Diet and dental health Dental diseases can be painful and have a considerable impact on self-esteem and eating ability both in childhood and older age.

In this article

Dental caries Diet and dental health Milk and cheese

Tea Fluoride

A note about chocolate Top tips for teeth

Tooth decay is one of the most common diseases in the world. Despite rates of dental caries falling in the last 30 years, it affects almost half of children and adolescents and more than 55 per cent of adults in the UK. Dental caries is a disease caused by acids - fermented sugars and starches - breaking down the tooth. It can be very painful and unsightly, and may lead to tooth loss if not managed. Thankfully it's preventable and manageable if detected early.

The white visible section of the teeth is called the tooth enamel. It's made up of minerals, especially calcium and phosphate. It's constantly being dissolved (demineralised) and reformed (remineralised) depending on its environment. The bacteria in our mouths produce acids when they break down carbohydrates. In the presence of these acids, some of the calcium within the enamel dissolves and is lost from the tooth surface. This process is known as demineralisation.

At this stage, surface damage to the tooth can be repaired. Saliva is one of the mouth's natural defences against this process and protects against dental caries in several ways:

• It helps to remove food from the teeth
• It contains bicarbonate that helps neutralise the acid production
• It delivers minerals such as calcium, phosphate and fluoride to the surface of the tooth, enabling remineralisation to take place.

Tooth decay occurs when there's more demineralisation than remineralisation.

The teeth of children under six years old, and the elderly are particularly vulnerable to demineralisation. In children the tooth enamel is still being developed and is relatively soft and in the elderly, the tooth enamel is worn.

Dental erosion is the irreversible loss of tooth enamel and the dentine layer below which are dissolved away by acid in the diet or other outside factors (eg gastric acid from vomiting). In severe cases erosion can lead to total destruction of the tooth. Sugary or carbonated soft drinks, sweetened yoghurts, pickles and acidic fruits and fruit juices all put the enamel at risk. Erosion can also be a sign of someone with an eating disorder including self-induced vomiting.

Diet plays a significant role in both dental caries (cavities or tooth decay) and dental erosion. Good nutrition prevents many dental problems and is important from the outset. From good nutrition during pregnancy to breastfeeding in infancy, a balanced diet throughout childhood and adulthood is as good for the teeth as it is for general health.

The modern UK diet contains a mix of sugars and other carbohydrates that can be fermented in the mouth by oral bacteria to produce acid. Research has shown that people in countries that eat more sugar have significantly higher levels of caries. Studies also show that when people ate less sugar, for example during World War II, there was also a reduction in dental caries.

Both total sugar intake and the frequency with which it's eaten are factors. Small amounts of sugar consumed frequently over a period of time will cause more damage than the same quantity consumed on a single occasion. Constant sugar nibbling encourages continuous demineralisation and the saliva doesn't have time to neutralise the acids. Sticky or chewy foods that remain in the mouth longer also cause more damage as the bacteria have more time to produce the acid.

Cows' milk contains the sugar lactose - the least cariogenic (decay-causing) sugar. Milk on its own doesn't promote caries and this has been attributed to the presence of protective factors: calcium, phosphate, and the milk protein casein.

Cheese protects against dental caries, partly because eating cheese causes more saliva to flow and neutralise acids, and partly because the cheese increases calcium concentration in the plaque stopping demineralisation. The fat in cheese also reduces the amount of bacteria on the surface of the teeth. So a small lump of cheese eaten after a meal or a sugary/acidic drink will help protect tooth enamel.

There has been some research that shows that tea may fight tooth decay. Tea contains polyphenols, which suppress the growth of bacteria in teeth. However, tea also contains fluoride so it's unclear whether the protective effect is due to the fluoride or the polyphenols, or both and whether it's the milk added to tea that adds to the protective effect.