How Your Gut Microbiome Shapes Immunity, Hormones, and Longevity: Insights from Microbiologist Kiran Krishnan

In a recent episode of Gut Check, host Caroline Carralero sat down with renowned microbiologist and microbiome expert Kiran Krishnan to explore the powerful link between the gut microbiome and every aspect of health — from immunity and hormones to stress and fertility.

The Gut-Immune Connection

Did you know that 70–80% of your immune system resides in your gut? According to Kiran, this immune tissue acts like a sampling station, assessing environmental inputs from food, water, and even the air we breathe. "Your immune system gets its training from your microbiome," he explains. "Without it, immune cells are like untrained soldiers — they don’t know friend from foe."

This connection is so profound that researchers can now predict a person’s COVID-19 outcome based on the state of their microbiome. People with metabolic diseases such as obesity and diabetes — conditions strongly linked to a dysfunctional gut — had significantly higher mortality rates.

Support your immune system with Daily Nouri's StayWell Digestion + Immunity mix.

Antibiotics: A Double-Edged Sword

One of the most alarming takeaways from the interview: by age two, the average child has received 2–3 rounds of antibiotics — and 50% of prescriptions are for illnesses they can't even treat.

"Antibiotics wipe out 90% of your gut bacteria with just one dose," Kiran says. "Even worse, the microbial fingerprint of that disruption can last up to two years — and impact others in your household."

Restore balance with Daily Nouri's targeted probiotics.

Autoimmunity and the Microbiome

Autoimmune diseases like Hashimoto’s are on the rise, and gut health may be a missing link. Kiran breaks down how the gut microbiome regulates immune response through T regulatory cells, which help prevent the immune system from attacking your own tissues. When these regulators are impaired — often due to poor gut health — autoimmunity becomes more likely.

Daily Nouri's StayWell formula helps support immune balance.

Hormones, Fertility, and the Estrobolome

Hormonal balance also starts in the gut. The estrobolome — a collection of gut bacteria that metabolize estrogen — plays a key role in regulating estrogen levels. Too much reactivation of estrogen due to an imbalanced microbiome can lead to estrogen dominance, a driver of PMS, PCOS, endometriosis, and even infertility.

"Estrogen gets processed in the liver, dumped into the gut, and ideally excreted," says Kiran. "But if the estrobolome is overactive, too much gets reabsorbed — and that’s where trouble begins."

Support hormonal balance with Daily Nouri's Hormone Balance Probiotic.

Stress, Cortisol, and Gut Dysfunction

Chronic stress damages your gut on multiple levels. Opportunistic bacteria sense elevated stress hormones like cortisol and use them as a signal to multiply and release toxins. Worse, these same microbes can perpetuate the stress cycle by triggering your fight-or-flight response — keeping your system inflamed and dysregulated.

Try Daily Nouri's gut-focused probiotics to support stress resilience.

The Power of Fiber

One of the simplest — yet most powerful — tools for gut health? Fiber. Kiran explains that high-viscosity fibers slow digestion, feed beneficial microbes, produce short-chain fatty acids, and blunt blood sugar spikes.

"These fibers act like natural GLP-1s. They improve satiety, regulate insulin, and support a diverse, resilient microbiome," he says. "And yet most people don’t get nearly enough."

Get high-viscosity fiber with Daily Nouri’s FeelFull Prebiotic Lemonade.

Five Daily Pillars for Gut and Whole-Body Health

To wrap the episode, Kiran shared five daily habits for gut health and longevity:

1. Clean up your diet: Focus on real, fiber-rich foods.

2. Manage stress: Even 20 minutes in nature can lower cortisol by 21%.

3. Exercise regularly: Weightlifting releases myokines that heal the gut.

4. Increase exposure to beneficial microbes: This includes playing outside, interacting with pets, and social connection.

5. Support with supplements: Use targeted probiotics, prebiotics, and gut support as needed.

Shop all of Daily Nouri’s gut health products.

This powerful episode is a must-watch for anyone looking to understand the foundational role gut health plays in everything from mood to metabolism. For more insights and resources, visit Daily Nouri and check out our Hormone Balance, StayWell, and Feelfull supplements.