Both fish oil and flax seed oil are high in omega 3 essential fatty acids and flax seed oil is a great essential fatty acid supplement for vegetarians as well as anyone who would prefer to have flax seed oil as opposed to fish oil as their supplement and it is recommended for those who have high blood pressure.
Fish oil and flax seed oil are both high in omega 3 essential fatty acids. Fish oil usually contains both EPA and DHA whereas flax seed oil usually contains just ALA. ALA however is converted by the body into EPA and DHA. EPA and DHA are the types of omega 3 essential fatty acids which the body uses more often but normally most people are able to break this down and don't experience problems no matter what type of supplement they take.
Diabetics though normally find it difficult to break the ALA in flax seed oil down into EPA and DHA and for diabetics it is therefore better to get their fatty acid supplement in the form of fish oil which already contains both these substances for immediate use by the body.
People suffering from schizophrenia also may not be able to break down ALA into EPA and DHA and are therefore also encouraged to use fish oil as opposed to flax seed oil supplementation.
People who suffer from high blood pressure on the other hand would be wise to use a flax seed oil supplement as opposed to a fish oil supplement as fish may contain a high level of mercury which is dangerous for those suffering from high blood pressure and both flax seed and fish oil contain the omega 3 fatty acids which are needed to reduce blood pressure levels.
Flax seed oil is also probably preferable for those suffering from Irritable Bowel Syndrome. Studies in animals seem to show that ALA probably works better for this disorder than EPA and DHA separately and the side effects of using fish oil supplements are often similar to those symptoms experienced by people suffering from Irritable Bowel Syndrome.
On the whole the benefits you will obtain from fish oil or flax seed oil supplementation are the same. Both of these supplements contain high levels of omega 3 essential fatty acids which are essential for mental and physical wellbeing. These omega 3 fatty acids are known to reduce the risk of heart disease, high cholesterol, stroke, weight loss, arthritis, osteoporosis and many other benefits.
On the whole the choice of whether you have fish oil or flax seed oil supplementation is up to you or your normal diet preferences, if you are a vegetarian. However there are certain circumstances such as diabetes, schizophrenia, IBS or high blood pressure where one form of supplementation is better than another.