[Rhonda]: Another organ, the gut, because it's another area of interest of mine, and
you recently published that the gut microbiome, so we'll quickly go through this.
The gut microbiome is also...well, bacteria are living organisms and they are also on
a circadian rhythm.
And what I found very interesting from some of your recent work is that you showed that
different bacterial species within the gut, at least in a mouse also seemed to, you seemed
to have more of these species during certain times of the day and less during certain times
of the day.
And this was different in obese animals versus, you know, non-obese animals or...
That is very fascinating.
Can you explain that just...
[Satchin]: Yeah, so bacteria, they're just like us.
They need their own niche, they need their own pH, temperature, nutrition, and all these
factors.
And now we can imagine that when we eat, we kind of change the gut environment, the content
of the gut slightly so that some bacteria may find it easier to grow and then some other
bacteria may find it very difficult to grow in that condition.
So what happens is when we eat in a time-restricted fashion, we have a very fixed eating and fasting
interval.
Then during eating, that environment will promote a certain set of bacteria to bloom
and then the other bacteria kind of become quiescent, quiet.
And then after few hours of fasting, then the second set of bacteria will bloom.
So in that way, what it helps is, it helps to nurture different, a wide variety of species
to cohabit in our gut.
And they also function at different time of the day.
During the daytime so, for example, when we are eating we need lot of bacteria to break
down starch and fibers, complex carbohydrates, and also conjugate some bile acids and etc.
So we need different players to do different things throughout day and night.
And by time-restrict feeding, this alternating two different types of environment, one where
there is lot of food and the pH is very different, versus one when there is fasting, there is
scarcity of food, and the pH is very different, by alternating between these two different
environment, we promote this diversity inside the gut.
And why this is important is we actually don't understand why, but research from a very different
field, from gut microbiome field, they are now finding it's much better to have a more
diverse microbiome in your gut than to have only one or two very simple species.
So in some way, by having the time-restricted feeding, it promotes the diversity
There are few interesting thing that we found, which we are still working on to figure out
why it happens, for example, mice that are time-restricted feeding, although the bacteria
could break down the complex carbohydrate to simple carbohydrate, for some reason that
simple carbohydrate could not be taken up by the gut.
It actually went out in the poop.
And that was a surprise because usually simple carbohydrates are the ones that get absorbed.
So we think that this compositional change somehow protects the complex carbohydrate
in the upper intestine.
So it comes back to the lower intestine where it gets degraded, but we know that the lower
intestine doesn't absorb sugar.
It's all in the upper intestine.
So in that way, by this compositional change, we can completely shift how nutrition is even
absorbed into the gut.
The other thing that we also found is bile acids, which are very...emerging as very important
players in health, those bile acids are also better managed with time-restricted feeding,
both in the liver and also in the gut.
Bile acids are made in liver and then they cycle back and forth between gut and liver.
And bile acids are made from cholesterol.
So there is an enzyme in liver that gets upregulated in time-restricted feeding.
And that enzyme breaks down cholesterol to bile.
So you get dual benefit.
You reduce cholesterol, increase bile acid.
And that bile acid comes to the gut and it helps absorb some fat back into the gut and
there it gets conjugated by this bacteria.
And for some reason we don't understand, in time-restricted feeding they get modified
in a different way than in normal feeding.
So these are some of the new research directions we are taking or trying to understand, how
this gut microbiome interacts with timing of food and then changes the compositional
aspect of the gut.
[Rhonda]: That's very interesting.