Midlife, Microbes, Feel-good hormones, and Stress Hormones

It is becoming clear how vital the microbiome is for health. In this post, we explore quality of life, our sense of vitality, and mood resilience. It may come as no surprise that our microbiome plays a vital role in our felt-sense of wellbeing.

The gut microbiota produces and regulates neurotransmitters that affect mood and energy. Neurotransmitters are hormones that send messages between nerve cells.

A Robust Microbiome Feeds Serotonin

Serotonin is a calming, feel-good neurotransmitter. The gut produces 95% of serotonin during a dynamic dance between microbes and special cells along the gut barrier. Gut microflora plays a central role in that production.


After transmitting its message, serotonin is absorbed by nerve cells, which means there’s less available circulating serotonin to send feel-good messages. Healthcare providers often prescribe antidepressant SSRIs (Selective Serotonin Reuptake Inhibitors) to treat depression and anxiety. SSRIs block this absorption into nerve cells. This keeps serotonin ‘out in the field’ transmitting messages. But there’s a hitch. Those medications are only as effective as the amount of serotonin produced by the body naturally. We need an abundant and diverse microbiome and a healthy gut to fill that production role. 

Serotonin is also involved in temperature regulation. During and after the menopause transition, serotonin plays a role in the severity of hot flashes and night sweats. SSRIs are often prescribed to treat these symptoms. But nourishing a healthy microbiome can also help quiet hot flashes and night sweats. 

There is a strong link between hot flashes and night sweats and the stress response and inflammation. The stress response triggers low-grade inflammation, and inflammation triggers a low-grade stress response. All of these are intimately connected. Since the gut–microbiome partnership produces 95% of serotonin, it plays a vital role in keeping the stress response from going into overdrive. As to the role of inflammation in hot flashes and night sweats: microbes nourish the gut lining where inflammation often starts. A healthy gut microbiota helps keep inflammation at bay and quiets the menopause symptoms that inflammation can stir.

hot flashes

Calming and Excitatory Neurotransmitters Rely on Microbes

The gut microbiome also produces and regulates the neurotransmitters GABA and dopamine. GABA (Gamma Aminobutyric Acid) is a calming neurotransmitter. It helps with gastrointestinal motility, too. When GABA is low, you might feel anxious or irritable or have difficulty sleeping. You may also struggle with constipation. Bifidobacteria produce GABA. You might recall from the last post that progesterone supports the production of Bifidobacteria. When progesterone declines during midlife (and toward the end of the menstrual cycle), replenishing Bifidobacteria with probiotics containing this type of bacteria can support your mood.

Dopamine is partially responsible for reward behavior and plays a role in feelings of satiation when we eat. This satiation is not so much a feeling of fullness as it is the sense that I’ve had enough and can put this down now. Sugar, alcohol, overly-processed foods, and other addictive substances can short-circuit the dopamine response, stimulating the desire for more. Food manufacturers deliberately play with the dopamine response to hook you into eating more. You know that old potato chip ad: You can’t eat just one.

Addictive foods and alcohol alter the gut microbiome in ways that tend to produce less dopamine. The desire gets stronger for the stuff that once stimulated the dopamine response. The trouble is there’s less dopamine in the system. So, the dopamine reward response is harder to come by. The drive for the reward response drives more consumption of the stuff that depletes dopamine in the first place. It’s a negative cycle that’s hard to get out of.

A combination nutrient-packed, plant-based diet with a multi-strain probiotic can help restore the balance of microbes. The restored microbiota will, in turn, support dopamine production and help re-balance this system. That re-balancing effect doesn’t happen overnight. It takes a little while, but it can be restored naturally.

The microbiome also produces excitatory neurotransmitters, such as epinephrine and norepinephrine. These chemicals are important for having the energy necessary to get through the day. They are also involved in the “fight–flight-freeze” response.

From Perfect Bliss to Gut-Wrenching

Let’s wander a side-path briefly to illustrate how your microbiome’s health might contribute to mood resilience. Bear in mind that any number of factors contribute to our moods. It would be overly simplistic to say that one thing or another caused a mood or made it go away. But let’s play with mood in the context of what we’ve explored about the microbiome. . . .

Let’s say you decide to take yourself on a picnic. It’s late spring. You hike to a meadow alone for some much-needed peace and quiet. Things have been nutso at work, and if you don’t recharge, you’re sure to call it quits. You brought your pup along for peace of mind.


Everything’s perfect: dappled sunlight, a warm breeze, birds singing you a sweet melody. The world seems a million miles away. You take a deep breath and close your eyes to take it all in, thinking, Ahhhh. . . . I might just stay here forever. You pull out your favorite picnic foods, arrange them on your blanket, and start to nibble.

Suddenly, someone screams at you to Take control of your damn dog! Put that mut on a [blah-blah] leash! You hadn’t realized that Fido slipped away and had, just now, chased a cat up a tree. You also hadn’t realized anyone was nearby, let alone a pet feline – a million miles from the world! Fido did a good job of keeping unwanted company at a distance. But that cat sought refuge atop one of those trees and is now dangling precariously from a limb, without a clue about how to get down!

Who knows what thoughts come to mind as this scene plays out, but it’s safe to say your bliss has been disrupted. And let’s just say this encounter comes to an end after the cat lets go of the limb and defies all odds, falling from a distance far too great to land on the ground feet first and trot off unscathed. This one manages to do so, only to scamper into the woods with screaming owner trailing behind. You can go back to your bliss now.

Only, you’re shaken. Nervous. You might even feel a churning in your gut. Dare we say something of this sudden episode felt a wee tad gut-wrenching if not altogether absurd?

All other things being equal, microbes may very well have a say in whether you recover quickly from this strange interruption or start fretting over what just happened.

Microbes Have Their Say

Stress hormones are busy traveling the information superhighway between your gut and brain, brain and gut. But if your gut microbiome is plentiful and rich with varieties of friendly microbes, especially the Bifidobacteria family, those bacteria are going to keep the balance of stress hormones in check. They’re already producing feel-goods. And those feel-good hormones help the bacteria that produce them proliferate and produce more feel-goods. Feel-good tends to beget feel-good. 

Stress hormones, on the other hand, tend to help the bacteria that produce them proliferate. Stress tends to beget more stress. A feel-good producing microbiome can help quiet stress.

Many middle-aged women struggle with anxiety and feel less tolerant of stress than when they were younger. This makes sense. Midlife tends to be a point of intersection for many life transitions. They can be stressful and anxiety-provoking. Along with these transitions, the microbiome changes in midlife, as we’ve discussed. There are fewer bacteria to produce feel-goods. It’s entirely doable to restore the gut microbiome to a feel-good producing partner. We’ll talk about how in the next two posts of this series. 

Gateway to Vibrant Wellbeing

1) You might have noticed that before your period or during the menopause transition, the volume on your emotions and moods runs a little, if not a lot, higher. What sensations, images, words, or reflections come to mind as you imagine your microbiome participating in your moods?

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