Effect of different brewing times on soluble oxalate content of loose-packed black teas and tea bags

Mahdavi, Reza; Yagin, Neda Lotfi; Liebman, Michael; Nikniaz, Zeinab

doi:10.1007/s00240-012-0521-z

Cited by 11 publications

(5 citation statements)

References 23 publications

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“…A particular example of high variability in oxalate content of foods is tea: black tea has higher oxalate concentration compared with oolong or green tea. Besides, other factors such as brewing time, tea quality, preparation, origin, and harvesting period influence urinary oxalate excretion [51][52][53].…”

Section: Oxalatementioning

confidence: 99%

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian–Vegan Diets

et al. 2020

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Nephrolithiasis is a common medical condition influenced by multiple environmental factors, including diet. Since nutritional habits play a relevant role in the genesis and recurrence of kidney stones disease, dietary manipulation has become a fundamental tool for the medical management of nephrolithiasis. Dietary advice aims to reduce the majority of lithogenic risk factors, reducing the supersaturation of urine, mainly for calcium oxalate, calcium phosphate, and uric acid. For this purpose, current guidelines recommend increasing fluid intake, maintaining a balanced calcium intake, reducing dietary intake of sodium and animal proteins, and increasing intake of fruits and fibers. In this review, we analyzed the effects of each dietary factor on nephrolithiasis incidence and recurrence rate. Available scientific evidence agrees on the harmful effects of high meat/animal protein intake and low calcium diets, whereas high content of fruits and vegetables associated with a balanced intake of low-fat dairy products carries the lowest risk for incident kidney stones. Furthermore, a balanced vegetarian diet with dairy products seems to be the most protective diet for kidney stone patients. Since no study prospectively examined the effects of vegan diets on nephrolithiasis risk factors, more scientific work should be made to define the best diet for different kidney stone phenotypes.

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Section: Oxalatementioning

confidence: 99%

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian–Vegan Diets

et al. 2020

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“…In addition, the exact estimate of dietary oxalate intake is affected by the intrinsic variability of oxalate content in foods. Different types of tea, for instance, contain varying levels of oxalate depending on specific characteristics such as harvesting period, brewing time, tea quality, and preparation [95][96][97].…”

Section: Nephrolithiasis and Nephrocalcinosismentioning

confidence: 99%

Dietary Oxalate Intake and Kidney Outcomes

et al. 2020

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Oxalate is both a plant-derived molecule and a terminal toxic metabolite with no known physiological function in humans. It is predominantly eliminated by the kidneys through glomerular filtration and tubular secretion. Regardless of the cause, the increased load of dietary oxalate presented to the kidneys has been linked to different kidney-related conditions and injuries, including calcium oxalate nephrolithiasis, acute and chronic kidney disease. In this paper, we review the current literature on the association between dietary oxalate intake and kidney outcomes.

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“…Tea contains oxalates in varying amounts depending on the type and duration of the infusion. The amount of oxalate measured for black tea varies from 2.7 to 4.8 mg/240 mL (one cup) of tea infused for 1–5 min [2], whereas the amount of oxalate in green tea ranges from 2.08 to 34.94 mg/250 mL of tea [3]. However, the amount of oxalate in green tea depends on its origin, quality, preparation, and time of harvest, thus probably explaining why some studies report a higher oxalate concentration in black tea compared to green tea [4].…”

Section: Introductionmentioning

confidence: 99%

Daily Green Tea Infusions in Hypercalciuric Renal Stone Patients: No Evidence for Increased Stone Risk Factors or Oxalate-Dependent Stones

et al. 2019

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Green tea is widely used as a ‘’healthy’’ beverage due to its high level of antioxidant polyphenol compounds. However tea is also known to contain significant amount of oxalate. The objective was to determine, in a cross-sectional observational study among a population of 273 hypercalciuric stone-formers referred to our center for metabolic evaluation, whether daily green tea drinkers (n = 41) experienced increased stone risk factors (especially for oxalate) compared to non-drinkers. Stone risk factors and stone composition were analyzed according to green tea status and sex. In 24-h urine collection, the comparison between green tea drinkers and non-drinkers showed no difference for stone risk factors such as urine oxalate, calcium, urate, citrate, and pH. In females, the prevalence of calcium oxalate dihydrate (COD) and calcium phosphate stones, assessed by infrared analysis (IRS) was similar between green tea drinkers and non-drinkers, whereas prevalence of calcium oxalate monohydrate (COM) stones was strikingly decreased in green tea drinkers (0% vs. 42%, p = 0.04), with data in accordance with a decreased oxalate supersaturation index. In males, stone composition and supersaturation indexes were similar between the two groups. Our data show no evidence for increased stone risk factors or oxalate-dependent stones in daily green tea drinkers.

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Effect of different brewing times on soluble oxalate content of loose-packed black teas and tea bags

Cited by 11 publications

References 23 publications

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian–Vegan Diets

Risk of Kidney Stones: Influence of Dietary Factors, Dietary Patterns, and Vegetarian–Vegan Diets

Dietary Oxalate Intake and Kidney Outcomes

Daily Green Tea Infusions in Hypercalciuric Renal Stone Patients: No Evidence for Increased Stone Risk Factors or Oxalate-Dependent Stones

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