Learn about Kefir, Kombucha and Kimchi. the "K" superfoods are good for your gut and digestion.

April 19, 2025

Discover whether Kefir, Kombucha or Kimchi is best for you.

Your gut is home to around 100 trillion microbes — bacteria, fungi, and viruses that make up the gut microbiome. This system affects everything from your immune response to your mood and sleep.

Keeping a healthy balance of gut bacteria is key. An imbalance has been linked to inflammation, insulin resistance, obesity, IBS, and even colorectal cancer. That’s where fermented foods like kefir, kimchi, and kombucha come in. They’re packed with probiotics — live microbes that support gut health.

These aren’t just wellness fads. Fermentation, a natural process where bacteria and yeasts break down sugars, has been used for centuries to preserve food. But not all store-bought versions are equal. A 2021 King’s College London study found many UK supermarket options had additives that reduced their benefits.

So how do you find the real deal? How should you eat them? And which is best? Here’s your no-nonsense guide to the “K” superfoods.

Kefir

Kefir is a probiotic-rich drink made by fermenting milk with live cultures of yeast and bacteria.

It’s similar to yogurt but thinner and fizzier, with a tangy kick. You’ll find it as a drink or in a thicker form to spoon over muesli.

Dr. Megan Rossi, gut health expert and founder of Smart Strains, calls it “yogurt’s cousin” — packed with live microbes that feed on milk sugars and produce organic acids, giving kefir its light sour taste and natural fizz. Fermentation also lowers its lactose content, so some people with lactose intolerance can still tolerate it.

There’s also water kefir — a dairy-free, bubbly alternative to sugary soft drinks — though it typically has fewer probiotics than milk-based kefir.

Not all kefir is equal. Rossi advises checking labels: skip ones with added sugars, emulsifiers, or thickeners. Those extras undercut the gut benefits you’re after.

Kefir is good for:

• Gut health: It’s rich in probiotics — live bacteria that help balance your gut microbiome.

• Digestion: The probiotics may ease issues like bloating, constipation, and symptoms of IBS.

• Immunity: A healthy gut supports your immune system, and kefir can help maintain that balance.

• Lactose digestion: Fermentation breaks down lactose, so kefir is often easier to digest than milk.

• Anti-inflammatory effects: The microbes and bioactive compounds may help reduce inflammation.

• Heart health: Some studies link kefir to lower blood pressure and cholesterol levels.

Kimchi

Kimchi often gets compared to sauerkraut, but it packs more variety — and benefits.

While sauerkraut is usually just fermented cabbage, kimchi includes extras like radish, carrot, spring onion, garlic, ginger, and chilli, giving it a wider range of nutrients and probiotic strains.

A Stanford study even found that fermented foods like kimchi boost gut microbiome diversity and help reduce inflammation — a key factor in conditions like rheumatoid arthritis, type 2 diabetes, and chronic stress.

Kimchi also offers prebiotics (plant fibers that feed good gut bacteria) and plenty of fibre. The only downside? Salt. Traditional kimchi can be high in sodium, so if you’re eating it regularly, it’s worth keeping an eye on your intake.

Kimchi is good for:

• Gut health: Packed with probiotics that support a healthy microbiome and digestion.

• Inflammation: Linked to reduced inflammation, which plays a role in conditions like arthritis, diabetes, and stress.

• Immunity: A diverse gut microbiome helps keep your immune system strong.

• Heart health: High in fibre and antioxidants, which may support cardiovascular health.

• Weight management: Low in calories, high in fibre, and may help regulate appetite and blood sugar.

• Nutrient intake: Made from a mix of vegetables and spices, it’s rich in vitamins A, B, and C, plus minerals like iron and calcium.

Kombucha

Kombucha is a fermented tea that’s earned its gut-friendly reputation. It’s rich in organic acids and antioxidant polyphenols — if it’s made the traditional way.

Dr. Megan Rossi points out that many commercial versions take shortcuts. Some add vinegar to fake the tangy taste, while others use artificial sweeteners and market it as sugar-free. Real kombucha needs sugar for fermentation, but the microbes consume most of it — so although sugar may appear high on the ingredients list, the actual sugar content is low.

Swapping kombucha for alcohol or sugary drinks? Much better choice.

Kombucha is good for:

• Gut health: It contains probiotics that support digestion and balance your gut microbiome.

• Digestion: The organic acids can help with stomach acidity and enzyme production.

• Immunity: A healthy gut helps strengthen your immune system.

• Antioxidant support: Made from tea, kombucha is rich in polyphenols that help fight oxidative stress.

• Blood sugar control: Some studies suggest it may help stabilize blood sugar, especially if made from green tea.

• A better drink swap: It’s a healthier alternative to alcohol or sugary soft drinks.

Kefir, kimchi or kombucha — which wins?

Truth is, variety is best. Each offers different microbes and benefits, so include all three if you can. Just check labels for additives and explore other fermented foods like miso, sauerkraut, natural yogurt, and even certain cheeses.

Want a happier gut?

• Eat more vegetables

• Chew well

• Stay hydrated

• Avoid late-night meals

Your gut thrives on variety — so mix it up.

Discover how Small Changes can improve your Nutrition