Summary
In periodontitis, chronic inflammation of the supportive tissues around the teeth causes pain and difficulty in eating, as well as altered dental aesthetics, leading to a decrease in quality of life. The anti-inflammatory properties of DHA have been shown in multiple research trials to have a beneficial effect on periodontitis.
 
Introduction
Periodontitis is a chronic inflammation of the supportive tissues around the teeth such as gum tissue; approximately one in ten persons worldwide are affected by a severe form of periodontitis. Symptoms commonly include discomfort and pain around and in the teeth.  Ultimately, periodontitis can lead to bone and tooth loss in severe stages of the disease. The disease is initiated by a pathological separation between gum tissue and teeth occurs, forming what is called a periodontal pocket where bacteria can accumulate. A microbial population of bacteria is permanently present in the mouth that supports normal health; an imbalance in this microbiome (such as occurs in periodontitis) is called dysbiosis. While the inflammation that characterizes periodontal disease is initiated by the accumulation of bacteria in the periodontal pockets, the main symptoms are caused by prolonged pro-inflammatory immune response. This (over)activation of the body’s own immune system leads to the tissue damage that is typical in periodontitis. This breakdown of tissue is then suggested to act as an energy source for bacteria in the periodontal pockets, establishing a self-strengthening pathological effect.
 
The main clinical parameters used to assess the stage (severity, ranging from level 1-4) of periodontitis are probing pocket depth, clinical attachment level (referring to how well gums are attached to the teeth) and bleeding upon probing. Clinical attachment level refers to how well gums are attached to the teeth. In periodontitis, treatments such as scaling and root planning can be administered, which aim to remove plaque and other buildup around the teeth and gumline and smoothen the tooth surface. As omega-3 polyunsaturated fatty acids such as DHA are known to have anti-inflammatory properties, their role in the mitigation of periodontitis has been the subject of population and intervention studies.
 
Research findings
In a large population study investigating the effects of dietary omega-3 polyunsaturated fatty acids, Naqvi and colleagues established associations between periodontitis and dietary omega-3 fatty acids EPA, DHA & ALA  (Naqvi et al., 2010). In a population of 9,182 adults over 19 years of age, data from periodontal exams was used to assess presence of periodontitis based on probing pocket depth and clinical attachment level. This was combined with data from dietary recall interviews ascertaining frequency of fish and shellfish consumption during the past 30 days to establish specific omega-3 polyunsaturated fatty acid intake. From this, the authors found an inverse association with dietary DHA intake and periodontitis prevalence, a similar but more moderate effect was also found for EPA dietary intake. Naqvi and colleagues went on to conclude that the positive effect of DHA against periodontitis prevalence is likely a result of reduced inflammatory response. Specifically, this reduction of inflammation-induced tissue breakdown likely decreases the energy source for accumulated bacteria in the periodontal pocket, further diminishing the inflammatory response.
 
Following up on their previous population-based study, Naqvi and collaborators assessed the effects of combined DHA and aspirin supplementation on periodontitis reduction (Naqvi et al., 2014). Forty-six individuals over 40 years of age with moderate periodontitis were divided into two groups. The only given treatment was daily aspirin (81mg) and supplementation with corn/soybean oil capsules (placebo group, 22 individuals) or 2000mg in algal oil-derived DHA capsules (test group, 24 individuals) for a period of three months. Compared to the control group after three months, the DHA supplementation group showed a decrease in local inflammation and improvements in moderate periodontitis.
 
In order to investigate benefits of omega-3 polyunsaturated fatty acid during non-surgical treatment of periodontitis, Stańdo and colleagues employed EPA + DHA supplementation  (Stańdo et al., 2020). All of the 30 study participants were middle aged and (non-surgically) treated for their stage 3 or 4 periodontitis with scaling and root planning. The test group consisting of 14 individuals was given daily supplementation of 2.6 g of EPA and 1.8 g of DHA for a period of 3 months. The remaining participants did not receive supplementation of any kind (control group). It was found that after 3 months, the omega-3 supplementation group showed improvements in the clinical parameters of bleeding upon probing and clinical attachment level compared to the control group. The authors conclude that supplementation with EPA and DHA may enhance the effects of certain periodontitis treatments.
 
Conclusion
Research has pointed towards a beneficial role of omega-3 polyunsaturated fatty acids in mitigating symptoms associated with periodontitis, with DHA having the most pronounced effect. Dietary intake of DHA is inversely associated with periodontitis prevalence, supplementation of DHA in combination with either EPA or aspirin has been shown to be effective in reducing clinical parameters of periodontitis after a brief period of just 3 months. Ensuring that sufficient DHA levels are maintained, for example through DHA supplementation, may therefore benefit against periodontitis.
 
References
Naqvi, A. Z., Buettner, C., Phillips, R. S., Davis, R. B., & Mukamal, K. J. (2010). N-3 Fatty Acids and Periodontitis in US Adults. Journal of the American Dietetic Association, 110(11), 1669–1675. https://doi.org/10.1016/j.jada.2010.08.009
 
Naqvi, A. Z., Hasturk, H., Mu, L., Phillips, R. S., Davis, R. B., Halem, S., Campos, H., Goodson, J. M., Van Dyke, T. E., & Mukamal, K. J. (2014). Docosahexaenoic Acid and Periodontitis in Adults: A Randomized Controlled Trial. Journal of Dental Research, 93(8), 767–773. https://doi.org/10.1177/0022034514541125
 
Stańdo, M., Piatek, P., Namiecinska, M., Lewkowicz, P., & Lewkowicz, N. (2020). Omega-3 Polyunsaturated Fatty Acids EPA and DHA as an Adjunct to Non-Surgical Treatment of Periodontitis: A Randomized Clinical Trial. Nutrients, 12(9), 2614. https://doi.org/10.3390/nu12092614