"Functional foods," "nutraceuticals," "designer foods" and "medicinal foods" are terms that describe properties above and beyond the simple nutritive value of many items available in the daily menu. Researchers, healthcare practitioners, laypersons, and the popular media use such terms interchangeably. Foods in this category contain natural ingredients that promote health by specific metabolic actions such as modulating the inflammatory response, inhibiting the growth of pathogenic organisms, promoting healing, fortifying tissue integrity, and hindering malignant transformation. They are natural medicines.

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The purpose of this article is to review the medicinal properties inherent in food sources--such as folic acid, glutamine and green tea (green tea contains oligoproanthocyanidins)--that support the health of gingival and periodontal tissues. An emphasis will be placed on ingredients that are effective topically since this method of administering medicinal agents is uniquely applicable to the oral cavity.

Green Tea and Ginkgo biloba
Japanese green tea (Camellia sinensis) and Ginkgo biloba contains oligomeric proanthocyanidins (OPC), flavanols that, along with flavonoids, belong in a subcategory of antioxidant polyphenols with widespread therapeutic applications. Catechins are another chemical entity involved in this complex, one aggregation of which is the active form of vitamin C. Without the complete complex of chemicals, none of its constituent parts is effective. But when activated, it has a natural affinity for tissues rich in glycosaminoglycans, binds to proteins that form the vascular walls, and provides the body with a protective mechanism that supports the healthy functioning of capillaries while protecting critical intercellular structures from free radical attack.(1)

The OPCs in green tea and Ginkgo biloba are ubiquitous in nature although they are found in the parts of plants that are normally removed in preparation. It is particularly abundant in the bark of trees (especially pine bark), in the leaves and blossoms of trees and shrubs, the skin of nuts and seeds (particularly grape seeds), and the peels and skin of fruit. Hence it is present in red wine but not white wine.(2-7) One particular OPC is considered by some to be a vitamin (vitamin P--the complete form of vitamin C), since the human body does not produce it, and plants are the sole source of it.(8) Taken together, there is ample evidence for the need to supplement the diet with OPCs.

Chinese green tea polyphenols in a concentration of 0.2% used as a rinse and dentifrice completely inhibited the growth of oral Streptococcus mutans with a significant improvement in both Plaque Index and Gingival Index.(9)

Among the catechins in green tea are catechin, epicatechin, gallocatechin, epigallocatechin, epicatechin gallate (ECg), and epigallocatechin gallate (EGCg). ECg and EGCg completely inhibited collagenase activity in the gingival crevicular fluid from highly progressive adult periodontitis.(10) One of these catechins demonstrated bactericidal activity against oral anaerobic rods, a decrease in gingival pocket depth, and reduced peptidase activity when combined with mechanical scaling of dental plaque in a series of Japanese patients.(11) Antibacterial activity is a property of many types of green (and black) tea catechins and is active against a wide variety of bacteria.(12,13) Of the catechins tested, theaflavin and its mono- and digallates, catechin, epicatechin, epicatechin and their enantiomers, galloyl esters of epicatechin, epigallocatechin and gallocatechin all showed inhibition of the glucosyltransferase activity of S. mutans. Rats in one of these studies had significantly lower caries scores when their drinking water contained crude tea polyphenolic compounds.(14)

EGCg is also one of many hydrolyzable tannins that have demonstrated cytotoxic activity against human oral squamous cell carcinoma and salivary gland tumor cell lines. The macrocyclic ellagitannin oligomers (dimeric)--such as oenothein B, woodfordin C and woodfordin D--had even greater activity than the monomerics EGCg and gallic acid.(15)

After rinsing with an aqueous solution of green tea extract (5.0 mg/ml), salivary concentrations of catechins remain elevated for a full hour.(16)

Wine
Red wine contains a number of chemicals that are health promoting. The polyphenol bioflavonoids resveratrol and quercitin, also found in green vegetables and citrus fruits, have demonstrated anti-inflammatory, antiviral and antitumor properties. In a laboratory culture of human oral squamous carcinoma cells one or both of these chemicals, in concentrations equivalent to that present in red wines, were effective in inhibiting the growth and proliferation of these cells.(17)

Folate
Although the effect of folic acid supplementation (taken internally) on gingival health is not striking,(18,19) a folate mouthwash significantly improved gingivitis in a double-blind study of 60 patients after four weeks of twice daily rinsing(20) and in another month-long study of women in their third trimester of pregnancy, where folate mouthwash produced highly significant improvement in the gingival index, but oral folate performed no better than placebo.(21) Plaque index did not improve in any of the study groups.

Aloe Vera
Topical Aloe vera improves wound healing by increasing the collagen content of granulation tissue as well as its degree of crosslinking. (22,23) Aloe also has antiinflammatory activity via the same arachidonic acid/cyclooxygenase pathway affected by aspirin and the NSAIDs.(24)

Bee Propolis and Manuka Honey
Propolis, a natural substance produced by the honey bee from various plant sources, has demonstrated antibacterial, antifungal and anti-inflammatory capabilities.(25) It contains amino acids, flavonoids, terpenes and cinnamic acid derivatives. In various in vitro and rat models propolis extract showed potent dose-related antiinflammatory activity, inhibiting platelet aggregation, eicosanoid synthesis, and the release of prostaglandins, leukotrienes and histamine.(26,27) In relation to its antimicrobial activity, some cinnamic and flavonoid components of propolis were found to uncouple the energy transducing cytoplasmic membrane and to inhibit bacterial motility, perhaps accounting for its synergism with selected antibiotics.(28)

In human use, a mouth rinse of propolis in aqueous alcohol solution not only aided the repair of surgical wounds after intra-buccal sulcoplasty but also exerted a small painkilling and anti-inflammatory effect.(29)

A particular honey, manuka honey, has demonstrated superior antimicrobial properties when used in the treatment of wound healing, peptic ulcers and bacterial gastroenteritis. It is believed to be noncariogenic in spite of its high sugar content. A study comparing chewable manuka "honey leather" to sugarless chewing gum (10 minutes, three times a day, after each meal) found highly significant reductions in mean plaque scores and percentage of gingival bleeding sites with the active treatment and no significant changes in the control group. (30)

Myrrh
Dentists use topical myrrh on the gingiva for its antibacterial and anesthetic properties. Myrrh also has antibacterial and antifungal activity against standard pathogenic strains of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. In addition, by blocking the inward sodium current of excitable mammalian membranes, myrrh has local anesthetic activity.(31)

Chamomile
Chamomile oil has antimicrobial activity(32) and has been used successfully as a mouthwash to treat oral mucositis, a complication of methotrexate used for rheumatoid arthritis.(33)

Herbal Chewing Gums
Several chewing gums made with natural products have proved effective in combating plaque. Mastic (Pistacia lentiscus) chewing gum has antibacterial effects on Helicobacter pylori and has significantly reduced plaque index and gingival index when de novo plaque formation on tooth surfaces and gingival inflammation were treated over a seven-day period without mechanical oral hygiene.(34) Acacia arabica chewing gum has also produced highly significant improvements in mean gingival and plaque scores in two blind crossover trials.(35) A third study found that both funoran and eucalyptus extract-containing chewing gums significantly reduced plaque compared to a control gum.(36) Fourteen days of chewing gum containing 5 milligrams of pycnogenol, an antioxidant phytochemical shown to have antiinflammatory activity, significantly reduced gingival bleeding and prevented the significant increase in plaque accumulation experienced by a control group chewing gum without pycnogenol.(37)

Persica (Peelu) Mouthwash
An extract from the root of the Salvadora persica tree is known in Urdu as peelu and in Arabic as arak. Persica is available as breath mints, chewing gum, toothpaste and toothbrushes.(38) In a three-week study comparing Persica mouthwash with the vehicle alone as a placebo, both agents reduced gingival bleeding, but only the persica mouthwash significantly reduced the oral population of S. mutans. Neither agent produced improvement in plaque scores.(39)

A unique dental treatment has been utilized by Muslim populations for centuries. Salvadora persica not only produces an effective mouthwash, but the plant has a brush-like appendage that acts like a toothbrush to clean teeth and gums mechanically as it is chewed. It is called a miswak (chewing stick). Natural, safe and more effective than synthetic toothbrushes, miswak can reach more easily between the teeth, where a conventional plastic toothbrush often misses. Chewing miswak is both a religious and cultural practice in Islamic nations. When clinical studies compared miswak chewing to tooth brushing, the miswak resulted in significant reductions in plaque and gingival indices and also a significant reduction in oral Actinobacillus actinomycetemcomitans. In vitro observations confirm that extracts from S. persica interfere with the growth and leukotoxicity of A. actinomycetemcomitans.(40)

CoQ10 and Calcium Taken Internally
Mitochondrial succinate dehydrogenase-coenzyme Q10 reductase (CoQ10) was deficient in patients with periodontal disease.(41) All 29 patients in this study showed a deficiency of 20-63% of CoQ10-enzyme activity in gingival biopsies, while 86% of them showed deficiencies of 20-66% in corresponding blood samples. Inadequate dietary calcium is also a risk factor for periodontal disease.(42)

Summary
There are numerous natural agents, mostly present in common foods but some of exotic origin, that have proved effective in improving oral health. These agents can reduce the population of pathogenic organisms, hasten healing of gingival and periodontal disease, inhibit plaque formation, reduce caries, prevent or retard cancer formation, and generally improve oral tissue integrity. Most of the agents discussed in the article are effective topically and are available as rinses, dentifrices or direct topical applications. Testing of these agents has confirmed both their effectiveness and their safety.

© COPYRIGHT 2006 Dr. Gina L. Nick

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