Dark Skies and Light Pollution

The mission of the International Dark-Sky Association is “to preserve and protect the night time environment and our heritage of dark skies through quality outdoor lighting.”  They’re all about stressing the importance of lighting on health, light pollution, and some really interesting stuff.

For more on the topic, check out their website, darksky.org, and Paul Bogard’s book, The End of Night: Searching for Natural Darkness in an Age of Artificial Light.

 

 

Admittedly, the “Google Hangout” is somewhat of an awkward platform, but they recently put out a great video:

 

 

Needless to say, the IDA is staunchly against stuff like this (so am I): double whammy…

 

fry-lights

 

The video above covers a broad range of topics, including many aspects of circadian biology, the physics of light, and circadian disruption.

 

 

2015 is the International Year of Light

While it may seem like the opposite of IDA, it’s not.  Their M.O. seems to be more about educating on all things related to LIGHT: “Light plays a central role in human activities. On the most fundamental level through photosynthesis, light is necessary to the existence of life itself, and the many applications of light have revolutionized society through medicine, communications, entertainment and culture. Industries based on light are major economic drivers, and light-based technologies directly respond to the needs of humankind by providing access to information, promoting sustainable development, and increasing societal health and well-being.”

Tons of interesting blog posts on their website, light2015blog.org.

That’s all for now!

 

Some more reading, if you’re interested in light:

The hot Blue Blocker Experiment

Fiat Lux

Vitamin D, Fiat Lux, and Circadian Rhythms

 

 

calories proper

 

 

Share

Circadian Disruption Impairs Survival in the Wild

…just read that huge disasters, ranging from Exxon Valdez to Chernobyl, may have been due, in part, to ignorance of basic principles of circadian rhythms.  Gravitas.

 

circadian rhythms

Continue reading

Share

Meal timing and peripheral circadian clocks

More on why breakfast in the morning, with light onset is important to avoid circadian desynchrony.

FOOD is excellent at entraining peripheral circadian clocks: if you restrict animals to one meal per day, their peripheral circadian clocks rapidly become entrained to this, regardless of when the meal is administered (Hirao et al., 2010):

 

zeitgeber entraining

ZT0 = “zeitgeber time 0,” or “lights on.” pZT indicates a phase shift coinciding almost exactly with meal timing. Mice normally eat at night, but this doesn’t stop their peripheral clocks from entraining to the day time if that’s when their fed.

This study took it to the next level: they fed 2 meals per day, varying in size, time of day, and duration between meals in almost every conceivable combination.  Actually, it was a quite epic study… some poor grad students working, literally, around the clock, for months…

Continue reading

Share

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.

 

Continue reading

Share

Mushrooms are awesome (P<0.05)

“Without leaves, without buds, without flowers;
Yet they form fruit.
As a Food, as a tonic, as a medicine;
The entire creation is precious.”

-weird mushroom poem of sketchy origin

 

Mushrooms: They have B12! When exposed to UV light, they make vitamin D2.  Protein, fibre, and selenium.  Shall I go on?

Continue reading

Share

Vitamin D, Fiat Lux, and Circadian Rhythms

Vitamin D synthesis is TEAMWORK!

Skin: 7-dehydrocholesterol + UVB = previtamin D3.
Liver: Previtamin D3 –> 25(OH)-Vitamin D3.
Kidney: 25(OH)-Vitamin D3 –> 1,25(OH)2-Vitamin D3 if you need it or 24,25(OH)2-Vitamin D3 if you don’t.

N.B. one of the major regulatory pathways occurs in skin: if you’re getting a lot of sunlight, then skin darkens to block this step.  Supplemental and dietary Vitamin D3 bypass this… but the dietary Vitamin D supply rarely produces toxicity because it’s not very abundant.  In other words, sunlight Vitamin D never reaches toxic levels.  Supps could (rare, but possible).

Disclaimer: I’m not against Vit D supps, but prefer sunlight whenever possible.

The other major regulatory step is in the kidney.  Production of 1,25(OH)2-Vitamin D3 is tightly regulated — so blood levels don’t decline until your very deficient… so 25(OH)-Vitamin D3 is a better indicator of skin production and dietary intake.

Disclaimer #2: this post is not about any of the pleiotropic effects of Vitamin D or D supps, which range in value from worthless to helpful to possibly harmful.

For some of that stuff, see:

Vitamin D: still a scam, still immunosuppressive… by Jane Plain

The Vitamin D seminar by Ivor Cummins

Vitamin D 101 by Kris Gunnars

The Vitamin D Debacle with Ivor Cummins and Sam Feltham

all of the above are more pro-D supps than me, which I find perfectly OK.

 

Continue reading

Share

OmniCarb

Why Low Carb?

OmniCarb (Sacks et al., 2014)

Study design & results in a nutshell:

5 weeks, low(ish) vs. high carb (40 vs. 58%) with the calorie difference split between protein (23 vs. 16%) and fat (37 vs. 27%).  In other words, the low(ish) carb diet was higher in protein and fat.  And there was 2 versions of each diet —  a high and low glycemic index.  Lots of crossing over; all in all, weak intervention but decent study design & execution.

Aaaand nothing drastic happened.  Goal was insulin sensitivity, not weight loss.

 

glucose and insulin

 

Important points:

1) The participants were relatively healthy at baseline.  Anyone on meds was excluded.  Average BMI 32.  Mostly educated non-smokers.  This population is expected to respond reasonably well to any diet (wrt body weight… see next point).

2) “Calorie intake was adjusted to maintain initial body weight.”

^^^this really knocks the wind out of low carb. One of the big benefits of cutting carbs is spontaneous appetite suppression –- two points here: 1) this effect is most prominent in obese IR; and 2) it is more relevant to weight loss.  By not targeting insulin resistant and/or type 2 diabetics, and feeding specifically to prevent weight loss, I ask you this: Why Low Carb?

3) the biggest difference between the two diets was carbs (45% higher in low[ish] fat group), but the biggest difference from baseline, was protein in the LC group (53% increase).  In other words, the Low Carb group had their carbs decreased from 50 to 40% of calories. *meh*

4) Body composition wasn’t assessed; so even if LCHP induced nutrient partitioning and improved body comp, we wouldn’t know it.

5) Everyone was eating cereal or oatmeal for breakfast, bread with most meals, and pasta or rice for dinner.  What did you expect?  Really?

REALLY?

Prior posts in what seems to be developing into a series of rants:
2 New Diet Studies
CICO and rant 

 

calories proper

Share

Circadian phase: role of diet

Circadian phase advance: going to bed earlier, waking up earlier.  Blue blockers at sunset, bright light at sunrise.  Flying east.  Autumn.

Circadian phase delay: staying up late, sleeping in.  Flying west.  Spring.  Using smart phones, tablets, and iPads in bed at night.  Light pollution.

Relative to adolescents, infants and children are circadian phase advanced.  This is part of what is fueling the movement to delay high school start times.  Kids are mentally better prepared to work later in the day.  With early school start times, performance is down in the morning, but they kill it on video games after school.  Delaying start time by an hour won’t totally fix this, but could help.

Edit: it seems like a similar movement is happening for adults, too – ie, starting work an hour later.

I’m not saying everything healthwise deteriorates with age, but the gradual circadian phase delay that occurs with aging and overusing blue light-emitting devices at night might not be a good thing.  If a particular diet can promote phase advance, why not? (at least it’d be countering the phase delay).

 

 

Possible role of diet

In the top half of the figure below, it’s mice fed a “normal diet (ND) (high carbohydrate)” (Oishi et al., 2012).  During normal “light dark (LD)” conditions, movement and feeding is concentrated in the active phase.  When the lights are permanently turned off in “dark dark (DD)” conditions, the free-running circadian clock begins to shift slightly forward (phase advance), but nothing drastic.

 

Phase advance high protein diet

 

In the bottom half of the figure, during normal LD conditions the mice are switched to a low carb, high protein diet.  Note how activity shifts leftward (phase advance) during the LD condition.  When low carb, high protein-fed mice are then switched to DD, we can see a clear circadian phase advance.

 

High protein metabolism

 

Low carb, high protein-fed mice ate more but didn’t get fat; physical activity and body temperature were unchanged.  But this post isn’t about that.  Gene expression of key circadian transcription factors in liver and kidney exhibited phase advances.

The next figure is study to the one above, although instead of switching to a low carb, high protein diet, the mice were switched to a low carb, high fat diet (Oishi et al., 2009).

Note the similarity of control (high carb diet) mice: gradual phase advance when switched to DD:

 

Ketogenic circadian phase

 

The phase advance is markedly enhanced in low carb, high fat-fed mice.

The circadian regulation of activity is similarly affected by low carb, high protein, and low carb, high fat diets.  What do those two diets have in common?

A bit of a stretch? carbohydrate restriction mimics some aspects of avoiding artificial light at night and being young: phase advance.  Whether the carbs are replaced with protein or fat doesn’t seem to matter in this aspect.

 

Wanna know what else can do this?  FOOD.  The food-entrainable oscillator (FEO) kickstarts circadian rhythms.  Rodent studies have shown that timed feeding, regardless of the actual time, consistently realigns the circadian expression of numerous genes (eg, Polidarova et al., 2011 and Sherman et al., 2012).

So what’s the hack?  Food: do more of it, earlier in the day.  Phase advance.  Kind of like avoiding artificial light at night or being young.

 

Oh, and mice exposed to dim light at night (who are pretty much metabolically screwed)? phase DELAYED (Fonken et al., 2010).

 

Dim light at night phase delay

 

 

 

calories proper

 

Share

CICO and rant

“Wait… what?  nutrient partitioning?”

Calories In, Calories Out should not be interpreted as “eat less, move more,” but rather kept in its more meaningless form of: “if you eat less than you expend, you’ll lose weight.”  At least then, it’s correct… meaningless, but correct.  Eating less and moving more is no guarantee of fat loss, in part, because total energy expenditure isn’t constant and there’s that whole thing with nutrient partitioning.

For obese insulin resistant folks, this is Low Carb’s strong suit: it causes “eat less, move more”spontaneously.

For some obese insulin sensitive patients, for whatever reason, their adherence and success is greater with Low Fat.  You might say, “yeah, but those suckers had to count calories.”  To that, I’d counter with: “it doesn’t matter, THEY WERE MORE SUCCESSFUL COUNTING CALORIES ON LOW FAT THAN NOT COUNTING ON LOW CARB.”  The spontaneous reduction in appetite obviously didn’t cut it.  Do not be in denial of these cases.

Continue reading

Share

Ketone bodies as signaling metabolites

*non sequiter*

One of the ways dietary carbohydrate contributes to liver fat is via ChREBP: “carbohydrate-response element binding protein.”  It responds to a glucose metabolite and activates transcription of lipogenic genes.  Insulin helps.  Ketones do the opposite (Nakagawa et al., 2013), by inhibiting the translocation of ChREBP into the nucleus where it does it’s dirty work:

 

ChREBP

 

More interestingly, ketones are histone deacetylase inhibitors (HDACi)… this leads to more histone acetylation.  Benefits of fasting sans fasting?  Modulating of acetylation is a MAJOR regulator of circadian rhythmicity.

Butyrate is another HDACi, so have some fibrous plant foods with your red wine and dark chocolate.  Anti-aging (mostly worm studies, but still).

 

Continue reading

Share