Review Shows Fish Oil Supplements May Improve Periodontitis

Laird Harrison

April 26, 2012

April 26, 2012 — Fish oil and other supplements containing long-chain polyunsaturated omega-3 fatty acids may reduce periodontitis, according to researchers who presented a review of the literature on this topic at the Experimental Biology 2012 meeting in San Diego, California.

The researchers found 4 clinical trials in which patients' signs of periodontitis improved when they took these supplements, but the results reached statistical significance only in 2 studies that paired the supplements with aspirin.

In addition, 1 retrospective and 3 cross-sectional studies also showed that people whose regular diets contain more of the fatty acids — particularly if they ate a lot of fish — were less likely to suffer from periodontitis.

The studies contribute to an understanding of what causes periodontitis and could lead to more powerful therapies. In the past, researchers have focused on the bacteria that infect gingival tissue. But recent evidence suggests that the most serious damage results from inflammation; in an effort to kill the bacteria, the body destroys its own tissue.

"In periodontitis, there is a low-grade inflammation," lead researcher Alison Coates, PhD, a senior lecturer at the University of South Australia, Adelaide, told Medscape Medical News. "And we know from previous research that fish oil is really effective in treating inflammation."

Would Taking Resolvins Directly Be More Effective Than Fish Oil?

Metabolites of the omega-3 fatty acids called resolvins suppress this inflammation, Dr. Coates said. It is the same mechanism by which the fatty acids are believed to improve cardiovascular health and arthritis. Aspirin may affect the way the fatty acids are metabolized, resulting in a different quality or a different quantity of resolvins.

Taking resolvins directly might have a more powerful effect; they are being researched as potential new medications but have not yet been approved by the US Food and Drug Administration. Supplements that include omega-3 fatty acids in food stuffs such as fish oil don't need to meet the same standards under US law.

Some researchers theorize that humans evolved while consuming a diet that was higher in these fatty acids. Many people ate more fish in prehistoric times. And the meat that people eat has also changed. In many developed countries, it comes from animals raised in feed lots where they eat mostly corn and soybeans. As a result their meat contains lower amounts of the fatty acids than it does when they graze.

In 1 of the studies, published in 2010 in the Journal of the American Dietetic Association, researchers used the National Health and Nutrition Examination Survey to compare the amount of various fatty acids in Americans' diets to their rate of periodontitis. They found that people were about two thirds as likely to be diagnosed with periodontitis if they consumed some docosahexaenoic acid (a type of omega-3 fatty acid) than if they didn't consume any (odds ratio, 0.69; 95% confidence interval, 0.55 - 0.87; P = .009).

Australia Considers Omega-3 Fatty Acids Essential Nutrients

The evidence for the benefit of these fatty acids is so convincing that already the government of Australia sees omega-3 fatty acids as essential nutrients. It recommends 430 mg of long-chain omega-3 fatty acids per day for women and 610 mg/day for men. But the recommendation has not had a big effect. "In Australia, there is a small proportion of the population meeting their recommended daily allowance," said Dr. Coates.

The United States has so far not added these substances to the list of nutrients for which it recommends a daily allowance.

Asked to comment, Thomas Van Dyke, DDS, PhD, vice president for clinical and translational research at the Forsyth Institute in Cambridge, Massachusetts, told Medscape Medical News that the benefits of the fatty acids for periodontitis appear modest and that supplements can't take the place of standard treatments for periodontitis.

"It doesn't cure the disease," said Dr. Van Dyke, who worked on 1 of the studies included in Dr. Coates and colleagues' review. "What it shows is that if you're taking them long-term you tend to have less disease than people who don't take them."

Some research has suggested that there is an upper limit to the amount of the fatty acids that produce a benefit. Above about 3 g per day, they may cause blood thinning, said Dr. Coates. She advises people who are taking blood thinners to consult with a doctor before adding omega-3 supplements.

One question left unresolved by the studies so far is how well aspirin and omega-3 supplements might work independently of each other.

Larger, Longer-Term Studies on the Horizon

Because the clinical trials did not show a statistically significant benefit for the fatty acid supplements alone, Dr. Coates and her colleagues have launched a new trial that they hope will improve on some of the weaknesses of previous research.

The longest previous trial with fish oil alone was 16 weeks, she said. "It may not be long enough to get incorporation of fatty acids into membrane," she said. The Adelaide researchers plan to continue their study for 12 months.

They also plan to enroll 126 participants, compared with 80 for the largest previous trial. And they want to measure biomarkers that will tell them whether the participants are actually taking the supplements they are prescribed.

The study was not commercially funded. Dr. Coates and Dr. Van Dyke have disclosed no relevant financial relationships.

Experimental Biology 2012. Presented April 24, 2012.

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