People hoping to learn about fish oil often encounter two myths.
The first is that supplemental fish oil thins blood so much that it impairs clotting in response to injury or surgery.
That myth never had any clinical basis, and it was put to rest in an evidence review by William Harris, Ph.D., as we reported in “Can Fish Oil Cause Bleeding Risks?”.
In fact, people taking normal doses of fish oil appear to enjoy speedier, healthier recovery from surgery … see “Omega-3s May Enhance Post-Surgery Outcomes”.
The second myth is that the omega-3s in fish oil are easily oxidized in the body, thereby generating damaging free radicals … which in turn promote inflammation.
Omega-3 EPA and DHA are susceptible to oxidation when exposed to air, because they are highly unsaturated fats.
This is why warm seafood begins to smell “fishy” so rapidly, and why fish oil exposed to air turns rancid quite quickly.
Yet, the protective effects of dietary omega-3s against cardiovascular disease – which is promoted by oxidation of cholesterol and oxidation-related inflammation in artery walls – are well proven.
If fish oil is easily oxidized, how can we explain this apparent contradiction?
As with the baseless fear of bleeding, lab and clinical studies firmly refute the notion that fish oil generates free radicals inside the body:
Exciting new research on food-triggered changes to gene expression reveals the reason for this fortunate paradox.
The genetic basis of “antioxidant” foods
There’s ample evidence that berries, cocoa, tea, and other plant foods rich in polyphenols help deter the oxidative cell damage and inflammation caused by free radicals.
But it’s becoming clear that polyphenols do not exert direct antioxidant effects in the body… at least not to a very substantial extent.
Instead, polyphenols appear to reduce oxidation and inflammation via so-called “nutrigenomic” effects on gene switches (nuclear transcription factors) in our cells.
Polyphenols’ nutrigenomic effects tend to moderate inflammation and stimulate the body’s own antioxidant network … which includes enzymes, lipoic acid, CoQ10, melatonin, and vitamins C and E.
And three years ago, Dutch scientists conducted a clinical trial confirming that supplemental fish oil also stimulates the expression of anti-inflammatory genes (Bouwens M et al. 2009).
Fish oil stimulates anti-inflammatory genes
The Dutch team divided 111 subjects into three groups, who took their assigned capsules for 26 weeks:
High-Dose Fish Oil providing 1.8 grams of EPA+DHA
Low-Dose Fish Oil providing 0.4 grams of EPA+DHA
High-Oleic Sunflower Oil providing 4 grams of fatty acids (mostly monounsaturated fat and a very small amount of omega-6 fats).
Blood samples were collected before and after the trial period.
High-Dose Fish Oil changed the expression of 1,040 genes, whereas the High-Oleic Sunflower Oil changed the expression of only 298 genes.
And the High-Dose Fish Oil decreased the expression of genes involved in inflammation and processes that promote atherogenesis (buildup of dangerous arterial plaque).
Among others, these beneficial changes included:
Decreased expression of the pro-inflammatory gene switch called Nf-kappaB.
Decreased expression of genes that promote synthesis of pro-inflammatory prostaglandins.
Decreased expression of genes that promote accumulation of pro-inflammatory body fat (adipose tissue).
As the Dutch doctors wrote, “These results are the first to show that intake of [omega-3] EPA+DHA for 26 weeks can alter the gene expression profiles of PBMCs [white blood cells of the immune system] to a more anti-inflammatory and anti-atherogenic status.” (Bouwens M et al. 2009)
Now, a new cell study shows that omega-3s boost the body’s internal antioxidant network, which is the primary way we control pro-inflammatory free radicals (Schmidt S et al. 2012).
German study reveals omega-3s’ finds antioxidant effects
The recent cell study indicates that omega-3s also exert nutrigenomic effects that stimulate the body’s own antioxidant network (Schmidt S et al. 2012).
Researchers at Germany’s Leibniz University of Hannover recruited 10 men with normal blood lipid (triglyceride and cholesterol) profiles and 10 men with unhealthful lipid profiles.
They were assigned to take 2.7 grams per day of fish oil – providing 1.56 grams of EPA and 1.14 grams of DHA – for 12 weeks.
Analysis of gene expression in the men revealed that both groups displayed an increase in expression of antioxidant enzymes and a drop in the expression of pro-oxidant enzymes.
In fact, the supplemental omega-3 EPA and DHA produced an optimal balance in the men’s oxidation-control system.
As the German team wrote, “We suggest that n-3 PUFAs [polyunsaturated fatty acids] may have an antioxidative [antioxidant] potential.”
And the fish oil supplements also raised the men’s omega-3 blood levels into the range associated with a reduced risk of “sudden cardiac death”, which accounts for half of all heart-related fatalities.
The results suggest that men with and without cardiovascular risk factors may gain indirect but powerful antioxidant benefits from fish oil.
Schmidt S, Stahl F, Mutz KO, Scheper T, Hahn A, Schuchardt JP. Transcriptome-based identification of antioxidative gene expression after fish oil supplementation in normo- and dyslipidemic men. Nutr Metab (Lond). 2012 May 23;9(1):45.
Bouwens M, van de Rest O, Dellschaft N, Bromhaar MG, de Groot LC, Geleijnse JM, Müller M, Afman LA. Fish-oil supplementation induces antiinflammatory gene expression profiles in human blood mononuclear cells. Am J Clin Nutr. 2009 Aug;90(2):415-24. Epub 2009 Jun 10.