Can Your Bite Affect Your Digestion? The Surprising Connection Between Teeth, Diet, and Gut Health

By Dr. Bella Shen Garnett, Board-Certified Orthodontist | San Francisco

Most people think orthodontic treatment is about straightening teeth and creating a beautiful smile. But what if the way your teeth fit together could also influence how you eat, digest food, and maintain a healthy gut?

Your mouth is the beginning of your digestive system. Every time you eat, your teeth break food into smaller pieces, saliva begins breaking down starches, and your stomach and intestines continue the process.

But when your upper and lower teeth don't meet properly—as with an underbite, open bite, or crossbite—chewing can become less efficient.

And here's where it gets interesting: your bite may influence not only how well you chew, but also the foods you choose to eat. Those choices can affect your teeth, your gut bacteria, and your overall health.

1. Your Bite Can Affect How Well You Chew

Imagine trying to cut food with scissors whose blades don't meet. That's similar to what happens when your teeth don't fit together properly.

With an open bite, the front teeth don't touch, making it difficult to bite into foods such as apples or sandwiches. With a severe underbite or crossbite, the back teeth may not meet efficiently enough to grind food thoroughly.

A 2024 systematic review examining 29 studies found that more severe bite problems were generally associated with poorer chewing function, including reduced biting force and difficulty eating.

Some patients adapt without even realizing it. They may avoid tougher foods, cut everything into small pieces, or favor softer foods that require less chewing.

The important question is whether these changes affect what—and how—we eat.

Read the systematic review

2. Chewing Is the First Step in Digestion

Chewing does much more than make food small enough to swallow.

It breaks food into smaller particles, mixes it with saliva, and increases the surface area available to digestive enzymes.

Research shows that particle size can influence how efficiently food is digested.

In a 2020 laboratory study published in Food & Function, researchers compared pasta particles approximately 2 millimeters and 5 millimeters in size.

The smaller particles underwent substantially more starch digestion—at least twice as much under the experimental conditions.

Other research involving rice and plant-based foods has also demonstrated that chewing and food structure can influence how nutrients become available during digestion.

This doesn't mean that someone with a poor bite necessarily has digestive problems. Our digestive systems are remarkably adaptable.

But it demonstrates why chewing is an important part of the digestive process.

Read the pasta digestion study

3. Can a Poor Bite Affect Your Stomach?

Researchers have begun investigating whether poor chewing is associated with changes in stomach function.

A 2013 study published in the Journal of Oral Rehabilitation compared 11 women with malocclusion against 11 women with normal bites.

The women with malocclusion demonstrated poorer chewing performance and significantly slower gastric emptying.

Gastric emptying refers to how quickly food or liquid moves from the stomach into the small intestine.

The results were intriguing, but the study was small and cannot prove that the bite problem caused the slower emptying.

We need larger studies to determine whether correcting a bite can meaningfully improve digestion.

Read the gastric emptying study

4. The Foods You Eat Affect Both Your Teeth and Your Gut

One of the most interesting connections between oral health and overall health is diet.

Think about the difference between biting into a crisp apple and eating a sticky, sugary snack.

Crunchy fruits and vegetables require more chewing and stimulate saliva production. Saliva helps wash away loose food particles, neutralize acids, and protect tooth enamel.

Foods such as apples, carrots, and celery may help clear some food debris while chewing, but they do not remove dental plaque reliably or replace brushing and flossing.

By contrast, frequent consumption of sugary snacks and refined carbohydrates can create a different environment in the mouth.

Bacteria in dental plaque use fermentable carbohydrates to produce acids. Repeated acid exposure can weaken enamel and eventually cause cavities.

Sticky foods may remain around teeth longer, while frequent snacking gives saliva less time to help restore a healthier oral environment.

Importantly, it's not simply whether a food is processed or natural that determines cavity risk. The amount and frequency of sugar exposure, the food's texture, and how long carbohydrates remain around the teeth all matter.

What does this have to do with your gut?

Many foods that support oral health can also support digestive health.

Vegetables, fruits, legumes, nuts, and whole grains provide fiber and other nutrients that help nourish beneficial gut bacteria.

Highly processed dietary patterns that are low in fiber and high in added sugars are often associated with less favorable metabolic and gut-health outcomes.

So the foods you choose can influence two different microbial environments: the bacteria living in your mouth and the bacteria living in your intestines.

A diet that supports healthy teeth can also support a healthy gut.

5. What Is Your Gut Microbiome, and Why Does It Matter?

Your gut contains trillions of microorganisms, including bacteria, that make up your gut microbiome.

Think of it as an entire ecosystem living inside your digestive tract.

These microorganisms help break down certain carbohydrates and fibers that your body cannot digest on its own.

Some produce beneficial substances called short-chain fatty acids, including butyrate, which provides energy to the cells lining your colon and helps maintain the intestinal barrier.

Your microbiome also interacts with your immune system and influences several aspects of metabolism.

How does chewing influence your microbiome?

When you chew food, you change its particle size and physical structure.

Those changes can influence how much of certain nutrients is digested and absorbed in the small intestine and how much reaches the colon, where bacteria can ferment it.

Interestingly, more complete digestion is not always better for the microbiome. Some fibers and resistant starches are beneficial precisely because they reach the colon without being digested first.

This is why eating a variety of fiber-rich foods is so important.

Scientists are still studying whether chewing differences produce meaningful changes in the human gut microbiome.

Could a poor bite affect your food choices?

Consider someone who has difficulty biting into raw vegetables, chewing nuts, or eating certain fibrous foods.

That person might begin avoiding those foods and choosing softer, easier-to-chew alternatives.

If those choices reduce dietary variety or fiber intake, they could indirectly influence gut health.

This is a plausible connection, not a proven consequence of malocclusion.

The relationship between bite function, food choices, and the microbiome is an exciting area for future research.

6. Your Mouth and Gut Are More Connected Than You Think

Your mouth has its own microbiome, containing hundreds of different microbial species.

Most are harmless or beneficial when the oral environment is healthy.

But when plaque accumulates and gum disease develops, the balance of oral microorganisms can change.

Scientists are studying how bacteria from the mouth can travel through the digestive tract and interact with intestinal microorganisms.

A 2024 review in Nature Reviews Microbiology examined the oral–gut microbiome axis and its potential role in health and disease.

The findings suggest that oral and intestinal microbial communities can influence one another under certain conditions.

However, this does not mean that crooked teeth cause an unhealthy gut microbiome or that braces can restore it.

What the research does reinforce is that maintaining good oral hygiene, healthy gums, and a nutritious diet matters beyond the appearance of your smile.

Read the oral–gut microbiome review

7. Can Orthodontic Treatment Improve Chewing and Food Choices?

For patients with significant bite discrepancies, orthodontic treatment can improve how the upper and lower teeth fit together.

Correcting an open bite, underbite, or crossbite may make it easier to bite into and chew a wider variety of foods.

A 2024 systematic review and meta-analysis examined chewing performance and oral-health-related quality of life before and after orthodontic treatment.

The research supports the importance of evaluating chewing function during orthodontic treatment, although the degree of improvement varies among patients.

Improved chewing ability may make it more comfortable to enjoy foods such as vegetables, fruits, and other nutritious options.

But we cannot yet conclude that orthodontic treatment improves diet quality, prevents gastrointestinal symptoms, or changes the gut microbiome in a beneficial way.

Those questions require more research.

Read the orthodontic treatment review

8. A Healthy Bite Matters Beyond Digestion

A functional bite also plays an important role in long-term dental health.

Significant bite problems can contribute to excessive tooth wear, traumatic tooth contacts, and difficulty chewing.

Protruding upper front teeth are more vulnerable to injury, especially in children.

Crowded and overlapping teeth can also create areas that are difficult to clean, potentially increasing plaque accumulation.

Healthy gums are particularly important. Periodontal disease has been associated with cardiovascular disease and other systemic conditions, although these associations do not prove that gum disease directly causes those conditions.

Orthodontic treatment is not a treatment for heart disease or digestive disorders.

But improving tooth alignment, bite function, and the ability to maintain good oral hygiene can be valuable parts of long-term dental care.

9. Why I Look Beyond Straight Teeth

When I evaluate a patient, I don't simply look at whether their teeth are crooked.

I examine how the upper and lower teeth fit together, how many teeth make contact, and whether the bite allows for comfortable, efficient chewing.

Some patients have relatively straight-looking teeth but significant bite problems. Others have noticeable crowding yet function quite well.

That's why orthodontic treatment should always be individualized.

My goal is to create a smile that looks beautiful, functions properly, and is easier to maintain throughout life.

The Bottom Line: Your Smile, Your Diet, and Your Health

Your mouth is the beginning of your digestive system, and your teeth play an important role in how you process food.

Research shows that significant bite problems can affect chewing efficiency, while food particle size and dietary choices influence digestion.

A fiber-rich, varied diet supports both oral and gut health. And for patients with significant bite problems, orthodontic treatment may make chewing a wider variety of foods easier.

Scientists are still investigating whether improving bite function directly influences digestion or the gut microbiome.

A beautiful smile is important. But a healthy, functional bite that helps you comfortably enjoy nutritious foods is an equally important goal.

Dr. Bella Shen Garnett is a Harvard-trained, board-certified orthodontist and Invisalign Sapphire provider. She practices at Bella Smile in San Francisco, specializing in braces, Invisalign, and complex bite correction.

Scientific References

1. El Osta N, et al. (2024). Does malocclusion affect ingestion: a systematic review. Clinical Oral Investigations. PubMed
2. Cañas S, et al. (2020). Effect of cooking, 24 h cold storage, microwave reheating, and particle size on in vitro starch digestibility of dry and fresh pasta. Food & Function. Journal article
3. Koike S, et al. (2013). Gastric emptying rate in subjects with malocclusion examined by 13C breath test. Journal of Oral Rehabilitation. PubMed
4. Sabzevari B, et al. (2024). Masticatory performance and oral health related to quality of life before and after orthodontic treatment: a systematic review and meta-analysis. PubMed
5. Kunath BJ, et al. (2024). The oral–gut microbiome axis in health and disease. Nature Reviews Microbiology. PubMed
6. American Dental Association. Caries Risk Assessment and Management. ADA