L-Valine, Zinc supplementation, the Fructose Lipid Hypothesis, and the n=1 Updated

There's a paper casing a big buzz in the Hep C forums, with good cause.

Valine, a Branched-Chain Amino Acid, Reduced HCV Viral Load and Led to Eradication of HCV by Interferon Therapy in a Decompensated Cirrhotic Patient

The HCV viral load plummeted, from 5 log to less than 1.2, by the twelfth week of treatment (and only then was the patient given Interferon-alpha, one of the usual antiviral drugs, not very effective at all used on its own). This required fairly high intake of l-Valine, peaking at 12g/day. Which probably isn't something you'd want to do for more than 12 weeks. Alpha-fetoprotein also dropped back to normal, which is all to the good as elevated AFP is considered a risk marker for hepatocellular cancer. 

OK, so this is just one patient. An n=1 case study, so it's properly documented and peer-reviewed (not to be mistaken for any kind of an anecdote). Case studies tell us what CAN and DOES actually happen, but not how often it might be expected to happen (RCT study) or why it might happen (animal testing, usually).

How might it work? The authors suggest various mechanisms, but there is no detail as to how, for example, l-Valine might activate dendritic cells or improve liver function. I would like to suggest one. This is not a theory, it is not even a hypothesis, just something it might be rewarding to look at.

When amino acids, carbohydrates and (to a lesser extent) fats are metabolized by cells, the energy blocks (called substrates) are fed into the TCA (tricarboxylic acid), or Krebs (after its discoverer), or citric acid cycle. (at the bottom of the above diagram). This cycle generates energy (ATP and GTP), a variety of substrate building blocks for making sugars, amino acids and lipids etc, and reducing equivalents (NADH+ and FADH2) that are used to keep the cycle working and to reduce oxidised ubiquinone (co-enzyme Q10) to ubiquinol.

The TCA cycle generates NADH+ and ATP at a few points but only generates GTP (in hepatocytes) and significant amounts of FADH2 in two consecutive reactions. These are the conversion of succinyl-CoA to succinate, and the conversion of succinate to fumarate, respectively (have a look at table 13 in this paper, where FADH2 is called FPH2, to see what I mean. 484 of 562 mitochondrial FPH2 are generated at this step). Substrates can be removed from the cycle or added to it at many points (and it will presumably run unevenly or at a reduced rate if this intake/exhaust system is out of balance). If the succinyl-CoA substrate was drastically undersupplied, for example by removal of a previous substrate or by inhibition of a previous enzyme, there would be a deficiency of FADH2 (which might lead to inhibition elsewhere in the cycle). 

(The purpose of GTP in hepatocytes is something I know nothing about, but it must have a function distinct from ATP).

Now, how is extra succinyl-CoA made available to the TCA normally? (it's called an anaplerotic reaction, by the way). From propionate supplied by the breakdown of l-Valine mostly. Some also comes from metabolism of odd-chain fatty acids and phytanic acid, which are mainly present in the diet from dairy foods and ruminant fat (note that the l-valine, as far as I know, could be metabolized elsewhere, e.g. muscle, but.the propionate finds its way to the hepatic mitochondria). 

Feeding succinyl-CoA into the TCA cycle might be expected to increase the ratio of FADH2 to NADH+ in the mitochondrial respiratory complex. Peter at Hyperlipid has speculated at length on the implications of the FADH2:NADH+ ratio in his recent Protons series.

Disclosure:
There was a corroborating paper but I lost it. Something about succinate inhibiting viral replication in vitro (as did DHA, AA, and EPA in that order). Or, maybe it was suppressing excess gluconeogenesis in infected hepatocytes (another function of long-chain EFAs) - as l-Valine is a gluconeogenic animo acid this isn't as likely, but I can't rule it out. The first time I've lost a paper and, to my shame, not been able to quickly search it up again. I found it a few weeks before I read the l-Valine paper, while researching fish oil and krill oil. If anyone knows what paper I'm referring to... Anyway, there is definitely a succinate-counters-HCV connection on record out there somewhere.

So is "fixing" the TCA cycle undoing something that HCV has manipulated for its own benefit? Does HCV virion assembly require lots of alpha-oxoglutarate, depleting succinyl-CoA? Does the extra supply of succinyl-CoA mean an equal amount of another substrate has to come out of the cycle (cataplerosis), and if so, what? And does this also apply to dendritic cells? Is l-valine synergistic with alpha-lipoic acid in this scenario (which would tend to confirm the succinyl-CoA mechanism)? I could go on (about HCV core protein inhibiting mitochondrial respiratory complex I and FADH2 feeding complex II, for example), but I've given you enough homework for the Xmas break.

Zinc Supplementation Improves the Outcome of Chronic Hepatitis C and Liver Cirrhosis (2009)

Zinc supplementation therapy improves the outcome of patients with chronic hepatitis C (2012)

This makes sense because HCV sequesters zinc in one of its proteins, and a zinc metalloprotein is required to break down collagen (fibrosis is a repair process and the extra collagen scaffolding - scarring - is meant to be removed). You won't recover from fibrosis if you don't get enough zinc (you need more than just zinc, but these studies show that zinc alone can give significant protection). They used polaprezinc, which is a carnosine-zinc chelate supplying 33mg/day.

A recent review from New Zealand summarizes the evidence that sugar (and high-GI starches), not fat or salt, is the main dietary cause of cardiovascular disease (PDF). John Yudkin's ghost is smiling.

An update on the hygeine hypothesis n=1. I have had one day of hay fever, moderate by previous standards but there nonetheless. I modified my protocol by restricting cheese (the obvious hole in the first n=1 post) and by restoring probiotics (either lactobacillus/bifidus or Del Immune V), which hadn't prevented hay fever without "raw water" therapy, but which seem to be synergistic in combination with it. And everything has been fine since. it's high pollen weather, midsummer, everything's flowering, other people have hay fever but mine is minimal. (updated: another baddish day today. Water gave some relief eventually - I didn't expect it to work like an inefficient drug. Can disease states tend back to homeostasis - is that why drugs often stop working eventually? Next time I write about this I hope to be able to assess it properly)

P.S. Just a little Christmas bonus: 

Consumption of n-3 fatty acids and fish reduces risk of hepatocellular carcinoma

We investigated the association between fish and n-3 PUFA consumption and HCC incidence (n = 398) in a population-based prospective cohort study of 90,296 Japanese subjects (aged, 45–74 y). Hazard ratios and 95% confidence intervals (CIs) for the highest vs the lowest quintile were estimated from multivariable adjusted Cox proportional hazards regression models. We also conducted subanalyses of subjects with known hepatitis B virus (HBV) or hepatitis C virus (HCV) status, and of subjects who were anti-HCV and/or hepatitis B surface antigen positive. All tests of statistical significance were 2-sided.

Results

Among all subjects, consumption of n-3 PUFA-rich fish and individual n-3 PUFAs was associated inversely with HCC, in a dose-dependent manner. Hazard ratios for the highest vs lowest quintiles were 0.64 (95% CI, 0.42–0.96) for n-3 PUFA-rich fish, 0.56 (95% CI, 0.36–0.85) for EPA, 0.64 (95% CI, 0.41–0.98) for DPA, and 0.56 (95% CI, 0.35–0.87) for DHA. These inverse associations were similar irrespective of HCV or HBV status.