|Food cues - and as it seems the insulin response - are important "Zeitgeber" for the circadian clock.|
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.
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!
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:
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
"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.
- Sato et al. "The Role of the Endocrine System in Feeding-Induced Tissue-Specific Circadian Entrainment". Cell Reports (2014). http://dx.doi.org/10.1016/j.celrep.2014.06.015
- Shibata, Shigenobu, and Yu Tahara. "Circadian rhythm and exercise." The Journal of Physical Fitness and Sports Medicine 3.1 (2014): 65-72.