Table 1. Summary depicting outcome of the reviewed studies.

CDRS = Children's Depression Rating Scale; CDRS-R = Children's Depression Rating Scale, Revised; CDI = Children's Depression Inventory; CGI = Clinical Global Impressions Scale; CES-D = Center for Epidemiologic Studies Depression Scale; BDI = Beck's Depression Inventory

Studies	No. of Patients	No. of patients who dropped out	Age range	Duration of       treatment	The scale used   to measure	Outcome	Side- effects
Nemets et al., 2006 [39]	20 (10 in omega-3 and 10 in placebo)	8	6-12 years	16 weeks	CDRS, CDI, CGI	7/10 had a greater than 50% reduction in CDRS scores and showed statistical significance	None
Arnold et al., 2017 [40]	64 (28 in omega-3 and 34 in placebo)	8	7-14 years	12 weeks	CDRS-R	CRDS-R score showed significant improvement in the combined PEP and omega-3 group but not in the other groups	None
Trebaticka et al., 2017 [41]	35 (17 in omega-3 and 18 in omega-6 placebo)	3	7-18 years	16 weeks	CDI	CDI score was reduced in the omega-3 group from 24.4 to 25.5% which showed s statistical significance	None
Trebaticka et al., 2020 [42]	58 (29 in omega-3 and 29 in omega-6 placebo)	2	7-18 years	16 weeks	CDI	CDI score in the Om3 group was observed after 10 weeks and showed the highest reduction from −7.6, −27.4% of baseline score which showed statistical significance	1/29 in the omega-3 group had frequent defecation (2–3x daily).
Fristad et al., 2016 [43]	69	15	7-14 years	12 weeks	CDRS-R	No significant improvement	1 or no S/E out of constipation, diarrhea, stomach-ache, increased/decreased appetite, burping, fishy breath, nausea
Gabbay et al., 2019 [44]	39 (21 in omega-3 and 13 in placebo)	12	12-19 years	10 weeks	CDRS-R, BDI, Beck Scale for suicidal ideations	CDRS-R score of ≤28 which meant no significant improvement	None
Van der Wurff et al., 2020 [45]	256 at baseline; 199 at 12 months (95 krill oil, 104 placebo)	57	Second-year high-school students (14-18 years)	12 months	CES-D	Not significant statistically	None