. Fast forward to the later 1800’s and the “Great Masticator,” Horace Fletcher, a self-proclaimed dietary expert who performed experiments that led him to conclude the importance of chewing. "Fletcherising," as it became known, would turn "a pitiable glutton into an intelligent epicurean," he proclaimed. "Nature shall castigate those who don't masticate" was one catch phrase. To Fletcher, it didn’t matter what you ate, as long as you waited until you were truly hungry, and then chewed, and chewed, and chewed each and every bite until it basically “swallowed itself,” a minimum of 32 times, once for each tooth in your mouth. Fletcher’s experiments showed that some foods needed more that 32 chews, meat for example often took 50 chews to reach the proscribed swallowing state. Even Mark Twain, one of the original skeptics about so many subjects, tried the Fletcher dietary advice, as did President Theodore Roosevelt, John D. Rockefeller, Upton Sinclair, Henry James, and Franz Kafka, among others. Erict, “Chew Your Food 32 Times: Where Did This Advice Come From?” CulinaryLore (Jul. 2, 2016). https://culinarylore.com/food-history:chew-your-food-32-times/; Pera, P., et al., “Influence of Mastication on Gastric Emptying,” J. Dental Rsch. 81(3):179-181 (2002). https://doi.org/10.1177/0810179
What happens to you if you chew each bite 32 times? Does the taste of the food change? How about how much you eat? When all is said and done, is 32 the magic number for you?