Flax Oil vs Fish Oil

Flax oil vs fish oil seems to be the debate among essential fatty acid enthusiasts these days. This may be especially true for vegetarians, who are counting on flax oil for the majority of their omega-3 fatty acids. If you're TTC and have been wondering whether flax oil or fish oil would be better for you, please read on. I will go over the details of these popular omega-3 fatty acid sources.

Both flax oil and fish oil are high in omega-3 fatty acids. Flax oil is approximately 50-60% Alpha-Linolenic acid (ALA), while concentrated fish oil contains both Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA). If you're not understanding these terms, you may want to check out my EFA Overview page. It important to remember that the body can't use ALA. ALA must be converted to EPA and DHA in the body.

If you're trying to decide between fish oil vs flax oil, you must consider that the omega-3 fatty acid, ALA, in flax oil must undergo 2 conversion processes. First, the enzyme Delta 6 Desaturase (D6D) transforms ALA into Steridonic acid and then the enzyme Delta 5 Desaturase (D5D) transforms Steridonic acid to EPA. Some EPA is then converted into DHA.

The success of these conversions is dependent on a number of factors. The enzymes D6D and D5D are decreased and their function is disrupted with transfatty acid ingestion, insufficient vitamins or minerals cofactors, excess saturated fats, alcohol, tobacco and radiation. So, the conversion of ALA to EPA and DHA can be hampered with poor nutrition or unhealthy diets. The following are the numbers to keep in mind if consuming flax oil as the primary source of omega-3 fatty acids:

• ALA is converted to EPA at a rate of 2-15%
• ALA is converted to DHA at a rate of 2-5%
• Flaxseed oil has 50-60% ALA (omega-3), along 24% Linoleic acid (omega-6) and 19% Oleic acid (omega-9)
• Minimum combined EPA and DHA doses according to Dr. Andrew Stoll of Harvard University are 1000-2000 mg daily.
• At top conversion rates, if you took 13,000 mg of flax oil, you'd get about 1000 mg of EPA and 325 mg of DHA for a combined does of 1325 mg.

One of the major proponents of flax oil (in the flax oil vs fish oil debate) is Udo Erasmus, PhD, the author of Fats that Heal, Fats that Kill. The study that he refers to in support of the superiority of flax oil vs fish oil is based on 6 women in 2002. These women converted ALA at a rate of 21% EPA, 6% DPA, and 9% DHA. In this study 3 women were taking birth control pills, which elevated their estrogen and enhanced their conversion rates. A second study with 6 men showed that they converted ALA at a rate of 8% EPA and 8% DPA. In this study, the men produced no DHA at all. Of the studies that I've read, these are the highest conversion rates that I've seen. The consensus among most researchers is closer to the bulleted data above.

So, fish oil vs flax oil? I hope that I've presented enough information for you to make an educated decision. If you're a vegetarian or for other reasons can't take fish oil, it's important to be aware of conversion rates. However, if you're able to take fish oil, please be sure to take a high quality, pharmaceutical grade fish oil that has been tested for heavy metals.

I just want to add a note about flaxseeds. If you are on the side of flax oil in the flax oil vs fish oil debate and you are consuming fresh flaxseeds, it's important to note that the seed husks contain naturally occurring cyanogenic nitrates and linamarin. These can be toxic at high doses. Cyanogenic nitrates may be a concern, as they interfere with iodine uptake by the thyroid. Also, flaxseeds contain lignans, which have some estrogenic, antiestrogenic and steroid activity. Dr. Andrew Stoll of Harvard University recommends limiting flaxseed (not flax oil) consumption to 2-3 tablespoons a day.