Concentration
This refers to the exact quantity of the most important omega-3 fatty acids in a capsule, i.e. the DHA and EPA concentration. A 1.000 mg fish oil capsule may only contain half that amount, or even less, in DHA and EPA, the rest consisting of, for example, vegetable oil or omega-6. It is not because a capsule weighs 1.000 mg that it actually contains 1.000 mg of pure omega-3 fatty acids. Always check the amount of DHA and EPA per capsule.
Dosage
The dosage depends on the EPA and DHA concentration. Higher concentrations of EPA or DHA require fewer capsules per day to meet your daily requirement. With some brands you require four, six, even up to ten capsules per day in order to reach the necessary daily dose of EPA or DHA.
Cost
Don’t be fooled by the cost of a pack of 30, 60 or 90 capsules. Calculate how many capsules you need to take each day and how long a package will last. Cheaper products soon become expensive if you require four or more capsules per day.
Content
Check the ingredients in each capsule. Many manufacturers use sunflower or groundnut oil, or even saturated fats or other fillers that might well be unhealthy, in addition to (small) amounts of EPA and DHA.
Impact on the environment
Choose fish or algae oil derived from non-endangered species and a product that has been purified in an environmentally friendly way. It is advisable to opt for smaller fish species (mackerel, anchovies). Tuna is an endangered species, which also contains considerable amounts of mercury and PCBs. The optimal guarantee is an EMAS certificate (Eco-Management and Audit Scheme, approved by the European Parliament).