Gut Health 101: What Your Microbiome Does

Updated: Jul 4

Your gut microbiome is a dynamic community of trillions of microorganisms, mostly bacteria, but also viruses, fungi, and archaea, that live primarily in your large intestine. Your gut isn’t just where food gets digested, it’s where your immune system is trained, your mood is regulated, and your hormones are fine-tuned. It’s not just a digestion thing. It’s a whole-body thing.

Every person’s microbiome is unique, kind of like a fingerprint. And like a neighborhood, it can be balanced and thriving, or out of sync and struggling.

What influences it?

Your diet
Sleep patterns
Stress levels
Antibiotics and medications
Hormonal fluctuations
Even how you were born (C-section vs. vaginal birth)

1. Digestion

Before you even finish chewing, your gut bacteria are preparing to help break down fibers and starches that you can’t digest on your own. They ferment these leftovers into short-chain fatty acids (like butyrate), which:

Nourish your gut lining
Reduce inflammation
Support regular bowel movements

Without a diverse microbiome, you’re more likely to struggle with:

Gas and bloating
Constipation or diarrhea
Food intolerances

2. Mood & Mental Health

Your gut is often called your “second brain” for a reason. That’s because it’s lined with over 100 million neurons and produces more than 90% of your serotonin, the feel-good brain chemical.

Your gut can directly influence:

How much serotonin you make
How well you respond to stress
Your risk of anxiety or depression

The gut-brain axis is a two-way street. When your gut is inflamed or out of balance, it can increase cortisol (your stress hormone) and even trigger low mood or brain fog.

3. Immunity

Here’s something not many of us realise: around 70% of your immune system lives in your gut.

Your microbiome helps:

Train your immune cells to respond appropriately (not overreact or underperform)
Create natural antimicrobials to fight off pathogens
Maintain the protective lining of your gut wall, preventing things from “leaking” into your bloodstream

When this barrier breaks down (sometimes called leaky gut), you may start to see symptoms like:

Chronic fatigue
Skin flare-ups (eczema, acne)
Food sensitivities
Autoimmune issues

4. Hormone Balance

This part surprises a lot of women: your gut plays a huge role in regulating estrogen.

Inside your gut lives a subset of bacteria called the estrobolome. Their job? To process and recycle estrogen once your liver has done its part.

If your gut is out of balance, it can cause estrogen dominance, too much estrogen circulating through your body, which may lead to:

PMS or PMDD symptoms
Painful periods
Bloating and breast tenderness
Increased risk of fibroids or endometriosis

On the flip side, too little estrogen can slow digestion and shrink microbial diversity, so it really is a two-way street.

Your gut and hormones are in constant conversation. Keeping your microbiome healthy supports better mood, easier periods, and a smoother menopausal transition.

Signs Your Gut Might Be Out of Balance

These signs often point to microbial imbalance or gut inflammation:

Bloating after meals
Irregular or painful bowel movements
Frequent food cravings (especially sugar)
Skin issues like eczema, acne, or rosacea
Fatigue, especially after eating
Anxiety, irritability, or brain fog
Recurring yeast or urinary tract infections
Poor immunity (catching every cold going around)

These symptoms can overlap with hormonal issues, because they’re often connected. Your gut might be the missing piece.

Your gut isn’t just where digestion happens, it’s where health happens. It influences how you feel physically, mentally, and emotionally. It shapes your energy, immunity, metabolism, and mood.

You can support it daily with simple things: