Study	Reason for exclusion
Alicandro 2013	Omega‐3 supplementation compared with large omega‐6 fatty acid source (germ oil) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).
Christophe 1992	Omega‐3 supplementation compared with large omega‐6 fatty acid source (borache oil) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).
EUCTR2006‐004155038‐BE	No published outcome data available.
Katz 1996	Parenteral (via blood stream), not enteral (oral) supplementation with omega‐3 fatty acids.
Koletzko 2000	Eligibility unclear, attempts made to contact author for further information, but no response received.
Kurlandsky 1994	Omega‐3 supplementation compared with large omega‐6 fatty acid source (sunflower oil) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).
Lloyd‐Still 2006	Omega‐3 supplementation compared with large omega‐6 fatty acid source (corn/soy) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).
NCT02518672	Omega‐3 supplementation with large omega‐6 fatty acid source (sunflower oil) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).
NCT02646995	Omega‐3 supplementation not compared to placebo. Fish oil compared to actively modified lipid.
NCT02690857	Omega‐3 supplementation with large omega‐6 fatty acid source (sunflower oil) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).
NCT03045198	Clinical trial currently still in enrolment by invitation.
O'Connor 2016	Omega‐3 supplementation with large omega‐6 fatty acid source (sunflower oil) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).
O'Sullivan 2011	Eligibility unclear. Attempts made to contact the author for further information , but no response received.
Pastor 2019	Study to identify a suitable approach for monitoring the incorporation of omega‐3 fatty acids in nutritional studies, not a comparison of omega‐3 fatty acids with control.
Romano 1997	Eligibility unclear, attempts made to contact author for further information, but no response received.
Starling 1988	Eligibility unclear, attempts made to contact author for further information, but no response received.
van Biervliet 2008	Omega‐3 supplementation compared with large omega‐6 fatty acid source (sunflower oil) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).
Vericel 2019	Omega‐3 supplementation with large omega‐6 fatty acid source (sunflower oil) rather than a neutral placebo that contains relatively little omega‐3 or omega‐6 fatty acid (olive oil).