Why Fish Oil is Dangerous


You can’t effectively squeeze lemon on a fish oil capsule.

Can You Tell It’s Rancid?

Most fresh fish is odor­less. It shocks me whenever restau­rants garnish rancid fish with a lemon wedge for diners to squeeze and neutral­ize malodor. It bewilders me when fish lovers say the only downside is the stench that lingers after cooking it. With your apparent interest in gastroenterology, does it also shock you? Who is the worst offender, the chefs who serve fetid fish or the patrons who happily citru­size and gulp it down? What other fetid meats do consume?

Sure, citrus fruits may be used as part of a recipe, if you like, but not to mask unplea­sant smells and rot. When I was a pesca­tarian, nearly 80% of my restau­rant-ordered salmon entrees were rejected based on the odor.

Because of price, convenience, pref­erence, or potential mer­cury contamina­tion, most people do not consume enough fresh fish to receive all the essen­tial nutri­ents. Therefore, they resort to less expen­sive and more con­veni­ent supple­ments like fish oil. Fish oil is commonly used in Vietnamese, Thai and other Asian dishes.

Benefits of Fish Oil

A number of health benefits are attri­buted to fish oil. It aids in the treatment of heart diseases, high cholesterol, depression, anxiety, ADHD, low immunity, cancer, diabetes, inflammation, arthritis, IBD, AIDS, Alzheimer's disease, eye disorders, macular degeneration, and ulcers. It also provides nutrition for weight loss, pregnancy, fertility, and skin care (particularly for conditions such as psoriasis and acne). That’s quite a resumé!

The presence of omega-3 essential fatty acids like Docosa­hexae­noic acid (DHA) and Eico­sapen­taenoic acid (EPA) account for most health benefits. Other useful essential fatty acids include Alpha-linolenic acid (ALA) and Gamma-linolenic acid (GLA).

Sources of omega-3 fatty acids for vege­tarians include walnuts, flax seeds, soy­beans, tofu, flax seed oil, and eggs. However, these generally have much lower assimi­lated concen­tra­tion of this bene­ficial nutrient as fresh fish or fish oil. Get in the habit of cook­ing with flax seed oil instead of butter, olive or other vege­table oils to increase omega-3 intake.

Fish Oil Capsules

Fish oil supplements are usually made from mackerel, herring, tuna, halibut, salmon, cod liver, whale blubber, or seal blubber. The supple­ments often contain small amounts of vitamin E to prevent spoilage.

Licensed acupuncturist, Chris Kresser indicates, “Omega-3 fatty acids are highly vulnerable to oxida­tive damage. When fat particles oxidize, they break down into smaller com­pounds, like malon­dial­dehyde (MDA), that are danger­ous because they damage proteins, DNA, and other impor­tant cellular struc­tures.

“There is no evi­dence that people other than those with arrhyth­mia and chronic heart failure benefit from taking fish oil or that doses higher than one gram of omega-3 fatty acids per day provide any benefit over smaller doses.” Kressler recom­mends eating fatty fish a couple times per week, and taking cod liver oil daily.

Potential Fish Oil Dangers

The National Academy of Medicine sets the daily adequate intake (AI) of omega-3 fatty acids as 1.6 grams for adult men and 1.1 grams for adult women. Standard supple­ments typically contain about 1 gram of fish oil, with 120 milligrams of EPA and 120 milligrams of DHA—the two types of omega-3 fatty acids.

In high doses (overdose levels), fish oil supple­ments can be toxic. Get emer­gency help if you have symp­toms of an allergic reac­tion, including hives, difficulty breath­ing, swelling of throat, tongue, lips or face. Discon­tinue taking fish oil if you experi­ence irregu­lar heart­beats, flu-like symptoms or chest pain.

Side Effects From Hyperdoses of Fish Oil
Increased risk of bleedingIf taking extremely large amounts, hemorrhagic stroke, blood in the urine and nosebleeds may be manifested.
Vitamin toxicityFish liver and fish liver oils (like cod liver oil) contain high amounts of vitamins D and A. Fish oil supplements, however, do not contain too much vitamin A or D. Also, vitamin E is sometimes added.
Reduction in blood pressureSmall reduction in blood pressure corresponds to increased omega-3 intake, so people that take blood pressure lowering medications or those with low blood pressure should be careful.
Slight increases in fasting blood glucose for type-2 diabeticsIt seems, however, that scientific evidence doesn’t show any long-term side effects on diabetics from taking fish oil.
5 to 10% LDL increaseStudies show that LDL (bad cholesterol) levels increase slightly as you take more fish oil.
Upper respiratory tract swellingThis side effect of fish oil has only been found in some patients.
Allergic reactionsSkin rashes, itching, hives, swelling, difficulty breathing, swelling of the throat usually only happen in people who have fish allergies.
Stomach and gastrointestinal upsetSome people get diarrhea from fish oil and it only gets worse for them with higher amounts. Some people also claim fish oil side effects like heart­burn, bad breath, fishy aftertaste, burping, stomach pain and bloating, acid reflux, indigestion. These are actually the most common side effects of fish oil omega-3.
Too much DHA in infants and small childrenFish oil supplements may not be suitable for infants and small children because the brain doesn’t need EPA and in trying to get DHA, it gets too much EPA.

Okay, you say. Keep fish oil away from small children. If you have a fish allergy, don’t take fish oil capsules. Even without a known allergy, avoid overdosing on fish oil to reap all the benefits. Does that sum it up?

Most Fish Oil Is Rancid

Many fish oil products in the market sit on shelves for three years or more. There­fore, they are already rancid before consu­mers get them home. Likely you have heard the locution, “Repetition is the mother of reten­tion.” Well, if you have a ten­dency to “repeat” after inges­ting fish oil capsules, retention of the bottle is ill-advised.

Light, heat and air cause oxida­tion, affecting capsule longevity. The more a fat is unsatu­rated, the more likely it is to go rancid. The EPA and DHA in fish oil are both highly unsaturated fatty components. When damaged, the fats in fish oil oxidize and become lipid peroxides, which cause free-radical damage, hence diseases.

Norway is a leading nation in high-quality fish oil manufac­turing that supplies up to 40 percent of the world’s fish oil. A Norwegian clinical study showed that 95 percent of 113 over-the-counter fish oil cap­sules were so rancid that they did not meet official quality standards.

If you burp up fish oil all day long you should change to a dif­ferent brand. The oil is rancid.

“For years we have been telling people to open up their capsules—taste and smell what they are swallow­ing,” said Dr. Bo Martinsen, a native Norwegian and co-founder of Omega 3 Innovations in Venice, Florida, USA. “Now Norwegian research­ers are echoing these words and adding, ‘If you burp up fish oil all day long you should change to a dif­ferent brand. The oil is rancid.’”

Eat or Not?

High-quality fish oil capsules are viable supple­ments in regular small doses, provided they are not among the 95 percent of rancid capsules on shelves. Save your receipt whenever purchasing fish oil capsules. Before ingest­ing, pierce or cut one open and smell for rancid­ness. If it’s bad, don’t just squeeze a lemon on it; return it for a refund or throw it out.

During the manufacturing process, deodorization is performed by injecting water vapor into fish oil. In this way, volatiles that give the fishy smell and taste to a fish oil are removed by evapora­tion. After the deodorization step, the oil is cooled, and stabilized by the addition of antioxi­dants. The antioxi­dant blend is a mix of natural products consisting of toco­pherols and other food-grade antioxidants.

If you are a vegan, vegeta­rian, or if high-quality fish oil supplements are unavailable, include walnuts, flax seeds, soybeans, tofu, flax seed oil or eggs in your weekly diet. Microalgae oil is a vegetarian alternative to fish oil. Supplements produced from microalgae oil provide a balance of omega-3 fatty acids similar to fish oil, with a lower risk of pollutant exposure.

So what’s the bottom line? Omega-3 fatty acids provide numer­ous benefits and may even be prescribed by physi­cians to treat various health condi­tions. Fresh fish is the best source of omega-3 fatty acids. Because of price, conve­nience, and prefer­ence, most people do not con­sume enough fish nutrients. If you decide to take supplements, purchase a reputable Norwegian brand and pierce for smell test before consuming. Get essential omega-3 fatty acids one way or another for good health.

To support the writing of scholarly articles about gastroenterology, ClinicalPosters sells human anatomy charts, scientific posters and other products online. Slide extra posters into DeuPair Frames without removing from the wall or leave an encourag­ing comment to keep the work going. Visible content is optimized for device size.

Updated: Dec 27, 2022

Add Your Comment