Green tea, a beverage steeped in history and celebrated for its potential health benefits, has garnered significant attention as a "superfood" in recent years. Originating from the Camellia sinensis plant, the same source as black tea, green tea distinguishes itself through its unique processing method that preserves its healthful antioxidants. This article delves into the multifaceted benefits of green tea, exploring its potential impact on various aspects of health, from cardiovascular well-being to cognitive function and weight management.
What sets green tea apart?
The key difference between green and black tea lies in the oxidation process. Green tea leaves undergo minimal oxidation, typically involving steaming, pan-frying, or heat drying shortly after harvesting. This process helps retain the plant's beneficial antioxidants, particularly polyphenols, which are linked to a reduced risk of cardiovascular disease. In contrast, black tea leaves are fully oxidized, resulting in a darker color and a more robust flavor.
Health benefits of green tea
Fighting cancer-causing inflammation
Green tea leaves are rich in flavonoids called catechins, particularly epigallocatechin-3 gallate (EGCG), a potent antioxidant with anti-inflammatory properties. These antioxidants combat inflammation caused by cell-damaging free radicals. While some research suggests that milk may reduce the antioxidant benefits of tea, enjoying green tea without milk is generally encouraged. Studies suggest that the anti-inflammatory properties of green tea may lower the risk of certain cancers and cancer recurrence.
Preventing stroke and heart disease
Studies indicate that green tea can lower cholesterol levels, potentially reducing the risk of heart disease, heart attacks, and stroke. High cholesterol can clog arteries, a major risk factor for heart problems. A study found that consuming two to four cups of green tea daily could lower stroke risk by as much as 24%. Antioxidants in green tea, including EGCG and other catechins, can lower "bad" cholesterol (LDL) and total cholesterol. Additionally, green tea contains heart-protecting flavonoids like quercetin and theaflavins, which promote healthy blood flow by opening and relaxing blood vessels.
Boosting brain health
Amino acids, such as L-theanine, and catechins, like EGCG, in green tea may offer brain-protective benefits. Studies have shown that regular green tea drinkers may have a lower risk of memory loss and cognitive decline. Green tea may also decrease certain molecules (biomarkers) linked to Alzheimer's disease.
Read also: The Hoxsey Diet
Strengthening bones
Research suggests that the polyphenols in green tea, including EGCG, can strengthen bones by improving bone density and reducing age-related bone loss. A meta-analysis of 17 studies found that drinking tea could protect against osteoporosis and broken bones.
Lowering blood sugar
Green tea may benefit individuals with Type 2 diabetes or those at risk of developing it. Research suggests that L-theanine in green tea may help prevent diabetes, while other studies indicate that green tea improves blood sugar (glucose) levels and insulin sensitivity. A study in Japan found that drinking four or more cups of green tea daily could lower the risk of dying from Type 2 diabetes complications by as much as 40%.
Protecting the prostate
Laboratory studies suggest that green tea polyphenols, especially EGCG, may prevent benign prostatic hyperplasia (BPH), a condition that causes an enlarged prostate. EGCG may stop prostate cells from multiplying and enlarging the gland, although human research is needed to confirm these findings.
Easing stress and anxiety
L-theanine in green tea can help ease stress and anxiety. Research indicates that L-theanine can reduce the stimulating effects of caffeine and improve cognitive function, mood, and concentration.
Providing a gentle energy boost
With approximately 30 milligrams of caffeine per 8-ounce cup, green tea offers a moderate energy boost without the high stimulant levels found in coffee. This makes it a suitable choice for those looking to reduce their caffeine intake.
Read also: Walnut Keto Guide
Promoting youthful skin
The antioxidant properties of green tea may contribute to healthier, younger-looking skin. Studies have shown that green tea polyphenols can increase collagen and elasticity in the skin, helping to combat wrinkles and other signs of aging. Green tea extract applied to the skin may also help prevent acne and spot-treat pimples.
Aiding weight loss
Some research suggests that catechins in green tea can break down body fat and boost metabolism, potentially aiding weight loss. A study in Korea found that women who drank four or more cups of green tea daily had less abdominal fat than their male counterparts. Green tea may also help manage appetite and blood sugar levels, contributing to weight management when consumed regularly.
How much green tea should you drink?
While there's no definitive answer, most people can safely drink up to eight cups of green tea daily, with pregnant or nursing individuals advised to limit their intake to six cups. The appropriate amount depends on individual sensitivity to caffeine. For matcha, it's recommended to consume no more than 2-4 teaspoons per day due to its higher concentration of nutrients and antioxidants.
How to best enjoy green tea
Green tea offers a lighter flavor and less bitterness than black tea due to its quick harvesting and processing. Described as sweet, earthy, or nutty, it can be enjoyed in various ways. Matcha, a frothy beverage made from finely ground green tea leaves, provides an even stronger concentration of nutrients and antioxidants, although its bolder taste and chalkier texture may not appeal to everyone.
Green tea and weight loss: Unpacking the evidence
Green tea contains compounds that may promote weight loss by enhancing fat oxidation and boosting metabolism, including catechins and caffeine. These compounds may increase daily calorie burning (energy expenditure) and boost fat oxidation, metabolism, and thermogenesis.
Read also: Weight Loss with Low-FODMAP
The role of catechins and EGCG
Some research suggests that EGCG may help reduce markers associated with obesity, such as total body weight, body fat percentage, waist-to-hip ratio, waist circumference, and body mass index (BMI). Catechins in green tea, especially EGCG, may aid fat oxidation and lipolysis by boosting the effects of fat-burning hormones like catecholamine. EGCG may also inhibit an enzyme that breaks down norepinephrine, promoting fat breakdown.
Green tea and fat oxidation
Green tea may help fat cells break down more fat, which is released into the bloodstream for use as energy. Caffeine may also help boost fat metabolism, especially when consumed at rest.
Green tea supplements and extracts
Many weight loss and fat-burning supplements contain green tea. A review also found that taking green tea supplements and engaging in regular exercise may help with weight management. However, the researchers concluded that green tea supplementation had no impact on lipid markers like cholesterol and triglyceride levels.
Green tea and resting metabolic rate (RMR)
Some studies have found that green tea extract may help boost resting metabolic rate (RMR), potentially increasing calorie burning at rest. However, not all studies have shown positive results, and more research is needed.
Green tea and appetite
Studies show conflicting results on the effects of green tea on appetite. A review concluded that green tea extract supplementation had no significant effects on appetite-regulating hormones, leptin and ghrelin. However, the authors did find that green tea extract helped reduce body fat percentage, BMI, and malondialdehyde, a marker of oxidative stress.
Green tea and visceral fat
Some human and animal studies have found that green tea extracts and catechins may contribute to losing visceral fat, which surrounds the organs and is associated with chronic conditions like obesity, type 2 diabetes, and heart disease.
How much green tea for weight loss?
A review found that consuming at least 500 milligrams (mg) of green tea extract daily for 12 weeks helped reduce body weight and BMI, suggesting that green tea may promote weight loss when combined with a balanced diet and regular exercise.
Exploring green tea types and their benefits
Limited research has compared the weight loss effects of different types of green tea. Drinking regular green tea or taking green tea extracts may offer some benefits.
Additional potential health benefits
Beyond weight management, green tea has been studied for its potential impact on other health conditions:
Cancer prevention
In countries with high green tea consumption, some cancer rates tend to be lower. The topical application of green tea polyphenol extracts may protect the skin from UVB radiation. Green tea catechins may have positive impacts on breast, colorectal, esophageal, lung, prostate, and liver cancers.
Anti-inflammatory properties
Green tea exhibits anti-inflammatory effects, with studies showing that tea extract solutions promote anti-inflammatory responses when applied topically and improve skin microcirculation.
Cholesterol reduction
Green tea consumption can significantly lower total cholesterol and low-density lipoprotein cholesterol in people with moderate weight, overweight, or obesity.
Cardiovascular health
Drinking green tea may reduce the risk of death after a stroke or heart attack, with moderate consumption associated with a lower risk of stroke.
Diabetes management
Studies concerning the relationship between green tea and diabetes have been inconsistent. Some suggest a lower risk of type 2 diabetes in green tea drinkers, while others indicate a higher risk.
Cognitive function
Regular green tea consumption may be associated with better cognitive function, particularly executive function and memory. Certain amino acids in green tea may have an anti-stress effect that helps slow brain aging.
Other potential benefits
Green tea extract has been approved by the FDA as a prescription treatment option for genital warts. Green tea phytochemicals may reduce skin aging, prevent tooth decay, improve osteoarthritis pain, have an antiallergic effect, and promote wound healing.
Nutritional profile and forms of green tea
Unsweetened brewed green tea contains fewer than 3 calories per cup. It contains approximately 29 milligrams (mg) of caffeine per 8-ounce cup, along with polyphenols, including catechins like EGCG. Green tea is available in various forms, including bottled drinks, tea bags, loose leaf tea, instant powder, and supplements.
Potential side effects and risks
While green tea is generally safe for adults, it's important to be aware of potential side effects:
Caffeine sensitivity
Individuals with caffeine sensitivities may experience insomnia, anxiety, irritability, nausea, or an upset stomach.
Liver damage
High concentrations of green tea extract may adversely affect liver health in rare cases.
Interactions with other stimulants
Consuming green tea with stimulant drugs may increase blood pressure and heart rate.
Supplement safety
The FDA does not regulate green tea supplements, so they may contain other substances that are unsafe or have unproven health benefits.
Green tea and iron absorption
Green tea can reduce iron absorption, so it's best to take iron supplements separately. It may also interact with some medications, including those used to treat high blood pressure, heart problems, and osteoporosis.
Green tea with ginger: A powerful combination
Combining green tea with ginger may offer additional health benefits. Ginger has been used to treat digestive problems, arthritis, asthma, diabetes, and menstrual symptoms. Studies support its ability to ease nausea and vomiting and lower inflammation and pain.
Weight loss
Some studies suggest that green tea and ginger may aid weight loss.
Menstrual health
Green tea with or without ginger is sometimes used to ease painful periods and may help with conditions such as endometriosis, fibroids, and polycystic ovarian syndrome (PCOS).
Aging and cognitive function
Green tea has been tied to a lower risk of cognitive decline, with studies suggesting it could ease inflammation linked to depression, support weight control, and improve testosterone levels in middle-aged and older men.
Precautions and considerations
Too much ginger can cause diarrhea, heartburn, and even an irregular heartbeat. In rare cases, green tea extract may cause liver problems. It's essential to consult with a doctor before taking supplements and to follow dosing instructions carefully.
Making green tea with ginger and lemon
To make green tea with ginger and lemon, use these ingredients:
- 3 cups filtered water
- 4 green tea bags
- 1 tablespoon ginger root, peeled and thinly sliced
- 2 tablespoons fresh lemon juice, plus 4 slices for garnish
- 2 tablespoons honey
Then follow these directions:
- Bring water to just below boiling point. Remove from heat.
- Place tea bags in a pitcher, and add ginger slices. Pour hot water over the tea bags. Let them steep for 8-10 minutes. Remove the tea bags.
- Stir in lemon juice and honey.
- Serve warm or iced.