Often referred to as elephant grass or napiergrass, Pennisetum purpureum Schumach is extensively cultivated in Taiwan, primarily serving as feed for livestock. Recently, however, this resilient plant has gained attention for its inclusion in health beverages, attributed to its antioxidant properties.
A groundbreaking study published in the International Journal of Medical Sciences (IJMS) represents the first effort to assess the efficacy of this plant in combating sarcopenia, a condition characterized by muscle decline. The research involved collaboration between scholars from Taipei Medical University, Tungnan University, and Hosei University from Japan.
The study recruited 35 participants, who were randomized to receive either a 300mg capsule of Pennisetum purpureum Schumach or a placebo three times a day for a duration of 12 weeks.
The extract utilized in the study was sourced locally from Hualien County and produced by Natural Keeper Enterprise Co., Ltd.
To evaluate the impact of the plant extract, researchers conducted a comprehensive analysis, including anthropometric measurements, body composition assessments, blood pressure monitoring, hormone profiling, liver and kidney function evaluations, physical performance tests, and a dietary record over three days. These assessments were conducted at weeks eight and 12 of the study.
Improvement in Hand Grip Strength
The results revealed a notable increase in hand grip strength in participants receiving the extract after eight and twelve weeks of supplementation compared to initial measurements.
Specifically, grip strength in the intervention group rose from a baseline of 18.74 ± 5.61 kg to 22.48 ± 5.61 kg at week eight, and further increased to 23.51 ± 6.38 kg by week 12.
In contrast, there were no significant changes in grip strength within the placebo group over the 12-week period.
Despite the improvements in grip strength, supplementation with Pennisetum purpureum Schumach did not yield significant enhancements in other measures of physical function, such as the 10-meter walk test.
“These findings suggest that ongoing consumption of Pennisetum purpureum Schumach at a daily dosage of three times 300 mg over 12 weeks positively affects grip strength, but does not enhance performance in the 10-meter walk test,” noted the researchers.
Possible explanations for the observed improvement in grip strength may include the plant’s antioxidant capabilities.
The researchers pointed out that oxidative stress negatively influences skeletal muscle performance by disrupting mitochondrial function, accelerating protein breakdown, and inhibiting anabolic signaling.
“Bioactive constituents in Pennisetum purpureum Schumach, such as polyphenols and anthocyanins, may alleviate oxidative stress by neutralizing free radicals and enhancing redox homeostasis, potentially supporting testosterone levels since oxidative stress can negatively affect Leydig cell steroidogenesis,” they explained. “This sequential process—moving from antioxidant defense to hormonal modulation and consequently improved neuromuscular performance—provides a logical basis for the observed results.”
However, they cautioned that this proposed mechanism is still speculative and requires further research, as the study did not directly measure oxidative stress markers, mitochondrial function, or neuromuscular activation.
No Significant Changes in Anthropometric Measurements
Additionally, supplementation with Pennisetum purpureum Schumach did not result in significant changes in anthropometric measurements, such as upper arm circumference.
Conversely, while both the intervention and placebo groups experienced an increase in body mass index and thigh circumference, this indicates that such changes were not attributable to the supplementation of Pennisetum purpureum Schumach.
Slight Increase in Testosterone Levels
The intake of the plant extract was associated with a slight upward trend in testosterone levels among male participants exhibiting low muscle mass.
However, overall hormonal levels, including testosterone, remained largely unchanged in both the intervention and placebo groups.
Furthermore, the supplement did not provoke significant variations in liver and kidney function, suggesting that it may represent a safe, plant-based strategy for enhancing muscle strength in individuals showing early signs of muscle decline.
The researchers recommended that future studies should investigate the supplement’s synergistic effects when paired with resistance training, as well as its effectiveness in larger and more diverse populations, including older adults and those with chronic health conditions.
Source: International Journal of Medical Sciences, 23(3), 963-971. doi: 10.7150/ijms.124224. “Pennisetum purpureum Schumach Supplementation Enhances Grip Strength in Adults with Low Muscle Mass: A Randomized Controlled Trial.” Authors: Huang, S.W. et al.
