Fish Oils: Ethyl Ester versus Triglyceride forms

Low strength natural fish oils are in triglyceride (TG) form, as are most natural oils. To purify the oils by removing impurities and less desirable fatty acids and to concentrate the EPA and DHA fatty acid components, molecular distillation is used.  This process allows the oil to vaporize at low temperatures under pressure and is also known as vacuum distillation. The resulting vapor is collected and cooled, stratifying into distinct layers of fatty acids. This allows a purer esterified oil (called an ethyl ester form, or EE) with higher levels of EPA-DHA than crude fish oils and removal of triglycerides and cholesterol as well as other undesirable components. 

Some companies like to add triglycerides back in; this dilutes the fish oil concentrate by about 20% and the process also introduces mono- and di-glycerides, which don’t exist in natural fish oils to a significant degree but are thought responsible for higher absorption levels of this reconverted triglyceride form (rTG) oil over natural triglyceride and ethyl ester forms. If no triglycerides are added back, the body’s own store of triglycerides will be used to bond to the fatty acids after absorption, potentially lowering serum triglycerides more than an rTG oil. 

Absorption from our guts is always in the form of free fatty acids, so the oil’s original triglycerides are typically discarded during digestion and reattached later from body stores. This lowers the potential of the TG or rTG oils to lower triglycerides already in our bodies since they introduce additional triglycerides, which may be absorbed either into the body (adding more triglycerides into the liver) or into fiber or other materials that carry cholesterol out through the stool (potentially reducing the removal of cholesterol by competitive absorption). 

The prescription fish oils are in the ethyl ester form, not triglyceride form, because of the higher purity and higher strength of EE fish oils over TG or rTG forms resulting in better study outcomes on cardiovascular health measures. 

Krill oil is distinct because of its phospholipid matrix that greatly enhances omega-3 absorption more than the EE, TG, or rTG forms of fish oil.

Do bioflavonoids enhance Vitamin C absorption?

Vitamin C absorption from the gut is governed by sodium content for active transport. For passive absorption throughout the length of the intestine the vitamin does not use a similar co-factor.

The bioflavonoids come into play after vitamin C has been absorbed and is in circulation.  This vitamin has a relatively short half-life and depends on other antioxidants to act as electron donors to 'reduce' oxidized vitamin C (dehydroascorbate) back into the antioxidant form (ascorbate; ascorbic acid).  Various antioxidants, including bioflavonoids and polyphenols in fruits, are typically used to provide that extra benefit.  So the recycling and longevity of vitamin C after absorption depends greatly on the presence of other antioxidants; including not only rutin and bioflavonoids but also alpha lipoic acid, glutathione, and numerous other antioxidants.

So there is a benefit to using a base, often called vitamin C complex, in a vitamin C formula, but not so much in the initial absorption as in the vitamin's retention and recycling for re-use over time.  The variety of antioxidant-related nutrients in the human diet is thought responsible for why humans can retain vitamin C between meals when we cannot manufacture our own from blood sugar at will, as most mammals can.