Is Tea Bad for the Kidneys?
No, tea is not bad for the kidneys and may actually be protective, particularly for individuals with early-stage chronic kidney disease and for preventing kidney stone formation.
Evidence from Guidelines on Tea and Kidney Health
The most authoritative guideline evidence directly addresses tea consumption and kidney health:
Tea consumption reduces kidney stone risk. A 2006 Kidney International guideline explicitly states that "alcoholic beverages, coffee, and tea do not increase the risk of stone formation. In fact, observational studies have found that coffee, tea, beer, and wine reduce the risk of stone formation" 1.
Tea is safe for general kidney health. Multiple guidelines examining dietary factors in kidney disease do not identify tea as a harmful beverage 1.
Cardiovascular and Metabolic Benefits Relevant to Kidney Health
Guidelines emphasize tea's broader health benefits that indirectly protect kidney function:
Tea reduces cardiovascular disease risk, which is critical since cardiovascular disease is a major complication of chronic kidney disease. A 2016 Circulation guideline notes that "tea consumption is associated with lower risk of diabetes and CVD, especially comparing very frequent consumption (3-4 cups/day) with none" 1.
Blood pressure reduction occurs with regular tea consumption. Green tea (3 cups/710 mL daily) reduces systolic and diastolic blood pressure by approximately 2 mm Hg, while black tea (4-5 cups/946-1183 mL daily) reduces blood pressure by 1.8/1.3 mm Hg 1. Since hypertension accelerates kidney disease progression, this represents an indirect kidney-protective effect 1.
Tea contains beneficial polyphenols that inhibit advanced glycation end products (AGE) formation, which are implicated in diabetic kidney disease progression. Green tea catechins, particularly EGCG, prevent intracellular AGE formation and reduce inflammatory cytokine production 1.
Recent Research Evidence in CKD Populations
The highest quality recent research directly examined tea consumption in people with existing kidney disease:
A 2025 NHANES analysis of 17,575 CKD patients found that consuming up to 4 cups of tea daily was associated with 11% lower all-cause mortality in early CKD stages (HR=0.89,95% CI 0.79-0.99) 2. This is the most recent and directly relevant study for your question.
Oxidized tea (black tea) showed particular benefit, with each additional cup per day associated with 10% lower all-cause mortality in early CKD 2.
A 2019 study of 13,842 subjects demonstrated that daily tea consumption ≥240 mL (2 cups) was associated with lower kidney stone risk (OR=0.84,95% CI 0.71-0.99), with cumulative benefits over time 3.
A 2021 prospective study of 502,621 Chinese adults found that participants drinking ≥7 cups of tea daily had 27% lower kidney stone risk compared to non-tea drinkers (HR=0.73,95% CI 0.65-0.83) 4.
Kidney Function Studies
Research examining direct effects on glomerular filtration rate (eGFR):
A 2016 longitudinal study of 4,722 participants found no association between tea consumption and eGFR or changes in eGFR over 15 years, indicating tea does not cause glomerular hyperfiltration or kidney damage 5.
A 2014 cross-sectional study of 12,428 Chinese adults found no consistent negative associations between tea consumption and renal function measures 6.
Practical Recommendations by Population
For healthy adults:
- Tea consumption up to 8-10 cups daily (staying below 400 mg caffeine) is safe and potentially beneficial 7.
- Focus on 3-4 cups daily for optimal cardiovascular and potential kidney stone prevention benefits 1.
For patients with early-stage CKD (stages 1-2):
- Consume 2-4 cups of tea daily, with evidence supporting up to 4 cups for mortality reduction 2.
- Oxidized teas (black tea, oolong) may offer additional benefits over green tea in this population 2.
For kidney stone formers:
- Drink at least 2 cups (240 mL) of tea daily as part of overall fluid intake to achieve >2 liters urine output 1, 3.
- Higher consumption (up to 7 cups daily) shows dose-dependent stone risk reduction 4.
For pregnant women:
- Limit to 4-6 cups daily (staying below 200-300 mg caffeine) 7.
Important Caveats
Oxalate concerns are overstated:
- While tea contains oxalate, the 2006 Kidney International guideline does not list tea as a beverage to avoid for stone prevention 1.
- The protective effect of tea on stone formation outweighs theoretical oxalate concerns in population studies 3, 4.
Cranberry supplements differ from tea:
- A 2020 guideline specifically warns about cranberry supplements increasing urinary oxalate and stone risk, but makes no such warning about tea 1.
Green tea supplements vs. brewed tea:
- Concentrated green tea supplements containing EGCG may affect platelet function perioperatively, but this concern does not apply to regular brewed tea consumption 1.
Advanced CKD requires individualized assessment: