Herbal Tea and Kidney Stones: The Low-Oxalate End of the Tea Rack

2026-08-24 · By Sarah Chen, Data Editor · Dietary reference, not medical advice

For anyone with calcium oxalate stones, tea is the drink that needs a second look. The oxalate in tea is real, but it is not spread evenly across the tea rack — and the measured difference between a cup of black tea and a cup of peppermint tea is larger than most people expect.

The finding, plainly: A 2017 study in the Journal of Food Composition and Analysis measured oxalate across beverages. Black and green teas had the highest concentrations at 3.21 to 6.34 mg per 100 mL, while herbal teas sat at 0.08 to 0.87 mg per 100 mL — a roughly 10- to 40-fold gap. Two exceptions stood out among herbal teas: barley malt tea at 1.82 and mate-guarana at 1.21 mg per 100 mL. An older analysis (Asia Pacific Journal of Clinical Nutrition, 2002) found similar ordering, with black tea averaging about 12 mg per cup and herbal teas under 1 mg per cup.

Where the Oxalate Comes From

The oxalate in tea comes from the tea plant's leaves, and the amount that ends up in the cup depends on three things: the plant, the brew, and the brand. True teas — black, green, oolong, white — come from Camellia sinensis, which concentrates oxalate in its leaves, and the leaves release it into hot water during steeping. Herbal teas come from other plants entirely — chamomile, peppermint, hibiscus, rooibos — and most of them carry little oxalate. Brewing time matters too: the same tea bag steeped five minutes instead of one can roughly double the oxalate in the cup, because more leaf time means more oxalate dissolved.

The practical rule is simpler than the chemistry: black and green tea in moderation is fine for most people, and switching the afternoon cup to an herbal tea is the easiest way to cut oxalate from the beverage column without giving up warm drinks. For people with high urine oxalate, the swap from true tea to herbal tea is one of the cleanest single changes available.

The boundary, stated clearly: these are measured ranges from two published studies; exact values vary by brand, leaf amount, and steep time. Tea is not a stone cause for most people at moderate intake — the fluid it provides usually outweighs the oxalate — but for high-oxalate stone formers, the herb rack is the safer shelf.

The Beverage Rack, Measured

The oxalate values from the Harvard database put the everyday drinks in perspective:

Food	Oxalate (mg)	Serving	Rating
Water, still	0 mg	1 glass	Safe
Sparkling water, plain	0 mg	1 can	Safe
Tea, black, brewed	14 mg	1 cup	Safe
Banana	6 mg	1 medium	Safe
Apple, fresh	2 mg	1 medium	Safe

Water and sparkling water carry no oxalate and remain the default. Black tea at 14 mg per cup is moderate — fine for most people, and worth watching only for heavy daily drinkers with high urine oxalate. The measured studies put herbal teas far below black tea, which is why the herb rack is the recommended swap for those who want a warm drink without the oxalate load.

What to Do With This

Three habits cover most of the upside. If you drink several cups of black or green tea a day and have high urine oxalate, move the afternoon cups to herbal tea — peppermint, chamomile, rooibos — where the measured oxalate is near zero. Steep true tea briefly and drink it moderately rather than brewing a long, strong pot. And keep water as the base of the day; tea is the flavor, water is the hydration, and that division keeps the oxalate ledger in check.

Frequently Asked Questions

Is herbal tea safe for kidney stones?

Measured data put most herbal teas at 0.08 to 0.87 mg per 100 mL — near zero and far below black tea. The two exceptions are barley malt and mate-guarana teas, which run higher. For most stone formers, herbal tea is a safe warm drink.

Should I stop drinking black tea?

Not necessarily. A cup or two of black tea (about 14 mg oxalate per cup) is moderate and fine for most people, and the fluid it provides is helpful. Heavy daily intake in someone with high urine oxalate is where switching to herbal tea earns its keep.

Sources:
Harvard T.H. Chan School of Public Health Oxalate Database (2024); USDA FoodData Central; Oxalate content of beverages. J Food Compos Anal. 2017 (black/green vs herbal measured ranges); Harvard oxalate database values. All oxalate values are lab-measured via ion chromatography. This page is a dietary reference tool, not medical advice.

See how oxalate values are measured and verified on our data methodology page.

Medical Disclaimer: This site is a dietary reference tool based on published food composition data. It does not provide medical advice, diagnose, or treat any condition. Talk to your doctor or a registered dietitian before changing your diet, especially if you have kidney stones, kidney disease, or other medical conditions.