Short answer
There is no good evidence that kombucha helps the kidneys. Healthy adults who drink it in moderation are not known to be harmed by it. People with kidney disease, or who are on dialysis, need personal advice from their care team, because their fluid, sugar and mineral limits are different. If you have kidney disease, check with your nephrologist or dietitian before you drink it.
What kidneys need from fluids
Your kidneys filter waste from your blood, balance fluid and keep minerals such as sodium, potassium and phosphorus in range. Most healthy adults can drink a range of fluids without problems. People with reduced kidney function may need to limit fluids, potassium or phosphorus, depending on their stage of disease and their treatment. Dialysis adds another layer, because extra fluid can build up between sessions.
For that reason, a drink that suits a healthy person may not suit someone with kidney disease.
What the research shows
Most of what is known about kombucha and the kidneys comes from lab and animal studies. Some studies have looked at antioxidant effects on kidney tissue, but this does not tell us how kombucha affects people with kidney disease. Human trials are lacking. So there is no reliable evidence that kombucha protects, cleanses or repairs the kidneys, and claims that it does should be treated with caution.
Who should check with a care team first
- People with kidney disease of any stage, including those on dialysis or who have had a transplant
- People with a weakened immune system, because kombucha is unpasteurised and contains live microbes
- Pregnant or breastfeeding women, and young children, who are generally advised to avoid it or check first
Some health sources advise people with kidney disease to avoid kombucha altogether, while others say it can be discussed with a care team. Either way, the advice should come from someone who knows your history.
What to check on the label
If you do drink kombucha, check these on the label or ask the maker:
- Sugar: flavoured and sweetened kombucha can contain a lot. This matters for blood sugar and for weight, both of which affect kidney health.
- Potassium and phosphorus: content varies by brand and flavour, and some fruit juices are high in potassium. Ask your dietitian which levels suit you.
- Added juice or flavouring: these change the sugar and mineral content.
- Alcohol: a small amount is normal, but some products contain more. Check the label.
Home-brewed kombucha: extra risks
Homemade kombucha is not pasteurised, so hygiene matters. Rare, serious problems, including high acid levels in the blood (acidosis) and liver or kidney problems, have been reported in people who drank large amounts or who drank poorly made homebrew. In the cases reported, a direct link was not proven. These problems are rare, but they are one reason to brew carefully and to discuss kombucha with your care team before you start.
Questions to ask your nephrologist or dietitian
- Is kombucha suitable for my stage of kidney disease?
- How much fluid counts as part of my daily limit?
- Are the sugar, potassium or phosphorus levels in the brand I buy a concern?
- Does my treatment, such as dialysis, change the answer?
Healthy kidneys: a moderate approach
If you have healthy kidneys, a small glass a day is a reasonable place to start, as long as it sits well with you. One university food-science guide suggests beginning with about 120 ml (4 oz) a day for new drinkers. Keep an eye on sugar, and stop if you notice stomach upset or other symptoms. If you have any kidney concern, talk to your doctor before you start.
For a general introduction to the drink, see what is kombucha. For more on health claims and what the research shows, see the health benefits of ginger kombucha.