The value of dairy

Dairy products have a bio-active role in oral health and prevention of dental caries. Consuming milk and other dairy products on a daily basis provide calcium and other nutrients to the diet which have protective functions against the formation of dental caries in children and adults.

Dental caries or tooth decay is a major public health concern. Dental caries is a disease that is the result of cavities in the tooth enamel. Infections that lead to tooth decay are caused by plaque, a biofilm over tooth enamel consisting of a viable (capable of developing under favourable conditions) and non-viable bacteria. Extrinsic sugars (added to food) are more readily available for metabolism by oral bacteria and therefore potentially more cariogenic (tend to produce dental caries) than intrinsic sugars (integrated into cellular structure of food). Good nutrition and eating habits play a key role in preventing dental caries.

Acid foods and beverages with refined sugars contain fermentable carbohydrates, which reduce the pH of plaque that directly causes teeth to demineralise. Tooth enamel begins to dissolve when pH of plaque is reduced to less than 5.5. Acids dissolve the tooth-strengthening minerals i.e. calcium and phosphate on the tooth surface. These minerals are found in dairy. Calcium and phosphate assist with the repair process of teeth after acid attacks, as they remineralise tooth enamel surfaces.   

Protein foods such as eggs, fish, meat and many vegetables do not cause a lowering in salivary pH to 5.5 or less as with fermentable carbohydrates. Other unrefined carbohydrate-containing foods such as rice, potatoes and fresh fruit have a low potential to cause dental caries due to their intrinsic sugar content.

The casein proteins in milk, in which the bio-active peptides occur, are of fundamental importance for growth, development and repair of damaged body tissue. Casein provides a protective film over the enamel surface on teeth. The phosphopeptides in milk inhibit acid disintegration of enamel.

Saliva is the body’s natural defense against dental caries. Milk and milk-based drinks may be a good saliva substitute for those who have decreased salivary flow, especially for older people with difficulty in chewing, tasting and swallowing food. Milk-based drinks provide moisture and lubrication for dehydrated oral tissue, buffering oral acidity, reducing enamel solubility and contributing to enamel remineralistion.  

The role of milk

• Within its food matrix, milk nutrients, such as calcium, phosphorus, magnesium and vitamin D support the development of teeth and oral tissue. These nutrients may help protect against dental caries from a young age.
• Milk is non-cariogenic. This means that it contributes favourably to dental health by re-mineralising teeth and discouraging the acid that causes dental caries.
• Milk is a neutral liquid. It clears the mouth faster and is less likely than sugars or snack foods such as potato chips and cookies to cause tooth decay.
• Removal of casein (major type of protein found in milk), fat or lactose from milk does not affect the protective capacity on demineralization (such as low-fat milk or lactose-reduced milk).

Recommendations

Tooth decay remains a critical health problem. Dairy products such as milk, cheese and yoghurt contain special anti-decay nutrients such as casein, calcium and phosphorus. To maintain good oral health, keep the following in mind:

• Choose tooth-friendly foods and drinks such as milk, flavoured milk, cheese and fruits
• Avoid frequent consumption of acidic foods and drinks, limiting them to mealtimes
• Dairy products such as milk, yoghurt and especially cheese, have a low potential to cause dental caries and could be included on a daily basis. The recommended 3-A-DAY™ servings of dairy products are advised
• A good habit to follow after eating sugary food is to rinse one’s mouth with milk or water if it is not possible to brush.

References

AIMUTID WR. 2004. J Nutr. 134: 9895-9955.
http://www.nationaldairycouncil.org.
Scandinavian Journal of Nutrition. 2000. 46(3): 119-122.
Mahan LK & Escott-Stump S. 2000. Food nutrition and diet therapy. 10th ed. WB Saunders Company.
BMJ. 2000. 320: 1717-1719.
World Review of Nutrition & Dietetics. 1989. Diet and Nutrition. Crucial factors in dental health of children.
Herod EL. 1991. Australian Dental J. 36(2): 120-125.
Rugg-Gunn AJ. 1993. Nutrition and Dental Health. Dental Caries – milk, cheese and other protective factors. Pp 239-259.
Reynolds FC. 1995. Proceedings of the Nutrition Society of Australia. Dairy products and dental health. 19: 95-102.
British Dental Journal. 2002. 193: 563-568.
http://www.dairyaustralia.com