1. Green Tea Extract Concurrent with an Oral Nutritional Supplement Acutely Enhances Muscle Microvascular Blood Flow without Altering Leg Glucose Uptake in Healthy Older Adults
- Author
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Jonathan N. Lund, Tanvir S. Sian, Amanda Gates, John P. Williams, Ushnah S. U. Din, Kenneth Smith, Ricardo Rueda, Suzette L. Pereira, Philip J. Atherton, Bethan E. Phillips, and Colleen S. Deane
- Subjects
Blood Glucose ,Male ,medicine.medical_specialty ,Brachial Artery ,medicine.medical_treatment ,Glucose uptake ,glucose metabolism ,Blood volume ,Green tea extract ,Article ,Internal medicine ,medicine ,blood flow ,Humans ,Insulin ,TX341-641 ,Single-Blind Method ,green tea extract ,skeletal muscle ,Muscle, Skeletal ,Aged ,Aged, 80 and over ,Leg ,Cross-Over Studies ,Nutrition and Dietetics ,Tea ,Nutrition. Foods and food supply ,business.industry ,Plant Extracts ,Microcirculation ,Area under the curve ,Venous blood ,Postprandial Period ,Healthy Volunteers ,Endocrinology ,medicine.anatomical_structure ,Postprandial ,Dietary Supplements ,Vascular resistance ,epigallocatechin-3-gallate ,Female ,business ,Food Science - Abstract
Postprandial macro- and microvascular blood flow and metabolic dysfunction manifest with advancing age, so vascular transmuting interventions are desirable. In this randomised, single-blind, placebo-controlled, crossover trial, we investigated the impact of the acute administration of green tea extract (GTE, containing ~500 mg epigallocatechin-3-gallate) versus placebo (CON), alongside an oral nutritional supplement (ONS), on muscle macro- and microvascular, cerebral macrovascular (via ultrasound) and leg glucose/insulin metabolic responses (via arterialised/venous blood samples) in twelve healthy older adults (42% male, 74 ± 1 y). GTE increased m. vastus lateralis microvascular blood volume (MBV) at 180 and 240 min after ONS (baseline: 1.0 vs. 180 min: 1.11 ± 0.02 vs. 240 min: 1.08 ± 0.04, both p <, 0.005), with MBV significantly higher than CON at 180 min (p <, 0.05). Neither the ONS nor the GTE impacted m. tibialis anterior perfusion (p >, 0.05). Leg blood flow and vascular conductance increased, and vascular resistance decreased similarly in both conditions (p <, 0.05). Small non-significant increases in brachial artery flow-mediated dilation were observed in the GTE only and middle cerebral artery blood flow did not change in response to GTE or CON (p >, 0.05). Glucose uptake increased with the GTE only (0 min: 0.03 ± 0.01 vs. 35 min: 0.11 ± 0.02 mmol/min/leg, p = 0.007), however, glucose area under the curve and insulin kinetics were similar between conditions (p >, 0.05). Acute GTE supplementation enhances MBV beyond the effects of an oral mixed meal, but this improved perfusion does not translate to increased leg muscle glucose uptake in healthy older adults.
- Published
- 2021