Fish oil, a supplement fish in omega-3 fatty acids, has a variety of benefits, from boosting cognitive function to protecting your heart. It may also provide benefits for your joints, specifically your knees. To get the highest amount of fish oil in your diet, choose fatty fish such as mackerel, albacore tuna and salmon. To avoid side effects, don't consume more than 3 grams of omega-3 fatty acid supplements -- including fish oil capsules -- daily, recommends the University of Maryland Medical Center.
Getting adequate amounts of fish oil in your diet may help prevent painful arthritis in your knees that may curtail athletic and fitness activities as well as everyday movements such as walking and climbing stairs. A study in the May-June 2005 issue of "La Clinica Terapeutica," an Italian medical journal, indicates that omega-3 fatty acids may improve symptoms associated with rheumatoid arthritis and decrease your need for pain medication.
Knee inflammation is generally associated with arthritis, but it may also occur if you injure your knee -- twisting, wrenching and over-stretching may trigger knee inflammation that can cause pain. Fish oil is a good option for reducing inflammation. Research published in the June 2011 issue of "Phytotherapy Research" correlates omega-3 fatty acids in linseed oil with decreased inflammation in the joints. Presumably, you would derive the same benefits from the omega-3 fatty acids in fatty fish.
Muscle pain from knee joint flexion and use of the quadriceps may occur in any number of athletic activities, but consuming fish oil may help reduce that pain. Evidence available in the March 2009 "Clinical Journal of Sport Medicine" suggests that consuming omega-3 fatty acids relieves pain within 48 hours of exercise. This makes fish oil potentially effective for easing delayed-onset pain in muscles surrounding the knees.
Fish oil is good for helping the knees; too little in the diet may contribute to knee cartilage loss. The body needs a balance of omega-3 and omega-6 acids, and too many omega-6 acids may trigger bone marrow lesions according to a study in the May 2008 issue of the journal "Osteoarthritis and Cartilage." Researchers note that you should consume more fish oil to help keep the correct balance of fatty acids.