Can Fish Oil Cause Abdominal Gas?

Fish oil supplements promise plenty of benefits, but some people may experience some unpleasant side effects — like bad breath or acid reflux — when taking them.
Image Credit: Evgeniia Siiankovskaia/Moment/GettyImages

Fish oil has a pretty positive reputation.

It's no wonder, then, that it's massively popular in the U.S. According to the comprehensive 2012 National Health Interview Survey, approximately 18.8 million adults had taken a fish oil supplement in the previous 30 days, per the National Institutes of Health (NIH).

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The supplement, which contains anti-inflammatory omega-3 fatty acids, is associated with a bevy of health benefits, including the potential to improve heart health, lower cholesterol and boost cognitive function.

While there's a lot to celebrate about the potential of fish oil, the supplement is linked with at least a few undesirable side effects — namely unpleasant gastrointestinal symptoms, which can include gas, bloating and belching.

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The Smelly Side Effects of Fish Oil

When taken as recommended, fish oil is considered safe. Some people may need to take precaution around fish oil, according to the NIH.

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For example, if you're taking medicine that affects blood clotting or if you're allergic to fish or shellfish, you'll want to consult your health care provider before taking omega-3 supplements

Some of the most common side effects associated with fish oil vitamins, per the Mayo Clinic, include:

  • A fishy or unpleasant aftertaste
  • Bad breath
  • Bad-smelling sweat
  • Headache
  • Heartburn
  • Nausea
  • Diarrhea
  • Rash

Diarrhea and Fish Oil

Gastrointestinal symptoms are a common concern when it comes to both fish oil and, more broadly, omega-3 supplements in general.

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November 2013 research in ​Pharmacy and Therapeutics​ found diarrhea to be one of the most commonly reported negative experiences with fish oil. Other digestive issues, including flatulence, were also associated with fish oil.

Omega-3s and flatulence also appear to share a link — it does seem possible that omega-3s can give you gas. A September 2017 study in the Journal of Renal Nutrition revealed that flaxseed oil sometimes caused a laxative effect. The oil was also associated with more frequent bowel movements.

Flaxseed oil is a vegetarian omega-3 source that is often used by those looking for an alternative to fish oil, whether for dietary reasons or otherwise.

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Acid Reflux and Fish Oil

Acid reflux and its associated symptoms, including belching, nausea and stomach discomfort, have been linked to fish oil supplements.

Fish oil's high fat content is likely the culprit of this gassiness and stomach discomfort, as fat has been shown to trigger indigestion, per an April 2016 study in ​Advanced Biomedical Research​.

5 Ways to Reduce the Fishy Taste of Fish Oil

There are some techniques that may help reduce some of the common side effects linked to fish oil.

If your fish oil supplement is leaving behind an unpleasant or fishy aftertaste, there are a few tricks to consider:

  1. Take the supplement at the beginning of your meal. The food you consume with the fish oil may help to trap the oil in the stomach and prevent the icky taste from lingering, per the Mayo Clinic.
  2. Freeze your fish oil capsules. You can actually store the supplement bottle in the freezer. Freezing slows the breakdown of fish oil in the stomach, which may help to reduce fishy burps. Don't worry, the frozen fish oil will still be properly digested.
  3. Try a different supplement. If you're not a brand loyalist, you might test out a few different brands of fish oil to find the one that sits with you best. Some manufacturers make a pure omega-3 fatty acids product, which doesn't taste fishy, per the Mayo Clinic. These are likely to be more expensive than other fish oil products.
  4. Choose a supplement with enteric coating. Some brands offer supplements with a special coating that can prevent the fish oil from being digested until it reaches the small intestine, according to the Arthritis Foundation.
  5. Choose a supplement that contains lipase. Lipase, an enzyme that helps digest fats and it may help reduce reflux symptoms associated with the supplement.

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