Creamy, tangy, and refreshing, kefir is one of the few superfoods that’s equal parts delicious and nutritious.

It has also been tied to a number of health benefits, thanks to both its nutritional value and probiotic content.

However, drinking too much can cause several side effects. Some people may need to limit their intake or even eliminate kefir from their diet altogether.

This article explores a few of the possible side effects of kefir and discusses how much you should drink.

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Kefir is a fermented drink that has been associated with a number of powerful health benefits.

Traditionally, it’s made by adding kefir grains, which are a mix of beneficial bacteria and yeast, to cow’s milk or goat’s milk. The process results in a tangy drink with a creamy, yogurt-like texture.

However, you can also add kefir grains to sugar water to make water kefir, which is a tart and tangy beverage similar to kombucha.

Both milk kefir and water kefir are rich in probiotics, a type of bacteria found in your gut that can support healthy digestion, immune function, heart health, and more (1).

What’s more, milk kefir contains several key nutrients, including protein, calcium, phosphorus, and vitamin B12 (2).

Summary

Kefir is a fermented drink made by adding kefir grains to milk or water. It’s rich in probiotics, which have been associated with many health benefits. Milk kefir also contains many important nutrients, including protein, vitamins, and minerals.

Fermented foods and drinks like kefir contain small amounts of alcohol.

Although the alcohol content can vary depending on the specific brand and type of kefir, most varieties contain 0.5–2% alcohol (3).

For reference, regular beer comprises about 5% alcohol, while light beers generally contain about 4.2% alcohol (4).

While the amount of alcohol in kefir is very low and not likely a concern for most people, it may be something to keep in mind if you have alcohol intolerance or are avoiding alcohol for other reasons.

It may also be an important consideration if you’re drinking multiple servings per day, as the amount can quickly add up.

Summary

Kefir contains a small amount of alcohol in each serving, which may be an important consideration for people with an alcohol intolerance or those who choose to avoid alcohol.

Increasing your intake of probiotic-rich foods very quickly may cause digestive problems for some people.

Some of the most common issues reported with probiotic consumption include gas, constipation, and nausea (5).

In some cases, probiotics could also cause other gastrointestinal issues, such as diarrhea, stomach cramps, vomiting, changes in taste, and decreased appetite (6, 7).

However, keep in mind that these symptoms are more common with the use of probiotic supplements, which contain a more concentrated amount of probiotics compared with fermented beverages like kefir.

Furthermore, these symptoms typically tend to subside over time with continued consumption of kefir and other probiotic foods.

Summary

Increasing your intake of probiotics could initially cause digestive issues like gas, constipation, nausea, diarrhea, and stomach cramps.

While the exact nutritional content of kefir can vary by brand, it typically contains some carbohydrates in each serving.

For example, 1 cup (243 mL) of plain, low fat milk kefir provides about 12 grams of carbs. Similarly, 1 cup (240 mL) of water kefir contains about 13 grams (2, 8).

While this may not be an issue for most people, those on low carb or ketogenic diets may need to limit their intake of foods that contain carbs, including kefir.

Additionally, people with diabetes may also need to monitor their carb consumption carefully to manage their blood sugar levels.

For those with diabetes, it may be best to limit your intake of kefir to 1–2 cups (237–473 mL) per day to maintain healthy blood sugar levels, and be sure to count the carbs in kefir toward your daily carb intake.

Summary

Because kefir generally contains 12–13 grams of carbs per serving, those with diabetes and people following a low carb diet may need to limit their intake.

If you have any conditions that affect your immune system, you should talk with a healthcare professional before adding probiotic-rich foods like kefir to your diet.

While research generally suggests that these ingredients are likely safe for people with autoimmune conditions, some case reports have linked probiotic use to serious side effects, such as an increased risk of infection (9).

Although rare, probiotics have also been associated with issues like sepsis, which is a potentially life threatening complication of an infection (6).

Still, more research is needed to determine how kefir specifically may affect those with autoimmune disorders.

Summary

In rare cases, consuming probiotics could increase the risk of infections in people with conditions that affect the immune system. More research is needed on kefir’s effect in these populations.

Kefir can be a healthy and delicious addition to a well-rounded diet.

For best results, stick to around 1–3 cups (237–710 mL) per day and pair it with a variety of other fermented foods and beverages to increase your intake of probiotics.

However, certain people may need to limit their intake depending on their daily carb allotment, including people with diabetes, those following a low carb or ketogenic diet, and people who avoid alcohol.

People with conditions that weaken the immune system should also check with a healthcare professional before adding kefir or other foods high in probiotics to their diets.

If you experience any adverse side effects after drinking kefir, consider reducing your intake or discontinuing consumption.

Summary

Drinking 1–3 cups (237–710 mL) of kefir daily can be a great way to boost your intake of probiotics. Certain people may need to limit their intake, including people with diabetes or autoimmune disorders and those following a low carb or ketogenic diet.

Adding kefir to your diet can be an easy and delicious way to increase your intake of probiotics.

However, drinking too much can have several side effects, including digestive issues. It also contains carbs and a small amount of alcohol, so it may not be suitable for everyone.

Therefore, it’s best to enjoy kefir in moderation as part of a healthy, well-rounded diet alongside a variety of other fermented ingredients, including kombucha, kimchi, sauerkraut, and yogurt.