Is flax oil a good source of Omega-3?
Flax seeds are the richest plant source of Omega-3s, followed by chia seeds and walnuts.
At first glance it seems that flax seed oil is the best source of plant (parent) Omega-3 available. Many flax oils are over 50% by weight of Omega-3s, and they also have one of the best Omega-3 / Omega-6 ratios of all food sources. It seems like a no-brainer to take half a teaspoon every day. So what's the problem?
Well, there are several problems.
The first problem is that flax seed oil is one of the most unstable edible oils. Most polyunsaturated food oils are unstable and should be used with caution, as I explain in Grow Youthful. But flax seed oil can turn from therapeutic food to toxic with just half an hour of exposure to hot bright sunlight, or with hours or days of exposure to air, light or heat. Of course, you should never heat it in the kitchen.
A fresh and undamaged flax oil should have a pleasant, nutty and slightly sweet flavour. However, flax oil usually has a less pleasant "seed" rather than nut taste, and is more sour than sweet. When it is rancid, it becomes linseed oil, used to oil cricket bats and used in paint manufacture. Linseed oil has a characteristic oil paint smell, and if there is the slightest hint of that smell in the edible oil, it is rancid.
Flax oil is a seed, and in Grow Youthful I detail why it is wise to avoid all seed oils in a healthy diet. Flax seeds have a high concentration of lignans, which bind to estrogen receptors around the body. Flax phytoestrogens can cause estrogen dominance.
Animal and plant sources of Omega-3s are different to each other. Oily fish are a good source of Omega-3s (mackerel, wild salmon, herring, anchovy, sardines), as are grass-fed animals. Eggs from poultry fed on fresh greens (especially purslane) and natural foods and forage that they can find while free ranging are also a good source. (Eggs from birds fed on stock feed are a poor source of Omega-3).
Plant Omega-3s come in the form of ALA (alpha-linoleic acid). ALA is not much use on its own, and must be inefficiently converted to EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). EPA and DHA is the form that Omega-3s come from animals.
Many stores sell ground flax seeds. Some writers suggest that the oil in milled flax seeds is a lot more stable than extracted flax oil. This is not true. Whole flax seeds deteriorate faster than many other seeds. If flax seeds are ground into flax meal the oil in the meal deteriorates almost as quickly as extracted oil.
In summary, it is difficult to obtain fresh, undamaged flax seed oil. It is so delicate and unstable that it is usually damaged in the supply chain, even when it comes in an opaque bottle topped with an inert gas, and kept in the refrigerator. In any case, plant-based Omega-3s must be converted to EPA and DHA, a process that is not efficient, and is further inhibited by the Omega-6 fats that are present in nuts and seeds. It is better to eat fresh nuts and seeds to get plant-based Omega-3s, and get your EPA and DHA from free-range, grass-fed, natural-diet meat, eggs and butter.