A recent international trial has delivered striking results for people on dialysis, showing that daily fish oil supplements can sharply reduce serious heart-related events, according to the researchers.
Patients taking fish oil had far fewer heart attacks, strokes and cardiac deaths than those on placebo, which they said was especially important because dialysis patients face extreme cardiovascular risk and few proven treatment options.
The findings mark a rare breakthrough in kidney care.
The research was co-led in Australia by Monash Health and the School of Clinical Sciences at Monash University.
The study – the PISCES trial – followed 1 228 participants receiving dialysis at 26 sites across Australia and Canada. The findings were unveiled at the American Society of Nephrology Kidney Week 2025 and released at the same time in The New England Journal of Medicine.
Participants who took four grams of fish oil each day showed striking improvements: the supplement contained the natural omega-3 fatty acids EPA and DHA. Compared with those given a placebo, these patients experienced a 43% reduction in serious cardiovascular events.
The outcomes measured included heart attacks, strokes, cardiac-related deaths and vascular-related amputations.
Adjunct Professor Kevan Polkinghorne, a nephrologist at Monash Health and adjunct in the School of Clinical Sciences, led the Australian portion of the trial.
“Patients on dialysis have extremely high cardiovascular risk, and very few therapies have been shown to reduce that risk,” he said. “In a field where many trials have been negative, this is a significant finding.
“Dialysis patients typically have much lower levels of EPA and DHA than the general population. This may help explain the magnitude of benefit observed in this group.”
Findings apply only to dialysis patients
Polkinghorne emphasised that the results are specific to people receiving haemodialysis for kidney failure. He cautioned that the findings should not be extended to healthy individuals or other patient populations.
The Australian arm of the trial was funded by the National Health and Medical Research Council (NHMRC). Overall trial co-ordination was managed by the Australasian Kidney Trials Network (AKTN). About 200 Australian patients took part in the study, including 44 who were treated at Monash Health.
International leadership of the PISCES trial came from Professor Charmaine Lok and her colleagues at the University Health Network in Toronto and the University of Calgary.
Study details
Fish-Oil Supplementation and Cardiovascular Events in Patients Receiving Haemodialysis
Charmaine Lok, Michael Farkouh, Brenda Hemmelgarn, Louise Moist, Kevan Polkinghorne, George Tomlinson, Paul Tam, Marcello Tonelli and Jacob Udell.
Published in The New England Journal of Medicine on 7 November 2025
Abstract
Background
Cardiovascular disease is the leading cause of death in patients receiving haemodialysis, yet effective preventive therapies remain limited. Supplementation with n−3 polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may have cardiovascular benefits in the general population, but efficacy among patients receiving haemodialysis is uncertain.
Methods
In a double-blind, randomised, placebo-controlled trial conducted at 26 sites in Canada and Australia, we assigned adult patients receiving maintenance haemodialysis to daily supplementation with fish oil (4 g of n−3 polyunsaturated fatty acids [1.6 g of EPA and 0.8 g of DHA]) or corn-oil placebo. The primary end point was a composite of all serious cardiovascular events including sudden and non-sudden cardiac death, fatal and nonfatal myocardial infarction, peripheral vascular disease leading to amputation, and fatal and nonfatal stroke. Secondary end points included extension of the primary end point to include non-cardiac causes of death, the individual components of the primary end point, and a first cardiovascular event or death from any cause.
Results
Between November 28, 2013, and July 22, 2019, a total of 1228 participants underwent randomisation; 610 were assigned to the fish-oil group and 618 to the placebo group. During 3.5 years of follow-up, the rate of serious cardiovascular events was significantly lower in the fish-oil group than in the placebo group (0.31 vs. 0.61 per 1000 patient-days; hazard ratio, 0.57; 95% confidence interval [CI], 0.47 to 0.70; P<0.001). The rate of the extended primary end point that included non-cardiac causes of death appeared to be lower in the fish-oil group than in the placebo group, with a hazard ratio of 0.77 (95% CI, 0.65 to 0.90). The hazard ratio for cardiac death was 0.55 (95% CI, 0.40 to 0.75); for fatal and nonfatal myocardial infarction, 0.56 (95% CI, 0.40 to 0.80); for peripheral vascular disease leading to amputation, 0.57 (95% CI, 0.38 to 0.86); for fatal and non-fatal stroke, 0.37 (95% CI, 0.18 to 0.76); and for a first cardiovascular event or death from any cause, 0.73 (95% CI, 0.61 to 0.87). Adherence to the trial regimen and the incidence of adverse events did not differ meaningfully between the groups.
Conclusions
The rate of serious cardiovascular events among participants receiving maintenance haemodialysis was lower with daily supplementation with n−3 fatty acids than with placebo.
See more from MedicalBrief archives:
Omega-3 fish oil supplements linked with lower CVD risk
Lawsuits take on fish oil supplement over heart health claims
Fish oil supplements may increase heart conditions risk – global study