The randomised double-blind placebo control crossover study, funded by Gencor Pacific Ltd., provided either a placebo or 450mg of dried Jiaogulan leaf extract (Gynostemma pentaphyllum) to 16 healthy untrained young males.
After supplementing participants with four weeks, the authors from Australia and China concluded: “G.pentaphyllum supplementation improved mitochondrial respiration, lowered muscle total Acetyl-CoA carboxylase (ACC), and plasma leptin levels at rest and improved performance in a 20 km time trial (TT) by approximately 4% in healthy males.”
G. pentaphyllum is a creeping perennial herb from the Cucurbitacea family commonly found in South and East Asia, and has reportedly been used as a food and supplemental product for more than 500 years.
It contains bioactive components such as saponin, flavonoids, and sterols, and has been suggested to be beneficial in the treatment of various health conditions, such as obesity, hyperlipidemia, inflammation, and tumour suppression.
Previous studies have shown that supplementation with G. pentaphyllum significantly reduced total abdominal fat area, subcutaneous fat, and waist circumference.
G. pentaphyllum has also been shown to increase the phosphorylation of AMP-activated protein kinase (AMPK) - an intracellular energy sensor that regulates metabolic homoeostasis - in L6 myotube cells and enhance glucose uptake.
AMPK enhances adenosine triphosphate (ATP) production and is activated during heat stress, excessive training, hypoxia, and starvation.
While research remains limited, one previous mouse study found that the activation of AMPK increased exercise performance.
Mitochondria are a primary source of ATP production in the cell. Therefore, the authors of the current study suggest that any reduction in ATP synthesis in mitochondria may induce AMPK activation.
It was previously observed in rats under energy stress that AMPK was activated, increasing mitochondrial biogenesis in skeletal muscles, and the authors hypothesise that any substance that activates AMPK may act as an exercise simulator to enhance mitochondrial biogenesis in muscles.
Yet according to the authors, besides the positive impact on AMPK and mitochondria in cellular models, no studies have investigated the effects of G. pentaphyllum on muscle AMPK expression and mitochondrial function in healthy humans.
Therefore, they aimed to evaluate the effects of G. pentaphyllum supplementation on exercise performance, AMPK activity and signalling, and mitochondrial function in healthy males.
16 healthy untrained males (aged 18–35 years) with BMIs less than 25 kg/m2 were recruited via social media and sporting organisations, and provided placebo or 450 mg of G. pentaphyllum dried leaf extract equivalent to 2.25 g of dry leaf per day.
The effects of supplementation or placebo on aerobic exercise performance were investigated using two different measures; steady-state and time to exhaustion (TtE) tests, and a 20 km TT.
Following four-week supplementation with G. pentaphyllum, participants were found to have a significantly lower leptin and blood glucose level, and improved time trial TT performance over 20 km, which corresponded with a higher muscle oxygen flux compared to placebo.
Additionally, muscle AMPK Thr172 phosphorylation significantly increased after 60 minutes of exercise following G. pentaphyllum supplementation.
AMPK Thr172 phosphorylation levels relative to total AMPK increased earlier following exercise with G. pentaphyllum compared to placebo. Total ACC-α was lower following G. pentaphyllum supplementation compared to placebo.
The authors conclude: “G. pentaphyllum supplementation increased mRNA expression of P13K and Forkhead box protein O1 (FOXO1A) following 30 min of exercise, which was earlier than the changes observed at 60 min following placebo.”
They note that P13K may increase insulin induced glucose uptake in muscles, and increase expression of FOXO1A, stimulating the expression of lipoprotein lipase in muscle cells, therefore enhancing fatty acid availability to muscles.
They summarise: “These changes, along with the changes observed in resting and exercise blood glucose levels, improvements in mitochondrial oxidative capacity and AMPK pathways, suggest that G. pentaphyllum supplementation may affect skeletal muscle metabolism via multiple mechanisms.”
The authors do however note some limitations, explaining that the study only recruited healthy males, and “future studies are required to further understand the effects of G. pentaphyllum supplementation on skeletal muscle and exercise performance, along with leptin and adiponectin level, in healthy trained individuals as well as individuals with obesity and diabetes.”
Gynostemma Pentaphyllum Increases Exercise Performance and Alters Mitochondrial Respiration and AMPK in Healthy Males
Authors: Deepti Nayyar, Xu Yan, Guoqin Xi, Min Shi, Andrew P. Garnham, Michael L. Mathai, and Andrew J. McAinch.