The mouth has been called a mirror of health, and a healthy mouth is indeed a pleasant sight to see in the mirror. It is not news to anyone that proper nutrition is an important component of overall health and well-being, but you may not know that food choices affect oral health in more ways than just preventing cavities. Learning how to use the power of good nutrition is particularly important for people with diabetes, since diabetes of any kind has been associated with a higher risk of oral health problems.
The oral complications of diabetes can range in severity from annoying to dangerous. The most common complications are periodontal disease, including gingivitis (inflammation and infection of the soft gum tissue) and periodontitis (inflammation and infection of the supporting ligaments and bones of the teeth); oral candidiasis (yeast infection); cavities (known to dentists as caries); xerostomia (dry mouth); burning mouth syndrome; and impaired taste function. As with other complications of diabetes, tight blood glucose control is imperative in the prevention and control of oral problems. Of course, proper oral hygiene and regular dentist visits are also important. In addition, there are some simple nutrition practices that may help guard against the development and progression of oral health complications.
Periodontal disease has been called the “sixth complication” of diabetes because of the link between the two diseases. Having periodontal disease may increase the risk of death from ischemic heart disease (in which blood flow, and therefore oxygen, is restricted to the heart) or nephropathy (damage to the kidneys). Because people with diabetes have a high risk of developing periodontal disease, awareness of the risks, symptoms, and preventive measures is important.
Periodontal disease is a chronic disease that involves the gums and bone structure of the mouth. Gingivitis is the precursor to periodontitis and is characterized by spaces, or pockets, developing between the teeth and gums. Plaque, a sticky film of bacteria, inhabits these pockets, promoting the growth of more bacteria and gradually destroying the gums and a type of bone in the mouth called alveolar bone, which anchors the teeth in place. Left untreated, periodontitis can lead to tooth loss.
Periodontal disease results in chronic inflammation of tissues in the mouth. Similarly, both diabetes and cardiovascular disease are associated with inflammation. Since these conditions are all linked to inflammation, it should be no surprise that they are linked to one another, as well. In fact, not only is diabetes a risk factor for periodontal disease, but periodontal disease has been marked as a risk factor for developing diabetes. Moreover, periodontitis seems to negatively affect blood glucose control. Other risk factors for periodontal disease include smoking, hormonal changes (such as occur in adolescence, pregnancy, and menopause), genetics, poor dental hygiene, and poor nutrition.
While it is still not entirely understood why people with diabetes are at increased risk for periodontitis, there are some plausible theories. One is that the immune system may function somewhat abnormally in people with diabetes; this would both decrease the ability of the body to fight bacterial invasion and increase inflammation in the mouth. Inflammation in the mouth may also be partially attributed to the increase in harmful blood lipids (triglycerides and LDL [“bad”] cholesterol) common to diabetes. People with diabetes additionally have a decreased ability to produce collagen, a protein that provides strength and elasticity in the cells, hindering the healing of wounds in the mouth. Lastly, chronic high blood glucose leads to both increased glucose availability for oral bacteria to thrive upon and the destruction of oral tissues due to oxidation (a process of breaking down).
Besides controlling blood glucose levels through meal planning, exercise, and consistent use of medicines, there are nutritional strategies one can use to specifically combat the development of periodontal disease, which will also benefit the heart, arteries, kidneys, and various other areas of the body.
As stated earlier, oxidation of oral tissue contributes to progression of gingivitis and periodontitis. From the oxidative reactions in the body come by-products called free radicals, which damage and kill cells. There are nutrients within the body called antioxidants, which police free radicals, either by neutralizing them or by creating a protective barrier around the cells that prevents oxidative damage.
The most well known antioxidant nutrients are vitamins C, E, and A and the carotenoids, such as beta-carotene. A 2003 review of the research on the effect of antioxidants on gum disease showed that a diet high in antioxidants may help lessen the development of gum disease. Notably, this research also finds obesity to be a risk factor for gum disease due to its potential to increase inflammation and negatively affect the immune system. Luckily, a diet rich in antioxidants is a diet rich in healthy foods, which can assist in weight management as well as blood glucose control.
Vitamin C is a powerful antioxidant. Diets low in vitamin C have been shown to increase the risk of periodontal disease in the general population. Vitamin C helps promote collagen formation, neutralizes free radicals, and helps vitamin E regenerate, or change back to its form as an active antioxidant after it has been altered by its protective activity. The recommended dietary allowance (RDA) for vitamin C is 90 milligrams per day (mg/day) for adult men and 75 mg/day for adult women. Smokers need an additional 35 mg above the RDA to help combat the additional oxidative damage caused by smoking. Citrus fruits such as oranges, grapefruits, and lemons and their juices are well known for having vitamin C, but red bell peppers, broccoli, Brussels sprouts, kale, strawberries, kiwifruit, and cantaloupe all pack more than 50 mg per typical serving. Be careful about using fruit and vegetable juices to acquire your vitamins, since even 100% juice with no added sugar is high in natural sugar and will rapidly increase blood glucose, add concentrated calories to the diet, and increase your risk for cavities. Whole fruits and vegetables are lower in calories and higher in fiber than juice, so choosing them in place of juice will help with weight management and blood glucose control.
Vitamin C itself is sensitive to oxidation, which means that cooking and exposure to light and air will destroy the nutrient. For this reason, fresh sources of vitamin C are best, and quick cooking methods such as steaming and microwaving are preferred to help food retain its vitamin C. Vitamin C is also water soluble, which means that it will leach into cooking liquids, so foods should be cooked with as little moisture as possible. Many packaged foods are fortified with vitamin C, both for its nutrient value and because it is a natural preservative. Check Nutrition Facts labels for Percent Daily Value of vitamin C, and look for more than 20% per serving.
Supplemental forms of vitamin C (sometimes listed on supplement labels as ascorbic acid) are also widely available. If you choose to take vitamin C supplements, the safe upper limit is 2,000 mg/day, although it is generally recommended that a vitamin supplement contain no more than two times one’s RDA. For vitamin C, this would be 150–250 mg/day, depending on your sex and smoking habits. Also, select the capsule form rather than the chewable form of vitamin C, because the acidity and oral retention of the chewable form may increase your risk for cavities.
Vitamin E is a fat-soluble vitamin that protects the cell membranes (the outer layer of a cell) from free radical damage. Being fat-soluble, vitamin E is generally found in foods that contain fat. Vegetable oil, nuts, and whole grains are good sources of vitamin E. Since these foods — particularly oils and nuts — also provide fat calories, it is wise to choose sources of fat that will also have a positive impact on your blood cholesterol level and heart health. Some good choices include canola and safflower oil, almonds, nonhydrogenated margarine (with 0 grams of trans fat), wheat germ, whole wheat bread, and whole-grain cereals. Processed grains such as white flour and white bread are poor sources of vitamin E. Dark-green leafy vegetables are a low-fat, high-fiber source, although they are much lower in vitamin E content than the oily sources.
The RDA for vitamin E is 15 mg/day for adults, but it is commonly listed on supplements in IU (International Units). The safe upper limit is set at 1,500 IU, but in 2004, a review of 19 clinical trials found that taking a vitamin E supplement greater than or equal to 400 IU daily may increase the risk of death. The decision whether to take vitamin E supplements should therefore be made with care. It is considered safe to take a vitamin E supplement of up to 400 IU, but trying to get what you need from oils, nuts, whole grains, and green leafy vegetables is the preferred course of action.
The carotenoids and vitamin A promote a healthy mouth through their roles in collagen formation, antioxidant activity, and healthy production of the epithelial cells that line the oral cavity. Carotenoids are a group of phytochemicals (plant chemicals) called provitamins of vitamin A, which means they are converted to vitamin A in the body. By themselves, they also have individual antioxidant properties. The best-known carotenoid is beta-carotene. However, lycopene and lutein are also becoming notable for their possible roles in prostate and eye health, respectively. Carotenoids are actually the pigments that give orange-yellow fruits and vegetables their color. They are easily recognized in carrots, squash, pumpkin, sweet potato, apricots, mango, and peaches. Dark-green vegetables like spinach and kale are also packed with beta-carotene, but the color is masked by the green-colored chlorophyll. There is no RDA for beta-carotene or the other carotenoids, but consuming these vegetables is the best route to obtaining adequate vitamin A, as well as fiber and other nutrients. Carotenoids are also heat stable, so they are only minimally diminished by cooking.
Preformed vitamin A is found in animal products and certain fortified foods and does not need to be converted in the body like the provitamins. The RDA for vitamin A (including converted carotenoids) is 700 micrograms per day (µg/day) for women and 900 µg/day for men. Food sources of preformed vitamin A include liver, egg yolks, and dairy products. While the body needs some vitamin A, too much preformed vitamin A is very toxic and can cause liver damage, birth defects, and bone damage; chronic supplementation of only two or three times the RDA can have these effects. Food is unlikely to cause toxicity, but supplements can easily do so. Neither supplementation of beta-carotene nor preformed vitamin A is recommended unless a person is at risk for deficiency. Since liver and egg yolks are high in cholesterol, choosing low-fat or nonfat dairy products and filling your grocery cart with beta-carotene-rich green and orange produce is the way to get your daily vitamin A.
Fat and cholesterol
Several studies have shown an association between blood cholesterol levels and periodontitis. Another study found that dietary cholesterol intake (which raises blood cholesterol) worsened periodontitis in rats. A diet low in saturated fat (less than 7% of calories or, for most people, less than 15 grams per day), trans fat (less than 1% of total calories, which is 2 grams per day for a person eating 2,000 calories a day), and cholesterol (less than 200 mg/day) helps control blood cholesterol level, which has a positive impact on both oral health and the cardiovascular system.
Saturated fat is found primarily in animal products such as beef, pork, poultry (particularly in the skin), and dairy products made from whole milk. Tropical oils such as palm oil and coconut oil are the only major plant sources of saturated fat. When eating animal protein, choose the varieties that are lowest in saturated fat, such as skinless chicken, fish, and low-fat or nonfat dairy products. Limit portions of animal proteins to one or two 3-ounce servings (about the size of a deck of cards or checkbook) per day; this will help control both saturated fat and calorie intake. Include more plant proteins such as legumes (lentils and dried beans), nuts, soy products, and whole grains, which contain very little saturated fat, in your menus.
Cholesterol is only found in animal products, so plant oils, grains, fruits, and vegetables do not contain cholesterol. Most foods containing cholesterol also come with saturated fat, making it easy to cut back on both at the same time. Foods highest in cholesterol are organ meats such as liver, egg yolks, and shellfish. Shellfish is actually very low in saturated fat, but its cholesterol content warrants eating shrimp, lobster, crab, and other varieties of shellfish only occasionally. Egg whites contain no cholesterol and are a good source of protein, so they are a better choice than whole eggs. Another popular source of cholesterol in the diet is dairy products. To enjoy dairy products while keeping saturated fat and cholesterol intake low, choose low-fat or nonfat dairy products, and minimize your intake of butter, cream, cream cheese, and whole-fat cheeses. Read labels on packaged goods, and buy foods whose % Daily Value for both cholesterol and saturated fat are no higher than 20% (and preferably lower).
Trans fat is found in packaged products containing partially hydrogenated oils and in many of the fried foods served at fast-food and other restaurants. Trans fat is now listed on food labels, so it can be easily avoided in packaged goods. Look for 0 grams of trans fat, and make sure the ingredients list does not list any partially hydrogenated oil. At restaurants, avoid fried menu items and baked goods (such as French fries, fried fish or chicken, doughnuts, and pies) unless you are sure that they do not use partially hydrogenated oils in their frying bins and baked goods. Keep trans fat consumption as low as possible; the American Heart Association recommends a limit of less than 1% of total daily calories (2 grams per day for someone eating 2,000 calories daily).
Cavities are also more prevalent among people with diabetes than in the general population. Cavities are the result of bacteria, plaque, an acidic oral environment, and the presence of carbohydrate in the mouth. Bacteria and plaque are best controlled through proper dental care, but acidity and the amount of carbohydrate in the mouth are factors that can be affected by diet.
A cariogenic, or cavity-causing, environment is one where the pH (relative acidity) is less than 5.5 (low pH means higher acidity). Certain foods such as fruit juice, soda (even diet soda), chewable vitamin C tablets, and sports drinks create a cavity-friendly level of acidity in the mouth. Most people with diabetes probably already limit their consumption of drinks with added sugar, but consumption of artificially sweetened sodas should also be limited.
Amount, type, duration, and frequency of carbohydrate intake all affect cavity development. However, choosing the right types of carbohydrate will reduce the risk of cavities while still controlling blood glucose levels. Consumption of high amounts of simple sugars like sucrose (table sugar) is considered highly cariogenic and should be minimized. Starchy foods such as rice, pasta, bread, and potatoes are not cariogenic unless eaten with added sugars. Dietary fiber has been found to help reduce the incidence of cavities, so eating unrefined starches should not promote cavities. Choosing high-fiber carbohydrates is already recommended for both people with and without diabetes, and having fewer cavities is yet another reason to do so.
People with diabetes are often instructed to eat small, frequent meals and to space their carbohydrate intake over the course of the day. People who frequently need to treat low blood glucose (hypoglycemia) may also suck on hard candies to raise blood glucose. While frequent and prolonged exposure to carbohydrate increases the risk for cavities, it is only thought to be a problem when carbohydrate (simple sugars, in particular) is eaten alone, without protein or fat. Meals in a balanced diabetes meal plan typically contain protein, fat, and carbohydrate, so eating small, frequent meals for diabetes control should contribute to, not detract from, oral health. However sucking on candy or mints can lead to increased cavities, so it is wise to use glucose tablets or beverages to treat or prevent hypoglycemia, since they clear the mouth more quickly than hard candies.
Fluoride is a mineral that is known to prevent cavities but is not found readily in most foods. However, it is available in toothpaste, mouth rinses, and fluoridated water. Check with your dentist on the amount of fluoride in your local water supply (some communities do not have fluoridated water) to see if you should consider taking supplemental fluoride.
Eating protein with meals is anticariogenic because it serves as a pH buffer, preventing acidic conditions in the mouth. Again, choose proteins that are low in fat and cholesterol, and emphasize fibrous plant proteins. Fiber, a type of carbohydrate, is not metabolized by the oral bacteria, so it cannot produce cavities. Fibrous foods also require more chewing than nonfibrous foods, and chewing stimulates saliva secretion. (Low salivary flow is also linked to increased dental cavities.)
Dairy products contain the anticariogenic nutrients casein, calcium, and phosphorous; in addition, milk sugar, or lactose, is the only simple sugar that is not considered to be cariogenic. Low-fat and nonfat dairy products provide the same anticariogenic nutrients without the harmful fat and cholesterol found in full-fat products. Dark-green vegetables are good plant sources of anticariogenic calcium, and they also provide beta-carotene and fiber.
Both xylitol and tea are emerging as strongly anticariogenic foods. Xylitol, a sugar alcohol, is not widely used in foods but is found in some brands of sugarless gum. Xylitol has a minimal effect on blood glucose level, so chewing gum containing it should not disrupt blood glucose control. Chewing gum that contains xylitol after meals and snacks provides the mouth with xylitol, helps clear the mouth of cariogenic foods, and stimulates saliva flow. If gum chewing is not possible, drinking a cup of green or black tea may produce similar benefits. The tea plant, Camellia sinensis, may have antimicrobial and other preventative effects on cavity formation. To help prevent cavities, at the very least, rinse your mouth after meals with our most vital nutrient, water.
(Click here to learn more about nutrients that promote oral health.)
Other oral health problems
Oral candidiasis, also known as a yeast infection, or thrush, and other fungal infections are common among people with diabetes, and denture wearers may be at particularly high risk. Elevated levels of glucose in the saliva, abnormal immune system functioning, and xerostomia (dry mouth) are thought to be predisposing factors. Salivary glucose can be reduced by exercising tight blood glucose control.
Xerostomia may affect up to 80% of people with diabetes. There may be several underlying causes of this condition, including certain medicines, chronic high blood glucose levels, and dehydration, which can be a consequence of high blood glucose. Xerostomia is thought to be related to taste dysfunction in some people. Burning mouth syndrome (also known as glossodynia) may be a result of candidiasis, xerostomia, or peripheral neuropathy. If you have xerostomia, you should discuss your medicines with your doctor and consult your dentist regarding the use of products such as artificial saliva.
There are also simple ways you can eat to keep your mouth moist, which may help control infections and glossodynia and of course help you feel more comfortable. The most obvious solution to dry mouth is hydration. Frequently sipping plain water, preferably fluoridated tap water, is the first course of action. Avoid caffeinated and alcoholic beverages, since they may exacerbate dryness and dehydration. Eating moist foods like soups, sauces, fruits, and vegetables while avoiding dry and salty foods like pretzels and chips as well as citrus juices will also help keep oral tissues moist. Paying attention to the temperature of foods and beverages is also important, since hot foods and beverages can be very drying or burn the mouth. Taking small bites and chewing food thoroughly will help stimulate saliva flow. Chewing gums containing xylitol may also be helpful for people who have xerostomia.
As you can see, eating for oral health is not so different from eating for overall health. Focusing on low-fat proteins, whole grains, and colorful fruits and vegetables is the basis of a healthy diet for the whole body. Eating regularly scheduled meals, avoiding concentrated sweets, and controlling blood glucose are no doubt already familiar concepts. Combining nutrition with proper dental hygiene and regular dental care should keep a smile on your face and keep appointments with your dental care team as stress-free as possible.