Can fish oil cause inflammation?

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I recently wrote an article for magazine, which discussed chronic inflammation in relation to autism. Part of the pro-inflammatory state involves an excess of omega-6 fatty acids. So, part of the DeFlaming approach involved taking some omega-3 fish oil.

Important to understand is that a 1000 mg capsule of fish oil does not mean you are getting 1000 mg of omega-3 fatty acids. For example a 1200 mg capsule of the Anabolic Labs fish oil product contains 600 mg of omega-3 fatty acids. You always want to make sure you are going by the omega-3 content, not the total oil amount.

The typical recommendation for fish oil supplementation is to get 1000-3000 mg of omega-3 per day. For perspective, there is 9 calories per 1000 mg of a fat or oil. So if you were to take 2 fish oil capsules that contain 1200 mg of total oil per capsule, you would be taking 2400 mg of total fish oil, which amounts to 21.6 calories. This would deliver 1200 mg of omega-3 fatty acids, which means that a little more than half of the 21.6 calories are omega-3 fatty acids. This is clearly not a lot of fish oil or omega-3s.

Shortly after the article was published, I was contacted by a reader who claimed that taking 1000-3000 mg of fish oil per day would promote inflammation because the omega-3s would oxidize. He said that, over time, this would cause chronic diseases such rheumatoid arthritis, Alzheimers disease, and host of immunological, neurological, and endocrine problems.

The original studies with fish oil supplements for humans with rheumatoid arthritis demonstrated that taking well over 3000 mg of omega-3s per day led to improved symptoms, so the likelihood that taking less than 3000 mg could cause rheumatoid arthritis is quite unlikely. Nonetheless, I asked him to send me references that supported his claim. Here are two articles he sent:

  • Umegaki K et al. Docosahexaenoic acid supplementation-increased oxidative damage to bone marrow DNA in aged rats and its relation to antioxidant vitamins. Free Radic Res. 2001;34:427-35.
  • Song JH et al. Enhanced level of n-3 fatty acid in membrane phospholipids induced lipid peroxidation in rats fed dietary docosahexaenoic acid oil. Atherosclerosis. 2001;155:9-18.

In the Umegaki study, they supplemented the rats with 300 mg of omega-3 per kilogram of body weight, which is a lot of fish oil, and becomes very obvious when you apply those amounts to humans. An 80 kg man weighs just 176 pounds, which translates in 24,000 mg of omega-3 fatty acids per day, which is 8-24 times more than the typical recommendation of 1000-3000 mg per day.

In the Song study, they gave rats 140 mg of omega-3 for every 100 grams of rat weight. This translates into 1400 mg of omega-3 for every kilogram of body weight. So for a 80 kg (176 pounds) man, this means he would need to take 112,000 mg of omega-3 fatty acids per day. This represents 37-112 times more than such a man would take, and in this case, fish oil would likely oxidize and cause inflammation. However, no one takes any where near this much fish oil.

The reason why researchers would dose rats with such massively high levels of omega-3 fatty acids is a mystery to me. An even greater mystery to me is why someone would contact me and repeatedly defend, in multiple emails, the absurd notion that taking 1000-3000 mg of omega-3 fatty acids per day is remotely harmful.

The message in this blog is straightforward. It is important to read the details of the actual article that is being used to promote an idea. When it comes to nutritional supplements, it is most common for people to substantially exaggerate their curative effects. This blog article is an example of someone who went the other way and conjured the notion that omega-3 fatty acids can cause disease, even though the rat studies had absolutely no relationship to what humans would take.