I continue to be concerned about how fish oil is almost always portrayed in a positive light. There are all kinds of statements being made about the benefits of fish oil without looking at the research.
For example, you often hear that fish oil helps with allergies. Yet this meta-analysis done last year concludes that:
"Contrary to the evidence from basic science and epidemiological studies, our systematic review and meta-analysis suggests that supplementation with omega 3 and omega 6 oils is probably unlikely to play an important role as a strategy for the primary prevention of sensitization or allergic disease."
Of course you can find different studies (and different meta-analyses) that say the opposite. Still, if fish oil was 100% effective, then wouldn't any meta-analysis find this to be true?
One problem with fish oil may be absorption. Krill oil has become popular in recent years as a substitute for fish oil. The omega-3 in fish oil comes in a triglyceride form, while the omega-3 in krill oil comes in phospholipid form. The body stores omega-3 in phospholipid form, so this is why krill oil may result in better absorption. A recent study showed that essential fatty acid deficiency is better treated by omega-3 phospholipids than omega-3 triglycerides.
Over on the Eades blog a couple years back, this portion from the book "Brain Trust" was highlighted:
"Krill oil also naturally contains high concentrations of a number of healthy antioxidant compounds that not only protect the krill oil but also protect your brain… These include vitamin A, vitamin E, astaxanthin, and canthaxanthin. Astaxanthin forms a special linkage with EPA and DHA, thus making it more readily available to the body than other antioxidants on the market. For this reason, while consumption of fish oil breaks down and therefore decreases your body’s antioxidant concentrations, krill oil actually increases levels of antioxidants in the body."
If absorption is a key issue, then a couple of other things make sense. Let's assume that some of the omega-3s in fish oil get absorbed by the body. Studies show that when mothers-to-be supplement with fish oil, they can reduce the risk of asthma and allergy in their children. I think the key here is that the mother can absorb part of the fish oil omega-3s in her cells, but then that omega-3 is now in phospholipid form which can be readily absorbed by the fetus. This would also explain why fish oil omega-3s consumed during pregnancy have a much greater impact than just giving infants fish oil in formula.
To be fair, this study says the opposite: that fish consumption during infancy is more important than maternal fish intake during pregnancy. However, the study does point out that it is the intake of fish and not just fish oil that is important. This could be another absorption issue: just taking fish oil by itself may not be absorbed as well compared to eating whole fish.
The absorption issue could explain some other findings. In this study , it showed that preschoolers with atopy have lower omega-3 levels in their red blood cells. However, just giving children fish oil does not in general improve atopic conditions. If the fish oil omega-3 isn't being absorbed into the cells, then there will be no effect on atopy.
Regardless of what the studies say, fish oil just doesn't agree with me. If I take some, it puts me in a mental fog for about 24 hours. Clearly, I'm not absorbing it. Since I don't like seafood, I may give krill oil a try this month.
One more related note: I found this interesting blog post about krill oil and absorption. A mother who was breastfeeding saw that her baby was developing eczema. The mother began taking krill oil, and within a week the baby's eczema went away! (Check out the pictures) This connects with what I've discussed in this post: the phospholipid omega-3 in krill oil is readily absorbed by the cells, and then it is given to the baby in this form.