The effect of green tea and sour tea on blood pressure of patients with type 2 diabetes: a randomized clinical trial

J Diet Suppl. 2013 Jun;10(2):105-15. doi: 10.3109/19390211.2013.790333.


Introduction: The use of herbal medicines including different types of tea is among the different strategies for preventing and controlling the side-effects of diabetes. The aim of the present study was to compare the effect of sour tea and green tea on mildly hypertensive patients with diabetes.

Methods: The present study was a randomized clinical trial in which 100 mildly hypertensive patients with diabetes were randomly assigned into sour tea group (ST) and green tea group (GT). They were instructed to drink sour tea and green tea infusion, respectively, three times a day 2 hr after each meal for 4 weeks. The participants' blood pressure was measured at days 1, 15, and at the end of study.

Results: The systolic pressure of both groups statistically decreased at the end of the study; it decreased from 123.1 ± 15.5 to 116.8 ± 16.3 mmHg in the ST and from 119.4 ± 15.1 to 114.8 ± 15.9 mmHg in the GT. The diastolic pressure of both groups statistically decreased by the end of the study; it decreased from 79.4 ± 11.1 to 74.5 ± 9.3 mmHg in the ST and from 78.9 ± 8.3 to 75.3 ± 7.7 mmHg in the GT. The therapeutic effectiveness of tea drinking by the end of intervention was 43.5% in the ST and 39.6% in the GT compared to the beginning.

Conclusions: The present study revealed that mildly hypertensive type 2 diabetic individuals who drink three glasses of green or sour tea daily for 4 weeks show significant decreased systolic and diastolic blood pressures.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Antihypertensive Agents / therapeutic use*
  • Beverages*
  • Combined Modality Therapy
  • Diabetes Mellitus, Type 2 / complications*
  • Diabetes Mellitus, Type 2 / drug therapy
  • Diabetic Angiopathies / diet therapy*
  • Diabetic Angiopathies / physiopathology
  • Diet / ethnology
  • Female
  • Flowers / chemistry*
  • Food Handling
  • Hibiscus / chemistry*
  • Humans
  • Hypertension / complications
  • Hypertension / diet therapy*
  • Hypertension / drug therapy
  • Hypertension / physiopathology
  • Hypoglycemic Agents / therapeutic use
  • Iran
  • Male
  • Middle Aged
  • Postprandial Period
  • Severity of Illness Index
  • Tea


  • Antihypertensive Agents
  • Hypoglycemic Agents
  • Tea