Fish oil products have made them among the most popular dietary supplements on the market in Taiwan. How to choose right fish oil supplements is likely to be the choice customers often face.


The most important indicator of fish oil is freshness, which is also a key factor affecting the flavor of fish oil. All oils are susceptible to oxidation, but fish oil is highly susceptible due to its characteristic of fatty acid. Light, oxygen exposure, and heat can all contribute to oxidation. Once the fish oil begins to oxidize, it will start creating unpleasant fishy flavor and odors, which could also cause a risk to the human body. Therefore, it is necessary to make sure the quality assurance process from the source manufacturer!

The easiest way to tell whether or not your fish oil supplement is fresh is to put it through the taste and smell test. The first step is to break a fish oil capsule open, if your nose gets a strong fishy smell, it means your fish oil supplement has been oxidized and you should just throw it away. Getting a third-party laboratory inspection report is a more accurate way to provide evidence. The first is the PV value, also known as the “Peroxide Value”. The second indicator is the AV value, the AV value refers to the “Anisidine Value”, and the third value is the AV + 2 (PV) = TOTOX value. These values will give you a clear picture of the freshness level of your fish oil supplement. Just remember, the lower these numbers are, the better.

In short : PV (Peroxide Value) = The peroxide content contained now in fish oil is the PV value. AV (Anisidine Value) = Further oxidation of the peroxide will form an AV value. The AV value represents how the fish oil is treated at the front end of the manufacturing plant. When it is manufactured, if it encounters a poor high temperature and oxygen-containing process, and an initial oxide will be formed, which will further become the subsequent Anisidine Value. As a result, the most intact indicator is the TOTOX value = AV+2 (PV)

As for the values, what are the qualifications? All third-party organizations such as the Global Organization for EPA and DHA Omega-3 (GOED) and the Council for Responsible Nutrition (CRN) have recommended: PV should be less than 5 mEq/kg, AV should be less than 20 mEq/kg, and TOTOX should be less than 26 mEq/kg. Therefore, you should purchase the fish oil products from the manufacturers who can provide you the report that meets the standard.


There are many types of fish oil products on the market, including concentrated re-esterified triglyceride fish oil, natural triglyceride type fish oil, free fatty acid fish oil, and ethyl ester type concentrated fish oil. Which type has a higher absorption rate and best for the human body?

Fish naturally contain the omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) as triglyceride esters. A general Natural TG fish oil capsule provides a maximum of 300 mg of combined EPA and DHA per 1,000 mg of oil. To reduce the intake amount of capsules, the manufacturer produces concentrated fish oil instead, and increase the EPA and DHA content. Usually A 1000 mg concentrated fish oil capsule can be raised to more than 500 mg of EPA + DHA. Before purifying fish oil and increasing EPA and DHA levels, individual EPA and DHA fatty acids must be removed from their triglyceride structure and excess fatty acids need to be removed as well. Once the expected concentration of EPA and DHA is reached, the manufacturer must choose between two different options. The first is to reconnect EPA and DHA fatty acids to reconstitute the natural triglyceride structure (a process known as “re-esterification”). The cost of the second option is much lower: let the fatty acid retain a concentrated esterification pattern (EE FORM), which is a “new state” fatty acid type with only 20 years of history in human diet.

Many of the concentrated fish oil supplements on the market choose the Ester form (EE form), for the reason of lower cost. However, the TG molecular type of natural essential fatty acids ensures the higher rate of absorption and utilization, thereby achieving high quality results. A recent study in September 2010 has confirmed that the re-esterified triglyceride (rTG) has proven to be the most effective type. The results showed that that the unadjusted mean relative bioavailability EPA+DHA was 73% from EE, 91% from FFA and 124% from rTG. The re-esterified triglycerides was superior (124%) compared with natural fish oil.