The Global Organization for EPA and DHA Omega-3s (GOED; Salt Lake City, UT) has issued a new industry recommendation on how to correctly express the content of omega-3 fatty acids EPA, DHA and other fatty acids in oils. GOED explains in the recommendation that according to the voluntary GOED monograph of the association, which industry and association members are welcome to follow, the content of EPA, DHA and total omega-3 fatty acids in oils should be expressed in weight (mg / g /) Measure and not area percentage.
The weight of fatty acids, according to the guidelines, should be expressed as free fatty acid equivalents in mg / g oil, and each fatty acid should be expressed as mg / g of the specific chemical form such as triglycerides and ethyl esters. For capsules, the fatty acid content should be given in mg per capsule, while the content of liquid products should be given in mg per ml. In addition, the contents should be based on the mass of the portion and not on the volume, since it cannot be assumed that 1 ml of oil weighs 1 gram, according to the instructions.
The reason that quantifying fatty acid content by weight is the ideal method is that a weight measurement defines the exact amount of fatty acids in the product. In contrast, the quantification of the fatty acid content based on area percentages does not take into account any other components that may be present in the oil. Oils can contain other lipids and substances depending on the type of oil and processing. “If the weight of these other substances is not corrected, using an area percentage to determine the content of a particular fatty acid leads to an error in the indication of the fatty acid content of the oil,” writes GOED. “This error is greater when there is a higher proportion of lipids and other substances that do not contribute to the fatty acid profile measured by the fatty acid analysis.”
Unfortunately, the instructions explain that today fatty acids are often measured by a combination of gas chromatography, which separates the various fatty acids, and a detection technique such as flame ionization detection or mass spectrometry. “The detector measures each fatty acid as a specific signal peak, the size of the peak corresponding to its concentration. By adding up the total area of the peaks and determining the area corresponding to a peak of a particular fatty acid, one can calculate an area percentage (percent of the total area) of the fatty acid in question, ”the instructions say. “This percentage corresponds neither to the content of this single fatty acid nor to a percentage by weight.”
To illustrate the unreliability of an area percentage measurement, GOED explains that the dilution by adding water does not change the area percentage, while the weight content would be much lower due to the dilution. In addition, not all fatty acids in the detector produce the same peak response, which means that the area percentage of one fatty acid does not correspond to the same amount of another fatty acid with the same area percentage. “Since different peaks contribute differently to the calculated total area percentage, it cannot be assumed that the area percentage determined for a certain fatty acid exactly reflects its concentration in the oil,” explains GOED. However, giving the free fatty acid content by weight makes it easier to compare the EPA and DHA content in omega-3 oils and between products of different chemical forms, says GOED.
GOED also provides examples of how an area percentage measurement of a fatty acid inflates the oil content when it is converted into weight concentration. In one sample, the EPA area percentage was calculated to be 23.24, which corresponds to 232 mg EPA when calculated from area percentage. However, when using the GOED method, the EPA weight content was 216 mg / g triglycerides.
GOED says this discrepancy is an example of how using area percentages can artificially inflate the calculated amount of oil in a product – and how this could be harmful to consumers. “As a result, it can then appear that less oil is needed to formulate a particular product. The use of less oil in the formulation leads to an incorrect and lower dose than intended for the consumer, ”writes GOED. “Put simply, an incorrect content expression can lead to label declarations not being adhered to. If a nutrient has to be present at 100% of the declared value, compliance cannot be consistently achieved with area percentages, and the deviations vary from one type of oil to another. “