This seems to be the week of omega-3 oil publications. First there was a PATHETIC study whose authors claimed they had proved that O-3 supplements increase prostate cancer.
http://jnci.oxfordjournals.org/content/early/2013/07/09/jnci.djt174.abstract.
A boat load of scientists responded in the harshest terms, suggesting the author was trying to get attention (“the work of a junior professor”) and wondering how such a worthless study got published (“I have no idea how this study got accepted for publication”).
The study contradicted previous research but only because of it’s bad design and the investigators’ truly horrible interpretation. It does seem that they were quite beyond their depth, purposefully hoping to grab attention or using ephemeral data to tout a predetermined conclusion. The nature of the study design could sometimes identify an association between factors but it can never prove causation. This study was far too poorly designed to even prove an association.
One very simple and obvious point was that they did not determine where the omega-3 in the blood of their subjects came from (food or supplements). However, without that fundamental bit of information, the lead author was quoted “We’ve shown once again that the use of nutritional supplements might be harmful”.
Sources of the oil could be crucial factor. Toxic contamination of fish and some supplements is a problem.Environmental toxins (especially dioxins and pesticides) have been linked to prostate cancer. This was just one of many overlooked confounders. Heavy tobacco and alcohol intakes appear to lead to more aggressive prostate cancer. In their data, smoking and alcohol both lowered the risk. Their research seems have been conducted in “opposite land”.
The difference in blood levels between the highest and lowest groups was so small that the food the subject ate that day would change their grouping. The overall levels were so low that, if projected, the typical levels found among people living in countries where fish is most widely consumed (Scandinavia, Japan) would cause huge elevations in prostate cancer rates. That is not at all what we see. Other research has found 60-80% reduction in prostate cancer rates.The second study showed the importance of another fundamental issue overlooked by authors of the first. http://www.ncbi.nlm.nih.gov/pubmed?term=Garc%C3%ADa-Hernández%20VM%5BAuthor%5D&cauthor=true&cauthor_uid=23863036. This study, published in the International Journal of Food Science and Nutrition on July 18, compared the effects of different fish oil supplements on cholesterol and triglyceride levels.
People think of omega-3 oils as “anti-inflammatory”. That is reasonable. The counterbalance to “anti-inflammatory” or “anti-oxidant”. Oxidization is sort of biochemical rust. Cancer and heart disease are among the health problems linked to this type of biochemical damage. The word “oxidizing” might sound familiar as it is related to the gas we must breath to live, oxygen. Fish oils vary in all kinds of ways, including oxidation.
When an oil is rancid, it is oxidized. How do you keep that from happening? You keep the oil bottled up away from the oxidizing oxygen. Dark and cold storage also help but keeping air away from the oil is most important. That is why I prefer encapsulated fish oil whenever possible. But encapsulation is not a guarantee that that the oil was not oxidized or toxic before it went into the capsule.
The point of this study was to evaluate the differing consequences of ingesting differing quality oils. They found that highly oxidized fish oils RAISED cholesterol while low oxidized fish oils lowered cholesterol and triglyceride blood levels.
All in all, remember that the quality of the foods and supplements you consume is of paramount importance. Something that should be good, can be bad and too often is bad.