Chronic musculoskeletal pain contributes to mobility disability among older adults. Nutritional interventions, like omega-3 fatty acids, may help manage pain and improve physical function. Supplementation with krill oil may offer advantages to fish oil due to better absorption and additional nutrients. This pilot study aims to assess the feasibility of a clinical trial to determine the impact of krill oil supplementation on pain and function in older adults, informing future research.

Mobility is a critical factor in the maintenance of independence and quality of life of older adults. Chronic musculoskeletal pain contributes to mobility disability disproportionately among older adults. Current treatments for pain and functional decline are often ineffective and add to heightened risks of polypharmacy in older adults. As such, nutritional interventions can play a significant role in promoting health and longevity, managing pain, and enhancing physical function in older adults. Omega (ω)-3 polyunsaturated fatty acids (PUFAs) are essential nutrients that are well recognized for their anti-inflammatory and cardioprotective benefits, as well as their analgesic and anti-nociceptive properties. Most American adults do not meet the recommendations for ω-3 intakes, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), found primarily in seafood. Due to competing pathways, an elevated ω-6 to ω-3 ratio contributes to an overproduction of pro-inflammatory eicosanoids and the development of chronic diseases. A high ω-6:ω-3 ratio is associated with higher chronic pain prevalence and increased pain severity. Additionally, ω-3 PUFAs may play a role in the preservation of muscle and physical function in older adults. Low levels of ω-3s in blood are associated with reduced muscle strength, slower gait speed, and mobility disability among older adults. Considered largely safe and cost-effective, ω-3 supplementation may be crucial to increasing the intake of these essential nutrients and achieving optimal levels among older adults. Although the use of EPA and DHA has been incorporated into several guidelines, a scarcity of data has prevented the development of strong recommendations on the use of ω-3 supplementation for the maintenance of physical function in older adults, particularly those with chronic musculoskeletal pain. Krill oil has been recently proposed as an advantageous alternative to traditional fish oil supplements, due to a greater bioavailability of EPA and DHA and additional bioactive compounds. The goal of the proposed pilot study is to assess the feasibility of a 3-month randomized controlled trial to determine the effectiveness of krill oil supplementation on pain and physical function in older adults with chronic musculoskeletal pain. The investigators will enroll 40 older adults (≥60 years) who will be randomly assigned to 4 g krill oil (1,288 mg/d EPA+DHA, 0.45 mg astaxanthin, 320 mg choline) daily or matched placebo (mixed lipids without EPA and DHA). The investigators will determine the impact of krill oil supplementation on the omega-3 index (%EPA+DHA in erythrocytes), the ω-6/ω-3 ratio, and inflammatory biomarkers in blood, and obtain preliminary evidence of its impact on pain and physical function in older adults. The findings of this pilot will inform a future fully-powered randomized controlled trial by assessing the feasibility and acceptability of krill oil supplementation among older U.S. adults with chronic musculoskeletal pain.

Inclusion Criteria:

• Able to provide informed consent
• Stated willingness to comply with all study procedures and availability for the duration of the study
• Male or female, aged ≥60 years
• Exhibiting chronic musculoskeletal pain of the hip, knees, or lower back (>3 months)
• Average pain ≥4 on a 0-10 numeric rating scale
• Exhibiting moderate mobility limitations (Short Physical Performance Battery score 4-10)
• Ability to take oral supplements and be willing to adhere to the supplementation regimen
• Agreement to adhere to Lifestyle Considerations throughout study duration

Exclusion Criteria:

• Any known coagulation or bleeding disorders
• Standing regimen of anticoagulants or full-dose aspirin
• Regular use of opioids or high-dose NSAIDs
• Taking medication known to affect muscle (e.g. steroids)
• Taking selective serotonin reuptake inhibitors (SSRIs)
• Omega-3 supplementation within the past 3 months
• High consumption of fatty fish (>2 servings/week)
• Habitual supplementation with other complementary medicines/supplements that may affect the study results, including St. John's Wort
• Known allergy to seafood
• Clinically significant conditions: diabetes, severe cardiovascular disease, seizure disorders, uncontrolled hypertension (>150/90mmhg at baseline), cancer or cancer that has been in remission >5 years
• History of atrial fibrillation or atrial flutter
• Dementia
• History of smoking, alcohol abuse, or illicit drug use
• Ambulatory impairments which would limit the ability to perform physical function tests
• Treatment with another investigational drug or other intervention within 3 months
• Planning a surgical procedure during the study period
• Planning to permanently leave the area during the study period

From baseline through study completion, up to 12 weeks.

Adverse events were collected systematically from baseline through the 12-week final assessment by participant report and study staff review. The number at risk includes all randomized participants.

This was a pilot feasibility study with a small sample size and was not powered to detect definitive treatment effects on clinical or biomarker outcomes.