Prebiotics and Circadian Regulation

Prebiotics and Circadian Regulation

Disruption of our sleep/wake cycle is commonplace in the modern world, and when our environment facilitates this misalignment in our biological rhythms, the result is a wide range of negative health consequences. Such consequences begin with lack of restorative sleep, and quickly lead to mood and metabolic disorders, as well as increased risk of heart disease.  In many fields of work such a disruption in health and function can have ramifications for others, as well as for the individual experiencing circadian irregularities.  This includes those who are in the military, first responders, pilots, and health care workers, all of whom “frequently experience chronic disruption of rhythms (CDR) due to altered light exposure, repeated jet lag, disturbed/restricted sleep, and eating unhealthy food at the wrong biological times of day”.

Now, that is most interesting: “eating unhealthy food at the wrong biological times of day”, can be a partial cause for circadian disruption. I have always understood that shift work and light exposure at night are disruptive to our sleep/wake cycles, but the food component is what caught my eye when I found the study we are going to examine here. More on that later. Of course, many people not in the military or health fields, also experience CRD due to working night shifts, jet lag, or even studying all night for school.  So, this particular health issue, which affects many members of society, became the subject of yet another study, one which had an interesting solution.

Our researchers put it this way in their introduction: “There is, therefore, a need for effective, non-invasive, readily translatable ways of facilitating realignment and reducing the probability of physiological rhythm misalignment. We propose that consumption of select dietary substrates could be a novel intervention for reducing the physiological strain of CDR.”

Circadian Rhythm

A circadian rhythm (or cycle) is a natural, internal process which regulates the sleep–wake cycle and repeats roughly every 24 hours. “It can refer to any process that originates within an organism (i.e., endogenous) and responds to the environment (entrained by the environment). These 24-hour rhythms are driven by a circadian clock, and they have been widely observed in plants, animals, fungi and cyanobacteria.” (Source)

Like most biological organisms, we “oscillate in circadian cycles of approximately 24-hour periods in coordination with the light/dark cycle. The coordination and regulation of circadian rhythms requires complex integration of brain-controlled signals, molecular gene clocks, as well as environmental cues. The light/dark cycle and diet are potent environmental cues that influence circadian rhythms. External light/dark cues help entrain the master pacemaker in the brain, the suprachiasmatic nucleus, while a consistent schedule of food ingestion and nutrient composition function as entrainment cues to peripheral clocks in the liver and intestine. Ideally, these entrainment cues (central and peripheral) and circadian clocks throughout the body are synchronized to support optimal function”.

A New Approach

The above material is from a new study out of the University of Colorado Boulder, published in the journal Brain, Behavior and Immunity, and funded by the U.S. Navy. Which makes sense since, as we established, such commonplace disruption in circadian rhythms amongst military personnel could have dangerous ramifications for other navy personnel, and civilians too.

According to lead author Robert Thompson, Navy personnel “are traveling all over the world and frequently changing time zones. For submariners, who can be underwater for months, circadian disruption can be a real challenge. The goal of this project is to find ways to mitigate those effects.”

This animal study followed other studies done by the same team, which showed that rats fed chow containing prebiotics had improved sleep cycles, and were more resilient to the physical effects of acute stress. That success led the researchers to further test out the use of prebiotics in order to determine if they could “also promote resilience to body-clock disruptions from things like jet lag, irregular work schedules or lack of natural daytime light — a reality many military personnel live with”.


To be clear, this study did not use probiotics, the friendly bacteria found in fermented foods like yogurt and sauerkraut, but only prebiotics. In this case a form of soluble fiber akin to that found in almonds, artichokes, garlic, leeks, legumes, and onions. (More prebiotic foods.) These fibrous foods provide indigestible carbohydrates, which pass through the small intestine, lingering in the gut and feeding the good bacteria that resides there.

Many studies have already established that prebiotics influence the gut, the brain, and behavior, and they do so by re-establishing an ideal microbiome, allowing friendly flora to thrive, and inhibiting the growth of bad bacteria. So, prebiotics work on the gut/brain axis by kicking up our production of probiotics, however they do so in a manner that is unique to each individual’s microbiome.

The Study

The rats in this study were given either regular food, or chow enriched with two prebiotics: galactooligosaccharides and polydextrose. At the same time, the researchers manipulated the rats’ light-dark cycle weekly for eight weeks, equivalent to traveling to a time zone 12 hours ahead.  Those rats that received prebiotics more quickly realigned their sleep-wake cycles, and more easily resisted alterations in gut flora that often follow high stress.

“This is one of the first studies to connect consuming prebiotics to specific bacterial changes that not only affect sleep but also the body’s response to circadian rhythm disruption,” said lead author Thompson.

There were two particular probiotics that were found to be increased in quantity in the guts of those test animals given prebiotics: Ruminiclostridium 5 (shown in other studies to reduce fragmented sleep) and Parabacteroides distasonis.  Those familiar with purchasing probiotic products will note that these two strains are never found in commercial products, another reason to appreciate the value of using prebiotics instead of probiotics.

What Does This Mean for Humans?

This study concluded with, “This work suggests that by promoting and stabilizing the good bacteria in the gut and the metabolites they release, we may be able to make our bodies more resilient to circadian disruption”.   (Study)

And, the same team is now holding clinical trials with humans to see if they can obtain the same effect that prebiotics had on rats. Such research may lead to prebiotic mixtures designed particularly for those whose work or lifestyles lead to circadian disruption.  So, can we obtain the benefits now by simply eating more foods rich in prebiotic fibers?

The authors don’t think so, reasoning that the rats were fed what would be considered an excessive amount of prebiotics for humans. And, they reiterate that simply taking probiotic products would also not provide the same benefits since prebiotics encourage colonization of the friendly bacteria we already have, whereas introducing new species of good bacteria (via probiotic products) may simply not take hold – as has been established in previous research.  But, are these scientists right when they assume that the amount of prebiotics given to the rats, when adjusted for human body weight, would be “excessive” for us?

Currently, dietary fiber intakes among adults in the United States averages about 15 grams a day: about half of what is recommended for good health. However, the ancestral human diet appears to have contained up to 100 grams of fiber daily.   (Source)

Now, we will experience digestive distress (mostly increased gas) if we too quickly up our intake of dietary fiber, thus increases in fiber are done slowly, in order to give the gut and microbiome time to adjust. For example, when using a fiber supplement, one generally starts with a five gram serving once a day, then moves up to two then three times per day. Once the digestive system has adjusted to this increased fiber, it is possible to take 15 grams all at once with no difficulty.

As well, we have the option of using superior prebiotics, such as Partially Hydrolyzed Guar Gum, and LactoSpore, which are effective at lower doses (the therapeutic dose for partially hydrolyzed guar gum is only five grams twice daily).

Both these prebiotic substances are found in our new Provide: Balance Vegan Smoothie Mix.

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