Miso is a traditional Japanese fermented paste made from soybeans, salt, and a starter culture (koji). Because soy products often contain FODMAPs, many people with IBS or digestive sensitivity wonder:
Is miso low FODMAP?
Yes — miso is considered low FODMAP in a small serving of about 1 tablespoon (≈12 g).
However, larger quantities can become high in GOS (galacto-oligosaccharides), a type of oligosaccharide that commonly triggers IBS symptoms.
Why Is Miso Low FODMAP in Small Amounts?
To understand this, we look at the fermentation process, the FODMAP structure, and the soybean content.
1. Fermentation Reduces FODMAPs
During fermentation, beneficial microbes break down complex carbohydrates from soybeans, including parts of the GOS content.
This significantly lowers the FODMAP load of the final paste.
2. Serving Size Matters
While miso is made from soybeans (a high-FODMAP ingredient), you only need 1–2 teaspoons to flavor soup, broth, or marinades.
These small amounts remain low in FODMAPs.
3. Most FODMAPs in Soy Are Water-Soluble
In dishes like miso soup, miso paste is blended in after the cooking process, which does not increase its FODMAP content.
FODMAP Classification of Miso
Below is the serving size breakdown commonly accepted in low FODMAP guidelines:
| Serving Size | FODMAP Level | Reason |
|---|---|---|
| 1 tbsp (≈12 g) | ✅ Low FODMAP | Fermentation reduces GOS; portion is small |
| 2 tbsp (≈24 g) | ⚠️ Moderate FODMAP | GOS levels increase |
| 3+ tbsp | ❌ High FODMAP | Too many soy-based oligosaccharides |
Is Miso Soup Low FODMAP?
Yes — miso soup can be low FODMAP if prepared correctly.
Low FODMAP miso soup tips:
- Use 1 tbsp or less of miso paste per serving.
- Avoid adding onions, garlic, or high-FODMAP vegetables.
- Choose firm tofu, not silken tofu.
- Add low FODMAP ingredients like spring onion tips, spinach, zucchini, or wakame.
Nutritional & Scientific Benefits of Miso
Miso is rich in:
- Probiotics (lactobacillus species) supporting gut microbiome balance
- Amino acids from soy protein
- Minerals such as manganese, copper, and zinc
- Bioactive compounds with antioxidant properties
Fermented foods like miso may even support digestive comfort — although people with IBS must still respect serving sizes.
Is White Miso or Red Miso Better for Low FODMAP?
Both are acceptable in small portions, but white miso (shiro miso) is usually:
- Fermented for a shorter time
- Slightly sweeter
- Lower in soybean content
- Less salty
This makes white miso the better low FODMAP choice.
Low FODMAP Recipe Idea: 5-Minute Miso Soup
Ingredients:
- 1 tbsp miso paste (white miso preferred)
- 1 cup hot water
- ½ cup firm tofu cubes
- 1 tbsp chopped spring onion tips (green only)
- A small handful of wakame
- Optional low FODMAP veggies: spinach, nori, zucchini slices
Instructions:
- Heat the water until hot but not boiling.
- Dissolve the miso paste in a small ladle of hot water, then add back to the bowl.
- Add tofu, wakame, and greens.
- Serve immediately.
Total FODMAP load: low.
Final Answer: Is Miso Low FODMAP?
Yes. Miso is low FODMAP in a small, recommended serving of about 1 tablespoon.
Thanks to fermentation, miso contains fewer FODMAPs than unfermented soy products. Miso soup and miso-based sauces can be safely enjoyed on a low FODMAP diet when portion sizes are kept moderate and high-FODMAP ingredients are avoided.