Skip to content

Linseed oil vs. fish oil

Leinöl vs. Fischöl

Are you one of those rapeseed oil guys who wouldn't eat anything with a face? Or are you a fish-eating machine that would eat pretty much any animal that doesn't wear a flea collar?

Regardless of your stance on meat vs. plant-based diets, if your goal is to look good naked, you'll probably be taking some sort of essential fatty acid supplement.

Linseed oil and fish oil are the most commonly consumed forms of essential fatty acids and many will consider these two sources of essential fatty acids to be interchangeable, but these two oils are distinctly different in many ways.

While both oils are rich in omega-3 fatty acids, there are distinct differences beyond the fact that flaxseed oil is suitable for vegetarians, while fish oil is not. Let's start with some basics about essential fatty acids. The two primary essential fatty acids (EFAs) are omega-3 and omega-6 fatty acids. These fatty acids are considered essential because your body cannot produce them itself and therefore they must be obtained from food.

Natural polyunsaturated omega-3 fatty acids

Polyunsaturated omega-6 fatty acids

Alpha-linolenic acid (LNA)

Linoleic acid (LA)

Stearidonic acid (SA)

Gamma-linoleic acid (GLA)

Eicosapentaenoic acid (EPA)

Arachidonic acid (AA)

Docosahexaenoic acid (DHA)

Table 1: Adapted from Fats that Heal, Fats that Kill by Udo Erasmus

According to research by Simopoulos, the typical Western diet contains about 20 times as many omega-6 as omega-3 fatty acids. When you compare this to the 2:1 ratio that scientists consider ideal, it quickly becomes clear how suboptimal our diet is in this regard.

There are three reasons for this unhealthy ratio of omega-6 to omega-3 fatty acids in our diet:

  • A deficiency of omega-3 fatty acids
  • Excessive consumption of omega-6 fatty acids
  • An inability of the body to convert dietary omega-3 fatty acids into omega-3 fatty acids that can be utilized by the body

The third point is the crux of the matter: can linseed oil fulfill its role as an omega-3 supplier?

Linseed oil is not an optimal source of omega-3 fatty acids

Twelve years ago, I looked into the effects of fish oil when a trainer at my gym complained of excessively dry skin on his hands during the winter. His hands looked as if they were covered in small cuts, some of which were even bleeding. When I asked him if he was taking omega-3 fatty acids, he told me that he was taking three tablespoons of linseed oil a day.

Referring to what I had read at the time, I recommended that he replace the linseed oil with fish oil for breakfast, lunch and dinner. And the result? Within a few days his hands healed completely - no more cracks and no more bleeding.

Why couldn't linseed oil do its job?

Linseed oil is one of the richest sources of alpha-linolenic acid (ALA) and contains over 50% ALA, which is why it is often referred to as one of the best sources of omega-3 fatty acids. The problem, however, is that the omega-3 fatty acids contained in linseed oil cannot be sufficiently converted into the actually important "players" in the body. The omega-3 fatty acids contained in linseed oil are simple ALS, which is a precursor to the magical EPA and DHA omega-3 fatty acids. However, just because linseed oil increases ALA levels in the blood does not mean that your body will convert this ALA into EPA and DHA. To confirm this, a 12-week study showed that linseed oil was not efficiently converted to DHA. Another study lasting 4 weeks showed that the EPA concentrations that could be achieved with the help of linseed oil were only half as high as when fish oil was used.

The inadequate conversion of ALA to EPA and DHA is related to competitive enzyme inhibition. Based on the fatty acid flow chart below, there are a number of intermediate steps that must be completed before ALA can be converted to EPA and then to DHA.

A very important enzyme called delta-6-desaturase (D6D) is required for this conversion.

Alpha-linolenic acid (linseed)

Δ-6 Desaturase

Octadecatetraenoic acid

Elongase enzyme

Eicosatetraenoic acid

Δ5 Desaturase

Eicosapentaenoic acid (EPA)

Elongase enzyme

Docosapentaenoic acid

Δ4 Desaturase

Docosahexaenoic acid (DHA)

Scientific research suggests that the amount of D6D decreases as we age. While we can't do much about the numbers on our birth certificate, it should be noted that diabetes, trans fats, alcohol and radiation have also been identified as causes of declining D6D levels.

If you're a regular reader of this site, then you should know how important blood sugar control is, so diabetes probably shouldn't be a concern. And if looking good naked is somewhere on your agenda, your trans fat consumption is likely to be minimal and your alcohol consumption below Lindsay Lohan levels.

As for radiation, it's everywhere. However, there are ways to minimize it. There are also some key nutrients you can supplement to build your D6D capacity, which include zinc and magnesium. Most of us are deficient in these two super minerals, which are crucial for many aspects of overall health.

(A tip on magnesium: if you have chocolate cravings all the time, this is a sign that you could be suffering from a magnesium deficiency. So if you've just eaten your child's birthday cake, you might want to get yourself some ZMA® ).

A second chance for flaxseed?

While flaxseed oil is probably not an effective way to get the amounts of EPA and DHA your body so desperately needs, flaxseed does have some benefits. Flaxseed is available in three forms: whole flaxseed, ground flaxseed and flaxseed oil. I prefer my clients to take whole flaxseed or ground flaxseed as both are an excellent source of fiber. Fiber helps cleanse the intestines and supports blood sugar control, which can lead to lower body fat levels.

Whole flaxseeds also contain lignans, which have been shown to affect estrogen levels. Many of my clients have symptoms of high estrogen levels and when I run hormone tests on them, 90% of them have elevated estradiol levels.

There are two primary reasons for this. Number one is estrogen mimicking compounds that are found in our environment called xenoestrogens. We are increasingly bombarded with xenoestrogens in the form of contaminated water and food, chemicals such as pesticides and herbicides, and plastics containing bisphenol A. The ugly thing about these little monsters is that they alter the conversion of cholesterol into steroid hormones.

Reason number two is the high activity of the enzyme aromatase. Aromatase is an enzyme that converts androgens like testosterone and androstenedione into estrogen. Remember all the hype about prohormones in the late nineties? Everyone had visions of cracking Mark McGuire's locker and reaching Bic Mac's proportions. Unfortunately, this is a prime example of something that looked good on paper but didn't work in the human body.

The main problem with androstenedione was that it can be converted into both testosterone and estrogen. So while some guys got more muscular and stronger from this stuff, others grew breasts and started asking their training partners if their training pants made their butts look bigger.

To reduce the amount of xenoestrogens you are exposed to, the first thing you need to do is reduce the amount of xenoestrogens you are exposed to. Limit the use of plastic, store your food in glass containers instead of plastic or Tupperware and never heat food in plastic packaging in the microwave. By doing so, you are giving your body real xenoestrogen injections.

As for aromatase, this is where the lignans in whole flaxseeds come in. Flaxseeds are the richest source of the plant lignan secoisolariciresinol diglucoside (SDG0) - a type of phytoestrogen similar in structure to endogenous sex hormones.

After consumption, the intestinal flora metabolizes SDG to enterodiol (ED) and enterolactone (EL), which are also known as mammalian lignans. There are studies that show that ED and EL both inhibit the aromatase enzyme.

Although I do not recommend flaxseed oil as a source of omega-3 fatty acids, I would recommend consuming flaxseed in shredded form or even as whole flaxseeds to inhibit the effects of the aromatase enzyme.

Use both to your advantage

In our world of Frankenstein foods and toxic fats, it's a smart idea to make omega-3 fatty acids a top priority - but relying on flaxseed oil is not such a good idea. Whether your goal is to build muscle, lose fat or boost your performance, an animal source of essential fatty acids like fish oil is much more effective than flaxseed oil.

But don't throw the flaxseed out with the fatty acid bath water. Whole or crushed flaxseeds still have important health benefits to offer. Try using a high quality fish oil supplement to meet your EPA and DHA needs and use some high fiber whole flaxseed for its benefits in blood sugar control and aromatase inhibition. While this may not help you land a vegan girlfriend, with more muscle, less fat and better overall health, I'd be very surprised if you have a hard time finding a carnivore to keep you company.


  1. Adlercreutz H, Bannwart C, Wähälä K, Mäkelä T, Brunow G, Hase T, Arosemena PJ, Kellis JT, Vickery LE. Inhibition of human aromatase by mammalian lignans and isoflavonoid phytoestrogens. J Steroid Biochem Mol Biol, 44:147-153, 1993
  2. Barceló-Coblijn G, Murphy EJ, Othman R, Moghadasian MH, Kashour T, Friel JK. Flaxseed oil and fish-oil capsule consumption alters human red blood cell n-3 fatty acid composition: a multiple-doing trial comparing 2 sources of n-c fatty acids. Am J Clin Nutr. 2008 Sep;88(3):801-9.
  3. Basch R, Bent S, Collins J, Dacey C, Hammerness P, Harrison M, Smith M, Szapary P, Ulbricht C, Vora M, Weissner W. Natural Standard Resource Collaboration. Flax and flax seed oil (Linum Usitatissimum) a review by the Natural Standard Research Colloboration. J Soc Integr Oncol 2007 Summer 5; (3): 92-105.
  4. Borriello SP, Setchell, KDR, Axelson M, Lawson AM. Production and metabolism of lignans by the human faecal flora. J Appl Bacteriol, 58:37-43, 1985.
  5. Erasmus, Udo. Fats that Heal Fats that Kill. Alive Books. Barnaby BC Canada. 1997.
  6. Simopoulos, Artemis. The Omega Diet. Harper Collins. New York, NY. 1999.
  7. Frye C, Bo E, Calamandrei G, Calzà L, Dessì-Fulgheri F, Fernández M, Fusani L, Kah O, Kajta M, Le Page Y, Patisaul HB, Venerosi A, Wojtowicz AK, Panzica GC. Endocrine Disrupters: a Review of SOMe Sources, Effects, and Mechanisms of Actions on Behavior and Neuroendocrine Systems. J Neuroendocrinol. 2011 Sep 27. doi: 10.1111/j.1365-2826.2011.02229.x. (Epub ahead of print)
  8. Horrin DF. Loss of delta-6-desaturase activity as a key factor in aging. Med Hypotheses. 1981 Sep;7(9):1211-1220.
  9. Lord, RS & Bralley JA. Laboratory Evaluations for Integrative and Functional Medicine. Duluth, GA: Metametrix Institute.
  10. Liu S, Baracos VE, Quinney HA, Clandin MT. Dietary omega-3 and polyunsaturated fatty acids modify fatty acyl composition and insulin binding in skeletal-muscle sarcolemma. Biochem J. 1994 May 1;299 (Pt 3): 831-7.
  11. Mantzioris, E, James MJ, Gibson RA, Cleland LG. Dietary substitution with an α-linolenic acid-rich vegetable oil increases eicosapentaenoic acid concentrations in tissues. Am J Clin Nutr-1994-Mantzioris-1304-9.
  12. Shimp JL, Bruckner L, Kinsella JE. The effects of dietary trilinoelaidin on fatty acid and acyl desaturases in rat liver. J Nutr. 1982 Apr;112(4):722-35.

By Robert Yang

Previous article 12 healthy foods that are rich in antioxidants