Table 3.

Summarized studies investigating the omega-3 effects on microbiota composition in stressed and depressed animal models.

Studies	Studied Population	Diets	Main Outcomes
Robertson et al. (2017) [92]	C57BL/6J mice	Control standard chow or omega-3 PUFA supplemented diet contained 1 g EPA + DHA/100 g diet (O3+), or omega-3 PUFA deficient diet (O3−)	O3+ diet leads to an increase of the abundance of Bifidobacterium and Lactobacillus genera; enhances cognition and dampens HPA axis activity.
Pusceddu et al. (2015) [99]	Maternally separated female rats	Saline water or EPA/DHA 0.4 g/kg/day (low dose) or EPA/DHA 1 g/kg/day (high dose)	Long-term administration of high dose of EPA/DHA leads to restoration of the normal Firmicutes/Bacteroidetes phyla ratio; increases level of the butyrate-producing bacteria Butyrivibrio genus; increases the levels of several members of anti-inflammatory Actinobacteria phylum (such as Aerococcus genus); decreases the abundance of pro-inflammatory Proteobacteria phylum (such as Undibacterium genus); and decreases other pro-inflammatory bacteria genera including Akkermansia and Flexibacter.
Davis et al. (2016) [103]	Socially isolated C57BL/6J mice	Control diet (modified AIN-93G diet composed by soybean, soy, and corn oils) or modified AIN-93G diet with the addition of 0.1% by weight DHA or modified AIN-93G diet with the addition of 1% by weight DHA	Addition of DHA leads to sex-specific compositional shifts within the Firmicutes phylum, more accentuated in male than in female, with an increase of Allobaculum genus (SCFAs-producing bacteria) and a decrease of Ruminococcus genus (involved in tryptophan metabolism).