Citrus Fruit And Oral Health

Introduction

Citrus fruits including oranges, lemons, grapefruits, pomelos, and limes are produced by plants in the rue family, Rutaceae. These plants are native to South Asia, East Asia, Southeast Asia, Melanesia, and Australia since ancient times. Various citrus species have been used and domesticated by indigenous cultures in these areas.

Citrus fruits are known for their unique aroma and juice containing a high quantity of citric and other organic acids, that gives them their characteristic sour, sharp flavour. The fragrance and flavour are attributed to the flavonoids and limonoids present in the rind of the fruit. Citrus fruits are excellent sources of vitamin C.

In addition, citrus fruit contains various health-beneficial components such as carotenoids and polyphenols, including flavonoids and anthocyanins. Additionally, citrus fruits contain biologically active compounds such as mono and triterpenoids, coumarins, alkaloids, phytosterols, pectin, and polymethoxy flavones. 

These compounds can prevent several acute and chronic diseases, through their synergistic (combined power working together) or cumulative effects with regular consumption. There is evidence showing that citrus consumption reduces the risk of cardiovascular disease, obesity and can promote weight loss and prevent infection.^1,2

Oral health or the health of our mouth is more important than many of us may realise. Untreated dental cavities are the most common health condition worldwide.³ A healthy mouth and well-functioning teeth are essential at all stages of life, since they support breathing, speaking, and eating. 

A healthy mouth includes not only the teeth but the gingival tissue (or gums) and the supporting bone (together known as periodontium), tongue, and cheek tissue. In a healthy mouth, all the tissues are moist, odour-free, and pain-free. 

A diet rich in fruits and vegetables can help in the maintenance of health and the prevention of chronic diseases. Several epidemiological studies suggest that a diet containing lots of fruits and vegetables can help prevent chronic diseases such as cardiovascular disease, stroke, and different forms of cancers.⁴

Historical association of citrus fruit and health

James Lind, a naval surgeon in the 1800s used lime, oranges and lemons in a study to treat scurvy. One group of sailors with scurvy was given different food ingredients such as cider, diluted vitriol (sulfuric acid), vinegar, seawater, lime/orange, and spicy paste. 

The supplements were given with acidic food for a month, but due to a shortage of supply, oranges and lemons were given only for 6 days. The symptoms of the sailors who received the citrus improved, while the other group of sailors had ongoing symptoms of scurvy. These results provided the impetus for further study on the role of citrus in the prevention of scurvy. Since then, lime and orange juice have become a part of the daily diet for sailors and a part of the human diet.

Benefits of citrus fruits for oral health

High Vitamin C content

Vitamin C, also known as L-ascorbic acid, a substance that cannot be synthesised in the body and has to be provided through a nutritious diet. About 90% of our daily requirement comes from vegetables and fruits, especially citrus fruit, which are excellent sources of this vitamin. The NHS recommends a daily dose of Vitamin C for adults (75 mg for women and 90 mg for men.)

Scurvy, a potentially fatal disease, is caused by a severe Vitamin C deficiency. Its symptoms consist of tiredness and weakness, difficult wound healing, swollen and bleeding gums, loosening of teeth, impaired immunity, and increased risk of severe infection such as pneumonia. 

In terms of oral health, the periodontal tissues (surrounding and supporting the teeth), severe Vitamin C deficiency can lead to periodontitis, which is associated with damage to the periodontal structures of the mouth. Symptoms include pain in the gums, swelling and bleeding as a result of fragile blood vessels, which may lead to tooth loss. Evidence suggests that inadequate dietary Vitamin C intake was associated with a 1.16 times higher likelihood of developing periodontitis in adults than in those with an adequate intake.⁵

Studies have also indicated that Vitamin C exerts anti-inflammatory effects in periodontal tissues by inhibiting oxidative stress and synthesis of proinflammatory mediators, inhibits the development of bacterial infection by increasing the phagocytic capacity of neutrophils, and increases collagen synthesis and strength of the vessels, leading to better tissue regeneration.⁵

Antimicrobial properties

Tooth decay is damage to the teeth caused by bacteria that disrupts the normal molecular interactions between the tooth surface and the normal microbial biofilm of the oral cavity. If not treated early, tooth decay can result in the formation of dental caries, or cavities and subsequent dentin loss and pulp (tooth material) injury.

Streptococcus mutans and Streptococcus sanguis, comprise a group of bacteria that are common in the normal flora of the oral cavity and are primarily responsible for the causation and progression of dental caries. The bacteria produce large polysaccharides (a class of carbohydrates) such as sucrose and are responsible for the development of tooth decay. Bacteria may enter the bloodstream after an injury or damage to the mucosa, and may lead to a serious condition such as bacterial endocarditis (infection of the heart).

Different parts of Citrus fruits (leaves, stem, root, juice, peel, and flower) have a broad spectrum of biological activity including antifungal, antibacterial, antiviral, antidiabetic and anticancer. The peel of citrus fruit is a rich source of coumarins, glycosides, flavonoids (chemical compounds), and volatile oils (easily evaporated at normal temperatures). Many varieties of citrus fruit are known for their antimicrobial activity and phytochemical compounds.

Various studies have also proven that Naringin, a flavonoid present in grapefruit, has proven results of inhibiting the growth of A.actinomycetemcomitans and P.gingivalis, two major bacterial complexes recognized for the pathogenesis of periodontal problems. 

Potential risks of citrus fruit for oral health

In protecting teeth against decay and cavities, initial defence is the tooth enamel, the outermost protective layer shielding the more susceptible dentin and pulp beneath. Being the hardest substance in the body, enamel is well-equipped for this task. Unfortunately, since it lacks living cells, once lost, it cannot regenerate.

When the oral cavity is exposed to acid, the enamel is eaten away by a process called erosion, leaving it vulnerable to decay as it weakens. Because tooth enamel protects the lower layers from acid and plaque (sticky film of bacteria), protecting this is vital to oral health. 

Dental erosion, a common occurrence in tooth wear and tear, is influenced by a variety of factors, including the elements:

• Chemical
• Biological
• Behavioural

The process begins with the softening of teeth and progresses to wear due to the cumulative impact of erosion along with normal mechanical forces such as attrition (rubbing away) and abrasion. 

Major consequences of erosion include:

• Tooth hypersensitivity
• Impaired functionality
• Aesthetic concerns
• Inflammation of dental pulp

Given its increasing prevalence, particularly among young people and children, and its severity, which tends to escalate with age, researchers and clinicians find this topic compelling. Studies indicate a prevalence of around 50% in deciduous dentition and 30% in permanent dentition. Notably, erosion in deciduous dentition occurs at a rate approximately four times that of permanent dentition. 

Even within permanent dentition, individuals with prior exposure to this condition are more likely to experience its progression.⁶

Acid exposure may arise from intrinsic sources like gastric hydrochloric acid or extrinsic factors such as acidic foods and beverages containing citrus, phosphoric or other acids. Dietary habits involving frequent consumption of acidic items between meals heighten the risk of developing tooth erosion.

While soft drinks are commonly implicated in tooth erosion, individuals consuming citrus sweets face twice the odds of developing the condition compared to those consuming citrus-flavoured soft drinks. The clinical impact of daily citrus sweet consumption on tooth erosion stems not only from their acidity when diluted in saliva but also their adherence to tooth surfaces, prolonging the deleterious effects.

Balancing consumption for optimal oral health

Oral care after citrus consumption

As previously mentioned, citrus fruit and beverages boast potent citric acid. While oranges, lemons, and grapefruits can contribute to a healthy diet, it is advisable to consume them promptly, preferably a part of a meal. 

Following consumption, it is crucial to promptly rinse the teeth to prevent their deleterious effects on the oral cavity. Special care should be taken to avoid brushing after consuming citrus fruit or acidic food or beverages because of the risk of further erosion of the softened enamel.

Saliva serves as the mouth's initial defence, neutralising acid harmful to teeth, containing calcium and phosphates essential for replenishing minerals depleted by bacterial acid. Rinsing away lingering acid residue in the mouth and refraining from brushing can promote saliva production, facilitating further remineralisation of the enamel.

Furthermore, the usage of a soft-bristled toothbrush and fluoride-containing toothpaste to maintain oral hygiene can prove to be highly useful for the effective prevention of demineralisation of the teeth. 

It is also recommended to avoid sucking on citrus fruit, particularly in the context of the home remedy practice of using lemon wedges for tooth whitening.

Dietary factors for oral health

Healthy eating habits, when combined with daily tooth brushing, flossing and regular dental checkups help to maintain an excellent oral cavity that is free from problems.

Fibre-rich food 

High-fibre food functions as mouth detergents, not only physically scrubbing the teeth but also promoting saliva flow through prolonged chewing. Crunchy, watery fruit and vegetables, with their high water content, help counterbalance the sugar content. These foods also serve as a fundamental component of a healthy diet, providing a dual benefit.

Water

In the context of oral health, water is indispensable. As the primary component of saliva, it plays a crucial role in maintaining both tooth and gum health. Water serves as an essential rinsing agent for foods and sugary drinks, and when fluoridated, it actively prevents tooth decay by fortifying tooth enamel.

Dairy products

Dairy products devoid of added sugar contribute to tooth health in various ways. Cheese stimulates saliva production, and its calcium content assists in replenishing minerals leached from the teeth. Other dairy items, such as milk and yoghurt, provide essential calcium and phosphates, with enriched milk also supplying vitamin D, crucial for calcium utilisation.

Nuts and dried fruit

Various nuts offer vitamins and minerals beneficial for dental health.

• Peanuts provide calcium and vitamin D
• Almonds contribute high levels of calcium for both teeth and gums 
• Cashews stimulate saliva production and aid in teeth cleaning
•  Walnuts offer fibre, folic acid, iron, thiamine, magnesium, niacin, vitamin E, vitamin B6, potassium, and zinc

Vitamins and Minerals

Foods rich in vitamins A, C, and D, along with calcium and phosphorus, are particularly advantageous for dental health. These items, including beef, eggs, fish, potatoes, spinach, fortified cereals, tofu, leafy green vegetables, beans, whole grains, and poultry, can also form part of a comprehensive and healthy diet.

FAQs

How can I eat citrus fruit without damaging my teeth?

The warmer weather may see more opportunities to snack on fresh fruit morning, noon and night. Protect your enamel by drinking a full glass of water after eating any citrus fruit. This can reduce the acid levels in the mouth by washing it away from the teeth.

Should I brush my teeth after eating oranges?

Oranges are very acidic, and the acid they produce can soften your enamel for up to an hour. If you brush your teeth while your enamel is soft, you can damage it. So after eating an orange, wait for an hour before brushing your teeth.

Are oranges good for the gums?

Citrus fruit like oranges, lemons and grapefruit are also great for gum health. They are packed with vitamin C, which helps to reduce inflammation and prevent gum disease. However, it’s important to note that consuming too much citrus can erode the enamel on your teeth, so it’s best to consume them in moderation.

What fruit is best for teeth?

Apples and citrus fruit.

An ‘apple a day’ is also great for teeth too. Although not a substitute for brushing and flossing, eating an apple or other fibrous fruit like oranges, carrots or celery can help clean your teeth and increase salivation, which can neutralise the citric and malic acid left behind in your mouth.

What’s the worst thing for receding gums?

• Brushing too hard or too aggressively
• Dental plaque or tartar build-up
• Periodical disease
• Trauma or injury to your gum tissue
• Abnormal tooth positioning (misalignment)
• Smoking and chewing tobacco use
• Lip and tongue piercings

Summary

To conclude, while citrus fruit undoubtedly offer a wide array of nutritional benefits, their impact on oral health should be approached with mindfulness. The high citric acid content, though rich in vitamin C and other phytochemicals, poses potential risks such as enamel erosion and heightened tooth sensitivity. Striking a balance in consumption, incorporating preventive measures and steps to maintain proper oral hygiene should not be overlooked. 

Additionally, recognising alternative sources of vitamin C and maintaining a diverse diet further contributes to overall oral health. By understanding and managing the implications of citrus fruit consumption, the health benefits can be achieved without the need to compromise the well-being of the oral cavity. Regular oral care practices, coupled with informed dietary choices, foster a harmonious relationship between citrus fruit and optimal oral health.