Probably one way of determining the amount of omega-3 you take also depends on your intake amount of omega-6 fatty acids. You can find omega-6 acids from common vegetable cooking oils like canola oil, soybean oil, corn oil and sunflower oil. These are present in a lot of food available in the supermarket, most especially the processed ones.
We need to balance the intake of omega-3 and omega-6 since the latter compete for enzymes with the former. And too much omega-6 could result to inflammation which can later affect the heart. The effects of omega-6 counters the benefits omega-3 gives the heart. According to some experts, having a ratio of 2 to 1, omega-6 to omega-3, would be the best combination to have. The ratio properly balances the effects of both essential fatty acids.
Other doctors recommend taking only a minimal quantity of say 2.5 grams per day or even lower depending on how much it will take to maintain your state of health. Taking too much might result to bodily imbalance which can become harmful to your overall health. However, if you have a certain disease or existing condition like, your doctors might prescribe you a stronger daily dosage of fish oil to help you cope and regain your health.
To sum up, the quantity of fish oil you should take depends on your state of health, diet, age, among other factors. Consulting your doctors would be the best move before starting on a daily intake of fish oil.