
We all speak in metaphors about our guts: we say we feel "butterflies," or that something is "gut-wrenching," or that we're "nauseous" when anxious. These are more than figures of speech. The gut and the brain are deeply intertwined — stress, mood, and emotion can ripple into your digestive system, and disturbances in your gut can send signals right back to your brain. This two-way street is called the gut–brain axis, and it's a real, biology-driven conversation between your microbial world and your nervous system.

In this post, I want to explain how the gut-brain axis works (in plain but scientifically grounded language), and then walk you through nutrients and foods you can use to support better gut health — and even how you might track some of those nutrients using the app Microgram.

## How the gut–brain axis works (quick tour)

Your brain and gut talk via:

**Nerves:** the vagus nerve and the enteric nervous system.

**Immune signals:** cytokines and inflammatory pathways linking the gut lining to brain function.

**Microbial metabolites:** short-chain fatty acids (SCFAs) like butyrate, plus tryptophan metabolites, which can influence mood circuits.

**Hormones/stress:** the HPA axis (cortisol) changes gut motility and sensitivity; gut signals feed back to stress pathways.

This two-way loop helps explain why stress can trigger cramps/loose stools — and why a disturbed gut can amplify anxiety or low mood.

## Signs your gut–brain axis may be off

- Stress consistently flares heartburn, cramps, or urgency
- "Sensitive" gut with pain out of proportion to triggers
- Bloating and irregularity that track with anxiety or poor sleep
- You feel better (digestion or mood) after fiber-rich, whole-food meals

If these hit home, it's worth nudging the axis from both ends: nutrition for the gut, and stress reduction for the brain.

## Nutrients and foods that support your gut–brain connection

Focus on a mix of micronutrients, fibers, and fermented foods that help your microbes make SCFAs, protect the gut lining, and calm inflammation.

**Key nutrients (and where to find them):**

**Vitamin D** — fatty fish, fortified milks, egg yolks

**Vitamin A & carotenoids** — carrots, sweet potatoes, leafy greens, liver

**Vitamin C** — citrus, berries, bell peppers, kiwi

**Vitamin E** — almonds, hazelnuts, seeds, spinach, vegetable oils

**B vitamins (esp. folate, B12)** — legumes, leafy greens, whole grains, eggs, dairy, meat

**Minerals (zinc, magnesium, iron)** — nuts/seeds, seafood, whole grains, greens

**Fiber & prebiotics** — oats, barley, legumes, apples, flax; inulin/FOS in garlic, onions, leeks, asparagus, chicory

**Resistant starch** — cooked-and-cooled potatoes or rice, legumes, green bananas

**Omega-3s** — salmon, sardines, mackerel; plant options like chia, walnuts

**Fermented foods** — yogurt, kefir, kimchi, sauerkraut, kombucha

## Simple daily pattern:

- Aim for 2+ fermented servings/week (yogurt or kefir is easy).
- Include 1–2 prebiotic foods/day (e.g., oats at breakfast; onions/garlic at dinner).
- Add resistant starch a few times per week (cook → cool potatoes/rice).
- Eat fatty fish 2x/week (or discuss omega-3 supplements with your clinician).
- Keep plant diversity high: different colors = different fibers/polyphenols.

## Track it in the Microgram app

Knowing what to eat is step one; knowing what you actually get is where Microgram helps. Log by photo, barcode, or search to see:

- Daily totals for vitamin D, folate, B12, vitamin A/C/E, zinc, iron, magnesium
- Fiber (grams) and omega-3 intake
- Trends over time so you can spot gaps (e.g., consistently low vitamin D or fiber) and adjust with specific foods

## What to expect (and how to go gently)

Changes take weeks as microbes adapt. Increase fibers/ferments gradually to reduce gas/bloating.

If you have IBS/IBD/SIBO or are on iron/zinc supplements, work with your clinician on pacing and forms.

Psychological therapies (e.g., CBT for IBS), relaxation, and sleep support can amplify nutrition benefits via the same axis.

## When to get help

Persistent pain, weight loss, blood in stool, nighttime symptoms, or iron-deficiency anemia deserve medical evaluation. Nutrition and stress tools are powerful, but red-flag symptoms need a clinician's eye.

### References (scientific sources)

Carabotti M, et al. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. *Front Neurosci.* 2015. [PMC4367209](https://pmc.ncbi.nlm.nih.gov/articles/PMC4367209/)

Cryan JF, et al. The microbiota–gut–brain axis. *Physiol Rev.* 2019. [PubMed:31460832](https://pubmed.ncbi.nlm.nih.gov/31460832/)

Mayer EA, et al. The gut–brain axis. *Annu Rev Med.* 2022. [DOI](https://doi.org/10.1146/annurev-med-042320-014032)

Facchin S, et al. Short-chain fatty acids and human health. *Nutrients.* 2024. [PMC11122327](https://pmc.ncbi.nlm.nih.gov/articles/PMC11122327/)

Silva YP, et al. The role of SCFAs in the gut–brain interplay. *Front Endocrinol.* 2020. [PMC7005631](https://pmc.ncbi.nlm.nih.gov/articles/PMC7005631/)

Chen Z, et al. Resistant starch and the gut microbiome. *Compr Rev Food Sci Food Saf.* 2024. [PMC10819196](https://pmc.ncbi.nlm.nih.gov/articles/PMC10819196/)

Wastyk HC, et al. Gut-microbiota-targeted diets modulate human immune status. *Cell.* 2021. [PubMed:34256014](https://pubmed.ncbi.nlm.nih.gov/34256014/)

Leeuwendaal NK, et al. Fermented foods, health and the gut microbiome. *Nutrients.* 2022. [PMC9003261](https://pmc.ncbi.nlm.nih.gov/articles/PMC9003261/)

Yao F, et al. Efficacy of psychological interventions for IBS: systematic review & meta-analysis. *J Gastroenterol Hepatol.* 2022. [PMC8913108](https://pmc.ncbi.nlm.nih.gov/articles/PMC8913108/)


The Gut–Brain Axis: How Your Diet Shapes Mood and Digestion

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