Supplement research seems to go one way then another. I think it has to do with patient/subject selection.

Studies can also be maniupulated with the math... to give certain outcomes. Choice of subjects also is a huge factor. The most publicized manipulations were done with the drugs (stimulants) for children. One well known doctor discovered this in the study he was running, and went public.
The drug company tried to censor him in fact.
http://www.ahrp.org/infomail/04/12/03.php

Another really terrible discovery was that Merck created a phoney journal in Australia to promote success in fake studies on their drugs.

http://abcnews.go.com/Health/Drugs/s...1#.UY4kb0qU8s0

These are just two incidents. Supplements have long been targeted by mainstream medicine...because they hold potential
for lowering medical costs and creating less need for RX drugs.
It is also very difficult to control variables in the subjects, to get clear results. People are so unique, have unique dietary preferences, activity levels, etc.
Another factor is placebo control. Drug companies give elaborate tests to weed out subjects who have placebo reactions.
http://www.wired.com/medtech/drugs/m...urrentPage=all

Fish oil really helped my son go Ritalin free...for HIS ADHD. It was totally dramatic. From 60mg a day of Ritalin to ZERO, with a huge improvement in his skills in high school. Fish oil contains DHA which is involved in forming and repairing membranes and receptors for neurotransmitters in the brain. The EPA in fish oil has anti-inflammatory effects as well. I know a fellow who had severe autoimmune disease attacking his kidneys, and his doctor found a paper from China about this and put him on 13 grams (a huge dose) of fish oil... which reversed this kidney damage successfully. So yes, the EPA and DHA are ESSENTIAL fatty acids which we need. You can choose to do it with diet, or supplements. Krill oil is now becoming more popular because of its improved solubility and absorption.

It just, therefore, may be that in the future we will see other studies on fishoil or EPA and DHA that state their success with heart disease. Studies are only a starting point, not an end point when considering effects of drugs, treatments, and supplements, therefore.