Effects of Green Tea and Coffee Polyphenols on Cardiometabolic Function in Women with Polycystic Ovary Syndrome

Abstract

Green tea (catechins, GTC) and coffee polyphenols (chlorogenic acids, CGA) have been associated with reduced diabetes and cardiovascular risk. However, detailed investigations in at risk populations are needed to corroborate their efficacy and understand the underlying mechanisms. This study aimed to evaluate the effects of a combined supplementation of GTC and CGA on insulin sensitivity (SI), nitric oxide (NO) production and cardiometabolic risk factors in women with polycystic ovary syndrome (PCOS), a condition characterized by insulin resistance, endothelial dysfunction and increased cardiometabolic risk. In a 16‐week, single‐blind, unilateral crossover trial, 12 PCOS women (mean ± SD: age, 28 ± 10 y; BMI, 35 ± 7 kg/m2; fasting insulin, 97 ± 52 pmol/L) underwent 8 weeks of placebo treatment followed by 8 weeks of active treatment (tablets providing 2093 mg GTC and 220 mg CGA/day). At baseline, post‐placebo and post‐active treatments participants undertook glucose tolerance and oral nitrate tests for isotopic assessment of SI and NO production and additional cardiometabolic risk factors were measured. The polyphenol intervention did not improve SI and NO production, but it was associated with reduced waist circumference (MD: 2.4 cm; P = 0.02), altered eicosanoid profile and non‐significant trends for reductions in diastolic blood pressure, total and LDL cholesterol. Combined intake of GTC and CGA may modulate eicosanoid pathways, thereby reducing inflammation and abdominal adiposity. These changes may prove cardioprotective in at risk populations, in longer term intervention studies. 
 [MRC UK]