This is something I have been on the lookout for quite a while now and certainly since I wrote the SSS article on Olive Oil - Better than Butter? I came across a few scientific papers with various claims on Omega-3 and/or -6 and their positive and/or negative effect on our health!
But the benefits or deleterious effects on our health are as contradictory as their varied nomenclature is confusing.
So here is my understanding - so far!
So here is my understanding - so far!
What are Omega-3 and -6?
Omega-3 and -6 are called essential fatty acids - Essentials because our body is not capable of making them even though they are necessary to the good development of our organs, notably our brain (hence the claim that eating Omega-3 rich food is important for school pupils - More on this here below).
For example, DHA (a type of Omega-3) is a major component of our brain and eye tissue and is vital during pregnancy and early infancy.
It’s recognised by health authorities, professionals and
nutritionists as a vital nutrient for promoting cardiovascular, brain,
joint, nerve, vision, skin and immune health.
Omega-3
Omega-3 can be found written as n-3 PUFA, ALA, EPA, DHA, ω-3. So what's the difference between all these?
PUFA is a general term and stands for PolyUnsaturated Fatty Acid - more on this HERE
ALA stands for Alpha Linolenic Acid - more on this HERE - and can be converted into EPA and DHA. It is not found in fish but in nuts and notable in flaxseed which is the richest source of ALA.
EPA (Eicosapentaenoic acid) and DHA (Docosahexaenoic
acid) are found almost exclusively in fish and seafood, although these forms of Omega-3 are formed
by their diet of single-celled marine organisms. The oilier the fish,
the more EPA and DHA are present. Exemples include salmon, mackerel
and tuna.
Adult humans
can convert ALA to DHA but only in small amounts, this is because it’s
mainly used for energy whereas EPA and DHA aren’t.
Omega-6
Omega-6 can be written n-6 PUFA, ω-6. It mostly
comes as Linolenic acid LA from plant oils such as corn
oil, soybean oil, and sunflower oil, as well as from chicken, eggs, avocado, nuts and seeds. As
you can imagine, we are consuming vast amount of Omega-6 daily. It can be converted into Arachidonic Acid AA. Another Omega-6 is Gamma-Linolenic acid GLA which was first isolated from the seed oil of evening primrose, but can be also found in safflower, blackcurrant, borage and hemp seed oils.
What happens to them once we have eaten them
If we look at the conversion mechanisms:
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| From HERE |
Linoleic acid (LA) and alpha-linolenic acid (ALA) have 18 carbons. LA has 2 double bonds and the first one is at carbon 6, therefore it is a member of Omega-6 (C18:2n-6). ALA's first double bond out of the 3 is at carbon 3 so is part of the Omega-3 family (C18:3n-3). Both of these fatty acids (LA and ALA) are
converted in the body to have more double bonds and increased number of
carbons. LA is converted to arachidonic acid (AA) with 20 carbons and 4
double bonds (20:4) and ALA is converted to eicosapentaenoic acid (EPA)
which has 20 carbons and 5 double bonds (20:5). EPA can be further
converted to docosahexaenoic acid (DHA) consisting of 22 carbons and 6
double bonds (22:6).
Why are they important?
Those converted products are precursors of Eicosanoids which are signaling molecules. For example, EPA is a precursor for prostaglandins-3 (inhibits platelet aggregation), thromboxane-3 and leukotrienes-5 group which are messengers involved in our immunity and inflammation response.
Both Omega-3 and -6 have pro-inflammatory effects, although Omega-3 less so than -6 or null depending on the tissue involved, which led to the popular understanding that -3 was anti-inflammatory is -6 was pro-inflammatory.
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| From HERE |
Both Omega-3 and Omega-6 compete for the same enzymes (Desaturase and Elongase represented here above in the middle) that will lead to these pro-inflammatory Eicosanoids.
Wikipedia tells us that the amounts and balance of these fats in a person's diet will affect the
body's eicosanoid-controlled functions, with effects on cardiovascular disease, triglycerides, blood pressure, and arthritis.
(NOTE: Anti-inflammatory drugs such as aspirin and ibuprofen, to name but a couple, act by downregulating eicosanoid synthesis.)
This competition for the enzymes sparked the wide belief that a balanced diet of Omega-3 and -6 was therefore essential for our body. Indeed, since our Westernized diet at an Omega-3 and -6 ratio of 1:20, due to the extensive use of Omega-6-rich vegetable oils, is far from the ideal 1:1 or the more realistic 1:4, it has been 'web-widely' speculated that it is the reason of our suffering from many diseases such as Cardiovascular disease, type 2
diabetes, obesity, metabolic syndrome, IBS & inflammatory bowel
disease, macular degeneration, rheumatoid arthritis, asthma, cancer,
psychiatric disorders.
Do I need to take supplements?
As for anything, the choice is yours!
Following the belief that taking Omega-3 supplements was boosting pupils brain's functions, a couple of studies have tested groups of pupils either by giving them supplements or a placebo, or by measuring their DHA levels vs diet vs their school results. Needless to say, none of these studies have shown unequivocally that taking supplements was the cause for an increase in cognitive behaviour. Indeed, even the pupils taking the placebos, for the simple fact that they were watched over, were improving. Regarding the lab analysis of their DHA levels, let's remember that association is not causation!
After a quick search, I found another trial, but this time, properly managed with controls and all. The results show no improvement!
But unfortunately it's not only on pupils brain's activities that Omega-3 have shown to have no effect, but also on adults's cardiovascular function and accident's incidence!
A large, randomized, controlled trial failed to demonstrate a
benefit to n-3 fatty acid supplementation in patients with
cardiovascular risk factors. Admittedly, one weakness of the study was that it failed to account for variability in patients' diets. However, in 1999, the GISSI Prevention Trial
found that n-3 fatty acids significantly reduced cardiac deaths in
people who had already experienced myocardial infarction. And in 2008, the GISSI-HF trial
found significantly reduced mortality and hospital admissions in heart
failure patients given fish oil capsules in conjunction with standard
therapy.
Personally, I think that cardiovascular incidents is a big umbrella underwhich many varied diseases are assembled. The little differences between each could bring out those differences in Omega-3 supplementation effects. It is my understanding that, in 2014, we still don't know for sure!
But, I didn't see anywhere that it was bad for your health! So... The choice is yours.
(However if you do suffer from cardiovascular disease, do not take my word for it, I'm not a GP Dr. It's best to listen to your GP or specialist!)
But, Omega-3 or -6 are bad for our health?
Although studies suggest that intake of ALA supplements may moderately decrease the incidence of cardiovascular incidents, the results are either slightly statistically significant or just confusing.
There are also a number of studies suggesting that high levels of ALA in the blood and fat cells may correlate with an higher risk of prostate cancer. Although a dietary supplement of 2g did increase a blood biomarker for Prostate cancer, the results were not significant. Why mention it then?
Other studies dispute the relevance of stating such an effect when observational studies show no concrete difference. On the other hand, some studies show a protective effect or a genetic predisposition to prostate cancer enhanced by ALA. Again, these data are all very confusing and have to be taken extremely lightly.
If you'd like some intense reading on this, check out this open access review, that will most likely reassure you.
These 2 nice articles on debugging the "fake" 'link' between Omega-3 supplements and Prostate cancer along with the comments will give you some nice insight into how to interpret results:
The Huffington postDr Geo's post
What's SSS take-home message?
Eat Fish!
As for Omega-3 pills, look out for DHA and EPA levels. I came across this website, and I think if you'd like a supplement, this one looks the best thought of.
I'm tempted to say, stay away from Omega-6 supplements. That is for that reason that I stopped giving my baby SMA toddler's milk that contain Omega-3 and Omega-6 supplements!
I think we'll never repeat it enough, the point of being healthy is not by taking tablets of all sorts or binge-gyming (an activity whereby you go to the gym 3 times a week for only one month/year, usually in January), but by adopting a healthy durable lifestyle! For more info on Detox programs and healthy lifestyle, check out SSS previous post.
See you Soon for more Sexy Science,
References
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3865857/
http://www.ncbi.nlm.nih.gov/pubmed/19921446
http://www.ncbi.nlm.nih.gov/pubmed/12442909
http://www.medpagetoday.com/Cardiology/Prevention/38969
http://www.badscience.net/2010/06/the-return-of-a-2bn-fishy-friend/#more-1675
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0066697
http://paleozonenutrition.com/2011/05/10/omega-6-and-3-in-nuts-oils-meat-and-fish-tools-to-get-it-right/
http://www.barebiology.com/pages/what-is-omega3
http://www.webmd.com/diet/healthy-kitchen-11/omega-fatty-acids
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3859488/
http://ajcn.nutrition.org/content/96/6/1262.long
http://www.ncbi.nlm.nih.gov/pubmed/15051847
http://www.ncbi.nlm.nih.gov/pubmed/18951003
