The Ethyl Ester vs. Triglyceride Form of Fish Oils

Introduction

There is no question that one of the major advances in nutritional medicine has been the introduction of highly purified fish oil products. Very sophisticated distillation and filtration processes can now eliminate virtually all of the toxic compounds such as mercury, lead, and pesticides from crude fish oil. There are several different methods to “molecularly distill” crude fish oil into these purified forms. To say a fish oil is molecularly distilled has become synonymous with the highest quality in the mind of many consumers, but the term really does little to assign quality any more than the term automobile tells a consumer the difference between a high priced luxury sedan versus a cheap import. Another misconception promoted by marketing propaganda is that the triglyceride form of fish oils is superior to the ethyl ester (EE) form.

Triglyceride vs. Ethyl EsterTriglyceride vs. Ethyl Ester

A triglyceride consists of a glycerol "backbone" with three 3 fatty acids attached. Fish oils naturally contain triglycerides containing DHA, EPA, and a saturated fat. During the production of all concentrated fish oils through “molecular distillation,” the fatty acids are liberated into free ethyl ester forms. Some fish oil products are made by synthesizing the free fatty acids back to a triglyceride form while others, including the pharmaceutical forms, maintain the purified oil in the ethyl ester (EE) form. Some companies selling fish oils claim that the triglyceride form is more natural, has better stability, and is better absorbed than the EE form. None of these claims is true. The recombined triglycerides are not necessarily in their natural form, they are not more stable, and they certainly are not better utilized by the body. My personal opinion is that the EE form actually possesses some advantages:

• In order for the body to utilize the DHA or EPA in a triglyceride form they must be liberated from the glycerol backbone. The EE form provides an easier to assimilate form for many and is significantly less likely to cause burping up of a fishy smell. Think of the EE form as a “pre-digested” form of fish oil.

• While early absorption studies showed an advantage to the triglyceride form, it turns out the studies were not taking into account the fact that the EE form is processed in a more efficient manner. Very detailed absorption studies have shown that the EE form is actually more bioavailable in that it is more easily processed by the cells that line the intestines and is also more easily incorporated into cell membranes.

• Though the triglyceride form is very effective, the EE form may produce even better clinical results. For example, studies looking at the effects of fish oils on reducing factors that promote dangerous blood clots as well in the important effect of lowering triglycerides show some greater benefits with the EE form. In one study, while the EE and triglyceride forms at equal concentrations showed a similar effect on raising blood levels, the EE form showed significant advantages in lowering triglycerides and reducing platelet aggregation than the triglyceride form.

• The EE form is backed by considerably more in depth scientific research and it is the form preferred when higher dosages of EPA and DHA are required.

• Our own detailed quality control analysis at Natural Factors has shown exceptional stability in soft gelatin capsules and studies have shown feeding humans either pure DHA or EPA EE at a dosage of 4 grams does not increase lipid peroxides or cause oxidative damage.

The bottom line

While there are certain advantages to the EE form, the truth is that both the EE form and the triglyceride form produce great benefit to human health because they both provide EPA and DHA. That is the critical effect that both forms provide. The reasons why these fatty substances are so important revolve around their role in cellular membranes. A diet that is deficient in omega-3 fatty acids, particularly EPA and DHA, results in altered cell membranes. Without a healthy membrane, cells lose their ability to hold water, vital nutrients, and electrolytes. They also lose their ability to communicate with other cells and be controlled by regulating hormones. They simply do not function properly. Cell membrane dysfunction is a critical factor in the development of virtually every chronic disease, especially cancer, diabetes, arthritis, and heart disease. Not surprisingly, fish oil supplementation whether as the EE or triglyceride form have shown tremendous beneficial or protective effects against all of these diseases. Again, the majority of this clinical research has been conducted with the EE form.

Practical recommendations

How much fish oil should you take? According to the latest scientific evidence, a daily dosage of 1,000 mg of EPA and DHA (combined) is sufficient to produce significant protection against heart disease and strokes. When there is a therapeutic indication for EPA and DHA such as in elevated triglycerides, rheumatoid arthritis, depression, and asthma the daily dosage is usually 3,000 mg of EPA and DHA. Keep in mind that these dosage recommendations are based upon the level of EPA and DHA versus the amount of fish oil in the capsules or liquid, so you must read the label carefully to make sure you are getting the correct amount. The specific fish oil product that I recommend is RxOmega-3 Factors from Natural Factors.

Key references:

1. Nordøy A, Barstad L, Connor WE, Hatcher L. Absorption of the n-3 eicosapentaenoic and docosahexaenoic acids as ethyl esters and triglycerides by humans. Am J Clin Nutr. 1991;53(5):1185-90.
2. Shimizu T, Fujii T, Suzuki R, Igarashi J, Ohtsuka Y, Nagata S, Yamashiro Y. Effects of highly purified eicosapentaenoic acid on erythrocyte fatty acid composition and leukocyte and colonic mucosa leukotriene B4 production in children with ulcerative colitis. J Pediatr Gastroenterol Nutr. 2003;37(5):581-5.
3. Wojenski CM, Silver MJ, Walker J. Eicosapentaenoic acid ethyl ester as an antithrombotic agent: comparison to an extract of fish oil. Biochim Biophys Acta. 1991;1081(1):33-8.
4. von Schacky C. A review of omega-3 ethyl esters for cardiovascular prevention and treatment of increased blood triglyceride levels. Vasc Health Risk Manag. 2006;2(3):251-62.
5. Zuijdgeest-van Leeuwen SD, Dagnelie PC, Rietveld T, van den Berg JW, Wilson JH. Incorporation and washout of orally administered n-3 fatty acid ethyl esters in different plasma lipid fractions. Br J Nutr. 1999;82(6):481-8.