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Green Tea Leaf Extract

Green Tea Leaf Extract

Green tea is made from the leaves and leaf buds of Camellia sinensis, a species of evergreen shrubs that is native to Southeast Asia. Aside from being one of the most consumed beverages in the world due to its nutty, bittersweet, or herbaceous flavor, green tea is also used in the treatment of several medical conditions such as high cholesterol, heart disease, hypertension, stroke, cognitive dysfunction, and mood disorders. The leaf extract of Camellia sinensis can also be taken in the form of capsule, liquid, or powder.

Overall Health Benefits of Green Tea Leaf Extract

  • Improves symptoms of diabetes [1-8]
  • Lowers blood pressure [9-15]
  • Boosts sexual vitality and improves sexual health [16-24]
  • Speeds up wound healing [25-27]
  • Prevents and treats nerve damage [28-30]
  • Lowers risk of stroke [31-37]
  • Lowers risk of cardiovascular disease [36-44]
  • Prevents Alzheimer’s disease (AD) and boosts cognitive health [45-52]
  • Prevents cancer [53-104]
  • Wards off depression and improves mood [105-109]

How Green Tea Leaf Extract Works

Green tea contains 2-4% caffeine that can boost thinking and alertness, increase urine output, and improve overall mood. It also contains various beneficial substances such as antioxidants, polyphenols, flavonoids, vitamin C, vitamin B2, folic acid, beta-carotene, vitamin E, theanine, saponins, fluorine, calcium, potassium, phosphorus, and manganese.

Proven Health Benefits of Green Tea Leaf Extract

Improves Symptoms of Diabetes

Several lines of clinical evidence show that green tea leaf extract has anti-diabetic properties:

  1. A study found that long-term consumption of green tea leaf extract is beneficial against type 2 diabetes. [1]
  2. A study reported that epigallocatechin gallate (EGCG) from green tea leaf has blood sugar-lowering properties. [2]
  3. In diabetic rats, green tea leaf extract notably decreased blood sugar levels. [3]
  4. A study found that the anti-diabetic properties of green tea leaf extract can be attributed to the amount of polyphenols and caffeine it contains. [4]
  5. A 2019 study reported that green tea leaf extract can help protect against diabetes mellitus and its complications via several mechanisms such as enhancing insulin action, preventing insulin resistance, activating signaling pathways involved in insulin secretion, reducing the levels of free radicals, and decreasing inflammatory substances. [5]
  6. A study also found that green tea leaf extract reduces blood sugar levels via its inhibitory effect against α-amylase and α-glucosidase in the digestive tract. [6]
  7. A study also reported that green tea leaf extract can help normalize blood sugar levels by improving fat metabolism and preventing obesity. [7]
  8. In diabetic patients, consumption of green tea leaf extract significantly reduced fasting blood glucose and hemoglobin. [8]

Lowers Blood Pressure

Evidence suggests that green tea leaf extract has antihypertensive properties:

  1. In 13 trials comprising of a total of 1,367 subjects consumption of green tea leaf extract reduced blood pressure. [9]
  2. In 24 trials composed of 1697 subjects, consumption of green tea leaf extract significantly reduced systolic blood pressure and diastolic blood pressure. [10]
  3. In overweight and obese adults, supplementation with green tea leaf extract significantly reduced blood pressure [11]
  4. A 2019 study reported that green tea leaf extract reduces blood pressure by relaxing smooth muscle via enhancement of endothelial nitric oxide synthase activity. [12]
  5. A study found that green tea leaf extract can reduce blood pressure through its anti-obesity effects. [13]
  6. In overweight and obese women, green tea leaf extract effectively reduced blood pressure by increasing leptin and reducing low density lipoprotein. [14]
  7. A study found that tea catechins in green tea leaf extract can help reduce blood pressure. [15]

Boosts Sexual Vitality and Improves Sexual Health

Studies also show that green tea leaf extract can help treat sexual dysfunction:

  1. In adult male albino rats, supplementation with green tea leaf extract improved sexual function. [16]
  2. In male rats, consumption of green tea leaf extract led significant improvement in penile erection. [17-19]
  3. In female hypertensive patients, consumption of green tea leaf extract was positively related with sexual orgasm and sexual satisfaction [20]
  4. In rats, supplementation with green tea leaf extract improved ejaculation. [21]
  5. In aged diabetic rats, the addition of green leaf extract to sildenafil treatment significantly improved penile erection. [22]
  6. In male Wistar rats, supplementation with green tea leaf extract improved sperm parameters. [23-24]

Speeds Up Wound Healing

There’s also a good deal of evidence supporting the beneficial effects of green tea leaf extract on wound healing:

  1. In Sprague Dawley rats, green tea leaf extract reduced inflammatory cells and increased collagen (protein necessary for wound repair) at the wound site. [25]
  2. In male Wistar rats, healing duration was faster in the group treated with green tea leaf extract than those treated with normal saline. [26]
  3. A study found that green tea leaf extract can help speed up wound healing through its antimicrobial properties. [27]

Prevents and Treats Nerve Damage

Several studies found that green tea leaf extract along with its components can help improve nerve health:

  1. A study found that catechins in green tea leaf extract can be used in the prevention and treatment of neurodegenerative diseases. [28]
  2. A study demonstrated that green tea leaf extract has anti-inflammatory effects which can help speed up nerve regeneration. [29]
  3. A study found that the epigallocatechin-3-gallate from green tea leaf extract has potent analgesic effect against neuropathic pain (also known as nerve pain). [30]

Lowers Risk of Stroke

Evidence suggests that consumption of green tea leaf extract is beneficial in reducing one’s risk of stroke:

  1. In middle-aged and older Korean men, higher consumption of green tea leaf extract was associated with a lower risk of stroke. [31]
  2. An analysis of 14 studies composed of 513 804 participants found that green tea leaf extract consumption was associated with a decreased risk of stroke, particularly ischemic stroke (caused by reduced blood supply to the brain). [32]
  3. A study reported that green tea leaf extract is a practical method for stroke prevention. [33]
  4. In a rat model of stroke, researchers found that green tea leaf extract can help protect against stroke via inhibition of endoplasmic reticulum stress (a form of cell injury). [34]
  5. In men and women with a history of stroke and heart disease, green tea leaf extract consumption reduced the risk of total stroke incidence, cerebral infarction (brain tissue death), and cerebral hemorrhage (bleeding in the brain). [35]
  6. A review of 9 Japanese studies found that green tea leaf extract consumption (1-3 cups per day) reduced the incidence of stroke. [36]
  7. Data from 9 studies involving 194 965 individuals found that green tea leaf extract consumption equaling 3 cups per day can help prevent ischemic stroke. [37]

Lowers Risk of Cardiovascular Disease

Studies also show that consumption of green tea leaf extract can significantly reduce the risk of cardiovascular disease:

  1. A review of 9 Japanese studies found that consumption of 1-3 cups of green tea leaf extract daily was associated with a lower risk of cardiovascular disease. [36]
  2. In male non-smokers, green tea leaf extract reduced the risk of stroke. [38]
  3. In the middle-aged and older Chinese populations, green tea leaf extract consumption was associated with a reduced risk of coronary heart disease (CHD). [39-40]
  4. A study found that green tea leaf extract can lower the risk of cardiovascular disease by inhibiting atherogenesis (plaque formation within the arteries). [41]
  5. A review of several studies found that green tea leaf extract can improve heart health by enhancing endothelial function, reducing inflammation, and protecting cardiomyocyte (heart cells) function. [42]
  6. In a large prospective study, researchers found that daily green tea leaf extract consumption was associated with a lower risk of ischemic heart disease (IHD). [43]
  7. A study found that green tea catechins can significantly reduce the risk of cardiovascular disease. [44]

Prevents Alzheimer’s Disease (AD) and Boosts Cognitive Health

There’s also increasing evidence supporting the benefits of green tea leaf extract on AD and cognitive health:

  1. A review of several studies found that higher consumption of green tea leaf extract was associated with a lower risk of dementia and AD. [45]
  2. A review of several clinical trials also found that green tea leaf extract protects against AD by reducing the levels of amyloid beta (abnormal protein structures in the brain). [46]
  3. A study found that catechins in green tea leaf extract improves cognitive health by preventing neuronal cell dysfunction and death in the brain. [47]
  4. A study reported that regular consumption of green tea leaf extract can help improve memory and attention. [48]
  5. In older adults, consumption of green tea leaf extract more than 4 times a day reduced the risk of cognitive decline. [49]
  6. In mice, epigallocatechin-3-gallate from green tea leaf extract alleviated cognitive deficits. [50]
  7. A study also found that epigallocatechin-3-gallate from green tea leaf extract exhibited protective effects against neuronal damage and brain inflammation. [51]
  8. A study found that flavonoids in green tea leaf extract can help protect against various states of cognitive dysfunction, AD, and dementia. [52]

Prevents Cancer

The anti-cancer properties of green tea leaf extract are backed by an overwhelming body of clinical evidence:

  1. Several studies found that epigallocatechin-3-gallate from green tea leaf extract can inhibit tumor growth and metastasis. [53-54]
  2. In animal models, oral administration of green tea leaf extract resulted in significant reduction in tumor growth and invasion. [55-63]
  3. In patients who had surgical removal of polyps (abnormal tissue growths), supplementation with Japanese-size cups of green tea daily and tablets of green tea extract significantly reduced the recurrence of colorectal cancer. [64]
  4. Studies show that epigallocatechin-3-gallate from green tea leaf extract exerts its anti-cancer effects in models of lung cancer by inhibiting cancer cell proliferation and colony formation. [65-72]
  5. In human colon cancer cells and animal models of colorectal cancer, epigallocatechin-3-gallate from green tea leaf extract suppressed the growth of cancer cells by inhibiting inflammation and signaling pathways necessary for survival. [73-79]
  6. In human prostate cancer cells, epigallocatechin-3-gallate from green tea leaf extract induced programmed cell death (apoptosis), which in turn inhibited the growth and reproduction of cancer cells. [80-86]
  7. A study found that green tea leaf extract alters the metabolic reprogramming of cancer cells, which in turn inhibits the propagation of cancer stem cells. [87]
  8. Studies reported that higher green tea consumption was associated with a lower risk of breast cancer. [88-90]
  9. In premenopausal patients with stage I and II breast cancer, increased consumption of green tea was associated with decreased numbers of breast cancer cells. [91]
  10. In breast cancer patients, epigallocatechin-3-gallate potentiated the efficacy of radiation therapy. [92]
  11. Several studies also found that higher green tea leaf extract consumption was associated with a lower risk of different types of cancer. [93-100]
  12. Studies reported that the addition of green tea leaf extract in chemotherapy produces a more potent anti-cancer effect. [101-104]

Wards off Depression and Improves Mood

Consumption of green tea leaf extract can also help treat depression and improve overall mood:

  1. In healthy individuals, oral administration of green tea leaf extract for 5 weeks increased reward learning and prevented depressive symptoms. [105]
  2. A study reported that green tea leaf extract exerts its antidepressant effects by modulating the activity of the brain chemical known as dopamine. [106]
  3. In the community-dwelling older population, frequent consumption of green tea was associated with a lower prevalence of depressive symptoms. [107]
  4. In male Albino Wistar rats, oral administration of green tea leaf extract for 5 weeks produced anti-anxiety effects. [108]
  5. In adult mice, administration of green tea polyphenols for 7 days produced antidepressant-like effects. [109]

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