If left unchecked, harmful bacteria growing in your mouth can cause gum disease, tooth decay, and bad breath.
These bacteria can also travel, affecting other aspects of your health.
Oral health is the health of your teeth, gums, and everything else in your mouth.
Many scientists suspect that there are links between oral health problems and other issues, like forms of heart disease, pregnancy complications, and pneumonia.
You can support your oral health by brushing your teeth and flossing regularly, avoiding smoking, and cutting down on foods and drinks that are high in sugar.
Conditions linked to oral health
The collection of bacteria and other microbes in your mouth is called your oral microbiome.
When your oral microbiome has too many harmful bacteria, the imbalance is called dysbiosis.
Though the research is in its early stages, there’s some evidence that dysbiosis and other oral health problems may contribute to a range of health conditions.
These health issues include:
Pregnancy complications: Research has associated harmful bacteria linked with gum disease and the risks of premature birth and preeclampsia. This condition can lead to dangerously high blood pressure during pregnancy.
Cardiovascular diseases: Studies point to links between oral dysbiosis and various forms of heart disease. One reason could be that harmful oral bacteria get into the bloodstream, leading to infection, increased inflammation, and blood clotting.
Pneumonia: Research suggests that people with tooth decay may have an increased risk of pneumonia, regardless of age and health status. One reason could be that harmful oral bacteria travel into our lungs.
Rheumatoid arthritis: People with gum disease may be more likely to have this condition. Research has shown that people with severe rheumatoid arthritis tend to have more signs of harmful oral bacteria in their bloodstreams. This could play a role in triggering the disease.
Diabetes: Diabetes and some diabetes medications can reduce how much saliva you produce. Saliva helps wash away bits of food that harmful bacteria could grow on. It also contains minerals that help fight tooth decay. People with diabetes have high levels of sugar in their saliva, too, which bacteria can feed on.
Parkinson’s disease: Some research suggests that people with Parkinson’s disease may experience more bleeding with gum disease, even when they clean their teeth regularly.
Obesity: Some studies have found links between specific oral bacteria and weight gain. Others have shown that people with obesity have more harmful bacteria in their oral microbiomes. But it’s too soon to say exactly how the two conditions influence each other.
Cancers: Research associates poor oral health with a higher risk of a form of throat cancer. Studies have also noted that tooth loss and mouth sores from dentures are both associated with an increased risk of stomach cancer.
Prof. Felice Jacka briefly discussed research into a link between dementia and the oral microbiome on the ZOE Science & Nutrition podcast.
If you’re interested in the latest research on diet and nutrition, including new insights from ZOE’s own scientists, you might enjoy our newsletter. You can sign up using the form below.
Join our mailing list
Sign up for fresh insights into our scientific discoveries and the latest nutrition updates. No spam, just science.
Causes of oral disease
The main causes of oral health diseases are:
Eating too much sugar: The bacteria in your mouth convert free sugars into acid. “Free sugars” are added sugars in foods and drinks plus the sugar already in honey, syrup, fruit juices, and purees. Over time, this acid eats into your teeth, leading to cavities.
Poor nutrition: A balanced diet, with enough protein and a variety of vegetables, provides minerals and vitamins for strong tooth enamel and healthy gums and saliva. Restrictive diets, or those high in ultra-processed foods, could stop you from getting the nutrients you need.
Poor dental hygiene: If we don’t regularly brush our teeth, plaque containing harmful bacteria forms and hardens, becoming difficult to remove. These bacteria can cause cavities, infections, and eventually tooth loss, as well as gum disease.
Smoking: Smoking tobacco is second only to poor hygiene when it comes to risk factors for gum disease. It’s also a leading cause of mouth cancers, as well as bad breath.
Drinking alcohol: Regularly drinking alcohol could change your oral microbiome, increasing levels of potentially harmful bacteria and reducing levels of “good” bacteria. Alcohol may reduce the amount and quality of your saliva, too. Plus, it’s linked with oral cancers.
Symptoms of oral disease
The symptoms of poor oral health vary, depending on the condition. However, see a dentist if you’re regularly experiencing:
bleeding or swollen gums
toothache or other mouth pain
loose or wobbly teeth
How to improve oral health and prevent disease
Good oral hygiene is essential, and here are some tips:
Brush your teeth 2–3 times a day. Evening brushing is very important.
Floss once a day, preferably before bed.
Cut back on acidic foods and drinks, like fruit juice and fizzy drinks.
Avoiding smoking is also crucial for your oral and overall health.
Nutrition and oral health
What you eat and drink is just as important as your hygiene for maintaining good oral health.
One of the biggest causes of tooth decay and gum disease are “free sugars.” These are sugars that manufacturers add, plus the sugars already in things like fruit juice, honey, and syrups.
Cutting down on sugar is good for your oral and overall health. But it’s not always easy to spot sources of sugar.
In our article on added sugars, we’ve listed different names sugar can have on labels and surprising products that contain sugar.
You can also cut down on free sugar by reducing your portion sizes or making swaps. So, you might:
Choose a smaller slice of cake for a treat and add some yogurt and fruit.
Swap a sugary soda for water, tea, or milk.
Swap out candy for fruit or nuts.
It helps to pair foods that contain sugar with foods containing fiber, protein, or healthy fats. This reduces your sugar intake — and it can slow the rate that your body absorbs sugar.
Above, we discussed foods to avoid. But what you do eat is also important for your oral health.
Getting enough calcium and phosphorus will help maintain the enamel that protects your teeth.
Foods rich in calcium include:
dairy products, such as milk and yogurt
leafy greens, such as spinach and collard greens
nuts, such as almonds
You can get phosphorus from protein-rich foods, like:
fish, such as salmon
nuts and seeds
cooked legumes, such as chickpeas and lentils
Also, many fruits and vegetables contain vitamin C, which helps keep your gums healthy. They often have vitamin A, too, another nutrient that helps build tooth enamel.
Meanwhile, the fiber and water in plant foods keep the sugar in these foods from being too concentrated. They also stimulate saliva production, which helps wash away acids and bits of food from your teeth.
Cutting down on free sugar can help you keep your teeth, gums, and mouth healthy.
Many vitamins and nutrients are good for your oral health. These include calcium, phosphorus, vitamin C, and vitamin A. Fiber can also play a role.
Without good oral hygiene, harmful bacteria can build up in your mouth.
This can lead to gum disease and tooth decay. Plus, it may contribute to health problems elsewhere in your body.
Scientists don’t fully understand the relationships yet — but evidence suggests links between oral health and several conditions, including pregnancy complications, pneumonia, and Alzheimer’s disease.
Likewise, some health issues, such as diabetes, could have negative effects on our oral health.
Symptoms of oral disease include swollen or bleeding gums, bad breath, toothaches, and wobbly teeth.
Regularly brushing and flossing, avoiding smoking, cutting down on sugar, and including more plants in your diet can help keep your teeth, gums, and mouth healthy.
Association between oral health and incidence of pneumonia: A population-based cohort study from Korea. Scientific Reports. (2020). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7293333/
Association between poor oral health and gastric cancer: A prospective cohort study. International Journal of Cancer. (2018). https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.31614
Diabetes, gum disease, & other dental problems. (2022). https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/gum-disease-dental-problems
Dose-response meta-analysis on tooth loss with the risk of cognitive impairment and dementia. Journal of the American Medical Directors Association. (2021). https://www.sciencedirect.com/science/article/abs/pii/S1525861021004734?via%3Dihub
Drinking alcohol is associated with variation in the human oral microbiome in a large study of American adults. Microbiome. (2018). https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-018-0448-x
Epidemiology of esophageal cancer. World Journal of Gastroenterology. (2013). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3769895/
Mouthrinse (mouthwash). (2021). https://www.ada.org/en/resources/research/science-and-research-institute/oral-health-topics/mouthrinse-mouthwash
Oral health. (2023). https://www.who.int/news-room/fact-sheets/detail/oral-health
Oral microbiota in human systematic diseases. International Journal of Oral Science. (2022). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8891310/
Parkinson’s disease is positively associated with periodontal inflammation. Journal of Periodontology. (2023). https://pubmed.ncbi.nlm.nih.gov/37433175/
Periodontal health, cognitive decline, and dementia: A systematic review and meta-analysis of longitudinal studies. Journal of the American Geriatrics Society. (2022). https://agsjournals.onlinelibrary.wiley.com/doi/10.1111/jgs.17978
Phosphorus. (2023). https://www.hsph.harvard.edu/nutritionsource/phosphorus/
Progress in oral microbiome related to oral and systemic diseases: An update. Diagnostics. (2021). https://www.mdpi.com/2075-4418/11/7/1283
Smoking & tobacco use: Health effects. (2020). https://www.cdc.gov/tobacco/basic_information/health_effects/index.htm
The oral microbiome in the pathophysiology of cardiovascular disease. Nature News Cardiology. (2023). https://www.nature.com/articles/s41569-022-00825-3
Xerostomia (dry mouth). (2023). https://www.ada.org/en/resources/research/science-and-research-institute/oral-health-topics/xerostomia