Krill Oil for Lupus (SLE)

Krill oil has been tested in lupus (SLE) in a single multicentre trial. It did what it was designed to do: 4 g a day raised the omega-3 index (the share of EPA and DHA in red blood cell membranes) from 4.57% to 7.17% after 4 weeks and 8.05% after 24 weeks, with no change on placebo [1]. What it did not do was lower lupus disease activity in the group as a whole [1].

Among the 9 patients per group with high disease activity at the start, scores fell more with krill oil at weeks 4, 8 and 16, but the difference was no longer significant at week 24 (p=0.54) [1]. That is a lead worth a larger trial, not evidence that krill oil treats lupus. The broader fish oil evidence is covered on our omega-3 for lupus page.

Omega-3 fatty acids help regulate inflammation and lipid metabolism, and low levels are common in lupus: 38% of patients in the krill oil trial started with an omega-3 index under 4%, and 88.5% were under 6% [1]. The trial authors note that an index under 4% is linked to higher cardiovascular risk and above 8% to lower risk, which matters in a disease where heart disease is markedly more common [1].

Krill oil carries its EPA and DHA mostly bound to phospholipids rather than triglycerides, and a network meta-analysis of 26 studies found it raised omega-3 levels more than fish oil at doses under 2,000 mg [2]. Krill oil is also rich in phosphatidylcholine (558 mg per 1 g capsule in the trial product) and contains small amounts of astaxanthin, an antioxidant pigment, typically 100-450 µg per gram [1].

The trial tested whether topping up omega-3 calms lupus, but it was sized to detect a change in the omega-3 index, not in disease activity, and the authors say it may have been too small to capture a clinical benefit [1]. On disease activity the result was mostly negative: the omega-3 index rose in nearly everyone, yet SLEDAI-2K scores, anti-dsDNA (an antibody that tracks lupus activity), complement C3 and C4, CRP, fatigue and pain scores did not differ from placebo overall [1].

Better absorption is also not better outcomes. The bioavailability advantage of krill oil comes from blood-level studies, not from trials of disease activity, and it was shown at doses under 2,000 mg; high-dose fish oil also raises the omega-3 index [2].

Patients took 4 g a day of krill oil concentrate as four 1 g capsules, two in the morning and two in the evening [1]. Each capsule held 322 mg of omega-3, so the daily dose supplied 1,288 mg of omega-3, including 772 mg EPA and 384 mg DHA [1]. The placebo was a blend of olive, maize, palm kernel and medium-chain oils [1].

This was a concentrate, so the gram figure on an ordinary krill oil bottle does not translate directly. Compare the EPA and DHA per serving with the trial's 772 mg and 384 mg. Everyone in the trial ate little seafood, avoided fatty fish during the study and took no other omega-3 supplement [1].

Salmon and colleagues randomised 78 adults with active lupus (SLEDAI-2K of 6 or more, 97% women) at 20 US sites to krill oil concentrate or placebo for 24 weeks, followed by a 24-week open-label extension [1]. The primary outcome was the omega-3 index, and it was met: krill oil raised it to 7.17% at week 4 and 8.05% at week 24 (each p<0.001), and patients who switched from placebo rose from 4.63% to 7.50% [1].

SLEDAI-2K scores did not differ between groups over the randomised period [1]. In the subset with a baseline score of 9 or more (9 per group), krill oil lowered scores more than placebo at weeks 4, 8 and 16 (p=0.04, 0.02 and 0.01), but not at week 24 (p=0.54) [1]. Physician global assessment and quality-of-life scores did not change [1].

Most lupus omega-3 research used fish oil. A 2020 meta-analysis of five RCTs (274 patients, 3 g a day or less) found omega-3 lowered disease activity by 0.9 SLEDAI points, rated low-certainty evidence [3]. A 2022 systematic review found that eight of ten trials measuring disease activity reported some improvement, but no benefit for kidney measures, C3, C4 or anti-dsDNA [4].

One 50-patient fish oil trial improved physician global assessment but not SLEDAI or fatigue scores [5]. Seen alongside these, the krill oil result fits the class pattern: a small, inconsistent signal on disease activity. Our omega-3 for lupus page covers those trials in detail.

The trial was powered for the omega-3 index, not disease activity, and the authors say a larger trial is needed to confirm any clinical benefit [1]. COVID-19 disruptions raised dropouts, leaving 25 krill oil patients with week-24 omega-3 data [1]. Only one dose was tested, and the krill oil and placebo were supplied by the manufacturer [1].

There are no trials comparing krill oil with fish oil in lupus, none in lupus nephritis, none in children or in pregnancy, and none measuring flares or steroid use as the main outcome.

Krill oil was well tolerated in the lupus trial, with no significant safety concerns over 48 weeks; adverse events were mostly mild or moderate, with 186 events in the krill oil group and 342 in the group first given placebo (which could switch to krill oil after week 24), and very few were thought to be treatment-related [1].

The main omega-3 risks come from larger cardiovascular trials. A meta-analysis of 11 RCTs (120,643 patients) found no overall increase in bleeding, though high-dose purified EPA raised the relative risk by 50%, an absolute increase of 0.6% [6]. Another meta-analysis linked marine omega-3 supplements to a 25% higher risk of atrial fibrillation, greater in trials using more than 1 g a day [7]. The lupus trial dose (about 1.3 g of omega-3 a day) is above that threshold [1].

In the trial, krill oil was added to a stable lupus treatment regimen without significant safety concerns [1]. It is an extra, not a substitute: the 2023 EULAR recommendations advise hydroxychloroquine for every patient with lupus, with steroids kept to the lowest dose and other medicines added as needed [9]. The interactions worth knowing are the general omega-3 ones: bleeding with blood thinners, and atrial fibrillation at higher doses [6][7].