Mercury free fish oil is the only safe way to go. Do not buy a fish oil that has not been through the process called molecular distillation. This is to separate the impurities by weight from the pure oil. These impurities are lead, mercury and PCBs etc.
Mercury poison symptoms are psychological disturbances like short term memory loss, loss of self control etc and neurological problems such as headaches, vertigo and shaking and more.
It is unfortunate that the fish that we once ate two or three times per week, can no longer be consumed so freely, because of the pollution in the worlds oceans. This contamination has found it’s way into our fish supply. Making it unsafe to consume on a regular basis because of the contaminations mentioned up above.
Mercury free fish oil supplements are regarded as the best way of getting the health benefits of fish oil without the risk of being poisoned. After the oil has been purified by molecular distillation it is then the purest oil you can buy. Some people call it pharmaceutical grade fish oil. It is then put into soft gel capsules that have the advantage of being real easy to swallow.
If you have the time I always advocate going to the manufacturers website and checking how or if the oil has been purified. While you are there check to see what type of fish are being used for the oil. This is important because some fish are naturally rich in the omega 3 fatty acids. While others are low in them.
It also pays to check whether the fish are processed close by to where they are landed. This is to ensure that the fish oil is fresh. Some oil is transported long distances and sometimes it starts to go rancid. Some of the cowboys are quite adept at hiding this fact by adding flavors to the oil.
To summarize: I buy my oil from a company that uses Hoki, a type of fish naturally rich in the Omega 3 fatty acids DHA and EPA. And they process their oil close to where the fish are landed. So I know the oil is fresh. They tell me how the oil is purified, so I know it is the purest I can buy. And the best thing is, I know it is MERCURY FREE.