The us population is deficient in omega 3 fatty acids. These are essential for proper production of neurotransmitters (brain chemicals). There are 2 ways to get these. 1) eat pacific cold water salmon 5 times a week, or 2)take a high quality omega 3 supplement.
Look for molecular distilled ( removes mercury ) and a 2:1 ratio of epa to dha. You should shoot for at least 3-5000mg of epa/dha total per day. Increasing omega 3 supplementation has been linked to improved brain function (concentration), decreased risk of alzheimers, improved joint function, lower cholesterol, and a decreased risk of sudden cardiac death. Check out brainplace.com for more info.