Is Your Fish Oil Rancid?

By Anne-Marie Chalmers, MD

Think fish oil. If your gut reaction is “yuck,” you are in good company. Whether it’s from remembering Grandma’s cod liver oil or

taking today’s capsules, many people believe fish oil ought to taste bad.

But the truth is that omega-3 supplements shouldn’t taste like yesteryear’s salmon. If your fish oil does, it’s likely rancid.

What Is Rancidity?
If you eat fish regularly, you probably know that fish spoils more easily than other foods if not kept cold or consumed quickly. The same is true of fish oil. The reason fish and fish oil spoil quickly – or ‘oxidize’, as the scientific community calls it – is that they are rich sources of the omega-3 fatty acids EPA and DHA.

EPA and DHA are the main workhorses of the omega-3 family. These fatty acids are known for their anti-inflammatory properties and role in promoting good brain health, to name just a few benefits. But their chemical structure also makes them highly prone to oxidation. If the EPA and DHA molecules oxidize, their molecular structure starts to change and the molecules break down into byproducts. These byproducts, known as lipid peroxides, give off the unpleasant smell and taste of spoiled fish.

How quickly omega-3s oxidize depends on numerous factors: how the fish was caught, how the fish oil was processed, how the final product was distributed, etc. Reducing exposure to oxygen, heat and light, as well as adding antioxidants, will help protect the oil. But if the oil has already started to oxidize, it is just a matter of time before it turns rancid.

How Rancidity Affects Your Health
Besides tasting and smelling bad, rancid fish oil could be harmful. Animal studies indicate that excessively oxidized fatty acids may cause organ damage and inflammation. And one 2013 study from Spain found that oxidized fish oil had negative effects on cholesterol levels. This was in comparison to non-oxidized fish oil, which provided the expected health benefits.

How to Combat Rancidity
Rancid fish oil is unfortunately common. Studies from Canada, New Zealand, Norway and other nations have found that a high percentage of omega-3 supplements exceed acceptable oxidation limits.

Yet fresh fish oil exists and can provide consumers with a relatively inexpensive, safe way to improve health. To ensure you get a fresh omega-3 product, do the following:

1. Evaluate your current product.
The best way to tell whether or not your omega-3 supplement is fresh is to put it through the taste and smell test. If you have capsules, break them open. If your nose gets a whiff of a strong fishy smell, get something else.

2: Make smart purchases.
Fish oil is perishable, just like milk or seafood. Beware of labels that have a two to three year expiration date. These products have likely been sitting on the shelf for years.

You can also ask manufacturers to share their fish oil’s oxidation numbers, better known as the peroxide, anisidine, and TOTOX values. These values will give you a good picture of the oil’s freshness level.

3: Remember that bigger is not always better.
Look for small containers when buying fish oil. The longer a fish oil is stored – even in gelatin capsules – the greater the chance it will turn rancid.

4: Keep it cold.
Buy fish oil that you can store in the freezer or refrigerator. Low temperatures slow down the enzymatic time bomb that is ticking away.

5: Use it or lose it.
All fish oils will turn rancid with time. When you first buy fish oil, remember to use it up.

This article was abbreviated from a longer version published on
omega3innovations.com. For the full text and references, visit:

https://omega3innovations.com/blog/is-your-fish-oil-rancid/

About Anne-Marie Chalmers, MD
Born and raised in the United States, Dr. Chalmers graduated from Brown University and completed her medical training at the University of Oslo in Norway. Dr. Chalmers practiced emergency, family, and preventive medicine in Norway for many years. Today, she serves as president of Omega3 Innovations.

Call us at 941.485.4400
www.omega3innovations.com