Fish Oil – How Fresh Is Yours?

Fish oil is a commonly known source of two significant omega-3 fatty acids, called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Supported by studies and research, many scientists and health professionals agree that omega-3 fatty acids provide an array of health benefits. Consuming omega-3 fatty acids helps to improve brain and eye development, heart and cholesterol health, immunity, sleep, and much more.

Since the human body can't naturally produce these fatty acids, we can only obtain these popular nutrients from foods or supplements.

The Problem

Omega-3 long-chain polyunsaturated fatty acids are highly prone to oxidation due to their large number of double bonds and their position within the fatty acid chain, causing a fish oil supplement to become rancid and less effective than fresh ones.

Although it is still unclear to what degree the oxidation of fish oil influences its efficacy or causes harm to humans, you will want to have the freshest fish oil possible when choosing fish oil supplements.

Choosing a Fresh Fish Oil

Freshness means low oxidation levels. It is important to read the label when choosing any dietary supplement however, the expiration date of the product may not always reflect the freshness of the product. Luckily, the degree of oxidation can be tested by both a simple smell test as well as industry-standard method.

The Smell Test

The best way to tell if your omega-3 supplement is fresh is to smell it. Cut open a soft gel and smell the oil. If you smell a strong rancid fishy smell you should be concerned. Fresh fish oil will have a faint oceanic aroma. Be aware that some products may have gone through unnecessary processing or adding fragrances to mask a rancid product.

Scientific Measurements

Freshness can be measured by total oxidation (TOTOX) value, which can be found in the product Certificate of Analysis. TOTOX value is made up of two components:

• Anisidine value (AV): provides a measurement of aldehydic compounds
• Peroxide value (PV): provides a quantitative measure of hydroperoxide levels

A number of authorities have published maximum limits of oxidation in fish oils, including the Global Organization for EPA and DHA Omega 3s (GOED). The maximum recommended limits from GOED are: PV 5 mEq/kg, AV 20, and TOTOX 26.[1]

Some manufacturers do not publish their anisidine values and although the peroxide values may be reasonable, the overall TOTOX value can be very high. Some manufacturers only test for peroxide value after encapsulation and after an elapsed period of time.

The peroxide values in a soft gel actually go down over time but the anisidine values go up, therefore pushing the TOTOX value up as well.