Kefir and kombucha are both fermented beverages with several touted health benefits.
While both drinks are in the fermented food category, they have several differences in terms of production, nutrition, flavor, and texture.
This article reviews the differences between kefir and kombucha to help you determine which one may be a healthier choice for you.
Both kefir and kombucha require a starter material to undergo fermentation, a process during which bacteria, yeasts, or other microorganisms break down glucose molecules, or sugar.
However, one major difference is that kefir is traditionally milk-based while kombucha is green- or black-tea-based.
Kefir grains, which technically aren’t grains, are the primary ingredient needed to make kefir. They contain a mixture of yeast and bacteria that’s bound together with milk proteins and complex sugars called polysaccharides.
These grains are added to milk and left to sit for 18–24 hours to ferment. Once fermentation is complete, the kefir grains are removed from the liquid and can be reused to make another batch. The leftover liquid is the kefir (
Note that there’s also water kefir, which is made using kefir grains with either coconut water or plain water and added sugar in place of milk. Water kefir is not as popular or widely available as traditional milk-based kefir.
Kombucha is made from tea, bacteria, and sugar. It’s made by mixing a symbiotic culture of bacteria and yeast (SCOBY) with green or black tea. This mixture sits for a period of 10–14 days, throughout which sugar is often added to give it a sweeter flavor (
While the kombucha ferments, another SCOBY forms at the top of the liquid. This is slimy and thick and can be removed, leaving the kombucha liquid. The SCOBY you remove can be used to make another batch of kombucha.
While less popular commercially, some people like to combine kombucha and kefir into one beverage at home. This is typically done by mixing finished kombucha and water kefir, with both the SCOBY and the kefir grains removed.
Kefir and kombucha are both fermented beverages made by using a starter material that can be reused to make additional batches. Kefir is usually milk-based, while kombucha is made with green or black tea.
Traditional kefir is milk-based and has a creamy consistency. Many people consider kefir to be a drinkable yogurt. It has a sour taste, and its degree of sweetness depends on whether sugar is added. Kefir comes in a number of flavors, which are primarily fruit-based, vanilla, or plain.
In comparison, kombucha is made primarily with black or green tea, giving it a thinner consistency. Many people know kombucha by its characteristic, slimy live culture that typically sinks to the bottom of the bottle.
At first smell, kombucha gives off a vinegar-rich aroma. It has a bitter taste and is usually carbonated and fizzy, characteristics that come from the carbon dioxide molecules that result from the acetic acid and other gases released during the fermentation process (
Kombucha comes in a wide range of flavors, including fruit, mint, and a number of spices, such as turmeric and ginger, to name a few.
Kefir is creamy, slightly sour, and often compared to a thinned yogurt. Kombucha is carbonated, and it has a vinegar smell, bitter taste, and characteristic slimy live culture that often sits at the bottom.
The fermentation processes used to make kefir and kombucha mean that both beverages are full of probiotics, which are good bacteria found in foods and your digestive system. They promote good gut health, as well as good overall health (
Still, kefir and kombucha contain some slightly different types and amounts of good bacteria. Both contain lactic acid bacteria, while kombucha also contains acetic acid (
The nutrient composition of these beverages can vary significantly depending on the ingredients used to make them, such as the type of milk used in kefir and amount of added sugar in kombucha.
One cup (240 mL) of kefir made with low fat dairy milk also provides 30% of the Daily Value (DV) for calcium, 5% of the DV for sodium, as well as 10% and 25% of the DV for vitamins A and D, respectively (
While the micronutrient content of kombucha is difficult to find on the nutrition facts label, older studies have found that it contains some B vitamins, vitamins C and A, zinc, copper, iron, and manganese (10, 11).
Again, the nutrition composition of kefir and kombucha can vary, so the best way to examine the nutritional offerings of these drinks is to examine their nutrient panels.
The nutritional composition of kefir and kombucha can vary significantly depending on what ingredients are used to make them. Both contain probiotics, such as lactic and acetic acid.
The main benefit of drinking kefir and kombucha is that they’re a source of probiotics, which are good bacteria that help promote a healthy bacterial balance in your digestive tract (
Kombucha not only contains probiotics but also offers the benefits of the tea used to make it. For instance, green and black teas are high in potent antioxidants, which are compounds that fight free radical damage that can lead to chronic disease (
Compounds in kombucha, such as acetic acid and likely others, appear to have antimicrobial activity, which may help kill potentially harmful organisms in the body (
Furthermore, kombucha may have a protective effect on your liver. Some animal studies have found that kombucha has the ability to reduce liver toxicity caused by toxic chemicals, in some cases by up to 70% (
Kefir and kombucha are full of probiotics, which are good bacteria that promote good gut and overall health. They may also have antimicrobial, antioxidant, anticancer, and anti-inflammatory effects.
While kefir and kombucha offer numerous gut-related health benefits, they may have downsides to consider.
Kefir is typically made from a lactose-containing milk, which means it’s unsuitable for people with either a milk protein allergy or lactose intolerance.
That said, some vegan options do exist. Some have been made from nondairy milk like cashew milk. Water kefir is also an option, as it’s made using coconut water or plain water with added sugar.
Kefir can also contain a high amount of sugar, depending on the type of milk used and whether added sugar or certain flavorings were used. Sugar-rich beverages may also increase your risk of obesity, heart disease, fatty liver disease, and type 2 diabetes (
Some people may also experience changes in bowel habits when first consuming kefir, such as constipation or abdominal pain.
Those who are immunocompromised may need to avoid food with cultures or probiotics. Please discuss this with your doctor.
A small study in healthy adults found that while kefir has a low to moderate glycemic index, meaning that it doesn’t spike your blood sugar very much, it has a high insulinemic index, meaning it may increase blood insulin levels more than other foods (
Furthermore, kefir didn’t keep the study participants much more full than a slice of refined white bread (
The effervescence of kombucha, which is due to the carbon dioxide molecules created during fermentation, may cause bloating if you’re not used to it (
Kombucha likewise contains caffeine from the tea, which could contribute to sleep disruptions. People with a caffeine sensitivity may also react to it in other ways, possibly feeling jittery or anxious (
Additionally, kombucha can contain a substantial amount of added sugar, depending on how much is used to make it. Excessive sugar intake can draw water into your intestines, potentially causing diarrhea (
Furthermore, kombucha contains compounds called FODMAPs (fermentable oligo-, di-, mono-saccharides, and polyols), which are specific types of carbohydrates that can cause an upset stomach in some people, especially those with irritable bowel syndrome (IBS) (
Kombucha also contains traces of alcohol due to the fermentation it undergoes, and some people may want to avoid it for this reason. While the amount is very low in commercial varieties — under 0.5% — it can be as high as 3% in home-brewed batches (
Plus, experts recommend that pregnant and breastfeeding women avoid alcohol. Alcohol can transfer into breast milk and thus infants if they’re nursed within 2 hours of the mother consuming it, and infants metabolize it much more slowly than adults
Pregnant and breastfeeding women may also want to avoid kombucha, as it’s an unpasteurized product. This puts it at a higher risk of containing potentially harmful bacteria like Listeria monocytogenes, which can cause miscarriage (
Lastly, pregnant and breastfeeding women may want to take kombucha’s caffeine content into account. While moderate caffeine intake is generally safe during pregnancy, a small amount of caffeine can transfer through breast milk and cause babies to become fussy (
Dairy-based kefir contains lactose, may be high in sugar, and appears to raise insulin. Kombucha may cause an upset stomach, be problematic for people with caffeine sensitivity, and should be limited or avoided by pregnant and breastfeeding women.
Kefir and kombucha are best known for being fermented, probiotic-rich beverages. While they undergo a similar fermentation process, kefir is traditionally made using milk while kombucha uses green or black tea.
Both beverages offer probiotics, which are good bacteria that promote gut health. They may also have antioxidant and antimicrobial effects.
Yet, there are potential downsides to consider, such as their added sugar, lactose, and caffeine contents, as well as other characteristics that may raise chronic disease risk.
Which one is healthiest may depend on what you’re looking to get from consuming these beverages.
Overall, both kefir and kombucha are healthy options that offer some benefits and potential downsides. In the end, which one you choose may depend primarily on your personal preference.
In any case, it’s a good idea to read the ingredient label and nutrition facts panel when deciding between the two or which brand to try.