Friday, August 29, 2014

Insulin, A Major Nutritional Modulator of the Circadian Clock!? Would a High Carb Dinner Qualify as Anti-Jet-Lag Meal? Plus: Exercise Before or After Breakfast?

Food cues - and as it seems the insulin response - are important "Zeitgeber" for the circadian clock.
As a SuppVersity reader you are well familiar with the notion that food not only nourishes the body but also affects its internal biological clock. The latter is the central controller of all cyclic processes in your body and influences almost all aspects of daily human behavior and biology.

Researchers from the Jamaguchi and the Saga University in Japan are now reporting in the latest issue of the Cell Press journal Cell Reports that they have gained new insights into how adjusting the clock through dietary manipulation may help patients with various conditions.
You can learn more about the circadian rhythm at the SuppVersity

Sunlight, Bluelight, Backlight and Your Clock

Sunlight a La Carte: "Hack" Your Rhythm
Breaking the Fast to Synchronize the Clock

Fasting (Re-)Sets the Peripheral Clock

Vitamin A & Caffeine Set the Clock

Pre-Workout Supps Could Ruin Your Sleep
And the tool Sato et al. are using is one you are all familiar with: insulin - insulin that is produced by your pancreas, not just in response to carbohydrates, but also in response to the ingestion of larg(er) quantities of fast digesting protein (see "Whey More Insulinogenic Than White Bread" | read more).

The notion that feeding / fasting can (re-)set the internal clock is not exactly new. The idea that it is insulin that mediates this process, on the other hand, is as new as it is logical: If it is insulin that synchronizes the central and peripheral clock, it is no wonder that the latter are always off in patients with type II diabetes!
Figure 1: No real shift in the lung.
Figure 2: A significant shift of Per2-Clock expression in the white adipose tissue after feeding (arrow | x-axes in h) of confirms: Insulin controls clocks related to energy storage / usage (Sato. 2014)
Chronic desynchronization between physiological and environmental rhythms not only decreases physiological performance but also carries a significant risk of diverse disorders such as diabetes, cardiovascular diseases, sleep disorders, and cancer," says Dr. Makoto Akashi, of Yamaguchi University, in Japan. -from the press release
The circadian clock involves two major pathways. The first, which responds to light, has been well characterized. The second, which responds to food, is less understood. The results Saito, Akashi et al. present in their latest paper do thus provide a new piece to a hitherto elusive puzzle:
"Insulin-mediated phase adjustment of the clock in feeding-relevant tissues may enable the synchronization between mealtime and tissue function, leading to effective digestion and absorption. In short, insulin may help the stomach clock synchronize with mealtime."
This would imply that an anti-jet-leg dinner should be high in carbs, because it would advance the circadian clock. Quite an interesting feat, because it would explain why people tend to try to fix their social jet lag (not going to bed early enough) with sugary junkfood.
Boking: Every endurance athletes knows and fears it, so wouldn't just that happen when you do your cardio on empty in the morning? And what about the effects on your brain power?
Only another piece to the puzzle: I am pretty sure that the insulin connection is not the last revelation with respect to the complex regulatory factors that are involved in the control of our circadian rhythm. That being said, exercise is another, commonly overlooked regulator of the circadian clock. In a recent paper in J Phys Fitness Sports Med, scientists from the Waseda University in Japan report that "[e]xercise before breakfast increases beta-oxidation and reduces serum TG levels, while exercise after breakfast decreases appetite and reduces serum TG." (Shibatata. 2014). Moreover, exercise performed at midnight produced phase-delay shifts, which would allow you to stay up longer, while performed similar physical activites in the early evening or late day will induce phase-advance shifts, that will allow you to go to bed at 8pm instead of 10pm...

I guess you will realize that even though Saito, Akahsi et al. may be right and insulin is an important regulator of the circadian clock, it stands out of question that it is only one out of many factors that influence the synchronicity between internal (light, sleep) and peripheral (food, exercise, etc.) clock | Comment on Facebook!
  • Sato et al. "The Role of the Endocrine System in Feeding-Induced Tissue-Specific Circadian Entrainment". Cell Reports (2014).
  • Shibata, Shigenobu, and Yu Tahara. "Circadian rhythm and exercise." The Journal of Physical Fitness and Sports Medicine 3.1 (2014): 65-72.