Lemon verbena (Lippia citriodora Kunth) from the Verbenaceae family is a medicinal plant with various traditional uses. (1)
This review has been done to assess the effect of lemon verbena on blood glucose, blood lipids, obesity, obesity-related diseases, and also to evaluate it as a natural supplement for improvement of muscle function of athletes.
1. Regulating Blood Glucose and Lipid Levels:
In 2020, a study was aimed to investigate the antidiabetic and antihyperlipidemic effects of lemon verbena extract on diabetic rats. For this purpose, the researchers fed normal and diabetic rats by the leaves aqueous extract of Lippia citriodora (LCLAE) (100 mg/kg) for 15 days. Then, they checked the whole glucose utilization and liver architecture and also assessed in vitro antioxidant activity of LCLAE.
The results showed that LCLAE lowered blood glucose and lipid levels in both groups. Furthermore, it improved the liver structure and exhibited antioxidant activity.
In conclusion, this study revealed the hypoglycemic and antihyperlipidemic effects of LCLAE in rats. (1)
2. Promoting Weight Loss:
Obesity, marked by a dysfunction in the adipose tissue and a subclinical inflammatory state, leads to insulin resistance and increased risk of cardiovascular diseases. It is also associated with intestinal dysbiosis contributing to inflammation development. (2) (An “imbalance” in the gut microbial community caused by changes in community members or in the relative abundance of microbes is called Dysbiosis.) (3)
Lippia citriodora contains high levels of polyphenol propanoids and has been shown to be helpful for obesity. While most therapeutic approaches have failed to improve obesity-induced metabolic disturbances, plant-polyphenols have shown the capacity to do it in both cell and animal models.
First Study:
In 2019, a double-blind, placebo-controlled, and randomized trial was conducted on 56 obese/overweight subjects for two months. The study was aimed to evaluate a dietary supplement containing 500 mg of a combination of polyphenolic extracts from Lippia citriodora L. and Hibiscus sabdariffa L. (LC-HS) in the context of an equilibrated isocaloric diet.
The researchers observed that in comparison with the control group (the subjects who did not use LC-HS), the consumption of the LC-HS polyphenols significantly improved body weight, abdominal circumference, body fat %, heart rate, and systolic blood pressure in overweight LC-HS participants. These changes were more modest in obese subjects.
Accordingly, consumption of 500 mg/day of LC-HS extracts enriched in polyphenols for two months, in the context of an isocaloric diet, by overweight subjects decreased symptoms associated with obesity-related diseases.. (9)
Second Study:
In 2020, a study was done to investigate an extract of LCE in a model of metabolic syndrome in mice. The researchers focused on the extract's effects on metabolic tissues, endothelial dysfunction, and microbiome. (2)
(“Endothelial dysfunction” is a type of non-obstructive coronary artery disease (CAD) in which there are no heart artery blockages, but the large blood vessels on the heart's surface constrict (narrow) instead of dilating (opening).) (4)
(The human microbiota is a wide range of bacteria, viruses, fungi, and other single-celled animals living in the body. All of the genes inside these microbial cells are called the microbiome. In humans, the intestinal microbiota provides energy, nutrients, and immunological protection. So, it plays an important role in the maintenance of host health.) (5)
In this study, the researchers fed the mice with a high-fat diet (HFD) for six weeks and treated them with LCE (1, 10, and 25 mg/kg a day). Then, they checked glucose and lipid metabolism and identified the inflammatory state in the metabolic tissues, the intestinal microbiota composition, and the endothelium‐dependent vasodilator response to acetylcholine.
Based on the results, LCE was reported to decrease fat accumulation and improve plasma glycemic and lipid profiles, the inflammatory process, and vascular dysfunction. Besides, in comparison with untreated HFD mice, LCE reduced intestinal dysbiosis and the Firmicutes/Bacteroidetes ratio and increased Akkermansia abundance. (2)
(In general terms, the Firmicutes/Bacteroidetes ratio in human gut microbiota composition is really notable (6); an increased ratio of Firmicutes/Bacteroidetes was observed in the gut microbiota in the obese human population. (7)
Akkermansia muciniphila is associated with a metabolically healthy status, and its abundance is lower in severe obesity. (8) )
The researchers concluded that the synergic effects of the LCE bioactive compounds might bring about its antiobesity therapeutic properties. (2)
3. Improving muscles and joints function/ Anti-inflammatory:
Exhaustive exercise causes muscle damage, oxidative stress, and inflammation leading to muscle fatigue and soreness. Lemon verbena leaves, regularly consumed as a tea or refreshing beverage, possess antioxidant and anti-inflammatory properties.
In 2018, a randomized, placebo-controlled, and double-blind study was carried out to assess the effects of a lemon verbena extract on muscle strength and recovery after exhaustive exercise in comparison to a placebo product. Lemon verbena extract was obtained by water extraction out of organic dried lemon verbena leaves. The extract and the placebo were both formulated in capsules of the same size and color.
Forty-four healthy males and females aged 22–50 years old and active in sports were randomly assigned to lemon verbena extract or placebo (400 mg/per day). The researchers asked the participants to take two capsules every morning 10 days before the exhaustive exercise test, on the test day, and four days after the test.
Then, they evaluated muscle strength, muscle damage (CK), oxidative stress (GPx), inflammation (IL6), and volunteer-reported muscle soreness intensity before and after the exercise test.
(Creatine kinase (CK) is a biomarker for muscle damage typically increased after an intense exercise. Exercise training is accompanied by oxidative stress via production of reactive oxygen species (ROS) and modulating the endogenous antioxidant defense system, including Glutathione peroxidase (GPx).)
The lemon verbena group experienced not only less muscle damage but also faster and full recovery. Full recovery following exercise-induced muscle damage generally needs two to seven days. In the lemon verbena group, complete recovery was reached after 48 hours only.
Compared to the placebo group, the lemon verbena group had:
- remarkably less exercise-related loss of muscle strength.
- improved glutathione peroxidase activity (the endogenous antioxidant defense system) by trend.
- less movement-induced pain by trend.
Creatine kinase and Interleukin-6 (IL-6) were almost the same in both groups.
The study reveals that ingestion of a 400 mg/day lemon verbena extract leads to significantly less muscle strength loss in healthy and moderately active adults. Its influences by trend on muscle soreness and antioxidative capacity emphasize this extract's potential for expediting recovery after an exhaustive exercise. (10)
1- https://pubmed.ncbi.nlm.nih.gov/
2- https://onlinelibrary.wiley.com/
3- https://www.sciencedirect.com/
4- https://stanfordhealthcare.org/
5- https://www.medicalnewstoday.com/
6- https://bmcmicrobiol.biomedcentral.com/
7- https://help.ezbiocloud.net/
8- https://journals.physiology.org/
9- https://www.nature.com/
10- https://www.researchgate.net/
