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Health Benefits of Flax Seed Oil & Fish Oil

What is Flax Seed Oil

Flax seed oil is the oil pressed from the seeds of the flax plant Linum usitatissimum. Taking flax seed oil is a good way to get additional essential fatty acids. There are only two fatty acids that must be obtained through the diet - linoleic acid and linolenic acid. Flax seed oil contains both of these. The reason these fatty acids are called essential is because your body cannot produce them. Once these two essential fatty acids are present, other fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (found in fish oil) can then be manufactured by the body.

Flax Seed Oil vs Fish Oil

There is some controversy over which type of oil is best. At present, fish oil seems to be more popular than flax seed oil. Basically, both fish oil and flax oil achieve the same thing - providing the body with essential fatty acids. Fish oil does this more directly than flax oil. For example, fish oil already contains EPA and DHA so the body doesn't have to convert anything. However, flax seed oil is an excellent alternative for vegetarians who don't want to consume any animal products. In addition, fish oil must be processed to remove mercury and this isn't an issue with flax.

Also, some researchers have found that fish oil supplements may decrease immune system functioning by inhibiting the inflammatory response (Schwerbrock et al. 2009). In some situations inhibiting the inflammatory response is a good thing. However, there are times when you need an inflammatory response. For example, during bacterial or viral illness and even during cancer you need an imflammatory response so that your body's immune system can mount an attack against the pathogen or mutated cells (as in cancer). However, flax seed oil also inhibits inflammation, but does not seem to depress the immune response.

Interestingly, Max Gerson (founder of the alternative cancer treatment known as the Gerson Therapy) found that the only type of oil that did not promote the growth of cancer was flax seed oil. Apparently cancer cells needs fat and oils to grow, but flax seed oil does not promote tumor growth. Instead it inhibits it.

However, some studies also find an anticancer effect from fish oil as well. For example, Mernitz et al. (2009) reported that fish oil supplementation inhibited lung cancer in mice.

Also, with flax, you can take the oil or just eat the ground seeds, or both. The seeds are an excellent source of fiber, plus they contain lignans. Lignans are estrogen-like phytochemicals that provide beneficial activity to the body. Many studies have found that flax seed oil and/or lignans reduce the incidence of cancer. Lignans in particular are have been found to decrease both breast and prostate cancer risk. This is true in both studies on animals and humans.

Another benefit to flax oil over fish oil is that it tastes better. Plain flax seed oil doesn't tastes that great, but you can easily mix it into something else and then you can barely taste it. In contrast, fish oil has such a strong flavor you must take it in capsule form. With flax seed oil I usually blend up some flax seed oil in my morning rice protein smoothie. I also throw in a tablespoon of ground flax seeds too. With fish oil you are stuck swallowing the large capsules because it tastes too bad to mix into anything.

Flax Seed Oil Health Benefits

  • Seems to inhibit tumor growth
  • Lowers cholesterol
  • Lowers risk of heart disease
  • Improved brain function
  • Improved skin, hair and nails

If you buy flax seed oil, buy only cold-pressed oil. You can buy it with or without lignans. If you choose to just eat the flax seeds themselves, make sure you either buy the ground seeds or grind them yourself. The whole seeds will provide dietary fiber, but you'll miss out on the other health benefits.

So, in summary, flax seed oil and fish oil achieve about the same thing, however, it appears that there might be more anti-cancer activity in flax oil than fish oil, but this has not been conclusively determined. In any case, it is certainly best to include one of these sources of essential fatty acids in your diet (but check with your doctor first to make sure they will be no drug interactions if you are taking medications). I happen to use both supplements, taking the flax oil every day and taking the fish oil sporadically throughout the week.


Schwerbrock, Nicole M. J., Karlsson, Erik A., Qing, Shi, Sheridan, Patricia A., & Beck, Melinda A. (2009). Fish oil-fed mice have impaired resistance to influenza infection. Journal of Nutrition 139(8): 1599-1594.

Mernitz, Heather, Lian, Fuzhi Smith, Donald E., Meydani, Simin Nikbin, Wang, Xiang-Dong (2009). Fish oil supplementation inhibits NNK-induced lung carcinogenesis in the A/J mouse. Nutrition and Cancer 61(5): 663-669.