International Omega-3 Learning and Education Consortium for Health and Medicine

Staple food products enriched with omega-3 fatty acids provide a low dose, long-term supply of the essential omega-3 fatty acids. Research on these fortified food products has shown that the omega-3 fatty acids that are added into traditional food products are absorbed by and incorporated into the blood lipids to be available for the biochemical and physiological functions in the body. Yep et al ¹ showed that supplementing human participants with as little as 60 mg of long-chain omega-3 fatty acid per day from bread that contained microencapsulated tuna oil (MTO, 20 mg of long-chain n-3 PUFA / slice) for three weeks significantly increased the proportions of 20:5n-3, 22:5n-3 (EPA), 22:6n-3 (DHA), and total n-3 PUFA in plasma. When comparing the usual omega-3 fatty acid supplements (a fish oil capsule) to MTO enriched food products, the bioavailability of omega-3 fatty acids was the same ². The bioavailability of alpha-linolenic acid (ALA) from ground flaxseed or flaxseed oil differs dramatically as reported by Patenaude and colleagues ³. Human subjects given ALA (96 g/day) as ground flaxseed in muffins had markedly lower levels of this omega-3 fatty acid compared to subjects that consumed the same amount of ALA as from flaxseed oil enriched in muffins. It can be concluded that omega-3 fatty acids from food products, either directly enriched with fish oil or vegetable oils, are readily bioavailable for human consumption. Omega-3 fatty acids in food products that are enriched with omega-3 fatty acids in the unprocessed form (such as ground flaxseed) may not be as bioavailable as the pure oil form. In the case of low absorption rate from muffins enriched with ground flaxseeds, seed matrix materials, such as fiber, may have slowed the digestion and/or absorption of fatty acids from ground flaxseed.

Another issue concerning the bioavailability of omega-3 fatty acids is the chemical form of these omega-3 fatty acids used in food products. There are two types of omega-3 fatty acids on the market for human consumption based on the chemical structure: those in triglyceride (TG) form and those in ethyl ester (EE) form. Omega-3 fatty acids naturally exist in TG form, while those in EE form are produced chemically from the TG form. The benefits of having omega-3 fatty acids in EE form are two-fold. First, since it is synthesized from fish oil that goes through several purification steps, the EE form does not contain any contaminants, which are of concern when consuming fish. The second benefit is that the EE form can be highly concentrated (it could be as pure as 98% EPA and DHA) and these concentrated forms are often used for therapeutic applications. Research examining the bioavailability of these two omega-3 fatty acid forms showed that they are both readily digested in the intestines and absorbed and incorporated into the body's lipid system. Krokan and coworkers studied the enteral absorption of EPA and DHA in EE form in comparison to natural fish oil (in TG form) of equivalent doses in healthy male volunteers for 14 days and concluded that there was no difference in enteral bioavailability of EPA and DHA from either the synthetic EE of EPA + DHA or the natural fish oil ⁴. However, in an earlier study, Beckermann and colleagues investigated the comparative bioavailability of EPA and DHA from TG, free fatty acids and EE in female volunteers in a randomized triple cross-over trial with baseline control ⁵. Based on the plasma levels of EPA and DHA, the authors determined that the relative bioavailability of EE is about 50% that of the TG form.

From a nutritionist's point of view, regardless of the chemical forms of these omega-3 fatty acids, they are all well absorbed and utilized in the body. Even though there are discrepancies in regard to their absorption and organ incorporation in the literature, we must keep in mind that there are numerous factors that could influence this in the human body, such as the composition of the meal (especially the fat content), one's physical and heath status and age as examples. Since omega-3 fatty acids in foods or supplements are well tolerated by humans, slight variation in their bioavailability should not be a significant concern for casual consumers who aim to meet the daily recommended omega-3 fatty acid intakes. However, for therapeutic purposes, more precise dosing should be carried out considering the target health problem, subject's age and health status, and if there are any complications that need to be addressed (e.g., drug interactions). Also for therapeutic use, the concentration of the effective component, EPA and DHA, should be considered. One report dealing with the clinical application of omega-3 fatty acids suggests that not only the dose, but also the concentration of the omega-3 fatty acid preparation affects the therapeutic outcome. In this study, the same dose (5.1 g/day) of omega-3 supplements with different concentrations (62.5%, 80%, and 85%) of EE EPA + DHA (EPA:DHA = 1.0:0.8) were given to human subjects for 14 days and all three supplements with different concentration resulted in a significant increase in the omega-3 content of blood phospholipids; however, the more concentrated supplement exhibited a more potent therapeutic effect as in serum triglyceride and VLDL cholesterol reductions ⁶.

With the advancement in food processing technology in microencapsulation, once unstable fish oil is now protected from oxidation during food preparation and storage, thus effectively maintaining the stability of the omega-3 fatty acids in the food and increasing the shelf life of these products. Microencapsulation also helps shield the possible unpleasant off flavor of fish oil, which helps enhance the acceptance of such enriched food products. In conclusion, aside from complicated applications of therapeutic uses of high purity omega-3 fatty acids, staple food products that are enriched with low levels of omega-3 fatty acids provide a convenient way for consumers to meet the daily recommended intake levels of this group of essential fatty acids.

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