I Resent This Title: "Fish Oil Reduces Alzheimers Risk"

Over at Retrospectacle, Shelley titled her blog post "Fish Oil Reduces Alzheimers Risk." Who can blame her? ScienceDaily did it, too. I haven't seen the title of the original article in the Journal of Neuroscience, but I suspect the researchers might have even included something about fish oil, too. But in their attempts to frame science, they're encouraging fish consumption for no good reason.

What all these authors really mean is that eating omega-3 fatty acids reduces risk of getting Alzheimers. But wild fish is just one of many good sources of omega-3. Flax seeds, for instance, have six times more omega-3 than your average fish. Kelp, walnuts, and acai palm fruit also have high levels. So do meat, cheese, and eggs from animals fed primarily grass (problem is, most animals are now fed corn instead of grass).

Michael Pollan has more on why our omega-3s are out of whack--because of the corn-fed animals we eat--and a great description of a shifting baseline. From The Omnivore's Dilemma:

One of the most important yet unnoticed changes to the human diet in modern times has been in the ratio between omega-3 and omega-6, the other fatty acid in our food. Omega-6 is produced in the seeds of plants; omega-3 in the leaves. As the name indicates, both kinds of fat are essential, but problems arise when they fall out of balance. (In fact, there's research to suggest that the ratio of these fats in our diet may be more important than the amounts.) Too high a ratio of omega-6 to omega-3 can contribute to heart disease, probably because omega-6 helps blood clot, while omega-3 helps it flow. As our diet--and the diet of the animals we eat--shifted from one based on green plants to one based on grain (from grass to corn), the ratio of omega-6 to omega-3 has gone from roughly one to one (in the diet of hunter-gatherers) to more than ten to one. (The process of hydrogenating oils also eliminates omega-3s.) We may one day come to regard this shift as one of the most deleterious dietary changes wrought by the industrialization of our food chain. It was a change we never noticed, since the importance of omega-3s was not recognized until the 1970s.

Pollan believes omega-3 is to today what oat bran was to the 1980s. But fish didn't suffer greater demand thanks to the oat bran hysteria. Fewer fish thanks to "efficient" meat devoid of omega-3. Just another shifting baseline...


More like this

The article refers specifically to docosahexaenoic acid (DHA), not omega-3 fatty acids in general. DHA is only abundant in fish. Flax seeds and other plant sources contain alpha-linolenic acid (ALA) instead. ALA is good to eat too, but I'm not aware of any research on ALA that's relevant to the article we're discussing here.

By ColoRambler (not verified) on 27 Dec 2007 #permalink

I'm not an omega-3 expert, though I would like to be, but a quick inquiry into some nutritional websites shows that modern farming practices have led to a reduction in DHA levels of eggs and meat, which could help explain why fish are now the most abundant source. Also, ALA can be converted in the body to EPA then to DHA, though the process is inefficient. Furthermore, it's probably true that the ratio is the most important thing as intakes of DHA and EPA have declined in the UK and other countries with a western diet over the last fifty years despite growing per captita fish consumption.

Last night I saw omega-3 enriched orange juice and looked at the ingredients: fish oil. I don't think it's a bad thing to start eating more fish oil. But I resent the fact that studies on omega-3 fatty acids always point to eating more fish without addressing the more deep-seated problem of why we're deficient to begin with: because we now eat corn-fed industrially raised animals.

But I resent the fact that studies on omega-3 fatty acids always point to eating more fish without addressing the more deep-seated problem of why we're deficient to begin with: because we now eat corn-fed industrially raised animals.

And lots of vegetable oils heavy on omega-6 fatty acids but little if any omega-3. If I remember correctly, this is what many nutritionists regard as the main culprit, even worse than the shift in livestock raising. Common omega-3 fats become rancid easily, so oils rich in omega-3 fats can't be used for repeated high-temperature uses (like fast-food frying). Even otherwise-healthful cooking oils used at home typically don't have much; canola oil is the only major exception.

In case it wasn't clear, I'm not disputing the idea that the Western diet has become very low in omega-3 fats from all sources, and there are lots of things we could do, besides eating fish, to change that. I was just noting that the study itself focused only on one omega-3 fatty acid, DHA, that currently can only be obtained easily from fish, and we don't know how its conclusion applies to other omega-3 fats (if it applies at all).

By ColoRambler (not verified) on 27 Dec 2007 #permalink

I just wanted to point out that my post on the article (weeks ago?) did not make this egregious error. But, to this I'll add that this was one of the most poorly written papers I've read in a long time. It was not easy to get the point. This is not acceptable because the paper really was written for a broader audience (of scientists) than many.

Jennifer, title changed on my post. I'll have a post up later answering the rest of your post.

The reason I chose fish oil rather than flax for my own supplementation is that I read the body can readily use DHA, while ALA must be converted to DHA and that conversion is not that efficient.

It was a couple of years ago, but I do recall reading a paper which found the conversion from ALA to DHA was in the single digits. Males had a lower conversion rate than females by a large margin.

I think there is non-fish derived DHA from algae available. That's where the fish get theirs. Probably expensive. I haven't searched for it in a while, but would like to find some, fish oil gives me a headache. If anyone knows of a good, reliable source, I would like to know about it. Thanks, rb

(Cross-posted at my blog)
Hi Jennifer, fish oil had an effect so the title was not inaccurate. Although I certainly see your point about promoting unmitigated fish consumption--and how that might lead to increased mercury--but many fish like sardines and herring are low in mercury and high in DHA. And as your commenters pointed out, fish oil is by far the most abundant source of DHA, and other routes of intake are inefficient. Fish oil supplements get around the mercury problem altogether, as it is purified and standardized. And as pointed out by commenters at my blog, fish oil has benefits outside of this one study, specifically it can regulate cholestorol and has anti-inflammatory and neuroprotective properties.

Shouldn't the focus be on how to make fishing sustainable rather than telling people *not* to eat fish, given the benefits?


As to whether the study shows that fish oil may *actually* decrease Alzheimers risk:

This study shows that dietary fish oil increases the protein LR11, which provides the specific molecular mechanism that fish oil affects amyloid production. It had already been determined in 2005 that administering dietary DHA reduced neurotoxic amyloid plaque load (http://www.jci.org/cgi/content/abstract/115/10/2774). The current paper shows us *why* that is the case by implicating the DHA-dependent protein LR11 in the molecular processing of amyloid.

Hi Arby, Shelley. This from Joel Fuhrman, M.D..

Docosahexaenoic acid (DHA) is a long-chain omega-3 fatty acid. About half of the brain and eyes are made up of fat, much of which is DHA, which is an essential nutrient for optimal brain and eye function.1 Children's diets today are notoriously low in the beneficial omega-3 fats found in foods such as walnuts, flax seeds, soybeans, leafy greens, and certain fish. I do not recommend fish as a preferred source of these beneficial fats for children because of contamination with pollutants and mercury.

The most commonly used supplement to add DHA to the diet is fish oils, but what is not widely known is that most of us can produce sufficient DHA from short-chain omega-3 fatty acids received from walnuts, flax seeds, and green vegetables. Many fish make their DHA from eating greens, too, from algae.

New products are available that contain DHA from algae, the fish's original source. Unlike fish oil, the algae-derived DHA, grown in the laboratory, is free of chemical pollutants and toxins that may be present in some fish oil-based brands. I recommend favorable DHA products that are designed for purity and are suitable for children. Neuromins is a common (non-fish-derived) brand of DHA sold in most health food stores, and I also have designed and manufactured an all-plant-derived DHA supplement, DHA Purity, available on my Web site and in my office.

In this case, I am not telling people not to eat fish (though I will be happy to). I am merely saying that we should be looking at alternative sources of DHA given that, at the moment, very few fish stocks are indeed sustainable and there are associated health risks (in addition to benefits) when consuming fish. It is even more important that we ask ourselves why we're so deficient in DHA to begin with when many of our ancestors actually ate LESS fish than we eat today. And then I come back to Michael Pollan and our corn-based society...

But I resent the fact that studies on omega-3 fatty acids always point to eating more fish without addressing the more deep-seated problem of why we're deficient to begin with: because we now eat corn-fed industrially raised animals.

Also, the fact that there are less fish than there ought to be doesn't change this study's (and others) positive findings about fish oil. So saying that researchers etc are encouraging increased fish consumption for 'no good reason' is disingenous. There certainly is good reason, the real question is whether that reason outweights the negative impacts on fish populations which would be the result of increased demand for fish. Perhaps encouraging artifical manufacturing of DHA would be a productive route. Either way, the health benefits and scientific studies of DHA (in whatever form) should not be dismissed because of a perception of increasing demand for fish.

What all these authors really mean is that eating omega-3 fatty acids reduces risk of getting Alzheimers.

The rats in the study were given dietary fish oil, since it is the richest source of DHA, so it is easy to confuse the point. Yes, it was the DHAs which increased LR11--but it was in fish oil which is currently the only efficent way to get DHAs.

Last thing: human clinical trials testing fish oil in Alzheimer's patients is already underway. Preliminary results from a 6 month fish oil trial delivering placebo or 1.7 g/d DHA to mild to moderate AD patients found no impact on cognitive decline in the overall group, but apparent stabilization in patients at the earliest stages of cognitive decline (Freund-Levi et al., 2006). This suggests that once AD is underway fish oil may not help much, but that prevention is where it could be of real benefit.

Perhaps encouraging artifical manufacturing of DHA would be a productive route.

I still think asking ourselves why our omega-3s are out of whack to begin with is the most productive route. But I managed to locate an article given to me titled "Relief for fish stocks: oceanic fatty acids in transgenic oilseeds"--written in 2005 by Domergue et al. in TRENDS in Plant Science (10)3. And it addresses this very issue.

it was in fish oil which is currently the only efficent way to get DHAs

Not true. As noted by the supplement Neuromin offered above.

As for encouraging fish consumption, I am totally serious when I ask who funded the study...

Ok, ok. So it's not a conspiracy. Shelley informed me the study was not funded by the fishing industry, but rather the National Center for Complementary and Alternative Medicine Grant the National Institute of Aging.

Still, I'll have more on that theory at a later date...

It was actually funded by the mayonnaise industry who are trying to encourage greater consumption of tuna salad sandwiches. And they're on the take from the pickle lobby.

By Randy Olson (not verified) on 27 Dec 2007 #permalink

"I still think asking ourselves why our omega-3s are out of whack to begin with is the most productive route."

This isn't a realistic goal. Why bother spending the time and energy fighting the corn/farming industry when you can quickly and easily take a fish oil pill or eat a couple more pieces of the fish Shelley just mentioned.

By John Shmitty (not verified) on 28 Dec 2007 #permalink

Jennifer, this study is very interesting
High Omega-3 Essential Fatty Acid Status in Nigerians and Low Status in Minnesotans by Holman et al. It is an example of a non-fish eating population with an acceptable fatty acid profile. I think in this case it's time to ask what else, besides fish, are they not eating? (hint: they are not eating corn).

The Susan Allport book Queen of Fats references this and other studies to argue that plant sources are good sources, but only if you are cutting levels of omega-6 in the diet.

I'm not a biochemist (I'm trained like you in envi econ), but it seems that omega-6 fats can drown out omega-3 fats. This letter
has a good summary

Excess omega-6 fats interfere with the health benefits of omega-3 fats because they compete for the same rate-limiting enzymes. A high proportion of omega-6 to omega-3 fat in the diet shifts the physiological state of the body toward the pathogenesis of many diseases: prothrombotic, proinflammatory and proconstrictive (1).

Chronic excessive production of omega-6 eicosanoids is associated with heart attacks, thrombotic stroke, arrhythmia, arthritis, osteoporosis, inflammation and cancer. Furthermore, coronary heart disease mortality has been demonstrated to be proportional to plasma levels of long chain omega -6 fat. (2)

Prior to industrialization, no population has been exposed to the current high levels of omega-6 polyunsaturated fats in westernized diets. Today we eat fat that did not exist 100 years ago, such as cottonseed oil (3). Humans evolved on a diet with a balanced ratio of omega-6 to omega-3 fats of about 1:1. Today, that ratio in westernized countries is near 17:1.

Other letters on that page also suggest problems with commercial fish oil preparations. Also interesting this letter has the conversion problem:

Vegans generally have diets lower in alpha-linolenic acid (ALA) (omega-3) than in linolenic acid (omega-6) and, thus, must wisely choose oils with higher ALA content. Alpha-linolenic acid is converted to eicosapentaenoic acid (EPA) (6% in some studies and 25% in others); however, conversion to docosahexaenoic acid (DHA) in the human body is poor. As well, the conversion is further limited (by as much as 40%) by excess omega-6 in the diet, which competes for the same enzyme system. Cardioprotective effects have been demonstrated for ALA; however, the results are not as robust as for EPA and DHA.

Some time ago, I had the opportunity to pick up an inexpensive 300 count supplement of either fish oil or flaxseed oil, both marketed for their omega-3 fatty acid content. At that time, never having heard of DHA or ALA, but being aware of the damage being done to the ocean environment due to fishing, I went for the flaxseed. I've also added flaxseed meal to baked goods recipies (it has a strong flavor that easily overwhelms, so I use it in moderation). Clearly here, the informed opinion is that DHA is not only better than whatever omega-6 fatty acid is in corn-fed animals, but better than ALA. Does anyone know or even have a clue as to whether unconverted ALA is better than the corn-derived omega-6 acids, or is its sole beneficial aspect as a precursor to DHA?

By Dangerous Dan (not verified) on 28 Dec 2007 #permalink

Melissa, Thanks for these great links. Unfortunately, they caused your comment to go the 'junk box' for a short while but I retrieved it! The comparison between Nigerians and Minnesotans is so interesting--I wish the writing in the article did it more justice. And yes, when it comes to omegas, it seems there are three things that matter: ratio, ratio, ratio. Sorry Dangerous, I don't know why DHA is better than ALA but it seems to have something to do with how easily the body can process it. But we can get supplements of DHA that are indeed fish free!

Daniel Pauly and I are working on a paper not far from the topic discussed here and here is his take on this post:

I see a great link to our previous paper. As we pointed out that people should not be expected to manage fisheries, they should not be expected to balance their micronutrients. When people have a varied diet, they automatically get what they need. The notion of managing ones diet one micronutrient at a time is ridiculous. I have a great book by Lewis Thomas which makes the point that he wouldnt like to be in charge of running his metabolism, i.e., that he would screw up, but that we can trust our bodies to do that, given healthy inputs

The wisdom of Pauly is complemented by more wisdom from Michael Pollan on the rise of NUTRITIONISM, an absolute must-read.

For those who are looking, there is a vegan/vegetarian source of both DHA and EPA. It's called V-Pure and here's the link:

It's a little pricey but I think totally worth it for a sustainable product.