Krill Oil Improves Mild Knee Joint Pain: A Randomized Control Trial

PLoS One. 2016 Oct 4;11(10):e0162769. doi: 10.1371/journal.pone.0162769. eCollection 2016.


Background: Krill oil is an edible oil extracted from krill, a small red-colored crustacean found in the Antarctic Ocean. The administration of krill oil is reported to mitigate inflammation in patients with cardiac disease, rheumatoid arthritis, or osteoarthritis. However, the effect of krill oil on mild knee pain has not yet been determined.

Objective: To assess the effect of krill oil on mild knee pain.

Design: A randomized, double-blind, parallel-group, placebo-controlled trial of fifty adults (38-85 years old) with mild knee pain attending the Fukushima Orthopedic Clinic (Tochigi, Japan) between September 2014 and March 2015.

Interventions: Participants were randomized to receive 2 g per day of either krill oil or an identical placebo for 30 days.

Outcomes: The primary outcome was improvement in subjective symptoms of knee pain as assessed by the Japanese Knee Osteoarthritis Measure (JKOM) and Japanese Orthopaedic Association score (JOA). Secondary outcomes included blood and urine biochemical parameters.

Results: Both the placebo and krill oil groups showed significant improvements in the questions in the JKOM and JOA questionnaires after administration. After the intervention, krill oil group showed more improvements than placebo group in two questions regarding the pain and stiffness in knees in JKOM. Controlling for age, sex, weight, and smoking and drinking habits, krill oil significantly mitigated knee pain in sleeping (P < 0.001), standing (P < 0.001) and the range of motion of both right and left knees (both P = 0.011) compared to placebo. Krill oil administration raised plasma EPA (P = 0.048) and EPA/AA ratio (P = 0.003).

Conclusion: This study indicates that krill oil administration (2 g/day, 30 days) improved the subjective symptoms of knee pain in adults with mild knee pain.

Trial registration: UMIN-CTR; ID UMIN000014413.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • Anti-Inflammatory Agents / administration & dosage
  • Anti-Inflammatory Agents / therapeutic use
  • Biomarkers
  • Euphausiacea / chemistry*
  • Female
  • Humans
  • Knee Joint / drug effects*
  • Knee Joint / physiopathology*
  • Male
  • Middle Aged
  • Oils / administration & dosage
  • Oils / therapeutic use*
  • Osteoarthritis, Knee / diagnosis
  • Osteoarthritis, Knee / drug therapy
  • Pain / drug therapy*
  • Pain Management
  • Pain Measurement
  • Phenotype
  • Therapeutics


  • Anti-Inflammatory Agents
  • Biomarkers
  • Oils

Grants and funding

This study was funded by Sunsho Pharmaceutical Co., Ltd. (Fuji, Shizuoka, Japan). The funders provided test supplements and held the key secret until the included data was finalized. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. This work was also supported by the Grant of Cross-Ministerial Strategic Innovation Promotion Program (SIP).