data is based on self reported questionnaire of whether or not participants "regularly use" fish oil, but unfortunately does not quantify the amount of intake.
"For participants with a diagnosis of a known cardiovascular disease, regular use of fish oil supplements was beneficial"
Furthermore, the ratio of omega-3 to omega 6 in ones diet seems to be a stronger correlator with outcomes vs asolute levels of omega-3 or fish oil consumption.
Overall, the data on the benefits of fish oil supplementation have been mixed (many studies reporting benefits, some studies reporting no benefit, very few studies reporting negative associations) in healthy populations.
It should also be noted that not all fish oil is the same, and not even all omega 3s are the same. the specific omega 3s that have had the most success in trials are eicosapentaenoic and docosahexaenoic acid.
Here is a brief summary of some recently published works
(2018)
"Supplementation with n−3 fatty acids
did not result in a lower incidence of major cardiovascular events or cancer"
(2020 RCT)
This randomized trial examines the effects on cardiovascular outcomes of a carboxylic acid formulation of EPA and DHA (omega-3 CA) with documented favorable effects on lipid and inflammatory markers in patients with atherogenic dyslipidemia and high cardiovascular risk.
jamanetwork.com
"Among statin-treated patients at high cardiovascular risk, the addition of omega-3 CA, compared with corn oil, to usual background therapies resulted in
no significant difference in a composite outcome of major adverse cardiovascular events."
Beneficial Outcomes of Omega-6 and Omega-3 Polyunsaturated Fatty Acids on Human Health: An Update for 2021 (2021 review)
"Intervention trials using EPA + DHA indicate
benefit on CVD mortality and a significant inverse linear dose–response relationship has been found between EPA + DHA intake and CVD outcomes"
(2022)
Objective To investigate whether vitamin D and marine derived long chain omega 3 fatty acids reduce autoimmune disease risk. Design Vitamin D and omega 3 trial (VITAL), a nationwide, randomized, double blind, placebo controlled trial with a two-by-two factorial design. Setting Nationwide in...
www.bmj.com
"omega 3 fatty acid supplementation with or without vitamin D
reduced the autoimmune disease rate by 15% (not statistically significant)"
(2022)
Background Despite early interest in the health effects of polyunsaturated fatty acids (PUFA), there is still substantial controversy and uncertainty on the evidence linking PUFA to cardiovascular diseases (CVDs). We investigated the effect of plasma concentration of omega-3 PUFA (i.e...
bmcmedicine.biomedcentral.com
our Mendelian randomization findings
do not support a protective role of circulating PUFA concentration on the risk of CVDs. However, horizontal pleiotropy via lipoprotein-related traits could be a key source of bias
(2022 meta analysis)
"supplementation of n-3 PUFAs in adults can improve CRP, TNF-α, and IL-6 concentrations under various health conditions.
n-3 PUFAs can be recommended as adjuvant anti-inflammatory agents."
(2023)
"Among individuals with increased 10-year risk for ASCVD,
rosuvastatin 5 mg daily lowered LDL-C significantly more than placebo, fish oil, cinnamon, garlic, turmeric, plant sterols, and red yeast rice."
(2023 meta analysis)
"Higher seafood derived n-3 PUFA levels were associated with
lower risk of incident [chronic kidney disease], although this association was not found for plant derived n-3 PUFAs."
(2023 review)
ment of mild cognitive decline and Alzheimer's disease. Supplementation with docosahexaenoic acid (DHA) in randomized controlled trials (RCTs) in those with mild cognitive impairment showed benefit on cognitive decline, whereas there was no benefit in Alzheimer's disease. In cognitively healthy...
journals.lww.com
"Of 15 RCTs in cognitively healthy individuals age more than 55 years,
seven reported benefit, whereas eight did not"
(2023 review)
"LC ω-3 PUFA supplementation showed
beneficial effects on [cardiovascular] death (RR: 0.94; 95% CI: 0.88, 0.99;
P = 0.029) and fatal or nonfatal MI (RR: 0.83; 95% CI: 0.72, 0.95;
P = 0.010). RCTs on EPA alone showed better results for 3-point [major adverse cardiovascular events], [cardiovascular] death, and fatal or nonfatal [myocardial infarction]. However, the benefits were not found for fatal or nonfatal stroke, all-cause mortality, and hospitalization for heart failure. Of note,
studies of both the EPA/DHA combination and EPA alone showed a significant increase in risk of new-onset atrial fibrillation."