Is Constipation a Side Effect of Using Fish Oil?

Recently I received a reader question inquiring about fish oil as a cause of constipation, and the owner of this site sent me a question inquiring about fish oil for constipation in children. Does fish oil constipate you? Can you use fish oil to treat constipation?

Fish Oil is More Likely to Loosen Bowels Than to Stop Them

I've simply never encountered anyone who became constipated after taking fish oil. I am not aware of any theoretical reasons fish oil should cause constipation. Diarrhea after taking fish oil, on the other hand, is a too-frequent event.

If you experience diarrhea after taking fish oil, it's not due to the fish oil in a capsule. It may be due to the marine liquids or "fish juice" that some companies allow to stay in the mix they use to make fish oil capsules. Some companies, notably Xtend-Life and Nordic Naturals, use strictly low-temperature methods to separate fish oil from fish. Others may use steam to boil it out of the fish, along with whatever other liquids may be steamed out. They don't filter the fish oil (Nordic Natural and Xtend-Life do), so there is a tiny bit of fish in every capsule.

And what happens to fish if you leave it out for a few months? That is what can happen to some brands of fish oil.

To be sure, the amounts of contamination are tiny even in the worst fish oils. You aren't going to catch food poisoning from fish oil. But if a product puts a lot of fish oil in every capsule, then there simply is not enough room for any contamination.

Which products put the most fish oil in every capsule?

  • CardioStat Omega-3 Fish Oil Triple Strength
  • NC Triple Strength
  • Life Extension Super Omega-3
  • Nordic Naturals
  • Solgar Omega-3
  • Spring Valley
  • Vital Oils
  • Xtend-Life.

Which products put the most "other liquids" in every capsule?

  • Dr. Sears Go Fish Strawberry- Lemon Flavor
  • Mercola Premium Select Krill Oil
  • New Chapter
  • NOW Neptune Krill Oil
  • The Simpsons Berry Squirts

If you look at these lists and you are thinking "Surely Dr. Mercola and Dr. Sears put out quality products," I'd say that I think so, too. But these are the kinds of products that are most likely to present problems with contamination on the shelf. If Drs. Mercola and Sears would like to share how they know their products are pure, please write us, and I am sure this site will publish the information.

But the least digestive upset comes with the purest products, the first list. If you choose from among these products, you won't suffer diarrhea-or constipation.

Frequently Asked Questions

Q. But can you use fish oil to treat constipation in children?

A. No. Try to avoid giving children pills and capsules, since their digestive tracts are shorter than adults and don't have as much space to dissolve them. To treat constipation in children, gradually increase servings of fruits, vegetables, and fiber-rich vegetables, and make sure they drink enough water.

Sometimes the problem in children's constipation is toilet training. One approach is to require your child to sit on the toilet for 5 to 10 minutes within 30 minutes of eating after every meal, even on weekends and holidays. Giving your child every opportunity to relieve the bowels sometimes works.

Children usually should not be given laxatives. Laxatives can change electrolyte balance, causing dehydration, muscle cramps, and even seizures. It is better for a child to go two or three times a week while following a higher-fiber diet than it is for a child to go every day with the help of laxatives.

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