Fish Oils: ethyl ester or triglyceride or...?

Most fish oils today are molecularly distilled, changing them from their natural triglyceride forms to ethyl ester (esterified) forms.

Anything stronger than a natural strength fish oil (up to about 30% EPA+DHA combined) is typically concentrated by molecular (vacuum) distillation to allow vaporizing at low temperatures, in the process converting to the ethyl ester form. This allows separation of the fatty acid constituents in order to add back some of the desired omega-3 fatty acids in order to concentrate them up to 60% or higher levels of the oil. This is accomplished by removing undesired fractions that were separated by the distillation, such as cholesterol, triglycerides, and various other fatty acids.

Because of the warming oceans, the naturally occurring amount of omega-3 fatty acids in most fish have declined from historically about 30% to somewhat less. Due to this change, most fish oil supplements containing 180 mg. of EPA and 120 mg. of DHA (300 mg. combined in a 1,000 mg. fish oil capsule) now need to spike the potencies by adding additional EPA and DHA fractionated from the original oils by molecular distillation. It is now unusual to find even a low strength fish oil capsule that is not at least partially molecularly distilled into ethyl ester forms. 

Some of these distilled oils are then partially reconverted to a triglyceride form in a process called reconversion that involves adding back 20% or more triglycerides to the esterified fatty acids to try to reattach the triglycerides to the fatty acids with enzymes. This imperfectly produces a highly processed combination of both triglyceride and mono-and-diglyceride forms of omega-3 with many of the original oil’s natural constituents deliberately removed (cholesterol, omega-6, omega-9, stearates, et al). This newly engineered combination is called a reconverted triglyceride form (rTG) containing typically at least 60% triglyceride form fatty acids that’s distinct from the original triglyceride (TG) form, but is as far from the original triglyceride form as can be produced by intentional chemical manipulation. Numerous brands offer this rTG form and inaccurately call it a natural triglyceride form, when it is in fact far removed from that oil.

This is done because of a prevailing and largely disproven belief that the natural triglyceride form is best. That's certainly untrue for cardiology and the form has recently been shown to be largely irrelevant to absorption and efficacy in general. 

Does Fish Oil Dissolve Styrofoam - and Does That Prove It's Bad?

Recent attention given to the effects of various fish oils on polystyrene (Styrofoam®) cups has led to some misunderstanding of how these products work in terms of nutrition and safety. It is unfortunate that the use of these stunts imply may confuse or even scare people away from taking this natural product which provides constituents that are essential to human health. Don’t be fooled by this trick! If someone tries to use it as a means to push one product over another, challenge them to explain exactly what the test is supposed to mean. Here’s what you need to know about the test, how it works, and what it means:
Styrofoam® (polystyrene) cups can be dissolved by pure fish oils. All fish oils will have this same effect on polystyrene, but some will take much longer than others. Various healthy natural substances, like fresh lemon oil, will also dissolve polystyrene. In the Styrofoam® cup test, the esterified ethyl ester form of fish oil works to dissolve Styrofoam® much faster than the triglyceride form simply because the number of chemical bonds in the two forms of oil are different; with ethyl ester fish oil having its number of bonds closer to that of Styrofoam®. This similar chemical polarity is the same reason why pure lemon oil also works quickly to dissolve Styrofoam®. No solvents are used to produce the fish oils, so none are present in the finished products. This magic trick does not translate into any legitimate safety concerns, despite its obvious visual impact. Fortunately, the human body is not composed of polystyrene and is not negatively affected by fish oils in its commonly available forms.

Fish oil naturally comes in a volatile triglyceride (triacylglycerol) form and can be esterified for additional benefits. As soon as a fish is caught the oils begin to degrade and can easily go rancid. Esterification is a process that stabilizes and maintains the freshness of fish oil to prevent rancidity and allows higher concentrations of the essential omega-3 EPA and DHA fatty acids to be available. During this esterification process, the triglycerides are removed, changing the number of molecular bonds in the fish oil. Both the purified ethyl ester form and the triglyceride form must be digested to a simpler fraction, the free fatty acid, to allow bioavailability from the human gut. Ethyl ester and triglyceride forms are equally well digested by lipase and available for absorption as free fatty acids, and the ethyl ester form is at least as bioavailable as the triglyceride form. (1)

There is some evidence that the ethyl ester form will sustain circulating levels of the omega-3 fatty acids EPA and DHA better than the triglyceride form. The ethyl ester form of EPA and DHA is the form that is used in most successful clinical studies evaluating the potential health benefits of supplemental Omega-3 fats. In fact, clinical trials on the ethyl ester form more consistently generate positive results than those done with the triglyceride form. Also EPA and DHA as ethyl esters inhibit platelet aggregability and control serum triglycerides while leaving other serum lipids essentially unaltered. (2) The ethyl ester forms build up body stores, allowing conversion to free fatty acids more consistently than the triglyceride form. (3) Because of their proven benefits and safety, it would be unfortunate if a misunderstood “test” causes some people to reject the use of solvent-free ethyl ester fish oils as part of their diet.

Expert opinion:

http://www.biosyntrx.com/articles.php?id=690

http://www.newton.dep.anl.gov/askasci/chem03/chem03994.htm

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Technical explanation:

Chemical Polarity plays a role in how compounds react with one another. Polarity refers to the electro-magnetic charges of a molecule, or the attraction between the positively and negatively charged parts of a molecule. Compounds are considered polar due to the unequal sharing or electrons. For example, water is a polar compound. A compound is non-polar when the electric charge is balanced. Edible oils are typically non-polar.

In Chemistry there is a rule to describe how polar and non-polar solvents react with similar solutes: “like dissolves like”. We all know that oil and water do not mix. The reason why is that water, which is polar, will not react (mix) with oil, which is non-polar. “Like dissolves like.”

Two common compounds, sugar and salt, are both polar and in nature they readily mix with water, another polar compound.

With polarity, compounds of differing polarity do not react/mix, while those with like polarity do mix. So a chemical reaction occurs when a non-polar compound comes into contact with another non-polar compound, and more readily when the number of chemical bonds in one substance more closely matches the other.

Polystyrene, a moisture-resistant foam commonly known as Styrofoam®, is formed from a long chain of polymers. This plastic is used in the manufacture of coffee cups and plates as an insulator and as packaging material, and is non-polar. What makes Styrofoam® ideal for keeping most hot beverages hot and cold beverages cold is that as a non-polar compound it will not react with the polar water used to make coffee, tea, and other beverages. This same material will react with any form of edible oil; this can be olive oil, lemon oil, fish oil, etc. This reaction is naturally occurring and its intensity is based solely upon the chemical properties of both compounds and the polarity of each.

All edible oils, which like Styrofoam® are non-polar, are made up of fatty acids; and these fatty acids are made up of a long chain of hydrocarbon molecules. With Fish Oils, some contain triglycerides and some contain ethyl esters. Both the triglyceride form and the ethyl ester form first need to be digested and broken down to a free fatty acid for absorption from the GI tract. After uptake, the free fatty acid is then converted to a triglyceride form in the liver by the addition of already available triglycerides obtained from circulating lipids (fats).

In the example of fish oils, ALL will react with Styrofoam over time; the length of time is determined by the number of chemical bonds in each type of fish oil relevant to the number of chemical bonds in Styrofoam®. Triglycerides will take longer to react with the cup, while oils bonded to ethyl esters, which have more chemical bonds, will naturally penetrate the cup wall faster.

REFERENCES:

1. Krokan HE, Bjerve KS, Mørk E. The enteral bioavailability of eicosapentaenoic acid and docosahexaenoic acid is as good from ethyl esters as from glyceryl esters in spite of lower hydrolytic rates by pancreatic lipase in vitro. Biochim Biophys Acta. 1993 May 20;1168(1):59-67. PMID: 8504143
2. 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. Review. PMID: 17326331
3. Rupp H, et al. Risk stratification by the "EPA+DHA level" and the "EPA/AA ratio" focus on anti-inflammatory and antiarrhythmogenic effects of long-chain omega-3 fatty acids. Herz. 2004 Nov;29(7):673-85. Review. Erratum in: Herz. 2004 Dec;29(8):805. PMID: 15580322

Essential fatty Acids (EFAs) interview, Natural Products Marketplace magazine, January, 2011

The awareness of EFAs, especially the Omega-3 fatty acids EPA and DHA, is large and growing larger. The accumulating mountain of evidence and the endorsement by popular health “gurus” assures continued growth in this important product category. As the benefits of specific fatty acids for regulation of various healthy body functions – such as inflammatory processes, hormonal health, and maintaining brain/nerve/cellular structures – becomes even more well known, more and more people recognize the potential for EFAs to positively affect their health.

While there are combination products that deliver Omega-3, Omega-6, and Omega-9 fatty acids together, the focus has been more on specific sources such as fish or flax, along with some more unusual ones. Of course, natural oil sources are not comprised of a single fatty acid. For example, natural fish oil can not only supply EPA and DHA but also originally supplies ALA, cholesterol, triglycerides, and other fatty acids; though many of these components can be removed during processing to provide purer and stronger materials that are richer in EPA and DHA to require far fewer capsules to reach desired levels of these two fractions. Flax oil is best known as a vegetarian source of the omega-3 fatty acid ALA (alpha-linolenic acid), but ALA levels are only about 55% of the total; flax oil also contains about 19% omega-9 as oleic acid, 14% omega-6 as linoleic acid, and 12% saturated fats. The conversion of ALA to EPA is a significant metabolic hurdle. Women do this conversion better than men; people who consume the most omega-6 in their diets have a more difficult time converting ALA to EPA. Typically between 5% and 15% of ALA converts to EPA and about 2% to 5% of ALA converts to DHA, making flax a much more dilute and less certain source of EPA-DHA.

Fish oil is subject to environmental concerns related to both sustainability and contaminants. Manufacturers audit their suppliers and set strict identity/safety specifications to assure the quality of products.

Most fish oils are molecularly distilled to remove contaminants, manufactured under strict quality assurance standards, and screened to be free of potentially harmful levels of contaminants and heavy metals, such as mercury, PCB’s, dioxins, and others.

Other types of EFAs include Flax seed oil, Evening Primrose Oil, Pumpkin seed oil, Black Currant seed oil, Wheat Germ oil, Castor Oil, and Virgin Coconut Oil.

Purity, potency, and freshness are always the challenges with EFAs.

The trend is toward more concentrated products of higher purity that allow people to get their EPA and DHA with smaller quantities of capsules or less volume of liquid. Liquids and smaller capsule sizes allow more children and seniors to enjoy the benefits of fish oils, while high strength capsules better hit the main demographic in between.

All fish oil supplements are typically hundreds of times safer than eating a serving of fish in relation to environmental factors; and typical esterified products have the added benefit of being free of cholesterol and triglycerides, which are undesirable food components for those with high cholesterol. By far, most of the studies proving the health benefits of supplemental fish oils have been with the esterified (ethyl ester) form, rather than the triglyceride form found in cold water fatty fish. There is very strong science supporting the use of this form.

Esterified fish oils also have been shown to sustain human serum levels better than the triglyceride form, over both a 24-hour period and a one-month period, which better supports a healthy heart rhythm. Notably, the most concentrated products are available only as esterified fatty acids. The ability of a consumer to get the 1-3 grams daily of EPA + DHA recommended by many health experts is enhanced by modern formulas that concentrate these essential fatty acids into fewer capsules and smaller serving sizes with fewer undesirable components, thus increasing customer compliance with a healthy nutritional protocol.

Both triglyceride and esterified ethyl ester fish oils are available in the marketplace, and both forms have their advocates. In the body, both forms must first be digested, stripping off the triglycerides or ethyl esters and leaving only free fatty acids that can be readily absorbed. These free fatty acids are then combined with triglycerides present in the liver before entering general circulation; so the circulating form will actually be the triglyceride form, no matter which form of fish oil one consumes. Both forms provide great value and important nutrients for the consumer; but the triglyceride form has no more proven value than the ethyl ester form, despite some excessive marketing claims.