Once seen as old-world kitchen staples, sauerkraut and kefir are back — this time, lining the fridges of modern health stores and topping “gut health” trend lists.
But beyond the buzz, these fermented foods are genuinely beneficial, backed by emerging research and centuries of traditional use.
They’re inexpensive, versatile, and surprisingly powerful when it comes to digestion, immunity, and even mood.
Let’s look at what science says — and how to choose the healthiest versions.
Fermented foods really matter
Both sauerkraut and kefir are rich in live probiotic bacteria, the kind your gut needs to function optimally.
These microbes help maintain a balanced gut microbiome — the community of bacteria in your digestive system that supports everything from immune response to nutrient absorption and inflammation control.
A healthy gut has been linked to:
• Stronger immunity
• Better digestion and regularity
• Reduced inflammation
• Improved mental health (via the gut-brain axis)
• Lower risk of metabolic disorders
In short: a healthy gut means better health — and fermented foods can help support that.
Sauerkraut: fermented cabbage with benefits
Real sauerkraut is raw, unpasteurised cabbage that has been fermented in its own juices with salt. The fermentation process produces lactic acid bacteria, which act as probiotics.
Health benefits:
• Improves digestion and helps break down food more efficiently
• Rich in vitamin C, vitamin K2, and natural enzymes
• Can support a healthy balance of gut flora
• Linked to better immune resilience (especially during winter)
• Contains glucosinolates and isothiocyanates — natural compounds that may have anticancer effects
A 2020 review published in Nutrients found that fermented vegetables like sauerkraut can reduce inflammation and may positively affect glucose control and blood pressure (doi:10.3390/nu12061567).
Kefir: a fermented milk powerhouse
Kefir is made by fermenting milk with kefir grains — clusters of bacteria and yeasts.
It contains up to 30 different strains of beneficial microbes, making it more diverse than yoghurt.
Health benefits:
• High in probiotics, particularly Lactobacillus kefiri, which is unique to kefir
• Naturally rich in calcium, B12, magnesium, and vitamin D
• May improve lactose digestion even in those with mild intolerance
• Can support the immune system through modulation of gut flora
• Shows antimicrobial effects in lab studies against common pathogens like E. coli and Salmonella
A 2015 study in Frontiers in Microbiology noted that kefir may have anti-inflammatory, antibacterial, and even anti-cancer properties, although more clinical trials are needed (doi:10.3389/fmicb.2015.01171).
What to look for when buying
For sauerkraut:
• Look for raw, unpasteurised varieties — these contain live cultures
• Avoid shelf-stable sauerkraut in jars or cans (usually heat-treated = no live bacteria)
• Ingredients should be simple: just cabbage and salt
• Organic cabbage is a plus (fermentation can concentrate pesticides in conventionally grown produce)
Best choice: Find a local brand with live cultures listed on the label, or make your own.
For kefir:
• Go for plain, unsweetened kefir — flavoured versions often contain high amounts of sugar
• Look for “live and active cultures” on the label
• Cow’s milk kefir has the most research behind it, but goat’s milk or even water kefir are options if you’re sensitive to dairy
• If possible, choose organic and full-fat — these tend to be less processed and better tolerated
Avoid anything ultra-processed or shelf-stable with additives or long ingredient lists.
Buying vs making your own sauerkraut
Making sauerkraut at home is surprisingly simple — and cost-effective.
All you need is organic cabbage, salt, and time. Homemade versions are often richer in probiotics than store-bought ones, especially if you let them ferment slowly at cooler temperatures (10–20°C for 2–3 weeks).
That said, good store-bought raw kraut is a perfectly solid option if you’re not ready to ferment at home.
Our thoughts…
If you’re looking to support your digestion, improve your immune system, or simply diversify your diet in a healthy, ancestral way — sauerkraut and kefir are excellent starting points.
They’re not miracle foods. But they are deeply functional, scientifically supported, and remarkably simple.
Best of all, they’re part of a tradition that existed long before gut health became a buzzword — and one that still holds up in 2025.
