Chewing Is Step No. 1 in Digestion—Here’s How Eating Rate Affects Gut Health, According to a Gastro

Have you ever been told you should chew your food more slowly to improve digestion… and simply chalked it up to an old wives’ tale? Guilty. But in a game of fact or fiction, we’ve come to learn there may be some truth to this story after all.

In fact, some researchers suggest that chewing food 32 (!) times per mouthful may be optimal for healthy digestion. But before you start counting your chomps—and totally exhaust your mandibles in the process—Will Bulsiewicz, MD, a gastroenterologist, bestselling author of The Fiber Fueled Cookbook, and U.S. medical director of Zoe, says you may want to hear this first: It’s not so much about how many times you’re chewing your food, as it is the rate in which you’re doing so. Ahead, Dr. Bulsiewicz explains the importance of observing your eating rate, aka how quickly or slowly you chew your food.

How does chewing food impact digestion?

According to Dr. Bulsiewicz, chewing is considered the first step in digestion. “If you have digestive health issues, I would strongly encourage you to focus on chewing as the first part of that process,” he says. So, why do chewing and digestion go hand in hand? Aside from the obvious fact that chewing helps make food small enough to physically swallow, several key chemical reactions also occur when we chew. Let’s expand on this.

1. It physically helps make food smaller and easier to swallow

For starters, chewing food makes it physically easier to swallow. “Chewing obviously breaks down the food. So breaking it down into pieces makes it easier for our body to process and digest it because we’ve already done a lot of the work,” Dr. Bulsiewicz says. He refers to this as the mechanical process, or component, of breaking down food into smaller bits and pieces to prep it for further digestion.

2. It introduces food to digestive enzymes found in saliva

Chewing introduces food to key digestive enzymes found in saliva. “There’s a few things that are sort of magical that happen [when you chew]. For starters, saliva contains digestive enzymes that mix with our food,” Dr. Bulsiewicz explains. “For example, saliva contains amylase, which helps us to break down the starches [a type of complex carbohydrates] in food. Our saliva also contains lipases, which break down fats. This means that two of the three macronutrients are already starting the process of being digested before they even get to your stomach,” he says.

3. It helps unlock key nutrients in plant compounds

According to Dr. Bulsiewicz, chewing can help unlock key nutrients in certain foods, including cruciferous vegetables. “Take kale, for example. It has plant-based phytochemicals that are cancer fighting. But in order to get to them, you need to unlock a chemical reaction,” he says.

Think of it like a bomb, Dr. Bulsiewicz explains. “Kale has these two chemicals separated into two compartments. When we chew kale, you basically break the compartments and they mix and unlock a chemical reaction that releases things like sulforaphane, [an anti-inflammatory compound],” he explains. “I wrote a big section on this amazing cancer-fighting phytochemical that’s found in cruciferous vegetables that you only get by chewing the food in my first book, Fiber Fueled,” Dr. Bulsiewicz notes.

Why eating rate may be more important than the number of times you chew

Through research, Dr. Bulsiewicz uncovered that setting a designated “magic number” for the quantity of times you should chew food doesn’t really make much sense. In fact, he says eating rate is rooted in science, whereas chewing food 32 times for optimal gut health is, well, not so much. “So, is there a specific number of bites that we need to do? Not really, because the issue is food varies. Do you need to do 30 bites on each sip of a smoothie,” Dr. Bulsiewicz asks rhetorically. “It’s better for us to chew adequately until the food is soft and easy to swallow,” he says, rather than fixating on a particular number of chews per mouthful.

In turn, Dr. Bulsiewicz highlights the importance of being mindful of your eating rate. “If people slow down how fast they eat, it affects them metabolically,” he says. “We did an analysis of our research from Predict 1 at Zoe and found a correlation between fast, slow, or average-rate eaters and their weight, visceral fat mass, and how much energy they consumed on a daily basis. Slow eaters that take their time chewing weighed on average 15 pounds less than a person who’s a fast eater,” Dr. Bulsiewicz explains. The analysis also showed that slow eaters also consumed less energy on a daily basis and had a more balanced blood sugar response after eating the exact same meal as a faster eater.

How mindful eating plays a role in digestion

Dr. Bulsiewicz encourages folks to practice mindful eating, a key technique intuitive eating registered dietitians rely on for building better relationships with food. “The main takeaway I want to share is the importance of bringing presence and consciousness to the meal,” he says. “It’s less about the mechanics and more about [the idea that] food is meant to be enjoyed,” Dr. Bulsiewicz says. His key words of advice: be present, be engaged, and eliminate devices during mealtime.

—reviewed by Jennifer Gilbert, MD, MPH