I'm about to do a blog post that talks about this, but the cost differences are often not what you think they are. As with any supps, you have to compare actual labels. Quality issues not withstanding, as mentioned prior, do you actually look at the % of active lipids? There is right out of my Fat Loss Revealed ebook:
Studies have used doses that are quite variable, so no exact dose is known in terms of optimal effects on fat loss, but 6 - 10 g/day (assuming 30% EPA + DHA) is a starting point. So, a 1000mg (1g) softgell cap of fish oil, would be approximately 180mg of EPA and 120mg of DHA, assuming the general rule of 30% total active lipids. Fish oil comes as 60/40 EPA to DHA.
I would recommend at least approximately 6g (6 1000mg caps) fish oils giving you a total of 1800mg of active lipids per day assuming 30% of 6g is EPA and DHA, but you must read the labels for exact numbers. Looking at specific brands for example:
Puritan's Pride uses a 1200mg cap, each containing 360mg total active lipids. You would need 5 caps to = 1800mg total active lipids.
Looking at The Life Extension Foundation: They use a 1000mg cap that gives 600mg total active lipids per cap, which means you would need 3 caps to equal the recommended 1800mg above.
Looking at Nordic Naturals, they use a 1000mg cap that gives a total of 275mg of active lipids per cap, so you will need 6-7 caps per day
Looking at Carlson's, they use a 1000mg cap that gives a total of 320mg of active Omega-3 lipids, so you would need 5-6 caps of this product.
