If there were a top 40 of good foods, a chart rundown of the right things to eat, then anything containing omega-3 fatty acids would have been number one for years. They even have their own international awareness day, which takes place this Wednesday.
Omega-3 is the name given to a family of unsaturated fatty acids found mainly in oily fish, such as salmon, herring, sardines and anchovies, and also in eggs, meat, milk and cheese.
The naturally occurring acids of the omega-3 family can apparently boost our brain power, keep our hearts healthy, strengthen our bones, and much more. You can ingest the fatty acids by eating a lot of the right kind of fish or by taking fish oil supplements - little golden capsules rich in omega-3.
Hardly a week goes by without yet another media report on "The wonders of omega-3 fatty acids" (as a headline in Canada put it recently).
Last month it was reported omega-3 can protect against psychotic disorders such a schizophrenia. An international team of researchers gave a daily dose to 81 people deemed to be at risk from psychosis and found it seemed to cut the rate of psychotic illness - including schizophrenia - by 25%.
But how much of this is hype, and how much reality? Is there a danger that a largely fish-derived fatty acid is being turned into a modern-day magic potion?
Dietician Evelyn Tribole is a firm believer in their potency.
"While it can seem that omega-3s do everything but wash your windows, it's important to remember that they are essential nutrients", says Ms Tribole, author of The Ultimate Omega-3 Diet: Maximise the Power of Omega-3s to Supercharge Your Health, Battle Inflammation, and Keep Your Mind Sharp.
She says modern forms of food production are reducing the amount of omega-3 in our foods, "contributing to a global omega-3 fat deficiency in the diets of most people".
"For example, animals that graze on grass have higher omega-3 contents in their meat - and the longer they are out to pasture, the more omega-3s accumulate in their meat. But today the great majority of animals dine on [corn grain], which is devoid of omega-3s."
That is bad, she says, because "remarkable and consistent" scientific studies show us omega-3 is good for brain function, mood disorders, heart health and more. And she dismisses the claim that this is just a fad.
"Yes, food and nutrition seem to run in fashionable trends, with followers and believers. In this case, however, there is a lot of good evidence for the benefits of omega-3s."
But others are sceptical.
Dr Lee Hooper, lead author of one of the most thorough studies on the apparent benefits of omega-3, published in the British Medical Journal in 2006, urges people not to get "carried away".
The interest in omega-3 has snowballed over the past decade, giving rise to more and more scientific studies, books about how omega-3 can make you super-healthy, and government- and corporate-funded omega-3 promotion groups, such as the Omega-3 International Awareness Day and The Omega-3 Group in Scotland.
Over the past 10 years, about 12,500 scientific studies on the benefits of omega-3 have been published, both reflecting and reinforcing the fashion for consuming this apparent super-food. Today, everything from loaves of bread to frozen fish fingers come with a "RICH IN OMEGA-3" tag.
Yet the "systematic review" carried out by Dr Hooper's team shows the claims are often as fishy as the omega-3-rich foods themselves.
"According to the evidence we have so far, omega-3 does not seem to help for cancer prevention or treatment; with children's learning or behaviour; with cognitive function; or in preventing cognitive decline with age or mental health problems, including bipolar disease, schizophrenia."
Similarly, there's "no evidence that the fatty acids assist with cystic fibrosis, allergies, asthma, ulcerative colitis, Crohn's disease, or kidney disease".
Dr Hooper's study found evidence omega-3 improves children's learning abilities and behaviour to be "very poor".
On the plus side, "omega-3 probably does help with arthritis, pain and stiffness," she says. And it definitely seems useful for people recovering from a heart attack.
"I would very much want anyone I know who has had a heart attack recently to be consuming omega-3."
It's beneficial for those who have had a heart attack because research shows that the "long-chain fatty acids" in the omega-3 family get into the membranes of our cells, helping to "improve the heart's electrical activity" and reduce blood pressure, among other things.
Crucially, though, this doesn't mean those who have not had a heart attack can reduce their risk of having one by consuming omega-3, says Dr Hooper.
"There's no evidence that omega-3 reduces the risk of death or heart attack or stroke or anything like that in those of us who have not recently had a heart attack," she says.
Dr Hooper says her aim is not to generate a backlash against a trendy nutrient, but simply to get to the truth about its limited benefits.
But if so many of the claims are just hype, how did it get to that stage? Why are so many benefits laid at the door of omega-3?
Dr Hooper says believes the fashion for omega-3 betrays our herd-instinct - how, "as a group", we periodically get overexcited about certain foodstuffs. There always seems to be some "new food panacea" to our problems, she says.
Another doctor, Michael Fitzpatrick, says the omega-3 fad is just the flipside of the anti-junk food campaign. Just as see certain kinds of "junk food" as "morally and constitutionally corruptive", we tend to elevate other foods as "saviours of human health".
So much so, says Dr Fitzpatrick, GP and author of The Tyranny of Health, that today there is almost a "cult of omega-3".
Below is a selection of your comments.
Why is it in the stories about Omega-3 that we rarely see a discussion of Omega-6 and the Omega-3 to -6 ratios? Similarly for Sodium, we rarely see discussions of Sodium/Potassium ratios. Isn't it so in each case that the interaction of the two substances is as or more important than the dose of either alone?
Steve Foster, Leiden, The Netherlands
I support the view of the dietician on this subject. There is a lot of robust evidence of its beneficial effects. It is clear from the patients I see that there is little to no intake of omega-3 in the diet - very little fish, organic chicken or nuts. I disagree with Dr Hooper - every single child which has started omega-3 capsules only without increasing intake of fish has shown improved concentration and behaviour (more balanced blood sugar which reduces aggression, volatility etc). In my experience there is a general improvement in depressive patients with the intake of omega 3 either in tablet form on natural fish intake.
Jennifer Hargreaves, Worthing, West Sussex
You seem to have missed the other scientific fact about omega 3 that no-one mentions. Only fish-derived omega-3 is proven to help with brain, heart and joint function, plant-derived omega-3 doesn't really help at all.
D Simpson, Edinburgh
Where is the science in this piece? You can't just dismiss various unnamed studies with another equally vague references to another study. In the absence of scientific detail am I just supposed to take the journalist's word for this?
Jonathan Gay, London
I think Dr Hooper should turn her attention to Aloe Vera next. It seems there nothing that won't cure as well.
I am sceptical about most things, in particular when they appear to be a fad, however, my son had some difficulties with concentration at school and also behaviour in the home. After reading about the effects of Omega 3 and in particular a range of products, which contain omega 3, 6 & 9 fatty acids, we decided that our son was going to try a course of the capsules. After about a week we had comments back from the school re. what had we done to change our sons behaviour? The level of concentration and cooperation in class had markedly improved in a short space of time. That improvement is still there today, some six years after we first started him on the capsules although he has long since ceased taking them as it is always preferable to obtain nutrients from our normal diets rather than processed versions.
This story takes me back to the early fifties when I was in the local infant school. Every moring we had to line up for our spoonful of malt and our cod liver oil. Of course we were still living with rationing then and another item doled out was orange juice. Modern diets seem deficient in a lot of good items - fruit and veggies especially'I don't see it as a "food fad" but more of the wheel turning a full circle and people are starting to realize that traditional food - meat and veggies etc., is not all bad.
John Wood, Hixon, BC, Canada
Having taken Omega 3 capsules for the last 4 years, both as a corporate CEO and as a part-time symphony orchestra conductor, my levels of mental concentration have increased tremendously, very noticeable shortly after beginning a daily regimen. A son in the US who owns a large graphic arts prepress business, claims his total focus for doing this work which requires extreme attention to detail, is possible only because he takes Omega 3 daily.
William Alexander, Acapulco Mexico
I live in a fishing town. Salmon is everywhere. I eat lots of salmon on my doctors recommendation. When I don't, my arthritis gets worse very quickly. When I eat it at least 6-8oz of it 2-3 times a week, arthritic pain and other symptoms do seem to greatly diminish over 2-3 weeks. I don't know about Omega-3 and all that, but if salmon has the highest concentrate of it, then maybe there's something to it.
Larry Weinberg, Gold Beach, OR USA