The Relationship Between Fermented Foods and Immunity

In recent years, we’ve started seeing new drinks, jars, and grainy liquids on supermarket shelves: kefir, kombucha, kimchi, pickles, water kefir, boza… In fact, most of these have long been part of our kitchens—they’re simply coming back into the spotlight under different names. What they all share is that they’re “fermented,” meaning they’ve been transformed by microorganisms. But does this transformation really contribute to our health?

What Is Fermentation?

Fermentation occurs when certain bacteria and yeasts break down the natural sugars and components in food. During this process:

- Foods become easier to digest

- Certain vitamins and acids increase

- Live microorganisms emerge

And this is exactly where immunity comes into play.

Probiotic or Prebiotic? They’re Not the Same

These two terms are often confused. Let’s keep it simple and clear:

- Probiotics: “Beneficial bacteria” that live in our gut.

→ Examples: kefir, yogurt, kombucha, kimchi…

- Prebiotics: Fibers that these bacteria need in order to thrive.

→ Examples: bananas, onions, garlic, oats, asparagus, whole grains…

So probiotics are “the good guys,” and prebiotics are “what feeds them.”

Because both support the gut microbiota, they play an important role in immunity.

The Immunity–Gut Connection Is Now Taken Seriously

There’s a sentence you hear often in medicine today: **“70% of the immune system is in the gut.”**

This isn’t an exaggeration—because the gut’s lymphoid tissues, microbiota, and nervous system all influence immune regulation.

Scientific studies show that:

- Probiotic-containing foods may reduce upper respiratory tract infections

- Certain probiotic strains may shorten the duration of diarrhea

- Fermented foods can produce molecules that reduce inflammation

- Prebiotic intake can support immune cell activity

The key point is this: fermented foods don’t create miracles; but by supporting gut balance, they can help build a more resilient system.

In Which Areas Can Fermented Foods Be Helpful?

Their effects have been studied more clearly in these areas:

- Digestive system: bloating, constipation, and diarrhea may improve

- Lactose intolerance: yogurt/kefir may be better tolerated

- Immunity: may be supportive in respiratory infections

- Inflammation: some gut-related inflammation may decrease

Especially products like kefir, yogurt, and kombucha can provide probiotic support because they contain live microorganisms.

Not Every Fermented Food Is the Same

Many people assume “fermented = healthy,” but a few details matter:

- Pasteurized kombucha contains no live bacteria (only the taste remains)

- If pickles are made with vinegar rather than fermentation, they won’t provide probiotics

- Heat-treated yogurt may have a lower live bacteria count

- Homemade products don’t contain controlled bacterial strains

So quality matters—especially when consuming them for immune support.

Who Should Be Cautious?

Fermented foods are generally safe, but these groups should be careful:

- During pregnancy (especially with products like kombucha)

- People with suppressed immune systems

- Those receiving steroids/chemotherapy

- People with low stomach acid

- Those with histamine intolerance

For these individuals, it’s best to consult a doctor.

How Can You Include Them in Daily Life?

You don’t have to drink kombucha. Simple examples:

- Yogurt or kefir at breakfast

- Homemade fermented pickles with dinner

- Kefir as a smoothie base

- For prebiotic support: oats + banana + almonds

- Use fermented dressings instead of vinegar in salads

If probiotics and prebiotics are consumed in the same meal (i.e., **synbiotics**), they may be more effective.

Our Approach at Bir Adım Sağlık

Fermented foods are one of the important tools that support gut health and, indirectly, immunity. However, if individual suitability, existing conditions, medications, digestive sensitivities, and overall dietary balance are ignored, they may cause discomfort rather than benefit.

That’s why at Bir Adım Sağlık, we support our clients by:

- Listening to their digestive and immune history

- Planning the prebiotic/probiotic balance together

- Building a personalized nutrition and support approach with clinical dietitian and physician evaluation

Fermented foods aren’t a miracle—but in the right person, in the right amount, at the right time, they can be a powerful support that strengthens the body’s resilience.