Omega-3 Fatty Acids & Gut Health

Over the past decade the research available investigating the role of the gut microbiome on human health has continually expanded. We now know that the gut microbiome plays a vital role in human health and disease. These bugs in our gut play a role in the immune system, digestion, detoxification and vitamin production, plus they have been linked to conditions like obesity, diabetes, depression and many inflammatory conditions. Sounds like these bugs are a pretty big deal, right?!

What we also know is that our diet is one of the most effective ways to influence the gut microbiome. You hear me harp on about this enough on instagram. In fact our diet can change the abundance of varying bacteria in a very short period of time, as little as a matter of days. Fibre is often the talk of the town with gut health but today we are looking at something else - Omega-3! Yes this well known fatty-acid is now looking like it also plays a role in a creating a healthy and thriving gut microbiome. 


Omega-3 & Microbiome Diversity 

When it comes to omega 3 fatty acids the two main bioactive forms are the long chain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These two can be synthesised from the dietary precursor alpha-linolenic acid (ALA) however as humans we are actually really bad at converting ALA to EPA and DHA (estimated about 5% conversion - this becomes important when we speak about omega 3 in a vegetarian or vegan diet, but that is another topic).

We know these long chain omega-3 fatty acids (EPA and DHA) are good for us, in fact we have some pretty good science to show they play a protective role in many chronic diseases like cardiovascular disease and depression (just to name a few). So what have these long chain omega-3s got to do with the gut?

What the research is pointing out is that a diet rich in these beneficial long chain omega-3 fatty acids is associated with a more diverse gut microbiome, particularly an increased abundance of Lachnospira and an increase in butyrate producing bacteria (butyrate is a beneficial short chain fatty acid associated with many health benefits). 

What don’t we know?

You know me and you know I am all about the science and what this means is we also need to avoid jumping to conclusions quickly. This area of research is relatively new and while we are starting to compile human trials we don’t know a few things like:

  • How much omega-3 is required?

  • Is omega-3 from food better than supplements (the data points towards yes but no conclusions yet)

  • Does this actually translate into health benefits and outcomes?

What does this mean?

So while we don’t know the answers to the above questions, we do know that omega-3 isn’t harmful and is like previously mentioned actually a nutrient that has been on numerous occasions shown to be associated with positive health outcomes. 


What we can take away is that we essentially have another reason to include long-chain omega-3 fatty acids in our diet (as if we didn’t have enough reasons already). Where can we find these long chain omega-3s:

  • Sardines 

  • Salmon

  • Mackerel

  • Rainbow trout

  • Herring

  • Tuna (check out my instagram post on tuna here)

  • Micro algae (vegan)

So next time contemplating what to cook for dinner see if you can sneak in some omega-3 and your gut will love you for it!

Marika xo


Costantini, L., Molinari, R., Farinon, B., & Merendino, N. (2017). Impact of Omega-3 Fatty Acids on the Gut Microbiota. International journal of molecular sciences18(12), 2645. doi:10.3390/ijms18122645

Rajkumar H., Mahmood N., Kumar M., Varikuti S.R., Challa H.R., Myakala S.P. Effect of probiotic (VSL#3) and omega-3 on lipid profile, insulin sensitivity, inflammatory markers, and gut colonization in overweight adults: A randomized, controlled trial. Mediat. Inflamm. 2014;2014:348959. doi: 10.1155/2014/348959.

Watson H., Mitra S., Croden F.C., Taylor M., Wood H.M., Perry S.L., Spencer J.A., Quirke P., Toogood G.J., Lawton C.L., et al. A randomised trial of the effect of omega-3 polyunsaturated fatty acid supplements on the human intestinal microbiota. Gut. 2017 doi: 10.1136/gutjnl-2017-314968.

Menni C., Zierer J., Pallister T., Jackson M.A., Long T., Mohney R.P., Steves C.J., Spector T.D., Valdes A.M. Omega-3 fatty acids correlate with gut microbiome diversity and production of N-carbamylglutamate in middle aged and elderly women. Sci. Rep. 2017;7:11079. doi: 10.1038/s41598-017-10382-2.