The omega-3s in krill oil are bound to phospholipids
Krill oil contains specialized fat molecules called phospholipids. The omega-3 fatty acids EPA and DHA are bound to these phospholipids. The phospholipid-bound forms of omega-3 fatty acids seem to have select advantages in how they are absorbed and utilized by the human body. A small number of studies have examined how phospholipid-bound fatty acids are used in comparison to triglyceride-bound forms.
For instance, a study published in November 2010 followed 113 healthy people, one third of whom were given krill oil, one third fish oil, and one third a placebo. The amount of omega-3s in the daily krill oil doses (543g, only 62% of the amount in the fish oil)) was significantly less than those in the fish oil (864g), but the results showed that the blood levels of omega-3s was the same.1
So you are likely to read on various Websites marketing fish oil that krill oil has less omega-3 fatty acids per dose. But now you know that, as far as your body is concerned, this makes no difference.
It is useful to note that the cell membranes of the human body (the covering around almost all cells) are made up of phospholipids – some of the same phospholipids found in krill oil (there are 69 of them). In this respect, the phospholipid forms of EPA and DHA found in krill oil are identical to the phospholipids in our own cell membranes.
More precisely, human cell membranes consist of two layers of phospholipids that surround the cytoplasm inside the cell, serving as a sort of skin separating the inner cell elements from the outer. The cell membrane determines which substances will be allowed to enter the cell and which will be allowed to leave the cell. The cell membrane is also where the receptors for almost all our vital operations exists. These receptors are the sites where our hormones and neurotransmitters bind (link) to carry out their actions on the cell. This includes neurochemicals such as serotonin, dopamine, insulin, and many others.