Saturday, June 16, 2012

Facts on Fish Oil: what is fish oil really good for?


What are the facts on fish oil? 
What is fish oil really good for?

In a previous post I described the results of randomized trials with fish oil to answer the question: what is fish oil good for?
Those who read that post will know that there are select groups of people that seem to benefit from fish oil supplements.

Now we have more facts on fish oil. The results of a large randomized controlled clinical trial were presented at the American Diabetes Association meeting this week. This study called ORIGIN randomly assigned over 12500 persons. All had elevations in blood glucose and 82% had  diabetes at the start of the study.  Treatment was given with insulin glargine (Lantus Insulin) to one half of the participants and usual care of the blood glucose to the other half.  I will discuss the results of the Lantus treatment in an upcoming post.

Half the ORIGIN group were given prescription fish oil in the form of Lovaza 1 gram per day and the other half received an identical appearing placebo pill. The average age of the participants was 63 years and about 60% had previous cardiovascular disease. They were followed closely for an average of more than 6 years.

So what did the ORIGIN investigators find were the effects of the fish oil supplement?  First we know that Lovaza and fish oil in general lowers triglycerides if you take enough. Even at this low dose of fish oil, the triglycerides were about 10% lower than in those who were given placebo. And the ORIGIN group as a whole did not have high triglycerides to start with; the median level was 140 mg/dl.

Fish oil had absolutely no effect on the occurrence of cardiovascular death, or heart attack (medically known as myocardial infarction)or on stroke.  Keep in mind that about half the patients were on statin therapy at the start of the study and statins are proven to reduce cardiovascular events. And two thirds were on the proven-to-benefit ACE inhibitors or ARBs.

So in this population of people with no recent myocardial infarction or heart failure, a fish oil supplement at this quite low amount was not helpful beyond the other treatments these people were getting. Would a higher dosage, say 4 grams per day have been effective? Many experts think so.

Keep in mind these facts on fish oil when you read all the hype. You can the read the published paper here.

Fish oil contains omega 3 fatty acids which lower triglycerides and may be helpful for people with:
  •       high triglycerides or
  •       heart failure or 
  •       people who have had a myocardial infarction in the previous 3 months.

Those are the main persons for whom there is fairly good evidence of benefit from fish oil omega 3 fatty acids. More details can be found in my previous post.

Watch for claims on omega 7 fatty acids. There are even less data to support their use. And a common omega 7 fatty acid,  palmitoleic acid, appears to raise LDL cholesterol, the “bad cholesterol”.

Maybe you should reconsider that fish oil supplement. 
Most people would be pleased to be taking fewer pills and saving some money too.

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