Omega-3 fatty acids are long molecules which consist of a chain of carbon and hydrogen atoms with an acid group at the omega end. The three most important omega-3 fatty acids for human physiology are unsaturated fatty acids. They have been implicated in a variety of health benefits and are considered essential fatty acids because our body cannot produce them on its own. The three important omega-3 fatty acids in human health are alpha linoleic acid (ALA) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) (1).
Dietary Sources Of Omega-3 Fatty Acids
The main source of dietary omega-3 fatty acids are oily fish like trout, salmon, mackerel, sardines and herring. Many health experts agree that two portions of 140g (5 oz.) of oily fish should contain a sufficient amount of omega-3 fatty acids to achieve the benefits that they provide. The majority of people do not eat enough oily fish in the diet. This may be a contributing factor as to why so many people develop the conditions that omega-3 fatty acids help to prevent. This may be in part because not enough people know about how important omega-3 fatty acids actually are (2).
Once people are aware however, it may still be difficult for them to obtain the correct amount of omega-3 fatty acids from their diet. For this reason, there are also omega-3 supplements available, which make meeting the requirements a bit cheaper and easier (3). There are vegetarian and vegan options available for those who don't wish to consume any fish products at all.
Another problem is that many people take in too many omega-6 fatty acids, which distorts the ratio between omega-3 and omega-6 fatty acids in the body. Omega-6 fatty acids can actually antagonize the effects of omega-3 fatty acids when the ratio is incorrect (4).
Western diets are very high in omega-6 fatty acids - which are present in poultry, eggs, vegetable oils, nuts and seeds (5). This is not to say that a person should avoid these foods, but rather that they should make sure that they are not excessively overeating them.
To get the right amount of omega-3 fatty acids, a person needs to eat two portions (5 oz each) of oily fish every week. Another option is to take omega-3 supplements. People should also be careful that they are not taking in too many omega-6 fatty acids, as this can reduce the health benefits of omega-3 fatty acids.
Why Are Omega-3 Fatty Acids So Important?
Omega-3 fatty acids perform a variety of roles in the body. One of the most important roles that they have been implicated in is controlling the fluidity of the cell membrane. This is an incredibly important function because it controls which compounds, such as chemical messengers, go in and out of the cell (6).
They also act to inhibit the arachidonic acid pathway. When cells or tissues are injured, they produce a substance called arachidonic acid from their membranes. This arachidonic acid is converted into other substances called prostaglandins and leukotrienes. Prostaglandin stimulates inflammation and blood clotting and leukotrienes stimulate bronchoconstriction or a tight chest. Omega-3 fatty acids compete for the same proteins that convert arachidonic acid into these substances so they slow the release down. This helps to reduce inflammation which reduces the risk of developing certain chronic diseases (7).
Omega-3 acids and their byproducts are an important part of a cell membrane. They help cells to communicate with one another. Omega-3 acids also mitigate signals of chronic inflammation and so they reduce the risk of developing the associated conditions.
Omega-3 Fatty acids And Cognitive Health
Apart from the functions mentioned above, omega-3 acids have specific roles in brain development and protection. They are also converted into chemical messengers by nerve cells in the brain in order to activate certain receptors on other nerve cells. This allows nerve cells to form connections which is how memories are created. Some of these signals are even able to stimulate the regeneration of brain tissue albeit on a small scale.
In terms of membrane fluidity, they specifically have a role in the functioning of neurotransmitters - protein chemical messengers in the brain. Changes in levels of omega-3 fatty acids have been associated with changes in the reuptake and breakdown of certain neurotransmitters which have important functions in the brain.
There is also clear evidence to show that omega-3 fatty acids are essential for brain development in a growing fetus. The mechanisms of this are not well understood, but it is thought to be because of the structural role that omega-3 fatty acids have in creating new cells especially for the brain (8).
Omega-3 fatty acids can both act as a chemical signal, or enhance the action of other chemical signals, which helps the brain cells to form more connections with one another. This improves brain plasticity - memory formation and knowledge storage.
How Omega-3 Fatty Acids Aid Heart Health
Heart cells able to contract because when they receive the relevant electrical signal, channels in their membranes open to allow calcium ions in. Calcium ions are a vital component for the interactions between the proteins that pull together to cause a heart contraction. In individuals who have arrhythmia, this process is disrupted. By restructuring the heart cell membranes to improve their calcium intake, omega-3 fatty acids help to reverse the contributing factors to certain arrhythmias.
As mentioned earlier, by inhibiting the formation of clotting factors, omega-3 fatty acids also reduce the risk of thrombus (clot) formation. They also reduce the number of sticky proteins on the inside of vessels, which otherwise cause blood cells to stick to them and form a thrombus. Thrombus formation is a major risk for a heart attack because that thrombus can block vessels in the heart which starves it of oxygen. Therefore, there it is recommended to increase your Omega-3 in order to help reduce the risk of coronary heart disease (9).