Wellness Health & Well-being 3 Things You Should Know About Fish Oil Supplements By Katherine Martinko Senior Writer University of Toronto Katherine Martinko is a writer and expert in sustainable living. She holds a degree in English Literature and History from the University of Toronto. our editorial process Twitter Twitter Katherine Martinko Updated October 11, 2018 CC BY 2.0. hitthatswitch Share Twitter Pinterest Email Wellness Health & Well-being Clean Beauty Fish oil supplements are the easiest way to get healthy omega-3 fatty acids, but according to Dr. Barry Sears in "The Mediterranean Zone," there are some things you should know before you go shopping. There was a time when people ate a lot more fish and benefited from a healthy intake of omega-3 fatty acids, but then many things changed. Species were hunted almost to the point of extinction, making fish far more expensive, and the oceans became a dumping ground for industrial and urban waste, spreading contamination throughout the marine food chain and making it unsafe to eat fish in great quantities. The result is that most people no longer have a regular source of omega-3s in their diet. Americans eat only 5 to 10 percent of the omega-3s they did a hundred years ago – and that’s a serious problem, especially when you consider that omega-3s are excellent at reducing inflammation, beneficial for brain and nervous system health, protective against heart disease, and can reduce the incidence and severity of many chronic diseases, including Alzheimer’s. Dr. Barry Sears, author of The Mediterranean Zone, is a firm believer in the importance of fish oil supplements to increase one’s intake of omega-3 fatty acids, but not just any brand will do. In his book, Dr. Sears explains the “dirty secrets” of fish oil marketing that can help guide you toward the cleanest, purest fish oil supplement. #1 – All fish oils contain PCBs. Regardless of what manufacturers or labels claim, it’s impossible to find a fish oil supplement that does not have any Polychlorinated Biphenyl (PCB) in it. Some have lower levels than others, but none is completely free from them. Here’s one little test you can do at home to test the purity (a.k.a. PCB content) of your fish oil: Pour the contents of five capsules into a shot glass and put it in the freezer. Five hours later, stick a toothpick into it. If it’s frozen solid, that’s an indicator of higher PCB content. If you can stick the toothpick in, that’s better. Dr. Sears recommends searching for technical data on the levels of all 209 PCB isomers before buying or continuing to take a particular fish oil supplement. That data should be available on the manufacturer’s website. If not, then don’t consume more than 1 gram (usually equivalent to 1 capsule) daily, or switch brands to one that’s more transparent about those numbers on its website. #2 – ‘Natural’ fish oil is often unnatural. Look for ‘refined’ fish oil and stay away from ‘natural’ fish oil, such as cod liver oil. As Dr. Sears writes, “This is the one case where refined is better than natural.” The former has higher levels of omega-3 fatty acids and generally lower levels of PCBs. The latter has an omega-3 content that will never exceed 30 percent, since that is the maximum level of fatty acids occurring in the fish from which its taken, and it must be heated in order to release those stored fats. There are alternative fish oils that should also be avoided. Krill oil, for example, is produced by dissolving the small shrimp-like creatures in hexane and treating with acetone, and it contains free fatty acids that are prone to oxidization. #3 – Most fish oil can easily go rancid. Rancidity is measured by something called a Totox (total oxidation) value. The upper limit, set by the World Health Organization, is 26 milliequivalents per kilogram; anything over 26 means that the product is rancid. If a fish oil is poorly refined, it will smell unpleasant and manufacturers will add flavourings to mask the smell, but that doesn’t make it any safer for human consumption. Check the manufacturer’s website; a good company should always post its PCB and Totox levels for each batch. If not, find another more transparent brand. Before you go shopping, check out LabDoor’s list of the 51 best fish oil supplements.