Flax oil versus Fish oil

Great question Grog!
Fish oils contain 2 crucial Omega 3 derivatives called EPA and DHA. These are essential components of brain cells, nerve cells, visual receptors, adrenal glands, sex glands etc.

If the body consumes flax oil (which is high in Omega 3's) then it has to perform this conversion process for itself. Most people should be able to convert fine (as long as all the necessary cofactors are present - i.e. eating a healthy balanced diet). But there is a possibility that a small percentage of the population may genetically be inefficient converters, for whom fish oil would be better than taking flax.

However fish oils are prone to going rancid very quickly (even more so than flax), and to compound this are seldom refrigerated.

Also there are pollution issues with fish oils, which organically grown flax doesn't have.

So Fish oil requires less conversion, but is more prone to pollutants, and spoiling.

Flax oil requires cofactors for efficient conversion (healthy balanced diet), but won't spoil as quickly and organically grown is free of pollutants.

Personally I would take flax oil mostly, and top it up by eating freshly caught, good-quality, low-temperature cooked oily fish a couple of times a week.

But either way, Fish oil and Flax are two of the healthiest things you can eat!