Diet is defined as the food and drink usually eaten or drunk by a person or a group(Cambridge Dictionary). It is common knowledge that a change in diet affects overall health and similarly it affects oral health. Oral cavity is a mirror of one’s general health and in turn oral diseases can adversely affect general health too. One of the early evidence suggesting change in diet affects oral health was given by Weston Price.
Weston Andrew Valleau Price was a Canadian dentist known primarily for his theories on the relationship between nutrition, dental health, and physical health. In 1939, he published ‘Nutrition and Physical Degeneration’, he studied the diets and nutrition of various cultures. He concluded that aspects of a modern Western diet (particularly flour, sugar, and modern processed vegetable fats) cause nutritional deficiencies that are a cause of many dental issues and health problems. He concluded that Western methods of commercially preparing and storing foods stripped away vitamins and minerals necessary to prevent several diseases. (https://en.wikipedia.org/wiki/Weston_Price#cite_note-history-1).
In the book ’Understanding Dental Caries :1 Etiology and Mechanisms, Basics and Clinical aspects’ by Gordon Nikiforuk, they noted that it was found that carious lesions were sparse in ancient man but increased dramatically in industrialized world. Epidemiological studies in many parts of the world support the hypotheses that increase in caries are associated with dietary changes. Therefore, when we think about how a change in diet can affect oral health it should address how it affects teeth, soft tissues and hard tissues of oral cavity. The discussion should also includes foods responsible for oral disease, primarily addressing the issue of sugar and how it affects teeth. Also, how proteins, lipids, vitamins and minerals affect oral health.
Dental Caries And Diet :
Dental caries is the irreversible demineralization of the hard tissues of the teeth i.e., enamel and dentin. This occurs due to formation of organic acids by bacteria in the dental plaque through the anaerobic metabolism of dietary sugars(Moynihan P, 2004).Dental caries can be seen in both deciduous and permanent teeth and teeth immediately after eruption are most susceptible to the initiation of dental caries. Some of the causes for caries differ between deciduous and permanent teeth. The cause of nursing bottle caries in children is when there is lack of teeth cleaning after night feeds.Sugars, particularly sucrose, are the most important dietary etiological cause of caries. Both the frequency of consumption and total amount of sugars is important in the etiology of caries. Foods rich in starch, without the addition of sugars, play a small role in coronal dental caries (Sheiham, 2001). The intake of extrinsic sugars beyond four times a day leads to an increase risk of dental caries.The current dose-response relationship between caries and extrinsic sugars suggests that the sugars levels above 60 g/person/day for teenagers and adults increases the rate of caries. For pre-school and young children the intakes should be proportional to those for teenagers; about 30 g/person/day for pre-school children.(Sheiham, 2001) Rugg-Gunn et al (1984),have found significant association between caries progression and dietary sugar intake in their longitudinal studies. The highest correlation was between caries increment and weight of daily intake of sugars. Weight of sugar intake appeared to be more strongly correlated to caries than frequency of intake; concentration of sugars in foods was positively related, and sugars in snacks were more strongly related to caries than total dietary sugars. Furthermore, a positive association was reported between dental caries and sugar consumption between meals (Granath, 1983). It was suggested that avoiding sugar intake between meals and reducing dietary sugar can minimize caries. Although frequency of sugar ingestion is a crucial factor in the initiation and progression of dental caries, the amount of sugar consumption influences the development of dental caries independently of frequency.( Mikx , 1975 and Gondivkar,2018)
The dieteary advice for infants should therefore include cleaning and removing milk from oral cavity after feeds, especially night feeds; weaning foods should not contain added sugar and snacking between meals should be discouraged.
Sugars :
The type of sugar consumed and type of food also plays an important role in the development of caries. Animal studies report a higher cariogenic potential of sucrose than other forms of sugars like fructose, maltose, lactose and glucose. (Mikx, 1975 and Moynihan, 2004). It is also evident that starch-rich staple foods have low cariogenic ability and individuals consuming high starch and low sugar diet have fewer caries compared to those with low starch and high sugar diet (Rugg-Gunn, 1984 and Scheinin, 1976). It has been found in one study that the mixtures of starch and sucrose exhibit greater cariogenic potential than sugars alone (Firestone,1982). There are controversial reports relating to the cariogenic potential of fruits, but to a lesser extent than sucrose. These studies suggested a positive association between frequency of fruits ingestion and dental caries (Hussein, 1996 and Imfeld, 1991).
Frequency Of Intake:
Enamel demineralization occurs when plaque pH falls below 5.5. The more frequently a child eats fermentable carbohydrate containing food, the more frequently the pH falls below 5.5 and therefore can cause increased caries. Although frequency of sugar ingestion is a crucial factor in the initiation and progression of dental caries, the amount of sugar consumption influences the development of dental caries independently of frequency.(Mikx,1975).
Three major studies on controlled human populations have greatly added to our knowledge of role of diet in dental caries.
1) Hopewood study in Australia: Sullivan and Harris 1958 and Harris 1963, studied 80 children in N.S.W. Australia who were admitted to a home in early infancy, age ranges 7-14 years at the end of 10 years. These children were given a natural diet which excluded refined carbohydrates - foods like wholemeal bread, wholemeal porridge, biscuits, wheat germ, fresh and dried fruits, vegetables along with butter, cheese, eggs and milk. They showed that the 13 year old children of Hopewood house showed a mean DMF per child of 1.6; the corresponding figure for general child population of state of N.S.W. was 10.7. Only 0.4% of 13 year old state school children were free from dental caries whereas 53%of Hopewood children experienced no caries. Thus caries incidence was less due to nature of diet and non-availability of sugar containing foods between meals.
2) Vipeholm study Sweden: Gustafsen et al (1954), Davies (1955) studied inmates of an institution for mentally challenged in Sweden. They studied consumption of sugar between meals and with meals, sticky and nonsticky form of sugar, and influence of increase or decrease in carbohydrate affecting decay.
They concluded that:
1. The risk of sugar increasing caries activity is great if sugar is consumed in a form with strong tendency to be retained on the surfaces of the teeth
2. The risk of sugar increasing caries activity is greatest if sugar is consumed between meals and in which the tendency to be retained on the surfaces of teeth is pronounced with a transiently high concentration of sugars on these surfaces.
3. Increase in caries activity due to intake of sugar rich foodstuff consumed in a manner favouring caries disappears on withdrawal of such foodstuffs from the diet
4. Carious lesions may continue to appear despite avoidance of refined sugar , maximum restriction of natural sugars and total dietary carbohydrates
5. The risk of an increase in caries activity is intensified with an increase in duration of sugar clearance from the saliva
3) Turku study: Another large scale and important experiment on caries in human subjects was carried out in Turku Finland by Scheinin and Makinen (1975) with the aim to compare carcinogenicity of sucrose, fructose and xylitol . The basis of this experiment being that xylitol is a sweet substance not metabolized by plaque microorganisms. The results showed after 1 year sucrose and fructose had equal carcinogenicity whereas xylitol produced almost no caries. By the second year caries increased in sucrose group but remained unchanged in fructose group.However in their 2 year results based on advanced cavities disregarding white spots the DMFS increment for sucrose and fructose was 3.33 and 3.57 respectively implying similar carcinogenicity while for xylitol it was 1.47. (Scheinin, 1979)
Dental Erosion And Diet:
Dental erosion is the progressive irreversible loss of dental hard tissue that is chemically etched away from the tooth surface by extrinsic and/or intrinsic acids and/or chelation by a process that does not involve bacteria.(Moynihan, 2004)The extrinsic acids are from the diet, e.g. citric acid, phosphoric acid, ascorbic acid, malic acid, tartaric acid and carbonic acids found in fruits and fruit juices, soft drinks—both carbonated and still, some herbal teas, dry wines and vinegar-containing foods. The critical pH of enamel is 5.5 and therefore any drink or food with a lower pH may cause erosion. Erosion reduces the size of the teeth and in severe cases leads to total tooth destruction(Moynihan, 2004) (Meurman, 1996)
Lipids And Proteins:
Lipids / fats consumed post-eruptive in diets of animals, has been correlated with caries reduction. The mechanism of action of fats in reducing caries may be due to a combination of several factors. The enamel surface may be protected from demineralization by formation of fatty films but this is unlikely in approximal surfaces. Another factor may be that contact between carbohydrate foods and bacteria is reduced in presence of fats. (Gordon Nikiforuk)
Protein and calorie deficiency and dental caries(Shaw 1970) (Navia 1979) showed protein deficiency in rats during dental development induced by underfeeding mothers in pregnancy and lactation led to smaller teeth , a delay in eruption and greater susceptibility to caries; they also found protein deficiency in suckling rat pups produced severe retardation in development and eruption of teeth. Total salivary volume and salivary protein levels were also reduced.
Oral Soft and Hard Tissue Health And Diet :
Nutritional status affects the teeth during pre-eruptive phases, the effects of dietary habits on development of dental caries is critically important in post-eruptive phases. Enamel hypoplasia is related to the nutritional deficiencies of vitamin A, vitamin D and protein energy malnutrition (PEM). In addition, PEM and vitamin A deficiency may cause atrophy of the salivary glands reducing salivary flow and buffering capacity thus decreasing the cleansing action of saliva and ability to buffer plaque acids. Moderate nutritional deficiencies of protein, vitamins, zinc and iron can limit the protective abilities saliva (Navia JM, 1996) and in combination with increased daily frequency and amount of sugar ingestion definitely lead to increased caries development and progression.(Gondivkar, 2018)
Antioxidant nutrients, for example, ascorbic acid (vitamin C), beta-carotene and alpha-tocopherol (vitamin E) are important buffers of reactive oxygen species and are found in many fruits and therefore are important constituents to diet. Deficiencies of certain micronutrients results in diseases of the oral mucosa. Vitamin B, iron and folate deficiencies are linked to recurrent apthous stomatitis (RAS), glossitis, cheilitis and angular stomatitis. (Gondivkar, 2018)Thus, Vitamins and minerals are essential diet constituents in child’s diet.
Safe Amounts Of Sugar Intake :
It is important that countries with a low intake of free sugars do not increase intake, as the available evidence shows that when free sugars consumption is < 15-20 kg/yr (∼6-10% energy intake), dental caries is low. For countries with high consumption levels it is recommended that national health authorities and decision-makers formulate country-specific and community-specific goals for reducing the amount of free sugars aiming towards the recommended maximum of no more than 10% of energy intake.
In addition, the frequency of consumption of foods containing free sugars should be limited to a maximum of 4 times per day. It is the responsibility of national authorities to ensure implementation of feasible fluoride programmes for their country.(Moynihan, 2004).Dietary foods and drinks, such as cheese and milk, have protective potential of teeth against teeth demineralization (Gedalia,1991) (Lewinstein I, 1993). Cow’s milk contains calcium, phosphate and casein which have a caries preventive action. Additionally, foods and drinks such as chewing gums, lemons and cheeses which can stimulate the salivary flow can reduce cariogenicity. (Gondivkar, 2018)
Conclusion:
Diet and oral health are closely related. The most important aspect about diet is that it can be changed and modified to reduce caries or to improve oral health. It is practical and is implemented by us in daily Pediatric Dental practice to inculcate good eating habits among children so as to ensure that the child doesn’t have repeated cavities. Use of diet charts to highlight frequency and quantity of intake make a huge difference. Today world over there is debate on how change in eating habits, eating softer foods is leading to smaller jaws and therefore crooked teeth. Changing to a more natural, unprocessed diet can therefore be helpful in preventing crooked teeth. Thus, diet when modified especially in young children can help them have good oral health and a caries free life.
Dr. Isha Angne; MDS, PG Cert. Pediatric Dentistry(UCL Eastman Dental Institute,UK).
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