USE OF SUPPLEMENTS CONTAINING FISH OIL OR OMEGA-3 FATTY ACIDS
Other than vitamin and mineral supplements, fish oil and flaxseed oil, rich sources of omega-3 fatty acids, are the most commonly used natural health products.1 Supplements containing omega-3 fatty acids in combination with other fatty acids found in food, known as omega 3/6/9 supplements, are also commonly used. In a recent survey of patients at a Canadian periodontal clinic, 11 percent of patients reported using fish oil supplements and 13 percent reported using omega 3/6/9 supplements.2 The percentage of fish oil and omega 3/6/9 supplement users was even greater among patients over 70 years of age. Thus, some clients that visit dental clinics are regularly using these products as a way to optimize their health – but they may not realize that they may also be supporting their periodontal health.
Why are fish oil and/or omega-3 fatty acid supplements so popular? It is likely because of media reports regarding potential health benefits. Omega-3 fats in fish were first linked to cardiovascular disease thirty years ago when it was observed that fewer Greenlanders, who consumed large quantities of fish, died from coronary heart disease compared to Danes and Americans.3 Since then, consumption of fish oil and/or intakes of long chain omega-3 fatty acids has been associated with prevention of a wide range of diseases including rheumatoid arthritis, diseases of the eye and brain, cancer, allergy, asthma, Crohn’s disease, diabetes, kidney disease, lupus, obesity, as well as better bone health, and now, periodontal disease. While it is important to note that the strength of evidence demonstrating a relationship between higher omega-3 fatty acid intake and risk of specific disease varies, emerging evidence from both observational studies and clinical trials suggests that an optimal intake of omega-3 fatty acids – at levels attainable only through frequent consumption of fish or use of fish oil supplements–plays an important role in preventing and treating periodontal disease. This article provides an update of this evidence. But first, we will briefly review some basics about dietary fatty acids.
A QUICK REVIEW OF DIETARY FAT
Dietary fats are classified as saturated, monounsaturated or polyunsaturated fatty acids based on the number of double bonds in its carbon chain. In general, saturated fats come from animal sources such as meat and dairy. Although saturated fat intake has been a concern for coronary heart disease, most sources of saturated fat are not harmful and some sources such as dairy have been associated with reduced incidences of cardiovascular disease.4 Monounsaturated fats, which include omega-9 fats, are abundant in plant-derived oils such as olive oil and canola oil. Polyunsaturated fats include the essential fatty acids called linoleic acid (LA) and alpha-linolenic acid (ALA) and they are omega-6 and omega-3 fatty acids, respectively. They are referred to as essential fatty acids because they cannot be synthesized in the body and therefore must be consumed in the diet. LA is abundant in vegetable oils and may also be high in dairy and meats depending on the diet of the animal. ALA is found in certain vegetable oils, nuts, flaxseed, beans, and soy products. LA and ALA can be converted to long chain fatty acids. The essential omega-6 fatty acid LA is converted into arachidonic acid (AA), while the essential omega-3 fatty acid ALA is converted into eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Conversion of ALA into EPA and DHA in humans, however, is relatively low, at most 10 percent.5 EPA and DHA can, however, be obtained in high amounts directly through fish, seafood and fish oils.6 Figure 1 shows the organization of dietary fatty acids and Table 1 lists the ALA, EPA and DHA content of some common foods and supplements.
FIGURE 1. Organization of dietary fatty acids.
The essential fatty acids – ALA and LA – and their long chain fatty acid derivatives – EPA, DHA and AA – have a number of important biological roles. They are required for the formation of membrane structural lipids, production of eicosanoids, normal epithelial cell function, regulation of gene expression, growth and neurological development. The long chain fatty acids (AA, EPA and DHA) in particular are needed to form cell-signaling molecules that are responsible for modulating inflammatory responses. One example is that EPA and DHA are needed to form resolvins; a family of molecules with anti-inflammatory activity, which are thought to explain the variety of health benefits of omega-3 fatty acids.7
TABLE 1. ALA, EPA and DHA content of foods and supplements
HIGHER INTAKES OF OMEGA-3 FATTY ACIDS ARE ASSOCIATED WITH A LOWER INCIDENCE OF PERIODONTAL DISEASE
Using cross-sectional data from the National Health and Nutrition Examination Survey (NHANES III), a survey that includes thousands of people across the United States, investigators have shown an inverse relationship between DHA intake and incidences of periodontal disease in adults ≥20 years of age.8 In this study, periodontitis was defined as having >4 mm pocket depth and >3 mm attachment loss in any one tooth. Individuals with the highest intakes of DHA (≥40 mg/day, approximately one to two servings of fish per week) were 22 percent less likely to develop periodontal disease compared to those with the lowest intakes. The associations between EPA (found in fish or fish oil supplements) or ALA (present in flax oil or flaxseed) intake and periodontitis were weaker compared to DHA intake and they did not reach statistical significance. The findings from NHANES III have also been replicated in a smaller cohort (n = 55) of elderly individuals in Japan.9 Those with the lowest intakes of DHA had 1.5 times more periodontal disease events (defined as the number of teeth with periodontal disease progression over five years) compared to those with the highest intakes of DHA. In this study, DHA intakes were >1000 mg/day for males and >600 mg/day for females, which are levels that would require consuming fish every day or taking a daily fish oil supplement. Thus, based on the available studies, it appears that higher dietary intakes of DHA play a protective role, decreasing the risk for periodontal disease.
PRELIMINARY RESULTS FROM CLINICAL TRIALS ARE PROMISING
Two main clinical studies have investigated the use of fish oil supplements in conjunction with scaling and root planing. One study included forty patients who were given a fish oil supplement (900 mg EPA + DHA/day) with low-dose aspirin (81 mg/day) and forty control patients who received a placebo for six months after scaling and root planning was performed.10 The treatment group had significantly greater reductions in probing depth and greater gains in attachment level compared to the placebo group. One limitation of this study is that the question remains of whether this was an effect of omega-3 fatty acids, aspirin or
a combination of both. However, this question may be answered by the next study, which tested the effects of omega-3 fatty acids without aspirin. In this study, thirty patients received an omega-3 supplement containing fish oils (180 mg EPA and 120 mg DHA per day) and thirty patients received a placebo, both in conjunction with scaling and root planning.11 The group receiving EPA and DHA experienced greater reductions in gingival index, sulcus bleeding index, pocket depth and clinical attachment loss compared to the placebo group at 12 weeks. Thus, supplementation with EPA and DHA appears to be beneficial for patients undergoing scaling and root planing. More studies are needed to confirm these findings and to better determine a recommended dose for clinical use. In the meantime, if patients were to follow dietary guidelines set by Health Canada for overall healthy eating and/or take a daily fish oil supplement to meet Health Canada’s recommendation, their intakes of omega-3 fatty acids would be at the levels shown to benefit periodontal health.
HOW MUCH OMEGA-3 FAT DO INDIVIDUALS NEED?
Recommendations for polyunsaturated fat intake are still being developed. For Canadians, the strongest evidence-based guidance comes from the dietary reference intakes set by the Institute of Medicine and used by Health Canada. For adult males, 1.6 g ALA/day and for adult females, 1.1 g ALA/day is recommended.12 There is currently insufficient data to make recommendations regarding EPA and DHA intake but for cardiovascular health the American Heart Association recommends a minimum of 2 servings of fish per week. Recommendations for ALA, EPA and DHA intake will likely be updated in the near future as a great deal of new research has emerged since 2002, when the dietary reference intakes were last revised. In the meantime, Canada’s Food Guide13 and Dieticians of Canada6 provide the following evidence-based dietary guidelines that help individuals attain sufficient ALA, DHA and EPA:
Essential omega-3 fatty acid intake, ALA: It is recommended that small amounts of unsaturated oils (2-3 tablespoons) be used everyday for cooking, salad dressing, mayonnaise and margarine. Examples of unsaturated oils include canola, flaxseed, soybean or walnut. It is worth mentioning that, despite being a healthy fat source, olive oil does not contain substantial amounts of omega-3 fatty acids. Some foods such as flaxseed, walnuts, almonds, beans and tofu are also excellent sources of ALA. Table 1 lists the ALA content of specific foods and supplements. Current recommendations do suggest limiting saturated fat intake, however, reducing fat intake in order to avoid saturated fat has not been shown to attenuate cardiovascular disease. Evidence suggests that a healthy diet can include saturated fat as long as polyunsaturated fats are also consumed.14
Long chain omega-3 fatty acids, EPA and DHA: It is recommended that individuals consume at least two servings of fatty fish (char, herring, mackerel, salmon, sardines and trout) each week. A serving of fish is 75 g, which is about the size and thickness of the palm of a hand. The EPA and DHA content does vary greatly between species of fish; salmon, for example, has much higher levels of EPA and DHA compared to tuna. Two weekly servings of fatty fish or daily fish oil supplementation should be able to provide sufficient EPA and DHA to reach levels that appear to benefit patients undergoing periodontal therapy (at least 300 mg EPA + DHA).10,11 Table 1 lists the EPA and DHA
content of specific foods and supplements.
•Alpha-linolenic acid (ALA) is an omega-3 fatty acid that must be obtained through the diet and is therefore referred to as an essential fatty acid. Flaxseed oil or ground flaxseed is a rich source of ALA.
•Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are long chain omega-3 fatty acids that play important roles in inflammatory processes. Fish, seafood and fish oils are the richest source of EPA and DHA.
•Higher DHA intake is associated with reduced incidence of periodontal disease.
•Use of fish oil supplements containing EPA and DHA result in greater improvements in periodontal health following scaling and root planning.
•In addition to periodontal disease, consuming appropriate levels of EPA and DHA are important for overall health including cardiovascular health.
ADVICE FOR PATIENTS
•Small amounts of unsaturated vegetable oils (e.g. 2-3 tablespoons of canola, flaxseed, walnut, soybean) and/or ALA rich foods (e.g. flaxseed, walnuts, beans, soy) should be consumed every day to provide sufficient ALA, an essential fatty acid (see Table 1 for serving size information).
•Two servings of fatty fish should be consumed every week in order to provide adequate levels of EPA and DHA. If fish is not consumed, a fish oil supplement (at least 1 capsule per day) provides the level of EPA and DHA that appears to support periodontal health.
David Dodington is currently a medical student at the University of Toronto. He recently completed graduate work in the area of nutrition and periodontal healing in the Faculty of Applied Health Sciences at Brock University.
Wendy Ward is a Canada Research Chair in Bone and Muscle Development in the Faculty of Applied Health Sciences at Brock University.
Peter Fritz is a certified specialist in Periodontics and is in full-time private practice in Fonthill, Ontario. Dr. Fritz is anAdjunct Professor in the Faculty of Applied Health Sciences at Brock University.
Oral Health welcomes this original article.
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