A Daily Shot of Green Tea Supports Heart, Brain, and Immune Health
Reviewed and Updated 2/2/23 By: Emily Parsell, RDN
Tea is one of the most commonly consumed beverages in the world, second only to water. The health benefits of tea have been widely studied, usually with an emphasis on green tea. A daily green tea shot (or cup) may contribute to both a longer lifespan and healthspan, meaning the years lived are healthier. Consumption of green tea or green tea extract has been researched for its role in promoting longevity, brain health, heart health, and a healthy weight and immune system, which we'll dive into deeper in this article.
The Basics of Green Tea
The high antioxidant and polyphenol content of green tea and its extracts can help to protect the body against inflammation and oxidative damage from free radicals, both driving forces of aging and various diseases.
Made from the leaves of the Camellia sinensis plant, green tea has health-boosting potential due to its many antioxidants and polyphenols. Most of the polyphenols are in the catechin family, which includes the most researched catechin derivative, epigallocatechin gallate (EGCG). Being water-soluble, the polyphenols are extracted from the leaves into the water when steeped and then consumed as tea.
Green tea is mainly consumed in its traditional liquid form, although some of the beneficial components, like EGCG, are also found in the supplemental form as green tea extract. Oxidative damage is a driving force behind accelerated aging and various chronic diseases.
Top 5 Benefits of Green Tea Consumption
1. Supports Longevity
The polyphenols in green tea, especially EGCG, have been shown to induce autophagy, which is the internal recycling process that removes damaged or toxic cells to improve overall health and increase longevity.
The China-PAR study, which looked at over 100,000 healthy Chinese adults over a seven-year study, found that those who habitually drank tea three times per week or more had a 1.26-year increase in life expectancy compared to those who never drank tea or drank it less than three times per week. In a sub-analysis of specific tea types, green tea consumption was associated with approximately 25% reduced risk of death from any cause, while no links were found between mortality reduction and black tea.
Another study that combined results from two cohorts, again with Chinese adults, found an inverse dose-response association between higher amounts of green tea consumption and all-cause mortality, with the greatest benefit being seen in men who had never smoked.
A similar relationship was found in Mediterranean adults, in which Greek adults over age 50 who consumed green tea had a higher “successful aging index” (SAI), which uses a scale of 10 factors related to a healthy aging process. Interestingly, black tea consumption was associated with a lower SAI, perhaps due to the lower amount of antioxidants compared to green tea.
2. Improves Brain Health
The development of neurodegenerative conditions has a strong inflammatory component. Green tea polyphenols, like EGCG, have been studied for their roles in reducing neuroinflammation.
A 2019 review found that the majority of observational studies showed a significant link between green tea consumption and a reduction in brain-related health conditions, while intervention studies in humans showed mixed results. The authors of these studies propose the mechanisms behind green tea's benefit to cognitive health include reducing inflammation, scavenging free radicals and reducing oxidative damage and inhibiting beta-amyloid plaque accumulation, which is a hallmark sign of memory loss.
3. Supports Heart Health
The catechins in green tea may benefit heart health by reducing vascular inflammation, reducing oxidative stress, and improving lipid profiles.
A randomized controlled trial of obese adults with high blood pressure found that those who received a daily supplement of green tea extract for three months had significant improvements in several cardiovascular health markers compared to the placebo group. This included reductions in blood pressure, fasting blood glucose, insulin, total cholesterol, LDL cholesterol, triglycerides, and the inflammatory markers C-reactive protein and tumor necrosis factor-alpha. The green tea extract group also had favorable increases in HDL cholesterol and total antioxidant status.
The China-PAR study discussed earlier also looked at the risk of developing heart health problems, and found that adults who were habitual tea drinkers had a reduction in both risk of and mortality from heart health conditions.
4. Aids in Weight Loss
Green tea has been studied for its impacts on weight loss and fat-burning, usually in a dose-dependent manner, with the greatest effects being seen when consumed at three to four cups per day.
This may be due to the combination of catechins and caffeine having a thermogenic effect. When this happens, the body would be more effective at burning calories and fat. These effects may be attributable more to the catechins than the caffeine. One study found that men who consumed a green tea extract (containing 50 mg caffeine and 90 mg EGCG) three times during the day had a significant increase in 24-hour energy expenditure compared to those who just consumed the 50 mg of caffeine, indicating that the EGCG provides additional thermogenic effects in this study.
Another mechanism in which green tea may promote weight loss is through the polyphenols leading to a generation of short-chain fatty acids in the gut, which can enhance fat metabolism through activation of the AMP-activated protein kinase pathway.
However, a randomized controlled trial of obese women did not see a significant difference in weight loss when consuming a green tea extract supplement, compared to placebo. Although no additional weight loss was seen, the green tea extract group did have significantly different increases in adiponectin, which is a hormone that helps with glucose metabolism and fatty acid oxidation.
5. Immune System Support
Lastly, the catechins in green tea may play a role in supporting immune health. The antiviral and antibacterial properties of EGCG could make green tea a beneficial component for fighting infections.
In cell cultures, EGCG has shown antimicrobial defense against a variety of bacteria, fungi, and viruses. The catechins are able to bind to the lipid bilayer of the bacterial cell membrane, thus damaging the bacteria's abilities to host cells or each other.
Lastly, EGCG has also been shown to increase the number of regulatory T-cells, a key component of the immune system.
How to get your daily green tea shot
You can get the health benefits of green tea in three ways:
- Traditional tea form
- Supplement form (typically EGCG)
- Matcha, a powdered form of green tea in which the whole tea leaf is consumed (rather than just the water the tea leaves are steeped in)
Supplement form is certainly the most convenient way to reap the health benefits of green tea, however it's additional research would be beneficial to understand which form best supports overall health and longevity.
Best Practices for Consumption
It's worth noting that the catechins from green tea can have low bioavailability. Consuming EGCG with a meal or in combination with dietary proteins may lower the bioavailability, while an empty stomach can increase the amount of catechins absorbed and utilized.
- The primary benefits of green tea shots come from their high amounts of antioxidants and polyphenols, specifically epigallocatechin gallate (EGCG).
- The habitual consumption of green tea has been correlated with increased longevity and healthier aging.
- Consuming either green tea extract or green tea has been linked to improvements in brain health, heart health and its biomarkers, and a supported immune system.
- Studies on green tea extract and weight loss have been mixed, although it does appear to increase energy expenditure in some research.
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- Dulloo AG, Duret C, Rohrer D, et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr. 1999;70(6):1040-1045. doi:10.1093/ajcn/70.6.1040
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- Wang X, Liu F, Li J, et al. Tea consumption and the risk of atherosclerotic cardiovascular disease and all-cause mortality: The China-PAR project [published online ahead of print, 2020 Jan 8]. Eur J Prev Cardiol. 2020;2047487319894685. doi:10.1177/2047487319894685
- Yang CS, Zhang J, Zhang L, Huang J, Wang Y. Mechanisms of body weight reduction and metabolic syndrome alleviation by tea. Mol Nutr Food Res. 2016;60(1):160-174. doi:10.1002/mnfr.201500428|
- Zhao LG, Li HL, Sun JW, et al. Green tea consumption and cause-specific mortality: Results from two prospective cohort studies in China. J Epidemiol. 2017;27(1):36-41. doi:10.1016/j.je.2016.08.004