Fish Oil, Krill Oil, and Hepatitis C

There's an action of VLCFA on blood lipids which isn't what we want; an increased demand for cholesterol which sees an increase in LDL-receptors (low LDL is the serum marker for this). If you've read the earlier entries in this blog you'll know that this favours fresh HCV infection of hepatocytes. And fish oil is the most inflammatory oil in models of liver disease exacerbated by excess polyunsaturates.

However, these effects can be minimised by consuming VLCFA in the context of a diet rich in saturated fat and cholesterol. A traditional fish-and-coconut, or herring and mutton,  based diet, with eggs or offal, for example. And no-one is ever going to supplement the amounts of fish oil (35% of calories) used in the alcohol/drug models of liver disease. 1% of calories as EPA and DHA - an effective dose from supplements - is about 6g fish oil or 10mls cod liver oil, about 3% and 5% fish oil calories on your imaginary 2000 kCal diet. Hmmn.

Anyhow, the fish oil-type omega 3s (which you will also find in pastured meat - lamb, goat, venison), and the omega 6 VLCFA arachidonic acid (ditto), are good and necessary things to have in the diet. 

For one thing, they all inhibit HCV replication.

This paper finds EPA and DHA effective: http://theses.gla.ac.uk/133/01/2008hubbphd.pdf

This adds AA to the picture: http://researcher.nsc.gov.tw/public/Harrison5782/Data/911201324971.pdf

 "In this study, we found that several polyunsaturated fatty acids (PUFAs) including arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) are able to exert anti-HCV activities using an HCV subgenomic RNA replicon system. The EC50 (50% effective concentration to inhibit HCV replication) of AA was 4 lM that falls in the range of physiologically relevant concentration. At 100 lM, a-linolenic acid, c-linolenic, and linoleic acid only reduced HCV RNA levels slightly and saturated fatty acids including oleic acid, myristic acid, palmitic acid, and stearic acid had no inhibitory activities toward HCV replication. When AA was combined with IFN-a, strong synergistic anti-HCV effect was observed as revealed by an isobologram analysis."

Some points: these VLCFA seem to be effective at normal physiological (non-toxic) concentrations; their vegetable precursors (LA, GLA and ALA) are not significantly effective, and neither is oleic acid (the omega 9 monounsaturated fatty acid found in meat fat and olive oil - interestingly it was called a saturated fatty acid here: compared to DHA, it is).

One way to optimize levels of DHA, AA, and EPA while minimizing the unwanted effects of PUFA on liver inflammation is to lower intakes of vegetable PUFA (cut out oils and grain, limit nuts and seeds) while eating adequate amounts of oily fish, eggs, meat and organ meats, in a context of saturated fats from coconut, dairy and animal drippings (or palm, cocoa butter).
"As the dietary saturated fat content increased, liver pathology scores and ALT values decreased (P < 0.05). At 30% dietary saturated fat, ethanol-induced hepatic necrosis was eliminated, and micro- and macrovesicular steatosis and inflammation were markedly reduced, even though the carbohydrate and total fat content of the diets and the ethanol dose were identical to those administered to rats fed the low-carbohydrate, unsaturated fat diets."
http://jn.nutrition.org/content/134/4/904.long

Should we ever supplement fish oils? There is another warning here: The administration of high amounts of n-3 polyunsaturated fatty acids reduces host defense to bacteria, viruses, parasites, or fungi. Inappropriate administration of n-3 polyunsaturated fatty acids in patients at risk of sepsis may cause adverse effects due to an increase in the susceptibility to infection. http://rd.springer.com/chapter/10.1007/978-1-60761-061-8_8

(click on "look inside" link).

Some of the benefit of fish oil might come from this very immunosuppressive action, but obviously we want to stay in the sweet spot between inflammation and infection.

Eat fish when you can; it needn't always be oily fish as the muscle of white fish such as cod is high in DHA.

Don't worry too much about mercury; anyone with Hep C should be getting a higher intake of selenium (seriously, the most important supplement you can take), which protects against mercury toxicity: http://www.ncbi.nlm.nih.gov/pubmed/23033886

Sardines are a good oily fish from low in the food chain. Canned tuna is of little use. Always buy canned fish packed in spring water, olive oil or oil-free tomato sauce; packing fish in soy oil (or "natural oil" on one deceptive mackerel label) counteracts any benefit of omega 3.

Cod liver oil has the benefit of supplying arachidonic acid, retinol and vitamin D not found in other fish oils. 

It should not be taken long-term in higher doses; a 5ml teaspoonful a day (supplying 500mg EPA and 500mg DHA) is probably safe. Concentrated fish oil pills, with more omega 3s, so you need only one or two daily, may be a good bet. But the best option for supplementation, if such is desired, is krill oil.

Krill oil is effective at significantly lower doses than fish oil because the VLCFA are in phospholipid form, not the usual triglycerides, so they get straight into the cell membranes without being oxidized (a similar mechanism might explain why whole nuts and seeds seem to be anti-inflammatory, yet their purified oils are full of pro-inflammatory linoleic acid). Krill oil, but not fish oil, reverses the elevated gluconeogenesis of diabetes, which can be a consequence of HCV infection: http://www.frontiersin.org/Nutrigenomics/10.3389/fgene.2011.00045/full

"We found that ω-3 PUFA supplements derived from a phospholipid krill fraction (KO) downregulated the activity of pathways involved in hepatic glucose production as well as lipid and cholesterol synthesis. The data also suggested that KO-supplementation increases the activity of the mitochondrial respiratory chain. Surprisingly, an equimolar dose of EPA and DHA derived from FO modulated fewer pathways than a KO-supplemented diet and did not modulate key metabolic pathways regulated by KO, including glucose metabolism, lipid metabolism and the mitochondrial respiratory chain. Moreover, FO upregulated the cholesterol synthesis pathway, which was the opposite effect of krill-supplementation."
This is pretty interesting too: http://www.ncbi.nlm.nih.gov/pubmed/21749725
Anandamide can be elevated from long-term consumption of high-omega 6, low omega 3 diets; it's a cannabinoid and and can produce - the sugar-craving munchies, just like the real thing!
(There's a cool discussion of the research by Emily Deans here: http://evolutionarypsychiatry.blogspot.co.nz/2012/09/omega-6-obesity-and-endocannabinoids.html

Anyhoo; what to recommend?

Remember to eat your saturates (see figure 1) http://atvb.ahajournals.org/content/12/8/911.full.pdf 

Eat fish regularly, but cook it in butter or dripping, or serve it with coconut...

Krill oil is the best daily omega 3 supplement, Cod Liver Oil or concentrated fish oil capsules are the best fish oils for temporary use, but are easily overdone. Limit your omega 6 intake from vegetable oils to the sparing use of olive oil, nuts, and seeds, and get some omega 3 intake from cold-weather greens (spinach, silver beet, kale, watercress). Ground flaxseed is a good occasional food for the gut. But vegetable omega-3s are no substitute for animal ones, and flaxseed oil is not worth supplementing.

The standard Paleo recommendation from the most reliable sources (Paul Jaminet, Kurt Harris) is to limit PUFA to 4% of calories. If you eat about 2/3 of your energy as fat, that fat should be about 6% PUFA on average. If half your fat comes from dripping, dairy and coconut, the other half from red and white meat, olive oil, fish,  nuts, seeds and greens, you'll come close enough to this magic figure; but it does kind of rule out taking 10mls of cod liver oil every day of your life.

I figure that we can count PUFAs in whole foods - fish and nuts - as being at least twice as beneficial and half as harmful as their purified triglyceride oils. No exact figures (except for krill oil), but good evidence that this type of difference is real. Peanuts? a) not a nut, b) source of the liver carcinogenic aflatoxins, and worth avoiding. Almonds and brazil nuts, black sesame and ground flaxseed are good sources of minerals, vitamins and prebiotics and worth having in the diet now and then.