Production

How Fish Oil Is Produced

Fish oil can be produced from whole oily fish, fish trimmings or other parts of fish generated during seafood processing. Common marine sources include anchovies, sardines, menhaden, mackerel and other species naturally rich in long-chain omega-3 fatty acids.

The exact process varies among manufacturers and according to whether the final product will be used as food, an ordinary dietary supplement, a concentrated omega-3 supplement or a pharmaceutical ingredient.

Extraction of the Oil

In conventional production, the raw fish material is heated and pressed or separated so that oil can be removed from water and protein-rich solids. Centrifuges are commonly used to separate these different fractions efficiently.

The resulting crude fish oil contains the desired fatty acids but may also contain moisture, free fatty acids, pigments, odor compounds, oxidation products and naturally occurring trace contaminants.

Refining Fish Oil

Crude oil normally undergoes several refining steps before it becomes a finished supplement ingredient. Depending on the process, these can include removal of free fatty acids, filtration, bleaching, deodorization and other purification steps.

Modern refining is designed to improve flavor, odor, stability and purity while retaining the desired fatty acids.

Contaminants and Purification

Fish can accumulate environmental contaminants, but this does not mean that the same concentrations automatically remain in the finished supplement. Processing and purification can substantially reduce contaminants.

The NIH Office of Dietary Supplements notes that omega-3 supplements have not generally been found to contain methylmercury because mercury is removed during processing and purification.

Consumers who are particularly concerned about product purity can look for manufacturers that provide contaminant specifications or independent testing rather than relying solely on terms such as “pharmaceutical grade” or “molecularly distilled.”

Concentrating EPA and DHA

Some fish oils undergo additional processing to increase their EPA and DHA concentration. These products may provide considerably more omega-3 fatty acids per capsule than conventional fish oil.

The omega-3 fatty acids may also be converted into ethyl esters and subsequently into re-esterified triglycerides. Different commercial products therefore can contain EPA and DHA in different concentrations and chemical forms.

Protecting Fish Oil From Oxidation

Because EPA and DHA contain multiple double bonds, fish oil is particularly sensitive to oxidation. Manufacturers try to reduce contact with oxygen, excessive heat and light throughout processing and storage.

Antioxidants such as tocopherols may be added to improve oxidative stability, and finished oils are usually packaged in containers designed to reduce exposure to air and light.

Once a product reaches the consumer, proper fish oil storage continues to matter.

More information about omega-3 supplement composition and purification is available from the NIH Office of Dietary Supplements.