To me, there’s nothing even remotely as exquisite as the circadian system. When researchers describe it as a symphony orchestra, they really couldn’t have hit the nail more directly on the head. Every cell, tissue, organ, signaling molecule, and hormone really has a part to play, and none should be ignored.
One of the reasons that I don’t believe one can optimize health without taking circadian rhythms in to consideration is because it’s really difficult to completely isolate parts of the “orchestra” while ignoring the others and still have a beautiful orchestral piece. In the same way, I don’t think you can isolate certain foods or nutrients and say, “This fixes leaky gut” or “This causes leaky gut”.
The reason people often fail so miserably at addressing leaky gut or gut problems in general is because they often ignore the circadian component. The reason it’s so easy to ignore the circadian component is that it’s difficult to do, time consuming, and doesn’t yield immediate results. The problem is, ignoring it virtually guarantees no results in the long term.
There’s no better example of this than looking at the hormone insulin. Once upon a time, we thought there was a circadian clock separate from the master clock called the food entrainable oscillator. Turns out it may not even exist; instead insulin is the feeding cue that synchronizes feeding with the master clock.
And this tells us a lot. Insulin is released when we eat and levels naturally plummet while we fast. Obviously, if we’re trying to sync up the master clock to when we eat, there really is no better way to do so. But what effects would we expect to see in the gut?
Well, for one, we’d expect our circadian system to resist leaky gut when we eat. I can think of no worse time to have a leaky gut than when there’s food in it. Sure enough, the insulin signal, which actually begins before food even hits your stomach, helps ready the gut for what’s to come by decreasing leaky gut.
A recent study which I’ve referenced more than a dozen times illustrates this nicely. Hyperglycemia in mice causes leaky gut, but if they’re treated with insulin at the same time, no leaky gut. In humans, HgA1c is the strongest predictor of bacterial invasion due to leaky gut, and it essentially functions as a 3 month average of blood glucose levels.
Chronically high insulin, which likely precedes elevated glucose and Type 2 diabetes, slows GI motility. This can promote issues such as delayed gastric emptying, acid damage to the stomach and duodenum, and SIBO. So first you see motility impairment, which proceeds to leaky gut and much larger problems.
And there are other problems as well. Artificial sweeteners, which stimulate insulin without the effect on blood glucose, can screw this signal up. That’s because there appears to be communication between taste receptors in the tongue that sense “sweet” and the pancreas.
So you can consume as much fiber, glutamine, and probiotics as you want. You can even avoid gluten, dairy, soy, or whatever you feel causes leaky gut. But if you don’t fundamentally address insulin sensitivity and behavior to match up with the circadian cycle, you’ll never solve your leaky gut problem.