Chewing is important for both physical and chemical digestion, and requires sufficient awareness and attention, therefore making it an integral part of mindful eating. Physically, chewing works by breaking down the food into pieces small enough for the digestive system to handle, creating a higher surface area to volume ratio for chemical digestion to act on the food. Chemical digestion involves the secretion of acids and enzymes throughout the digestive tract that assist in the breakdown of food particles. Chemical digestion begins in the mouth where salivary enzymes begin to break apart large molecules into smaller molecules. A significant enzyme in saliva is amylase, which begins the breakdown of carbohydrates. Once salivary amylase reaches the stomach the pH levels are too acidic for it to function, therefore it is important food is thoroughly chewed in order to give amylase sufficient time to partially break down the carbohydrate molecules before swallowing. Undigested carbohydrates in the digestive tract can cause a number of symptoms. These complex molecules undergo bacterial fermentation by the bacteria in the large intestine that release gases such as carbon dioxide and methane, leading to foul smelling gas and bloating. When carbohydrates accumulate in the large intestine it can cause more water to be pulled into the intestine, which results in diarrhea or watery stool, and may ultimately cause dehydration. This increase in gas and water in the large intestine can produce pain, cramping, distended abdomen, vitamin and mineral deficiencies, and fatigue.
Numerous studies have been conducted which provide evidence to support the benefits of longer and more thorough chewing on digestion and nutrient assimilation. One study took 21 healthy males, fed them each equal portions of pizza, and asked them to chew each bite either 15 or 40 times. Those who chewed 40 times per portioned bite resulted in higher levels of satiety-related hormones in the blood plasma (glucose, insulin, and glucose-dependent insulin-tropic peptide) as well as lower ghrelin concentration than those who were instructed to chew 15 times. Another study gave participants equal servings of almonds and asked them to chew them 10, 25, and 40 times. Those who chewed 40 times had less hunger and more fullness than those who chewed 25 times. When testing fecal samples, fecal fat excretion and energy loss was significantly higher after 10 and 25 chews than after 40 chews. The results indicated that the more times the almonds were chewed, the more likely its nutrients were absorbed.
The exact number of times a bite of food should be chewed is debatable, and depends on factors such as the type of food being consumed, how soft or hard it is, how ‘pre-digested’ it is, and how large of a bite was taken. The recommended figure ranges anywhere from 30-50 times. The George Mateljan Foundation for The World's Healthiest Foods recommends a personal approach when deciding how much food should be chewed; “A good rule of thumb is as follows: If you can tell what kind of food you are eating from the texture of the food in your mouth (not the taste), then you haven’t chewed it enough”. But, while time and emphasis on chewing may be optimal for the physical digestion, if it becomes a strenuous chore we may not be creating an ideal state of mind, which may hinder chemical digestion and therefore nutrient assimilation. Maya Tiwari, an international teacher of Ayurveda, encourages that one finds a balance in quiet relaxation, a nurturing wholesome attitude, and awareness to chewing and taste.
Tiwari also emphasizes the importance of tasting our food, noting, “When the juices of the mind and appetite whet the tongue, we are ready to receive the blissful memories each food gives… memories of the entire universe are held in the savoring of our food”. When we taste all the flavors of each bite, we tell the body what substances it will be receiving which allows the digestive tract to prepare itself with the necessary acids and enzymes in order to digest and assimilate the food and its nutrients. The taste buds on your tongue are comprised of groups of receptors specialized to detect chemicals in food which represent different tastes – sweet, salty, bitter, sour, and umami. Each taste sends a signal to a specific location in the gustatory cortex area of the brain. Evolutionarily, taste has assisted humans in recognizing elements in food that meet our nutritional or physiological requirements, while also acting as a precautionary tool to warn us when something we are tasting may be potentially harmful to us. Generally, the sweet taste represents carbohydrates and helps our bodies recognize an energy source; salty governs the body’s ability to maintain water balance and blood circulation; umami reflects protein; bitter, which is often aversive to humans, can represent something poisonous, but also assists in fat digestion (stimulating bile secretion); sour signals the presence of acids, which we may crave or reject in efforts to maintain a natural acid-base balance, or in avoiding spoiled foods. Allowing your taste buds to recognize each individual taste is an important factor in appropriate signaling between your brain and digestive organs for optimal digestion and absorption of all nutrients.
In addition to its effects on the mechanics of digestion, concentrating on chewing and tasting can have a profound effect on your consciousness – bringing attention to what and how you are eating - by opening up space in the mind to the practice of mindful eating. It forces you to slow down.
To learn more about Mindful Eating, read the many other posts within the Mindful Practice category.