Fermentation is a natural process in which beneficial microorganisms—primarily bacteria and yeasts—convert sugars into acids, gases, or alcohol. This not only preserves food but also creates compounds that can benefit health.
Common fermented foods include:
Kimchi (Korea)
Sauerkraut (Germany)
Kefir (Caucasus)
Yogurt
Miso
Tempeh
Kombucha
Traditional pickles fermented in brine
India has its own excellent fermented traditions—homemade dahi, chaas, kanji, fermented rice, and naturally fermented vegetables can provide many of the same benefits that have made kimchi and kefir so popular worldwide.
These foods often contain live microbes (though not always, depending on processing).
*How do they help the gut microbiome?*
Your gut houses roughly 30–40 trillion microorganisms that influence digestion, immunity, metabolism, inflammation, and even brain function.
Fermented foods may help in several ways:
1. They introduce beneficial bacteria
Many fermented foods contain live lactic acid bacteria such as:
Lactobacillus
Lactococcus
Leuconostoc
Bifidobacterium (in some products)
These microbes may not permanently colonise your gut, but they can exert beneficial effects while passing through.
2. They increase microbial diversity
Studies suggest that regularly eating a variety of fermented foods can increase the diversity of the gut microbiome. Higher diversity is generally associated with better health and lower inflammation.
3. They strengthen the gut barrier
Fermented foods produce compounds like:
Lactic acid
Short-chain fatty acids (indirectly)
Bioactive peptides
These support the intestinal lining and may reduce “leaky gut.”
4. They improve digestion
Beneficial bacteria partially digest food before you eat it, making nutrients easier to absorb.
Examples:
Less lactose in yogurt than milk.
Reduced phytic acid, improving mineral absorption.
Better digestion of certain proteins.
5. They modulate immunity
Around 70% of immune cells reside in and around the gut. A healthier microbiome helps train the immune system and may reduce inappropriate inflammation.
*What does the research say?*
One of the most discussed studies came from Stanford University (2021).
Researchers compared:
A high-fibre diet
A high-fermented-food diet
The fermented-food group showed:
Increased microbiome diversity
Reduced inflammatory markers
Improved immune regulation
Interestingly, simply adding more fibre didn’t produce the same microbiome changes over the study period, although fiber remains extremely important for long-term gut health.
*The key lesson:*
Fibre feeds your microbes; fermented foods may help diversify them. You need both.
Kefir: Why is everyone talking about it?
Kefir is often considered one of the richest natural probiotic foods.
Unlike yogurt, kefir contains:
Multiple bacterial strains
Beneficial yeasts
Sometimes over 30 different microorganisms.
Research suggests it may:
Improve lactose digestion
Reduce inflammation
Support bowel regularity
Produce antimicrobial compounds
Kimchi
Kimchi is fermented cabbage with garlic, ginger and chilli.
Benefits include:
High fibre
Vitamin C
Vitamin K
Live Lactobacillus species
Antioxidants
Because it contains vegetables as well as microbes, it provides both probiotics and prebiotic fibre.
One caution: traditional kimchi can be quite high in sodium.
Indian equivalents
India actually has a rich fermentation tradition, though much of it is overlooked.
1. *Homemade curd (dahi)*
Probably India’s best-known probiotic food.
Contains:
Lactobacillus
Streptococcus thermophilus
Other beneficial bacteria depending on the starter culture.
Fresh homemade curd generally contains more viable bacteria than many heat-treated commercial products.
2. *Traditional buttermilk (chaas)*
Especially when made from cultured curd rather than simply mixing yogurt with water.
Excellent daily probiotic.
3. *Kanji*
A North Indian fermented drink traditionally made from black carrots (or carrots and beetroot).
Rich in lactic acid bacteria.
Arguably India’s closest equivalent to kombucha or kefir (though the microbes differ).
4. *Fermented rice (Panta Bhat, Pazhaya Sadam)*
Common in eastern and southern India.
Cooked rice is soaked overnight and eaten the next day.
Studies suggest it develops beneficial lactic acid bacteria and may increase certain B vitamins.
5. *Fermented bamboo shoots*
Popular in northeast India.
Rich in beneficial microbes.
6. *Gundruk*
A fermented leafy vegetable from Himalayan regions (Nepal, Sikkim, Darjeeling).
Excellent source of lactic acid bacteria.
7. *Traditional fermented pickles*
Only if naturally fermented in salt water.
Many commercial pickles are preserved with vinegar or oil and don’t contain live probiotics.
8. *Idli and dosa batter*
Yes—but with an important distinction.
The fermentation produces beneficial bacteria and yeasts while the batter ferments.
However, steaming or cooking kills most of these microbes.
You still gain benefits such as:
Improved digestibility
Reduced antinutrients
Better nutrient availability
But idlis and dosas are not significant sources of live probiotics.
*What about probiotics versus prebiotics?*
Many people focus only on probiotics, but prebiotics are equally important.
Think of it this way:
Probiotics = the seeds (beneficial microbes)
Prebiotics = the fertiliser (food for those microbes)
Excellent Indian prebiotic foods include:
Onion
Garlic
Banana (especially slightly green)
Oats
Chickpeas
Lentils
Rajma
Apples
Flaxseed
Psyllium (isabgol)
Whole grains
Without prebiotics, probiotic bacteria often struggle to thrive.
*Do you need fermented foods every day?*
For most healthy people, yes—small amounts consumed regularly are likely more beneficial than occasional large servings.
A practical routine could be:
Homemade dahi or chaas daily.
Kanji several times a week when in season.
Naturally fermented vegetables or pickles a few times a week.
Plenty of fruits, vegetables, legumes and whole grains every day to nourish the microbiome.
*A few cautions*
Introduce fermented foods gradually if you have a sensitive gut, as they can initially cause bloating.
People with severe immune suppression should consult their physician before consuming large amounts of live fermented foods.
Be cautious with homemade ferments—good hygiene and proper fermentation techniques are essential.
Choose products labeled with “live and active cultures” if buying commercially; many shelf-stable or pasteurized products no longer contain live microbes.
The bottom line
Fermented foods are best viewed as one part of a healthy dietary pattern rather than a miracle cure. They can enrich the gut ecosystem, support immune function, and improve digestion, but they work best alongside a diet rich in diverse plant foods.