EPA and DHA Heart Disease study

[jim mcnamara]

TL;DR Summary

DHA/EPA diet reduces Cardiovascular Disease risks - Meta-analysis

“Effect of Omega-3 Dosage on Cardiovascular Outcomes: An Updated Meta-Analysis and Meta-Regression of Interventional Trials” by Aldo A. Bernasconi, PhD; Michelle M. Wiest, PhD; Carl J. Lavie, MD; Richard V. Milani, MD; and Jari A. Laukkanen, MD, PhD, 17 September 2020, Mayo Clinic Proceedings.
DOI: 10.1016/j.mayocp.2020.08.034

For non-Biologists:
https://scitechdaily.com/authoritat...o-cardioprotection-and-improved-heart-health/

The study corroborates this previous RCT study:

J Am Heart Assoc 2019 Oct;8(19):e013543.
doi: 10.1161/JAHA.11.013543. Epub 2019 Sep 30.
"Marine Omega-3 Supplementation and Cardiovascular Disease: An Updated Meta-Analysis of 13 Randomized Controlled Trials Involving 127477 Participants "

Docosahexanoic acid and Eicosapentanoic acid are required omega-3 fatty acids. We get them from foods like fatty fish (sardines, salmon), flaxseed oil, and from supplements. The suggested DRI for these nutrients from ILSA North America is 250mg - 500mg per day. The two meta-analyses found that supplementation of and addition of 1000mg of each/day had significant effects on heart disease risk. Some of the studies grouped together were for higher amounts of daily intakes.

Humans can synthesize DHA from α-linolenic acid, but the yield is ~15% because the biochemical pathway feeds others synthetic pathways, e.g. EPA synthesis, preferentially. So in order to get, say 1500mg, from flaxseed oil you would need at least 10 grams (2 US TSP) of oil, since it is 54% α-linolenic acid.

Why are these needed?
DHA
Slightly less than 60% of human brains are fatty acids, of that ~20-25% of the fatty acids are DHA. For normal brain development starting in utero until adolescence DHA is used to build brain tissue. It is also involved in LDL (VLDL, HDL, LDL(a ,b ,c ...)) metabolism which influences arterial deposition of cholesterol - likely why it influences cardiovascular outcomes.

EPA (this is the manager's version)
This is a way beyond the scope of this post- but this molecule is central to building eicosanoids which are intracellular signalling molecules. They are extremely involved in the pro-inflammatory and anti-inflammatory responses of the immune system. Deposition of arterial cholesterol and the subsequent buildup of plaque is a pro-infammatory response. EPA mostly produces anti-inflammatory eicosanoids. Which prevents plaque buildup until HDL removes the cholesterol blob.

Linoleic acid, omega-6, is generally involved in the synthesis of pro-infammatory eicosanoids.

This "antagonism" is the source of the omega-6/omega-3 ratio concept. Virtually any "vegetable oil", meaning seed-derived oils, are very high in omega-6 and some few have tiny amounts of omega-3. Not all. Some have zero. The exception being flax seed oil, which is NOT suitable for frying, due to a very low smoke point. Leonardo da Vinci used it as the drying oil in the 'Mona Lisa', for example. Linseed oil is another name artists use for it.

Using estimated per capita US consumption of vegetable oils (synthetic and natural) & fatty fish to get a ratio:
See what you calculate:
Recommended is 6::1, omega-6 :: omega-3
41g/day of vegetable oil and 135mg/day of DHA/EPA
Big number isn't it? 41000mg/135mg...

 

[Laroxe]

I think medicine generally has had a particular problem with making recommendations about fish oil. While there is often a clear bias against any therapy seen as alternative, particularly in the UK, this is one supplement that has been subject to extensive evaluation. People are often faced with the rather strange advice that eating oily fish is good but taking a supplement is isn't.
It may be that it is the size of the effects and differences induced by the research context that has been the major issue.

There is good evidence that fish oils have an anticoagulant effect, this acts by preventing platelet adhesion, this effect can be identified at the biochemical level at small doses but a measurable clinical effect apparently needs quite high doses. This effect can interact with other anitplatelet drugs like aspirin but not with warfarin.

There is some debate about its effect of blood fats, its generally believed to increase the levels of the high density fats, considered protective of heart disease but there are variable findings.
Its thought that there is an effect systemic indicators of inflammation.

There was evidence that large doses could influence the risk of cardiac arrhythmias and it was routinely given following heart attacks. Since then various studies have identified differences in the effect for different types of heart disease others have failed to find any effect. It tends not to be used for this reason now.

It seems the current view is that fish oils are unlikely to have much of an effect in prevention, but it is entirely possible that this is true when individual effects are looked at, but its possible that the combined effects could have a synergic effect. This analysis adds to the debate but when there is so much available it gets progressively more difficult to alter opinions.