Fish oil is commonly cited as being healthy for the heart, but is there any evidence for this claim? And if so, how much do you need to see the benefits?
There is, in fact, a large body of research suggesting that the long-chain omega-3 fatty acids found in fish oil can protect against cardiac events and mortality. Systematic review studies have shown that both fish consumption and supplementation with fish oil provide significant cardiac protection for both high-risk patients and average individuals. However there is still a great deal of confusion among the general public regarding the optimal dose and best sources of omega-3 fatty acids.
Omega-3 fatty acids are considered essential because your body cannot produce them on its own. For this reason, omega-3 fats should be considered as important to your diet as essential vitamins. The nutritionally relevant omega-3 fatty acids are alpha-linoleic acid (ALA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). ALA does not provide the same protection as the long-chain DHA and EPA.
DHA and EPA seem to work by several mechanisms, including integrating into cell membranes and increasing membrane fluidity. They also work as antioxidants to reduce inflammation. The functions of DHA and EPA in cardiac protection are likely to be different and complementary.
Though some plants produce omega-3s, vegetable sources can only provide ALA and not DHA or EPA. Though your body does convert some ALA to DHA and EPA, the conversion is very inefficient and vegetarians are typically advised to take DHA and EPA supplements to ensure adequate amounts. Algal DHA sources are available.
The optimal dose of fish oil depends on several factors, including genetics, baseline fish consumption and overall cardiac risk. There is some evidence that fish consumption is more effective than fish oil supplementation, and that adequate DHA and EPA can be achieved with diet alone if you consume two servings of oily fish per week.
High-risk patients, however, require more DHA and EPA for protection. The typical recommendation is for at least one gram per day, with even greater benefits seen at dosages of three grams per day or higher. For high-risk individuals, fish oil supplementation may be the best way to achieve adequate DHA and EPA intake.
To summarize, fish oil does protect against cardiac events and most people can achieve protection by consuming oily fish at least twice per week. Vegetarians and high-risk cardiovascular patients however should consider supplementing with at least one gram of DHA and EPA per day.
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