New findings suggest a combination of these natural extracts could pave the way for cost-effective supplements to combat muscle decline and boost athletic performance.
Study: Synergistic Effects of Korean Mistletoe and Apple Peel Extracts on Muscle Strength and Endurance. Image Credit: rsooll/Shutterstock.com
In a recent study published in Nutrients, researchers explored the role of mistletoe and apple peel extracts in improving muscle health and increasing endurance.
Their findings have implications for developing cost-effective and natural supplements for muscle growth, with applications in sports addressing age-related muscle decline and muscle development in children.
Background
Muscle strength and endurance are important components of physical fitness and essential to maintaining quality of life. However, skeletal muscle mass decreases by 3-8% per decade after a person turns 30, and this deterioration accelerates after age 60.
Physical activity helps maintain muscle mass, but activity levels have declined with modern technology and automation.
Studies indicate that in 2016, less than 30% of adults around the world were unable to meet weekly physical activity guidelines, increasing their risk of developing chronic diseases. In Europe, inadequate physical activity may contribute to more deaths than obesity.
Other than physical activity, natural plant products such as curcumin (found in turmeric), catechin (found in tea), and resveratrol (found in red grapes) may also improve muscle health. Extracts from mistletoe, which is rich in bioactive compounds, have been shown to enhance muscle strength and endurance, even outperforming resveratrol.
However, mistletoe can be difficult to harvest, making it expensive, and high doses may cause adverse effects. To address these issues, researchers are exploring complementing mistletoe extract with extracts from apple peels, which are safe, nutrient-rich, and affordable while containing beneficial polyphenols.
About the study
Researchers prepared mistletoe extract by mashing and blending the fruits, stems, and leaves before stirring them for 16 hours, centrifuging the mixture, filtering it, and freeze-drying it. Apple peel extract was prepared by blending the dried apple peels before using ethanol for extraction before filtering and freeze-drying. Levels of polyphenols and flavonoids in the extracts were measured.
Animal experiments were conducted, with male mice divided into six groups. The mice were treated with different doses of creatine, mistletoe, and apple peel extracts over four weeks. Their grip strength and treadmill endurance were measured after the treatment.
Grip strength was assessed using a force gauge with five trials per mouse, and endurance tests were performed on a treadmill with increasing speeds until the mice reached exhaustion.
Then, researchers analyzed the muscle tissue to understand the genetic mechanisms related to muscle function and to analyze protein levels in the tissue.
Findings
Researchers found that apple peel extraction techniques are underdeveloped compared to mistletoe, with the best extraction results achieved using 60% ethanol for 12 hours.
Analysis of the extracts showed that apple peel extract contained 1.08 mg/mL polyphenols and 0.65 mg/mL flavonoids. Combining apple peel and mistletoe extract yielded higher polyphenol levels (2.21 mg/mL) and flavonoid levels (0.98 mg/mL).
Mice who were treated with apple peel, mistletoe, or combined extracts for four weeks showed no significant difference in calorie intake or body weight among the groups.
However, groups with combined extracts showed significant improvements in muscle strength compared to control groups. They also showed a 233-258% increase in running time compared to the control groups in the endurance tests.
Further analysis showed that mice given combined extracts also showed an increase in muscle fiber size.
Combined abstracts also significantly reduce genes related to the degradation of proteins while increasing genes linked to protein synthesis and muscle growth. Certain proteins linked to muscle growth were activated at higher rates in the combined groups.
The combined extracts also led to a significant increase in mitochondrial content and gene expression related to mitochondrial biogenesis. Mitochondrial fission-related genes were reduced, while fusion-related genes were increased.
In terms of effects on muscle fiber, mice treated with mistletoe and combined extracts showed an increase in fibers important for endurance. Mice given combined extracts at half the concentration also showed improvements in muscle fiber compared to those in the control groups.
Conclusions
The study investigated whether combining mistletoe extract and apple peel extract could improve muscle strength and endurance more effectively than using each extract individually.
Researchers found that both extracts have high polyphenol content, but apple peel contains more flavonoids. The combination of mistletoe and apple peel extracts showed synergistic effects—enhancing muscle strength and endurance better than either extract alone.
The combined group observed larger muscle fiber cross-sectional areas and higher mitochondrial density, which are linked to increased muscle protein synthesis and reduced protein degradation.
Phenolic acids in mistletoe and flavonoids in apple peel likely contributed to the observed effects. Compounds like quercetin (in apple peel) and chlorogenic acid (in mistletoe) were noted for enhancing muscle strength and reducing inflammation.
While these findings are promising, longer study durations are needed to provide more evidence. Human trials are necessary to determine the efficacy, optimal dosage, and safety of these extracts for improving muscle function.
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