How diet impacts the immune system
BY Diana J. Lamoreux, RDH, BS, MEd
The connection between diet and dental caries is common knowledge, while the relationship between diet and periodontal disease has not been well established. What is clear is that poor diets can deteriorate the periodontium but that inadequate nutrition does not have a causal relationship with periodontal disease. Inferior eating habits have a negative impact on immune response, host susceptibility, and periodontal disease progression.
Periodontal health cannot be achieved and sustained unless nutrient deficiencies are rectified. Therefore, diet plays a predominant modifying role in the progression of periodontal disease.
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A well-nourished host has nutrients to help ward off bacterial assault and infection, maintain tissue integrity, and repair injured tissues expeditiously. Since many vitamins and minerals play critical roles in immune cell function and production, altered oral health status can be recognized early in the course of reduced nutrient consumption. For example, even a very mild protein deficiency can impair the host inflammatory response; neutrophil function becomes compromised and allows pathogen invasion, with color, contour, and consistency changes obvious to the experienced clinician.
Hygienists can educate patients about the impact of good nutrition on the supportive structures of the teeth. Knowing which nutrients maintain oral health or resolve unhealthy areas will help us advise patients. This information will be especially valuable for patients with active periodontal disease or those at high risk for developing periodontal disease. Dietary Guidelines for Americans (health.gov/dietaryguidelines2010) offers a myriad of suggestions for a healthy diet. The website for Choose My Plate details specific food choices relative to nutrient needs. The textbook, "Diet and Nutrition in Oral Health," is another valuable resource for hygienists.
Six Categories of Nutrients
Nutrients are divided into six categories: carbohydrates, lipids, proteins, vitamins, water, and minerals. There are six major minerals-calcium, chloride, magnesium, phosphorus, potassium, and sodium, as well as numerous trace minerals such as iron and zinc. Carbohydrates, lipids, and proteins are macronutrients that provide calories and energy.
Vitamins and minerals are noncaloric and inorganic micronutrients - very small amounts are required to maintain health. Vitamin deficiencies are uncommon in healthy individuals. Calcium, zinc, iron, and magnesium are the most common mineral shortages. Minerals are interdependent because excess of one can cause an imbalance of another. (Note that carbohydrates, water, and fluoride are purposefully omitted from this article, since the importance of them is obvious to dental hygienists.)
Some nutrients are measured in gram quantities and international units (IUs); others are calculated in milligrams or micrograms. Each nutrient plays an important role and works in concert to regulate body processes and support development, maintenance, infection resistance, and repair of the body tissues. This activity is disturbed when nutrients are missing, inadequate, or excessive. Dietary intake can have a positive or negative effect on the periodontium.
Nutrition during Growth and Development
A well-informed clinician can recognize if patients have been well nourished in the past and if they have current nutritional needs. When hygienists conduct an oral exam, tissues offer a wealth of information regarding past and present diet choices and habits. Nutrient availability during gestation is imperative for normal growth and development of the periodontium. Whether crucial nutrients were available in utero can make the difference between health and disease of oral structures throughout life. However, sometimes, if nutrients were insufficient prenatally, healthy eating habits can be developed to help counteract hard- or soft-tissue deficits.
Mineralization begins during the first trimester of pregnancy. The crowns of primary teeth are complete around the age of one. Well-calcified teeth may reduce the incidence of caries. Formation of the alveolus and cementum occur at approximately 16 weeks in utero, and it has been determined that formation requires protein, calcium, phosphorus, vitamin D, vitamin K, boron, and magnesium. (Not all nutrient demands for oral structure formation during gestation have been identified.)
Hygienists can inform appropriate patients about nutrient availability and its impact on the development of the oral cavity during pregnancy. Scarcity and excess should be addressed. Not all nutrients required for fetal development have been well researched, but the website for Choose My Plate is a good resource for nutritional guidelines during pregnancy (see related sidebar.)
• Protein is critical for the construction of all body tissues. Collagen is the protein involved in the formation of dentin, cementum, the maxilla, mandible, and the periodontal ligament. Other types of protein assist with the growth and development of other periodontal tissues.
• Vitamin A (calciferol) assists in the establishment of epithelium, mucous membranes, salivary gland cells, enamel, and dentin. When vitamin A is insufficient during development, abnormal enamel, dentin, and salivary gland formation and a cleft lip or palate can result. Too much vitamin A prenatally can cause facial deformities and other birth defects.
• Vitamin D is actually a type of hormone that facilitates the absorption of calcium, magnesium, and phosphorus, ensuring proper mineralization of bone and teeth. If levels are insufficient during tooth formation, delayed eruption and enamel or dentin hypoplasia can occur. Excess vitamin D can result in dental defects such as hypoplasia and pulp stones.
• The vitamin B-complex includes thiamin, riboflavin, niacin, pyroxidine, cobalamin, folic acid, biotin, and pantothenic acid. B vitamins are cofactors and work together - a deficiency involves more than one in the complex. Requirements for some of the B vitamins are high during periods of rapid growth and development in pregnancy because these nutrients contribute to effective cell division. Deficiency can cause spina bifida. The vitamin B-complex is abundant in many foods, so prenatal inadequacy is rare.
• Vitamin C (ascorbic acid) helps with the establishment of collagen, dentin, pulp, cementum, skeletal and alveolar bones, periodontal fibers, blood vessels, gingival nerves, connective tissues, and periodontal ligaments. Low levels of vitamin C can produce irregular formation or absence of dentin.
• Calcium, magnesium, and phosphorus are the principal minerals that build skeletal bones and teeth. Strength is provided to alveolar bone via these minerals. Ameloblasts also release calcium and phosphates. Too little of these minerals prenatally can cause bone deformities, incomplete tooth calcification, tooth malformation, and increased susceptibility to caries after tooth eruption.
• Iron deficiencies lead to the most common type of anemia and are of particular concern in pregnant women. A surplus of iron is rare.
• Zinc can become depleted in malnourished pregnant women. The first response of the body to inadequate zinc is reduced growth, with resulting skeletal abnormalities. Even a borderline zinc shortage increases risk of toxemia, premature delivery, spontaneous abortion, skeletal abnormalities, and impaired fetal growth and development.
Maintenance of Healthy Periodontal Tissues
After birth, nutritional quality impacts tissue synthesis as nutrients work in tandem to maintain and repair periodontal tissues when needed. Since mucosal cells have a turnover rate of three to seven days, portions of the oral cavity, especially the sulcular epithelium, can be some of the first to develop signs of unsatisfactory nutritional status. This rapid cell turnover demands steady nourishment; epithelial cells have rapid rates of metabolism, differentiation, and maturation. The lack or abundance of certain vitamins or minerals can cause salivary gland dysfunction, sulcular epithelium deterioration, pocket formation, hyperkeratinization of mucosa, and osteoporosis of the alveolar bones and other bones in the body.
When the host is vulnerable, bacteria attack periodontal tissues. The body then sends defenders to limit destructive activity and repair any damage. A thriving host possesses nutrients to assist with bacterial onslaught. Healthy oral tissue is the best defense against microbe invasion. Certain nutrients influence the process of maintaining (and repairing) periodontal structures more than others. Some have a singular benefit; others offer multiple advantages. Their combined effort affects soft and hard periodontal tissues, host susceptibility, immune response, and wound healing. During our lifetimes, optimal oral health depends on sufficient quantities of vitamins A, B-complex, C, D, and E; proteins; calcium, phosphorus and magnesium; iron; zinc; copper and some lipids, such as omega-3 fatty acids. Thus far, the exact amount of each nutrient category for optimal repair results is unknown.
• Lipids perform an important role in overall general health (energy, obesity, diabetes, and hypertension) and have minor implications for the control of oral health status. Lipids include triglycerides, phospholipids, sterols, and lipoproteins. In animal studies, fat has been associated with the inhibition of smooth-surface caries. The prevailing theory is that fat provides a protective layer on teeth and prevents biofilm adherence. Other theories are that some fatty acids have antibacterial properties and that low levels of omega-3 fatty acids correlate with a risk for periodontitis. Clinicians should exercise caution with recommending fat intake, as excess is implicated in several chronic diseases.
• Protein is known as the nutrient of repair and maintenance. Amino acids repair tissues and form antibodies to help resist infection. Protein deficiencies can affect the synthesis of new tissue, as key amino acids are needed for maintenance (and healing). Unacceptable amounts of protein in the diet increases susceptibility to infection, slows wound healing, and causes degeneration of periodontal connective tissues. Excessive protein can reduce calcium retention and affect bone health. People with plant-based diets need to pay special attention to acquiring sufficient amounts of protein in their diets. (Vitamin C is present in large amounts in neutrophils so, when protein intake in inadequate, this also can reduce the availability of vitamin C.)
• Vitamin A in adequate amounts helps maintain immune function and the integrity of sulcular epithelium, assists with bone remodeling, and keeps the salivary glands working properly. An early sign of this vitamin lacking in the diet is a decrease in the rate of epithelial cell differentiation. Deficiencies throughout life can cause salivary gland atrophy, hyperkeratinization of some oral structures, compromised periodontal tissue healing, or carotene coloration. Too much vitamin A can result in increased catabolism of collagen and bone.
• Vitamin D in consistent amounts is needed throughout life since calcified tissues remodel. Vitamin D is critical to overall general health because it regulates the presence of calcium, magnesium, and phosphorus in blood plasma. The risk for deficiency of vitamin D increases with age, lack of sunlight, and poor eating habits. Osteomalacia, osteopenia, osteoporosis, lamina dura and cementum loss, and an increased risk of developing some cancers can result. Excessive vitamin D can cause irreversible kidney and cardiovascular tissue damage. Vitamin D and calcium levels have been linked to periodontal problems due to their role in bone homeostasis, including attachment and bone and tooth loss. However, it is possible for depleted bone to rebuild with vitamin D supplementation.
• Vitamin E is a group of 10 lipid-soluble compounds that include tocopherols and tocotrienols. Vitamin E acts as an antioxidant and protects red blood cells. Inadequate vitamin E is uncommon but can manifest as hemolytic anemia. Overuse of vitamin E can create a vitamin K deficiency, interference with anticoagulant drugs, and bleeding problems.
• Vitamin K functions as a cofactor (enzyme partner) for the synthesis of prothrombin. Prothrombin is required for blood clotting and is manufactured by some intestinal bacteria. Deficiencies are caused by conditions that reduce fat absorption or by antimicrobial medications that alter intestinal flora. Symptoms include prolonged bleeding and clotting time. High doses of vitamin K interfere with anticoagulants, which could result in hemorrhage.
• Vitamin B-complex is a group of coenzymes. These coenzymes work together to maintain healthy oral tissues by forming new cells and preserving the immune system. Risk for a decline of these vitamins increases with age, ingestion of certain medications (phenytoin and methotrexate), eating disorders, addictions, and in vegans. A deficiency of these vitamins can produce increased oral tissue sensitivity, burning tongue, loss of taste, angular cheilosis, pernicious anemia, gingivitis, and frequent oral lesions.
• Vitamin C assists with collagen and connective tissue formation; helps with blood vessel integrity, phagocytosis, and wound healing; is a potent antioxidant; facilitates calcium and iron absorption; and protects vitamins A and E. Low levels of vitamin C produce an increased intracellular permeability of blood vessels and the sulcular epithelium, thus allowing microbial penetration into deeper structures. Often the first symptom of vitamin C lacking in the diet is exhibited as gingivitis. Enlarged, magenta, hemorrhagic gingiva along with a widened periodontal ligament is the result. Research also seems to indicate that low levels of vitamin C increase the risk for developing periodontal disease. When inadequate vitamin C intake is combined with smoking, the greatest negative effect on periodontal tissues is seen. Smokers have a higher metabolic turnover rate for vitamin C. Excessive vitamin C in the diet can interfere with anticoagulants.
• Calcium, magnesium, and phosphorus in too small amounts in the diet can impair absorption and produce aggressive bone resorption, increased tooth mobility, premature tooth loss, and increased risk of hemorrhage. Recent studies indicate that people who have the least calcium have the highest risk for gingival detachment (Grossi, 1998). Furthermore, reduced dietary intake of calcium results in more severe periodontal disease and low dietary intake is a risk factor for periodontal disease. A magnesium deficiency has been linked to fragility of alveolar bone and gingival hypertrophy (DePaola et al., 1999). Hypercalcemia, too much magnesium, and excess phosphorus are virtually unknown.
• Iron deficiency can result in angular cheilosis, pallor, burning tongue, glossitis, and atrophy or denudation of the filiform papillae, and candidiasis as a result of decreased immune function. Excessive iron is rare, as most individuals regulate the absorption of iron well.
• Zinc is a very important mineral needed for wound healing and new tissue formation. Zinc works along with iron and copper for optimal wound resolution. Anyone who is malnourished runs the risk of low zinc levels. Zinc levels are naturally suppressed during infection. Zinc deficiencies rapidly impair immunity and diminish antibody activity; even a moderate insufficiency of zinc can lead to increased opportunistic infections. Immune status is closely linked to zinc status - an important mineral to ward off or control periodontal disease. Patients needing more zinc in their diets may report the following changes: diminished taste and odor sensitivity, altered taste, and reduced appetite. Studies have shown that vegetarians often need 50% more zinc. Zinc toxicity is uncommon.
• Copper is an essential mineral, involved in both collagen and elastin formation and regeneration. A copper deficiency causes substantial reduction in the tensile strength of collagen. This produces bone lesions, deformed joints, bone fragility, and vascular lesions.
Repair of the Periodontium
Nutritional status correlates highly with the quality of host immune response. As good nutrition is needed to sustain healthy tissues, maintain the immune system, and protect against periodontal disease, the body needs certain nutrients to convert diseased tissue to healthy tissue, once gingivitis or periodontitis generates damage. Diet insufficiencies can alter immunocompetence and increase the risk and extent of oral infection.
Inadequate nutrition can impede the repair process in the gingival sulcus along with an increase in epithelial attachment permeability, allowing ease of bacterial entrance. Even marginal nutrient deficiencies may be associated with defects in connective tissue resulting in altered cell growth, wound healing, and infection outcome. The nutrients that have a principal function in repair are protein, vitamin C, iron, zinc, copper, and selenium. Protein supports healthy cell growth and infection resistance; vitamin C aids in collagen formation, capillary integrity, and immune response; iron, zinc, and copper assist with collagen formation and inflammatory response regulation; selenium has antioxidant qualities that help prevent harm to cells and tissues.
Nutrient-deprived people will not heal as fast; gingivitis and periodontal disease will progress faster if patients have poor diets. Diet has a modifying role in the initiation and progression of periodontal disease. This has been substantiated, because of what is known about the influence of nutrition on tissue synthesis, repair, and the immune system. However, due to numerous predisposing factors and variables for periodontal disease, it is difficult to determine the individual effect of each nutrient on the periodontium. Because of this, limited, precise data is unavailable about the impact of specific nutrients relative to periodontal disease. Therefore, no specific recommendations can be made.
However, review of the literature on the use of specific nutrients to prevent or treat periodontal diseases concluded that this condition can be treated with nutritional supplements or improved diet but the effects are minimal. The efficacy of prophylactic nutrient supplementation remains to be verified, as supplements cannot replace a healthy diet. Another theory that is gaining credibility is that refined and processed foods and additives are highly inflammatory and should be eliminated from the diet completely and permanently. The effects of tea and probiotics on periodontal health have been examined. The evidence remains inconclusive at this time; more research is needed. What appears promising is that the polyphenols in tea may have positive effects on oral health and there is emerging evidence that probiotics may inhibit the growth of biofilm and periodontal disease-associated bacteria.
For optimal oral health, hygienists should share their knowledge of healthy diet requirements and nutrition as part of patient assessment. The websites previously referred to provide valuable tools for clinicians and patients. However, when a nutritional deficiency is suspected, and more expertise is deemed necessary, a referral to a primary-care provider or registered dietician may be warranted for individualized advice. Nutrient-dense, natural-food choices are the first line of defense for meeting nutritional needs and reducing the risk of developing periodontal disease. RDH
Nutrient Food Sources
Zinc: meat, fish, poultry, eggs, nuts
Vitamin K: dairy, green leafy vegetables
Vitamin E: vegetable oils, whole grains, fortified food, nuts
Vitamin D: sunlight, fish, fortified food and drink
Vitamin C: citrus fruits and juices, broccoli, strawberries, peppers
Vitamin A: dairy, eggs, fortified food and drink
Protein: dairy, meat, fish, poultry, legumes, seeds, nuts
Probiotics: yogurt, cheeses, buttermilk, sauerkraut
Phosphorus: dairy, meats, soft drinks
Omega-3 fatty acids: fish, flaxseed, canola, soybean oils
Magnesium: whole grains, green leafy vegetables, nuts
Iron: meat, poultry, fish, eggs, dark green vegetables
Folic acid: green leafy vegetables, fortified food, legumes
Copper: soy, shellfish, oysters, crabs, liver, nuts
Calcium: dairy, fortified food, seafood
Boron: fruits, vegetables, legumes, some wines, nuts
DIANA J. LAMOREUX, RDH, BS, MEd, graduated from Ohio State University in 1972, practiced dental hygiene for over 30 years, was a part-time clinical instructor in the Cleveland area since 1981, and retired in December 2011.
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