Category Archives: liver

Entraining Central and Peripheral Circadian Rhythms

“Desynchronization between the central and peripheral clocks by, for instance, altered timing of food intake, can lead to uncoupling of peripheral clocks from the central pacemaker and is, in humans, related to the development of metabolic disorders, including obesity and type 2 diabetes.”

If you haven’t been following along, a few papers came out recently which dissect this aspect of circadian rhythms — setting the central vs. peripheral clocks.

In brief (1):  Central rhythms are set, in part, by a “light-entrainable oscillator (LEO),” located in the brain.  In this case, the zeitgeber is LIGHT.

Peripheral rhythms are controlled both by the brain, and the “food-entrainable oscillator (FEO),” which is reflected in just about every tissue in the body – and is differentially regulated in most tissues. In this case, the zeitgeber is FOOD.

In brief (2):  Bright light in the morning starts the LEO, and one readout is “dim-light melatonin onset (DLMO),” or melatonin secretion in the evening. Note the importance of timing (bright light *in the morning*) – if bright light occurs later in the day, DLMO is blunted: no bueno.

Morning bright light and breakfast (FEO) kickstart peripheral circadian rhythms, and one readout is diurnal regulation of known circadian genes in the periphery.  This happens differently (almost predictably) in different tissues: liver, a tissue which is highly involved in the processing of food, is rapidly entrained by food intake, whereas lung is slower.

Starting the central pacemarker with bright light in the morning but skimping on the peripheral pacemaker by skipping breakfast represents a circadian mismatch: Afternoon Diabetes? Central and peripheral circadian rhythms work together.  Bright light and breakfast in the morning.

 

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Because chocolate

To improve a memory, consider chocolate –NYT

Dark chocolate could improve memory by 25%, but you’d have to eat 7 bars a day –PBS

Dietary flavanols reverse age-related memory decline –Columbia University Medical Centre

dark chocolate

 

The actual study: Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults (Brickman et al., 2014)

High flavanol group: 900 mg cocoa flavanols and 138 mg epicatechin (that’d be a LOT of dark chocolate).

Control: 10 mg cocoa flavanols and 2 mg epicatechin

Study duration: 3 months

Funding: NIH & Mars lol

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Vegetable oil fatty acids are not essential. 

They are conditionally essential at best, only if docosahexaenoic acid (DHA) is lacking.  We can’t synthesize omega 3 fatty acids, and indeed they do prevent/cure certain manifestations of “essential fatty acid (EFA) deficiency” (Weise et al., 1958), but DHA can do all that and more.  Not that I recommend this, but a diet completely devoid of 18-carbon vege oil fatty acids will not produce EFA deficiency in the presence of DHA. (“vege,” rhymes with “wedge”)

Essential fatty acid metabolism

 

The “parent essential oils” are linoleic acid (LA) and alpha-linolenic acid (ALA).  The others, which I think are more important and the truly “essential” ones are eicosapentaenoic acid (EPA), arachidonic acid (AA), but mostly just DHA.

The first manifestation of EFA deficiency is dermatitis (Prottey et al., 1975).  Some people say LA is necessary to prevent this, but it would be better phrased as “LA prevents dermatitis;” not “LA is necessary to prevent dermatitis.”  All of the evidence suggesting LA is essential is in the context of DHA deficiency.

Technically, we can convert a bit of ALA to DHA, estrogen helps, testosterone doesn’t (women have better conversion rates)… and I’d speculate that the reverse is probably easier (DHA –> ALA).

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Circadian phase delays and metabolism

Remember the “jet lag-resistant” mice?  Guess what: screw with circadian biology and metabolism pays the price.

In brief, vasopressin was classically thought of as an anti-hypotensive hormone.  The vasopressin analog Desmopressin is used to treat bed-wetting.  But vasopressin biology is much more interesting than that: mice lacking both vasopressin receptors require very little time adapting to large circadian phase changes.  And as with many fundamental concepts in chronobiology, this is intimately linked with metabolism.

People with certain polymorphisms of the vasopressin receptor, V1A, exhibit elevated blood glucose levels and are at greater risk for diabetes (Enhorning et al., 2009):

genotype

This risk is strongest in men in the highest quartile of fat intake, and is statistically more significant after adjusting for age and physical activity:

Fat consumption

This study wasn’t designed to be a very powerful indicator of diet-disease relationships, but a little speculation: some think higher fat [and lower carb] intake should be protective against diabetes… which may be true, for people who can tell time.  Alter one nucleotide in the vasopressin 1A receptor gene and the game changes.

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Fish, dark chocolate, and red wine.

Fish oil fatty acids: EPA & DHA.

I’ve read that EPA tends to show slightly better results in outcomes related to mood, whereas DHA tends to be slightly better for cognition.  Not mutually exclusive; probably a lot of overlap.  This meta-analysis by Martins showed EPA fared better than DHA for depressive symptoms (2009); another one here, stressing the high %EPA relative to %DHA necessary for improvements (Sublette et al., 2011).  Whereas the reverse is true for certain cognitive outcomes in this study by Sinn and colleagues (2012).  Very few studies test EPA vs. DHA directly, and their effects on metabolism are relatively similar.  They’re the ball bearings of fatty acids.epa dpa dha

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Going Dutch on Dark Chocolate

During the production of dark chocolate, cacao beans are fermented, roasted, and processed into 3 components: chocolate liquorcocoa butter, and cocoa powder.  These are combined in various proportions to make unsweetened chocolate.  Sugar can be added to make dark chocolate, or milk & sugar added for milk chocolate.  White chocolate has no cocoa; it’s essentially cocoa butter, sugar, and milk.

ChocolateManufacturingChart

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Dietary protein does not negatively impact blood glucose control.

“Dietary protein-derived amino acids have a purpose, and that purpose is not carbs.”

At a reasonable level of dietary intake, protein is used for the maintenance of organs & tissues.  Lean body mass.  It’s functional.  Protein isn’t stored in any appreciable capacity, and most excess is either oxidized or stored as glycogen.  Theoretically, about 50-60% of protein-derived amino acids can be converted into glucose, mathematically, but it’s not what you think…

“At a reasonable level of dietary intake.”  A recent publication took a look at this (Fromentin et al., 2013).   They set out to determine how much protein is converted to glucose under “optimal gluconeogenic conditions.”  That is, the subjects were 12 hours fasted, which is a physiologically relevant, optimal gluconeogenic condition.  They were then given 4 eggs (~23 g protein) that were labeled with two stable isotopes (15N & 13C, derived from hens fed isotope-enriched diets!).  Throughout the entire study duration, the subjects were infused with a third isotope, 2H-glucose.  By collecting and analyzing the enrichment of isotopically-labeled metabolites like expired CO2, urea, and glucose, the researchers were able to determine the fate of those 23 grams of protein.

Some of the dietary protein-derived amino acids were used for protein synthesis, others were oxidized.  But blood glucose levels did not change.  Nor did the rate of gluconeogenesis.

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Ketosis: anti-brain fog. Neurotransmitters, dietary protein, and the gut microbiome.

Treatment for dietary protein-induced brain fog: dark chocolate with 3% GOS and 10% MCTs.  Who’s in?

#IntermediaryMetabolism (bear with me here)
Ketosis from liver’s perspective:  increased fatty acid influx & [partial] oxidation causes acetyl-CoA levels to rise dramatically.  Concomitantly, gluconeogenesis redirects oxaloacetate (OAA) away from combining with acetyl-CoA via TCA cycle citrate synthesis and toward gluconeogenesis.  Since the acetyl-CoA doesn’t have much OAA with which to couple, it does itself to make acetoacetate.  Ergo, ketosis, and fortunately liver lacks ketolytic apparatus.

ketosis

 

Brain is singing a different tune.  Ketones provide ample acetyl-CoA and are efficiently metabolized in the TCA cycle.  Ketolysis is not ketogenesis in reverse, else liver would consume ketones.keto metabolism

Teleologically speaking (and I don’t really know what that word means), ketones are meant to spare glucose for the brain by replacing glucose as a fuel for peripheral tissues like skeletal muscle and displacing some brain glucose utilization.  The former is vital as one of the few sources of “new” glucose is skeletal muscle amino acids, and they would be exhausted in a short amount of time if skeletal muscle kept burning glucose –> incompatible with survival.  Getting some of that fuel from fatty acids, ie, ketones, is just way better.  Thus, the “glucose sparing effect of fat-derived fuel.”  And by “glucose,” I mean “muscle;” and by “fat-derived fuel,” I mean “ketones.”  There are numerous intracellular signaling events and biochemical pathways pwned, but that’s the gist of it.

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MOA of MCTs – black magic or something less?

MCTs provide a respectable boost in diet-induced thermogenesis (in some studies [eg, Kasai 2002  & Clegg 2012], but not others [Alexandrou 2007]), but I don’t think that’s what does it.

The alternative?  MCTs aren’t “linoleate.” (sorry for lack of suspense)

Alcohol + MCTs vs. corn oil (from Kirpich 2013):

Kirpich

Further, feed rats a diet rich in either coconut oil, olive oil, safflower oil, evening primrose oil, or menhaden oil… and eventually the fat stored in their bodies reflect those fats – eg, linoleate only accumulated in the tissues of those fed safflower & evening primrose oils (Yaqoob 1995) (expect similar results with soybean & corn oils).

Researchers constantly refer to MCTs & coconut oil as “saturated fats,” but I always thought the chain length should be recognized.  Perhaps.  But with regard to certain benefits (eg, hepatoprotection), perhaps not.

Cacao butter has a lot of stearate (a fully saturated 18-carbon fatty acid) but not much linoleate or MCTs.  This linoleate may very well be more of a detriment than stearate or MCTs are a benefit… (with regard to certain benefits [eg, hepatoprotection])Beef and chocolate

(Leslie Roberts, 1988) (she’s talking about stearate)

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