Not only both Omega 3 and Omega 6 are essential components for human body, but to have them balance in the input is also very important. Why is that so?
Human body can actually produce most of the essential fatty acids or in short, fats, that we need for growth and repair. However there are two main fatty acids that our body can’t produce, that are Omega 3 and Omega 6.
Omega 3 (ω-3)
Omega 3 fats are a key family of polyunsaturated fats. There are three main omega 3, EPA, DHA, and ALA. Source of Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) also known as marine omega 3 are mainly acquire fish, eg. salmon, mackerel, sardines, tuna, etc. As for Alpha-linolenic acid (ALA) is found in food source such as vegetable oils (canola oil, soybean oil), nut (especially walnuts), flax seeds and flaxseed oil, leafy vegetables, and even from some grass-fed animal fat.
As in function, they are an integral part of cell membranes throughout the body and affect the function of the cell receptors in these membranes. They provide the starting point for making hormones that regulate blood clotting, contraction and relaxation of artery walls, and inflammation. They also bind to receptors in cells that regulate genetic function. Likely due to these effects, omega 3 fats have been shown to help prevent heart disease and stroke, may help control lupus, eczema, and rheumatoid arthritis, and may play protective roles in cancer and other conditions. (source)
Omega 6 (ω-6)
Most omega 6 fatty acids come from vegetable oils such linoleic acid (LA), and is normally convert to gamma-linolenic acid (GLA) in human body. It can further break down to arachidonic acid (AA). AA can be found in meat and eggs, while GLA can be found in various plant-based oils (evening primrose oil (EPO), borage oil, and black currant seed oil).
Omega 6 help stimulate skin and hair growth, maintain bone health, regulate metabolism, and maintain the reproductive system. But in high dose will induce inflammation. GLA may actually reduce inflammation. Much of the GLA taken as a supplement is converted to a substance called DGLA that fights inflammation. Having enough of certain nutrients in the body (including magnesium, zinc, and vitamins C, B3, and B6) helps promote the conversion of GLA to DGLA.
Omega 3 & Omega 6
Combination of Omega 3 & 6 are well known in nutritionist practice, and they need to be balance. Omega 6 is important for natural growth and regulate metabolism, however having too much will cause inflammation. Omega 3 will play the role in controlling the inflammation for instance. There are study showing ratio of 2-3/1 (ω-6/3) suppressed inflammation in patients with rheumatoid arthritis, while the ration of 5/1 shows beneficial effect on asthma patients. But ratio of 10/1 will have adverse effect. Source.
Should you acquire Omega 3 & 6 from natural food source or supplement?
It is highly depend on personal choices, the best is to obtain from natural food source. But as nowadays a well grown vegetable that rich in nutrients and wild fish are hardly obtain, most food we can get from groceries are produced from mass-farming. The percentage of nutrient will not be as good as old time where our great great grandparents used to eat. Supplement sometimes is the option for city people to acquire quality nutrient, but that comes as price as they are mostly not cheap. Cheap supplement may have their source obtain from contaminant food chain, such as deep sea fishes highly contaminated with heavy metal like mercury. It is always important to study every source of food and supplement before purchase them to acquire the needed nutrients.