Diet and nutrition are significant influencers of oral health, and can affect the development and progression of oral diseases and conditions such as caries, periodontal disease, erosion, and others. While nutrition can be defined as the micro- (vitamins and minerals) and macro- (carbohydrates, protein, and fat) nutrients as they relate to the body’s dietary needs, diet refers to the specific foods consumed. The relationship that diet and nutrition have with oral health is bidirectional, as compromised integrity of the oral cavity can also influence an individual’s functional ability to eat.1
There are different types of nutrition studies such as epidemiological studies, case-control studies, and clinical trials. While all study types may be used to generate useful information, they differ in terms of reliability and how to interpret the data. For instance, epidemiological studies are primarily observational, meaning that the populations compared can differ from each other by any number of uncontrolled factors. They look for associations between nutritional factors and a given outcome in large populations. It is important to remember that finding an association is not the same as demonstrating causation. In case-control studies, two groups of closely matched subjects (by age, sex, race, etc.) that differ in the presence or absence of a particular condition of interest are compared to see what factors might differ between the groups, providing potential clues about cause and prevention of that condition. However, even though a number of variables are matched, the populations compared can differ in important ways. Clinical trials generally control for more factors, using a sample size calculated to be sufficient to detect a statistically significant change in the variable of interest.2 With any study involving nutrient intake or dietary patterns, it can be challenging to follow participants for a meaningful length of time.
A variety of dietary factors are hypothesized to influence the oral cavity, including macro- and micronutrients, vitamins, pH properties, as well as the behaviors associated with their consumption. Additionally, factors such as stage of development, specific medical conditions, and socioeconomic status may indicate particular diet and nutritional considerations. Older patients, for example, may experience tooth loss, reduced masticatory ability, and decreased appetite, which may, in turn, influence their nutritional status.3 A systematic review examined the association between food intake and oral health in elderly found that tooth loss in the older population was associated with changes in food intake and nutritional deficiency.4
Dental caries is the most common disease worldwide. The term dental caries can be used to describe both the disease process and the cavitated or noncavitated lesions that form as a result of the disease process.5 The caries disease process is biofilm-mediated, sugar-driven, multifactorial, and dynamic in the phasic demineralization and remineralization of dental hard tissues.6
The relationship between caries and carbohydrates is fairly well understood; dental hard tissues are demineralized by acidic by-products produced by bacteria in biofilm (dental plaque) via fermentation of dietary carbohydrates.6 More specifically, there is a rapid fall in pH (to 5.5 or below) in tooth biofilm after carbohydrates are ingested. This lower pH can also affect the balance of microbes in the biofilm such that there is a higher proportion of acidic biofilm species, compounding tooth demineralization.7 Carbohydrate consumption is therefore an important nutritional factor in the development of caries.
For more information on dental caries, visit the ADA Oral Health Topics page on caries risk assessment and management.
Types of Carbohydrates
The relationship between carbohydrates and dental caries depends on the type of carbohydrate (sugars or starches) consumed because the cariogenic potential (i.e., promoting the development of tooth decay) of a given carbohydrate is dependent on how efficiently it can be metabolized by the bacteria that ferment it.8 Sugars, specifically, are considered to be the most important drivers of caries development. The term free sugar includes all sugars added to food/beverages, as well as the naturally occurring sugars found in fruit juices and concentrates, honey, and natural syrups. Collectively, natural and free sugars (e.g., sucrose, glucose, fructose) are considered the primary necessary factors in the development of caries.8 Sucrose, a disaccharide of glucose and fructose, is the most cariogenic sugar.8 Sucrose acts as a substrate for the synthesis of intra- and extracellular polysaccharides in dental plaque.8-10 Additionally, dental plaque formed in the presence of sucrose has been shown to have lower concentrations of calcium, inorganic phosphate, and fluoride, which are the ions required to remineralize enamel and dentin.10, 11 Sucrose and its constituent monosaccharides, glucose and fructose, are also more cariogenic than starches because they enter the glycolytic pathway more rapidly and result in a more pronounced drop in pH.12 Although lactose is also a sugar, it is less cariogenic than sucrose, fructose, and glucose because its fermentation produces a smaller drop in pH.9, 13
Amount/Frequency of Sugar Intake
In addition to the type of sugar consumed, the amount consumed may affect caries development. A 2014 systematic review examining the effect of free sugar consumption on dental caries observed a consistent association between free sugar intake and caries development; higher incidence of caries was found in populations where free sugar intake was greater than 10% of total energy intake compared to those with free sugar intake of less than 10%.14 This systematic review informs the World Health Organization (WHO) guidelines for sugar intake, which recommends that free sugars be less than 10% of total energy intake, with a further reduction to less than 5% suggested.15
Frequency, or how often free sugars are consumed, may also play a role in caries development. Increased frequency of sugar consumption and additional snacking between meals have been hypothesized to be more important in predicting caries risk than total sugar consumption.16-18 A possible rationale for this concept is that it takes approximately 30 minutes for the pH to drop after an intake of sugar, so additional sugar intake within that 30-minute period is less harmful than additional intake after 30 minutes.16 It is, however, difficult to determine the relative contribution of amount of sugar and frequency of sugar consumption to dental caries risk, given that the two are highly interrelated.16, 19
The recent systematic reviews and guidelines mentioned above14, 15, 20 present data that support the association between sugar consumption and/or snacking with caries development. Although not evidence for causality, these reviews are consistent in their findings that increased free sugar consumption is associated with an increased risk of caries.
There is ongoing research to determine strategies to decrease the consumption of sugar-sweetened beverages (SSBs), as they are a significant contributor to free sugar consumption. A tax on SSBs is one strategy that has been attempted; studies suggest that taxation of SSBs may decrease SSB consumption, caries incidence, and caries-related costs. Although public acceptance and efficacy of this strategy are still unclear, a 2019 systematic review and meta-analysis21 found that the equivalent of a 10% tax on SSBs was associated with an average decline in SSB purchase and intake of 10.0%.21-23 In addition to interventions effective at the population level, there is a need for high-quality evaluations with long-term study designs examining efficacy.24
Early childhood caries (ECC) is the presence of one or more decayed, missing, or filled tooth surface in children under 6 years of age.25 ECC was formerly referred to as “baby bottle tooth decay” and is primarily due to prolonged exposure of the enamel to sweetened liquids causing caries in small children. To address ECC, both the Academy of Nutrition and Dietetics and American Academy of Pediatrics promulgate guidance limiting fruit juice consumption by babies and toddlers.25, 26
Limited income or access to food can have a negative impact on intake of fruits and vegetables, lean meat, whole grains, and dairy. This inadequate consumption of nutrient-dense foods combined with a lower health literacy and limited access to oral health care can put low-income populations at an increased risk for caries and other oral diseases.25
Foods such as milk and dairy products, apples, cranberries, tea, and high-fiber foods have been suggested to have cariostatic properties (i.e., inhibiting the development of caries), although more careful examination is needed.27 It has been postulated that the calcium in dairy products offsets some of the cariogenic properties of lactose by limiting enamel undersaturation during acidogenesis. As mentioned above, lactose fermentation also results in a smaller reduction in pH compared with other simple sugars. Data from studies examining the association between milk consumption and caries suggests milk consumption does not increase caries risk and may actually reduce it.28
Some studies indicate that sugar alcohols such as xylitol and sorbitol used in chewing gums and as artificial sweeteners may have cariostatic effects, but overall findings are equivocal. Postulated mechanisms by which xylitol may reduce caries risk include simple substituting for fermentable carbohydrates,29 reducing the acidogenic potential,30 inhibiting the growth of Streptococcus mutans (plaque bacteria that contribute to tooth demineralization),31 or just increasing salivary flow (especially in the case of sugar-free chewing gums).32, 33 Although non-sugar sweetened gum is eligible for application to the ADA Seal of Acceptance, the ADA does not have a policy on the use of xylitol for caries prevention. The Council on Scientific Affairs expert panel report on Nonfluoride Caries-Preventive Agents concluded that evidence of xylitol’s benefit as an adjunctive therapy in children and adults who are at a high risk for developing caries is of low quality.34 For more information on chewing gum, visit the ADA Oral Health Topics page.
Vitamin D influences the regulation of calcium and phosphate metabolism.35 According to some observational studies, higher prenatal intakes of vitamin D and prenatal serum vitamin D levels may be associated with reduced caries risk in children and infants.36, 37 Historical reports38 as well as a 2016 cross-sectional study suggest an association between dental caries and lower serum levels of vitamin D in children.39
The American Academy of Periodontology defines periodontitis as “the inflammation of the periodontal tissues resulting in clinical attachment loss, alveolar bone loss, and periodontal pocketing.”40 It is caused by specific microorganisms in dental plaque and excessive host response to this bacterial challenge, resulting in progressive destruction of tooth-supporting apparatus (i.e., gingiva, periodontal ligament, and alveolar bone).41 The effect of nutrition status on the body’s immune response may modify factors affecting management of periodontal disease; however, the multifactorial nature of periodontal disease and nutritional status makes it difficult to determine such effects.25
Compared with caries, there are fewer studies exploring the relationship between nutrition and periodontal disease. Existing studies linking nutrition to periodontal disease have focused primarily on the intake of lipids and various micronutrients. However, the two systematic reviews examining the role of dietary minerals42 and lipids43 on the onset, severity/progression, and treatment of periodontal disease found insufficient evidence of any associations.
Dental erosion is clinically defined as “the progressive and irreversible loss of dental hard tissue caused by a chemical process of acid dissolution that does not involve bacteria,”44 and while acid reflux and some medications can contribute to erosive tooth wear, the most significant source of acid for tooth erosion is the diet.45 Specifically, frequency of consumption, patterns of consumption, and time in contact with acidic food or beverage influence erosive tooth wear.46 However, pH alone is not the only factor affecting how erosive a food/beverage may be. The pH and buffering capacity collectively determine how erosive a food or beverage is.47 Yogurt, for example, has a pH of about 4.0, but is not considered erosive due its high calcium content, which acts as a buffer.48
A meta-analysis conducted in 2012 found that soft drinks and chewable vitamin C tablets were both associated with the development of erosive tooth wear while juice, sports drinks, milk, and yogurt were not.49 This is somewhat at odds with a meta-analysis conducted in 2015 that found soft drinks and acidic snacks, as well as fruit juices, increased the odds for tooth erosion in children; and, in addition, found that intake of milk and yogurt was associated with a reduction in the occurrence of erosion.50
Dental erosion may also be caused by intrinsic factors such as stomach acid in those with gastroesophageal reflux disease (GERD) or individuals with who vomit frequently.51-53 Compared to erosion caused by extrinsic factors (i.e., dietary factors) which commonly affects the facial and occlusal surfaces of teeth, erosion caused by gastric acid primarily occurs on the palatal and occlusal surfaces of the anterior maxillary teeth and on the buccal and occlusal surfaces of the mandibular teeth.54
For more information on dental erosion, visit the ADA Oral Health Topics page on dental erosion.
Calcium is a mineral found in many foods, and is essential for forming and maintaining healthy bones and teeth,55 including hydroxyapatite, the primary calcium phosphate mineral in bone and enamel. Dietary calcium is absorbed from the intestine into the blood, from human or animal milk and dairy products (e.g., cheese, yogurt), or foods fortified with calcium (in accord with eCFR §104.20). The 2015-2020 Dietary Guidelines for Americans recommend 700 mg of calcium per day as the recommended dietary allowance (RDA) for children aged 1-3 years, and 1000 mg of calcium per day for children aged 4-8 years.56
In the United States, an estimated 72 percent of calcium intake occurs from consumption of dairy and products to which dairy has been added.55 Numerous varieties of plant-based milk alternatives, including products made with soy, almonds, oats, nuts, potato, flaxseed or hemp, are a growing segment of the consumer marketplace.57 Many exist in forms fortified with one or more nutrients, often including calcium.58-60 However, a technical report from national health and nutrition organizations concludes that plant milks/non-dairy beverages are not recommended from 0-12 months of age; and that unsweetened plant milks/non-dairy beverages other than soy milk are not recommended for exclusive consumption in place of dairy milk.61
Oral and Oropharyngeal Cancer
With the exception of heavy alcohol consumption, which is associated with an increased risk of developing oral cancer,62 other than generalized findings, no direct relation between diet and oral and oropharyngeal cancer risk has been identified. If consistent with what is observed with other cancers, the consumption of fruits and vegetables may be protective.1 A meta-analysis showed a lower risk of oral cancer associated with increased fruit and vegetable consumption,63 and a large prospective observational study64 found total fruit and vegetable intake was associated with a reduced head and neck cancer risk.
For more information on oral and oropharyngeal cancer, visit the ADA Oral Health Topics page on cancer of the head and neck.
There is a lack of rigorous studies examining the role of diet in the management of recurrent aphthous stomatitis (RAS), also known as canker sores. Reported dietary triggers include hard, acidic, and salty substances as well as alcoholic and carbonated beverages.65 Preliminary data suggest that zinc deficiency is more common in those with RAS than healthy individuals without them66 and that zinc-supplementation improved RAS resolution in zinc-deficient individuals.67
Xerostomia (dry mouth) and its associated effects on oral health and overall quality of life may be exacerbated by dietary factors such as dry or acidic foods, caffeine, and alcohol.68
For more information on dry mouth, visit the ADA Oral Health Topics page on xerostomia/dry mouth.
ADA Oral Health Topics
ADA MouthHealthy.org page on Nutrition
Department of Scientific Information, Evidence Synthesis & Translation Research, ADA Science & Research Institute, LLC.
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