New UK research has added to the growing body of evidence suggesting that, when included as part of a healthy diet, omega-3 can help improve the diversity of gut bacteria.

Carried out by researchers from the School of Medicine at Nottingham, the study is the largest to date to examine the relationship between omega-3, found commonly in fish oil, and the composition of the gut microbiome.

For the study the team recruited 876 middle-age and elderly women to test the diversity and amount of good bacteria in their gut against their omega-3 intake and their blood serum levels of omega-3 fatty acids. 

They found that the women who had a higher dietary intake of omega-3 and higher blood serum levels also had a more diverse gut microbiome, which is associated with a number of health benefits including lower risk of diabetes, obesity and inflammatory gut diseases like colitis or Crohn's. 

Omega-3 has also been shown in previous research to have a positive effect on various other health conditions, including insulin resistance in diabetes, hypertension (high blood pressure), arthritis, thrombosis (blood clots), some cancers and cognitive decline.

"We also found that specific bacteria that have been linked to lower inflammation and lower risk of obesity are increased in people who have a higher intake of omega-3 fatty acids," added Dr. Cristina Menni from King's College London, who also worked on the study. "We further explored how this related to compounds in feces and found that, in addition to fish protein and omega-3, high levels of omega-3 in blood are correlated with high levels of a compound called N-carbamylglutamate (NCG) in the gut."

"This compound has been shown in animals to reduce oxidative stress in the gut. We believe that some of the good effects of omega-3 in the gut may be due to the fact that omega 3 induces bacteria to produce this substance."

As well as fish oil, omega-3 can also be found in seafood, oils such as flaxseed oil, canola oil, perilla oil, walnut oil and chia oil, and nuts and seeds.

The results can be found published online in the journal Scientific Reports.