Is the world’s most widely used psychoactive stimulant drug. Caffeine causes stimulation of the central nervous system, increases focus and reduces general drowsiness.
The main mechanism of caffeine is that it is believed to block an inhibitory neurotransmitter called Adenosine leading to a net stimulant effect. This way, it actually increases the firing of neurons and the concentration of neurotransmitters like dopamine and norepinephrine (1, 2).
Adenosine is believe to increase in the brain throughout the day, building up a kind of a “sleep pressure.” The more Adenosine, the greater the tendency to feel tired and eventually fall asleep. Caffeine partly reverses this effect (3).
Caffeine has been intensively studied before and consistently leads to improvements in various aspects of brain function, including improved mood, vigilance, reaction time and memory (4).
Relaxes smooth muscles in the airway, making breathing easier while also stimulating both the rate and force of contraction of the heart.
Can also stimulate the heart, but it does have a mild diuretic effect and improves blood flow around the body, leading to a net reduction in blood pressure.
These all belong to a class of organic compounds called Xanthines.
Guayusa also has the amino acid L-theanine, which is able to cross the blood-brain barrier (5). It increases the activity of the inhibitory neurotransmitter GABA, which has anti-anxiety effects. It also increases dopamine and the production of alpha waves in the brain (6, 7, 8).
It increases the generation of certain brain waves called Alpha waves – these are associated with what you might consider an alert yet relaxed state. This is perhaps the main reason for the different, milder “buzz” that tea generates compared to coffee (9).
It may affect neurotransmitters in the brain such as GABA and Dopamine (10).
Some studies have suggested that L-Theanine, especially when combined with Caffeine, can improve attention and general cognitive function. Studies show that caffeine and L-theanine can have synergistic effects. The combination of the two is particularly potent at improving brain function (11, 12).
All of these components function as powerful antioxidants (13). It also contains Epigallocatechin Gallate (EGCG), which has been studied to treat various diseases and may be one of the main reasons Guayusa is thought of having such powerful medicinal properties. Catechins have other biological effects as well.
Some studies of green tea consumption show that they can kill bacteria and inhibit viruses like the influenza virus, potentially lowering your risk of infections. Guayusa has more catechins than green tea. (14, 15, 16, 17).
Streptococcus mutans is the primary harmful bacteria in the mouth. It causes plaque formation and is a leading contributor to cavities and tooth decay.
Studies show that the catechins in green tea can inhibit the growth of streptococcus mutans. Green tea consumption is associated with improved dental health and a lower risk of caries (18, 19, 20, 21, 22, 23).
Another awesome benefit of green tea… multiple studies show that it can reduce bad breath (24, 25).
Potential Benefits of Guayusa
Caffeine itself has also been shown to improve physical performance by mobilizing fatty acids from the fat tissues and making them available for use as energy (26, 27). In two separate review studies, caffeine has been shown to increase physical performance by 11-12%, on average (28, 29).
Antioxidant effect on cancer
It is well known that oxidative damage contributes to the development of cancer and that antioxidants can have a protective effect (30).
Many of the studies of antioxidant action relate to consumption of Green tea. Guayusa is an excellent source of powerful antioxidants, DOUBLE the amount found in good quality green tea so it makes perfect sense that it could reduce your risk of cancer, which it appears to do with green tea:
Breast cancer: A meta-analysis of observational studies found that whomen who drank the most green tea had a 22% lower risk of developing breast cancer, the most common cancer in women (31).
Prostate cancer: One study found that men drinking green tea had a 48% lower risk of developing prostate cancer, which is the most common cancer in men (32).
Colorectal cancer: A study of 69,710 Chinese women found that green tea drinkers had a 57% lower risk of colorectal cancer (33).
Multiple other observational studies show that green tea drinkers are significantly less likely to get various types of cancer (34, 35, 36).
Blood Sugar & Diabetes
Studies show that green tea can improve insulin sensitivity and reduce blood sugar levels (43). There have been few published studies on the possible medical benefits of guayusa, but one study has shown that ingesting guayusa helped reduce hyperglycemia and other side-effects of Type 1 diabetes in an animal model. (44).
One study in Japanese individuals found that those who drank the most green tea had a 42% lower risk of developing type II diabetes (44).
According to a review of 7 studies with a total of 286,701 individuals, green tea drinkers had an 18% lower risk of becoming diabetic (45).
The details below are not intended to provide medical advice, treatment or diagnosis – they are is purely a look at what bioactive components are inside a cup of Guayusa and related studies as to their effects. Many information sources above compiled by http://authoritynutrition.com/