Joint pain has a negative effect on quality of life by limiting daily physical activity, and can lead to reduced work capacity, chronic stress, sleep problems, fatigue and reduced social life. Many people with joint pain find that taking fish oils reduces joint pain, and this may be related to an anti-inflammatory effect of omega-3 polyundaturated fatty acids (PUFAs). The investigators have recently shown that another group of fatty acids, that is, omega-11 monounsaturated fatty acids (MUFAs), have a strong anti-inflammatory effect in rats with chronic inflammation. Therefore, the investigators want to continue researching health effects of omega-11 MUFAs and investigate whether an anti-inflammatory effect can also be observed in people with joint pain. Omega-11 MUFAs including cetoleic acid (C22:1n-11) are found in high amounts in oils from certain fish species such as herring. In this study the effects of marine oils given as supplements (capsules) will be investigated in adults with joint pain, with particular focus on changes in pain and stiffness in joints and on levels of selected inflammation markers in blood samples. The study has three arms; one group receives herring oil with regular content of omega-11 MUFAs, one group receives herring oil with high content of omega-11 MUFAs, and a third group receives a commercail fish oil that does contain omega-11 MUFAs. The omega-3 content is similar in all intervention capsule types.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
150
Capsules containing herring oil concentrate, taken daily for 6 months.
Capsules containing omega-11 concentrate, taken daily for 6 months
Capsules containing a control oil, taken daily for 6 months.
Joint inflammation
Inflammation will be assessed using three approaches: (1) The number of tender and swollen joints among the 28 joints included in the DAS28, a validated disease activity measure for rheumatoid arthritis; (2) ultrasound findings in tender and/or swollen joints; and (3) circulating levels of the inflammatory markers TNF-alpha and IL-6. Both the joint examination and ultrasound assessment will be performed by a rheumatologist. Ultrasound-detected synovitis will be assessed using the EULAR-OMERACT semiquantitative scoring system, with grey-scale synovitis and power Doppler signal graded from 0 to 3, where 0 represents the lowest grade and 3 the maximum grade.
Time frame: Change between baseline and endpoint (6 months)
Self-assessment of joint health using the RAID questionnaire
Study participants record their perceptions of their joint health, diet, and physical activity. A modified version of the validated Rheumatoid Arthritis Impact of Disease (RAID) questionnaire will be used to assess participants' self-reported joint health. The RAID comprises seven domains: pain, physical function, fatigue, sleep, physical well-being, emotional well-being, and coping. Each domain is rated on a 0-10 scale, with 0 indicating no symptoms and 10 representing the worst possible symptoms.
Time frame: Change between baseline, 3 months and endpoint (6 months)
Concentration of interleukin-6 in blood
Time frame: Change between baseline, 3 months and endpoint (6 months).
Concentration of TNF-alpha in blood
Time frame: Change between baseline, 3 months and endpoint (6 months).
Quantification of fatty acid contents in leucocytes
Leucocytes are isolated from heparine blood.
Time frame: Change between baseline, 3 months and endpoint (6 months)
Serum concentration of total cholesterol
Total cholesterol is measured in fasting samples
Time frame: Change between baseline, 3 months and endpoint (6 months)
Serum concentration of LDL-cholesterol
LDL-cholesterol is measured in fasting samples
Time frame: Change between baseline, 3 months and endpoint (6 months)
Serum concentration of HDL-cholesterol
HDL-cholesterol is measured in fasting samples
Time frame: Change between baseline, 3 months and endpoint (6 months)
Change from baseline in percent body fat
Percent body fat will be measured using bioimpedance
Time frame: Change between baseline, 3 months and endpoint (6 months)
Serum concentrations of amino acid and their metabolites
Time frame: Change between baseline and endpoint (6 months)
Serum concentrations of one-carbon metabolites
Time frame: Change between baseline and endpoint (6 months)
Serum concentration of non-esterified fatty acids
Time frame: Change between baseline, 3 months and endpoint (6 months)
Erythrocyte sedimentation rate
Time frame: Change between baseline, 3 months and endpoint (6 months)
Serum concentration of anti-Cyclic Citrullinated Peptide
Time frame: Change between baseline and endpoint (6 months)
Serum concentration of rheumatoid factor
Time frame: Change between baseline and endpoint (6 months)
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