Flaxseed and fish oil are good sources of omega 3 fatty acids, whcih have been shown in some studies to be antithrombotic (blocks the formation of clots) and anti-inflammatory. That is why they can improve the circulation and have been shown (at least in some studies) to decrease joint pain in rheumatoid arthritis. These should be differentiated from omega 6 fatty acids which are found in most seeds, vegetable oil, and meat which can have the opposite effect.