Both green and black tea are made from the leaves of the Camellia sinensis plant (1).
The key difference between the two is that black tea is fermented and green tea is not.
To make black tea, the leaves are first rolled and then exposed to air to trigger the fermentation process. This reaction causes the leaves to turn dark brown and allows the flavours to heighten and intensify (1).
On the other hand, green tea is pan-fried to prevent fermentation and thus is much lighter in colour than black tea.
This article explores the research behind green and black tea to determine which one is healthier.
Shared Benefits of Green and Black Tea
While green and black tea differ, they may provide some of the same health benefits.
Can Protect Your Heart
Both green and black tea are rich in a group of protective antioxidants called polyphenols.
Even more specifically, they both contain flavonoids, a subgroup of polyphenols.
However, they differ in the type and amount of flavonoids. For example, green tea contains a much higher amount of epigallocatechin-3-gallate (EGCG), whereas black tea is a rich source of theaflavins (2).
The flavonoids in both green and black tea are thought to protect your heart (2, 3).
One animal study found that green and black tea were equally effective in preventing blood vessel plaque formation by 26% at the lowest dose and up to 68% at the highest dose (4).
The study also found that both types of tea helped reduce “bad” LDL cholesterol and triglycerides (4).
Two reviews, each examining over 10 quality studies, found that drinking green and black tea can lower your blood pressure as well (5, 6).
What’s more, another review of green tea studies found that people who drank 1–3 cups per day had a 19% and 36% reduced risk of heart attack and stroke respectively, compared to those who had less than one cup of green tea each day (7).
Similarly, drinking at least three cups of black tea could reduce your risk of heart disease by 11% (2).
May Boost Brain Function
Green and black tea both contain caffeine, a known stimulant.
Green tea contains less caffeine than black tea — about 35 mg of caffeine per 8-oz (230-ml) cup for green tea, compared to 39–109 mg for the same serving of black tea (2, 8, 9).
Caffeine stimulates your nervous system by blocking the inhibitory neurotransmitter adenosine. It also aids the release of mood-enhancing neurotransmitters such as dopamine and serotonin (10, 11).
As a result, caffeine can boost alertness, mood, vigilance, reaction time and short-term recall (9).
Green and black teas also contain the amino acid L-theanine, which is not present in coffee.
L-theanine is thought to cross the blood-brain barrier and trigger the release of an inhibitory neurotransmitter in the brain called gamma-aminobutyric acid (GABA), which brings about a relaxed but alert state (12, 13, 14).
At the same time, it also promotes the release of the mood-enhancing hormones dopamine and serotonin (15).
L-theanine is thought to balance the effects of caffeine. The two substances may even have a mutually positive interaction. One study found that people who ingested L-theanine and caffeine together had better attention than when either was used alone (14, 16).
In general, there is slightly more L-theanine in green tea than black tea, though the amounts can vary considerably (14).
Both green and black tea are great alternatives to coffee for people who want a mood lift without coffee’s telltale restlessness.
Summary Green and black tea contain polyphenols that have strong antioxidant effects, potentially reducing your risk of heart disease. They both have caffeine to increase alertness and focus and L-theanine, which releases stress and calms your body.
Green Tea is Rich in the Powerful Antioxidant EGCG
Green tea is an excellent source of the potent antioxidant epigallocatechin-3-gallate (EGCG).
Though green tea contains other polyphenols, such as catechin and gallic acid, EGCG is considered the most powerful and likely responsible for many of green tea’s health benefits (17).
Here’s a list of the possible benefits of EGCG in green tea:
Cancer: Test-tube studies have found that EGCG in green tea can inhibit the multiplication of cancer cells and cause cancer cell death (18, 19).
Alzheimer’s disease: EGCG may be able to reduce the harmful effects of amyloid plaques that build up in Alzheimer’s patients (20, 21).
Anti-fatigue: A study found that mice consuming an EGCG-containing drink instead of water had prolonged swimming times before exhaustion (22).
Liver protection: EGCG has been shown to reduce the development of fatty liver in mice on a high-fat diet (23, 24).
Anti-microbial: This antioxidant can cause damage to bacterial cell walls and may even reduce the transmission of some viruses (25, 26, 27).
Calming: It may interact with receptors in your brain to have a calming effect on your body (28, 29).
Though most research on the attributes of EGCG in green tea has been carried out in test-tube or animal studies, the findings lend credibility to the long-reported benefits of drinking green tea.
Summary Green tea contains EGCG, an antioxidant which in test-tube and animal studies has been shown to fight cancer and bacterial cells and protect both your brain and liver.
Black Tea Contains Beneficial Theaflavins
Theaflavins are a group of polyphenols that are unique to black tea.
They’re formed during the fermentation process and represent 3–6% of all polyphenols in black tea (30).
Theaflavins seem to offer many health benefits — all related to their antioxidant ability.
These polyphenols can protect fat cells from damage by free radicals and may support your body’s natural antioxidant production (30, 31).
What’s more, they may be responsible for protecting your heart and blood vessels.
One animal study found that theaflavins can lower the risk of plaque formation in blood vessels by reducing inflammation and increasing the availability of nitric oxide, which helps your blood vessels dilate (32).
In addition, theaflavins have been shown to significantly reduce cholesterol and blood sugar levels (30, 33).
They may even promote fat breakdown and have been recommended as a potential aid for obesity management(34).
In fact, theaflavins in black tea may have the same antioxidant capacity as polyphenols in green tea (35).
Summary Theaflavins are unique to black tea. Through their antioxidant effects, they may improve blood vessel function and support fat loss.
Which One Should You Drink?
Green and black tea have similar benefits.
While they differ in their composition of polyphenols, they may bestow the same beneficial effects on blood vessel function (36).
Most research indicates that green tea has stronger antioxidant properties than black tea, but one study found that green and black teas exhibited equally effective antioxidant capacities (35, 37, 38).
Though both contain caffeine, black tea usually has more — making green the better choice for people sensitive to this stimulant. Furthermore, green tea contains more L-theanine, an amino acid which is calming and can balance the effects of caffeine (33).
But if you’re looking for a caffeine hit that is not as strong as coffee, black tea could be a great option for you.
Keep in mind that both black and green tea contains tannins, which can bind to minerals and reduce their absorption capacity. Therefore, tea may be best consumed between meals (39).
Summary Green tea may have a slightly better antioxidant profile than black tea, but black tea is best if you want a powerful caffeine buzz.
The Bottom Line
Green and black tea have similar health benefits, including for your heart and brain.
Their antioxidant profiles differ, but while green tea may have more powerful antioxidants, scientific evidence does not strongly favour one tea over the other.
Both contain the stimulant caffeine and L-theanine, which has a calming effect.
The truth is, both are great additions to your diet.