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2012-06-15

Do Omega-3s Really Offer No Cardiovascular Benefits or Protection from Alzheimer's?

This seems like a silly question since many studies have shown omega-3 fatty acids offer multiple benefits to many bodily systems, including the cardiovascular and nervous systems. However, results from two recently published studies cast a shadow of doubt on these benefits, so let's dig deeper.

First, a study using a pharmaceutical-type omega-3 product indicated no heart benefits, compared to placebo, for people at high risk of cardiovascular events. The researchers behind the Outcome Reduction with Initial Glargine Intervention (ORIGIN) Trial concluded: “Daily supplementation with 1 g of omega–3 fatty acids did not reduce the rate of cardiovascular events in patients at high risk for cardiovascular events.”

Since the totality of evidence for omega-3s give solid data to support its use, what could be behind the null results of this study at hand? For this study, researchers recruited 12,536 patients at high risk for cardiovascular events with diabetes, impaired fasting glucose, or impaired glucose tolerance. Patients were randomly assigned to receive either a daily placebo or a 1 g capsule with at least 900 mg omega-3 fatty acid ethyl esters. The participants were also taking “more concomitant cardioprotective therapies”, said the researchers.

A very likely reason for the null results is that subjects were taking a cocktail of cardiovascular drugs, and any potential benefits of EPA & DHA (the two main omega-3 fatty acids) were being overshadowed by the subjects' pharmacological regimens. This is evident from the fact that after six years of supplementation, the incidence of death from cardiovascular causes was reduced. Why this matters is that without enough cases of death in either group, the statistical power to flush out a benefit of omega-3 supplementation is diminished. While the sample size was quite large, a lack of statistical power would indicate that future studies conducted in a similar fashion may need many more subjects/patients to reach sufficient statistical power.

Another possible explanation is that the type of fish oil concentrate they used were ethyl esters. Fish oils are naturally found in the triglyceride form, which some studies suggest are superior to the "semi-synthetic" (and some go as far to say "synthetic") ethyl ester fish oils in terms of bioavailability and bioactivity.

Lastly, keep in mind that our initial understanding of the cardiovascular benefits of omega-3s come from population studies based on fish consumption. Since EPA and DHA are thought to be the major bioactive compounds in fish--in true pharmaceutical fashion--it makes sense to isolate these, chemically modify them (to ethyl esters), administer them to people, and expect a benefit.

Yet, we know that there is a lot more to fish than just EPA and DHA (e.g. phospholipids being just one example of many, which is partly why I personally continue to favour krill oil). It's unbelievably ignorant for anyone to think we can deliver EPA and DHA, omit everything else in fish, and expect to find the same benefits as eating the whole fish. I talked about this in THIS post last year.

Coincidentally, a meta-analysis that also just came out showed that fish consumption and omega-3s can reduce the risk of heart failure by 15%. Again, however, this was a population/epimediological study that looked a fish consumption, not an RCT/intervention study that administered fish or fish oil supplements.

Now, let's tackle the study on cognitive function and dementia. This was a systematic review (similar to a meta-analysis) that looked at three previously conducted studies, with a total of over 3500 elderly people over 60 years of age. The study provided evidence that omega-3 capsules or omega-3 enriched margarines offered no benefits for cognitive health over placebo (sunflower oil, olive oil or regular margarine).

However, with these studies only being short-term studies of a minimum of only six months and up to three and a half years, even the researchers themselves suggest this as a limitation and possible explanation of why they saw no beneficial effect from omega-3s. They concluded that longer term effects are worth investigating. This is true for any chronic disease, and unfortunately, an obstacle for intervention studies in the prevention of chronic diseases--ideally these studies should span many years, even decades (since most chronic diseases progress very slowly over decades). Six months is simply a total waste of time and money. I hope these weren't funded by the government using tax-payers' funds.

Also, none of the studies measured whether these volunteers went onto develop dementia, but volunteers were only given memory and thinking tests to monitor any cognitive decline. Participants given omega-3 did not score better in standard mental state examinations or in memory and verbal fluency tests than those given placebo.

The other arguments I made for the first study hold merit here as well. Several studies have suggested that omega-3s are essential for keeping nerve cells in the brain healthy, but this is based on studies that found people who regularly consume fish rich in omega-3s have a lower risk of developing memory loss or Alzheimer’s disease. But fish oil supplements are not fish.

There are other possible limitations and flaws with this study, but since I only had access to the abstract for this one (and not the full-text article), I'd be speculating--even though I'm confident my assumptions would be accurate.

So anyway, there you have my coverage on these ones. Just remember the totality of evidence suggests multiple health benefits. Even better, try krill oil, which includes many other beneficial components other than just the omega-3s. Bye for now.


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