Cup of black coffee surrounded by bowls of green tea leaves, cinnamon and other functional ingredients

Green Tea and Coffee: Benefits, Evidence, and Safety

by LJB Communications

Green tea coffee is coffee blended with green tea or green tea extract, which adds catechins such as EGCG and the amino acid L-theanine. Research suggests the mix may support focus and a small rise in energy use, but it is not a proven fat burner on its own.

Coffee and green tea are the two most popular caffeinated drinks in the world, and for a long time people treated them as rivals. You were either a coffee person or a tea person. Blends that combine the two are a newer idea, and they usually come with big promises about metabolism and "clean energy."

This guide looks at what green tea actually adds to a cup of coffee, what the research does and does not support, how much caffeine you end up with, and the safety points worth knowing before you make it a daily habit.

What is green tea coffee?

Green tea coffee is any coffee drink that also contains green tea in some form. In practice that means one of three things:

  1. Brewed green tea mixed with coffee. Some people simply combine the two drinks. This works, but the flavours compete and the amounts of active compounds are hard to know.
  2. Matcha with espresso. Matcha is powdered whole green tea leaf. Layered with espresso and milk it is sometimes sold as a "dirty matcha." You drink the whole leaf, so you get more of its compounds than from steeped tea.
  3. Coffee blended with green tea extract. This is the form used in most functional coffees. The extract is concentrated, so a small amount of powder replaces a lot of leaf, and it has little effect on taste.

What does green tea actually add?

Green tea leaves contain three groups of compounds that researchers care about:

- Catechins. These are plant polyphenols. The most abundant and most studied is EGCG (epigallocatechin gallate). Catechins are the main reason green tea is linked to antioxidant and metabolism research. - L-theanine. An amino acid found almost only in tea. It is studied for a calm, focused kind of alertness, and much of that research looks at it in combination with caffeine. - Caffeine. Green tea has its own caffeine, though usually less per cup than coffee. Extracts vary widely, and some are decaffeinated.

What does "100:1 extract" mean?

A ratio like 100:1 means roughly 100 parts of dried leaf went into making 1 part of finished extract. It tells you the extract is concentrated. It does not tell you the EGCG or caffeine content, which are the figures researchers usually measure, so ratios are hard to compare between products.

How does green tea coffee compare with regular coffee and green tea?

The short version: coffee brings most of the caffeine, green tea brings catechins and L-theanine, and a blend gives you some of both.

Feature Regular coffee Brewed green tea Green tea coffee
Main active compounds Caffeine, chlorogenic acids Catechins (EGCG), L-theanine, caffeine Caffeine, chlorogenic acids, plus catechins and sometimes L-theanine
Typical caffeine per cup Roughly 80 to 100 mg for 8 oz brewed Roughly 30 to 50 mg for 8 oz Mostly from the coffee; extract may add a little
How it tends to feel Fast, strong alertness Gentler, steadier alertness Coffee's lift, which L-theanine may smooth for some people
What it is studied for Alertness, exercise output, metabolism Antioxidant status, metabolism, heart markers Mostly studied as separate ingredients, not as a blend
Taste Depends on roast Grassy, vegetal Usually tastes like coffee; extract is mild
Main caution Too much caffeine Iron absorption, caffeine Total caffeine, and liver safety at high extract doses

The caffeine figures are typical ranges. Brewing method, bean, leaf grade and serving size all change them a lot.

What does the research say about green tea and metabolism?

Honest summary: green tea catechins combined with caffeine may produce a small increase in daily energy use and fat burning in controlled studies. In longer trials the effect on body weight has been small and inconsistent, and not large enough to matter much on its own.

Here is what the research reasonably supports:

  1. A small thermogenic effect. Early metabolic chamber studies found that green tea extract containing catechins and caffeine raised 24 hour energy expenditure more than caffeine alone or placebo. Later studies broadly agree there is an effect, but it is modest. For more on how this works, see our guide to thermogenic coffee.
  2. Catechins and caffeine seem to work together. One proposed reason is that catechins slow the breakdown of noradrenaline, a signal that tells the body to burn energy, while caffeine increases its release. This is a plausible mechanism, not a proven outcome.
  3. Effects on weight are small. A Cochrane review of green tea preparations in adults with overweight found weight changes that were small, not statistically significant in many analyses, and unlikely to be clinically important. Meta-analyses that found an effect describe it as modest, with results that vary by study.
  4. Habitual caffeine use may blunt the effect. Several analyses suggest people who already drink a lot of caffeine see less benefit, which is relevant for daily coffee drinkers.

Does green tea make coffee feel smoother?

This is the most interesting part of the blend for many people. Coffee can leave some drinkers jittery. L-theanine, the amino acid in tea, is studied for promoting relaxed alertness, and a handful of small, well controlled trials have looked at it alongside caffeine.

Those studies found that L-theanine plus caffeine improved performance on some attention and task switching tests compared with placebo, and in some cases compared with caffeine alone. Participants also sometimes reported feeling more alert and less tired. The studies were short and small, many used doses higher than you would get from a cup of tea, and they did not consistently show reduced jitters.

So it is fair to say L-theanine may support a calmer, more focused feel with caffeine for some people. It is not guaranteed, and it depends on how much L-theanine a product actually contains. If you want more on coffee and focus, our guide to dark roast coffee and focus covers the caffeine side.

What the evidence does and does not show

What it reasonably shows:

- Green tea is a well studied source of catechins with antioxidant activity in the body. - Catechins combined with caffeine may cause a small, short term rise in energy use. - L-theanine with caffeine may support attention on some lab tasks. - Regular green tea drinking is associated with better heart health markers in observational studies, though association is not proof of cause.

What it does not show:

- It does not show green tea coffee is a fat burner. Any metabolic effect is small and easily outweighed by diet, sleep and activity. - It does not show that more extract is better. Higher catechin doses raise safety concerns faster than they raise benefits. - It does not show blended products work like the studies. Most trials test standardised extracts at measured doses. A coffee listing "green tea" without amounts may contain far less. - It does not show anti-aging or disease prevention effects from drinking green tea coffee.

This article is educational and is not medical advice. Green tea and other functional ingredients may support normal wellbeing but do not diagnose, treat, cure or prevent any condition. Talk to your doctor before adding a new supplement, especially if you are pregnant or nursing, take medication, or have a medical condition.

Is green tea coffee safe?

For most healthy adults, green tea coffee in normal drink amounts is likely to be well tolerated. The main things to watch are total caffeine and concentrated extracts.

  1. Watch your total caffeine. The FDA cites 400 mg a day as an amount not generally linked to negative effects in healthy adults. Coffee, green tea, guarana, energy drinks and pre-workouts all count toward it. Too much can cause jitters, a racing heart, stomach upset and poor sleep.
  2. Be careful with high dose extracts. Rare cases of liver injury have been linked to concentrated green tea extract supplements. The European Food Safety Authority noted that EGCG doses of 800 mg a day or more from supplements were associated with raised liver enzymes. Brewed tea has not shown the same concern. Taking extracts with food rather than on an empty stomach is a sensible precaution.
  3. Iron absorption. Tea catechins can reduce absorption of iron from plant foods. If you have low iron, drink it between meals rather than with them.
  4. Medication interactions. Green tea can lower blood levels of some drugs, including the beta blocker nadolol, and caffeine interacts with several medications. Ask your pharmacist if you take regular medication.
  5. Who should check first. Pregnant or nursing women, people with liver disease, heart rhythm problems, anxiety disorders or high blood pressure, and anyone sensitive to caffeine should talk to a doctor before using green tea extract products.

What should you look for in a green tea coffee?

- A clear ingredient list. You should be able to see whether it uses brewed leaf, matcha or an extract. - Realistic language. "May support" is honest. "Melts fat" or promises of specific weight loss are not. - No mystery stimulant stack. Check for other caffeine sources such as guarana, and add them up. - Little or no added sugar. A sweet green tea latte can carry more sugar than a dessert, which undoes the point.

How should you drink green tea coffee?

  1. Keep it to the morning or early afternoon. Caffeine can affect sleep many hours later.
  2. Have it with or after food if your blend contains extract, both for comfort and as a liver precaution.
  3. Skip the sugary add-ins. Our guide to staying energized without sugar crashes explains why the spike and slump matters.
  4. Count all your caffeine. One blended cup plus a large tea and a soda adds up quickly.
  5. Pair it with the basics. Sleep, protein, fibre and movement do far more for energy and weight than any single ingredient. Our guide to coffee and weight loss support methods covers how coffee fits into that picture.

How does green tea fit with other coffee ingredients?

Green tea is often paired with other functional ingredients, and each one is studied for something different:

- Green coffee bean extract comes from unroasted coffee and is rich in chlorogenic acids. See our green coffee bean extract guide. - L-carnitine helps move fatty acids into cells for energy. See our L-carnitine coffee guide. - Ginseng is studied for fatigue and mental performance. See our ginseng coffee guide.

For a full rundown of these ingredients side by side, read our weight loss coffee ingredients guide.

Which Lean Joe Bean coffee contains green tea?

Both of our coffees include green tea, in different formulas.

Our Weight Loss Coffee lists green tea 100:1 extract alongside dark roast coffee, green coffee bean, Super CitriMax, Chromax, Garcinia cambogia 95%, ginseng 100:1 extract and L-carnitine with chromium. It contains no mushrooms.

Our Superfood Coffee lists green tea and L-theanine, together with lion's mane, cordyceps, chaga, shiitake and maitake mushrooms, Siberian ginseng, MCT, collagen protein, turmeric, cinnamon, ginger, guarana (Paullinia cupana), an HSO probiotic and added vitamins. Because it contains guarana, which has its own caffeine, count it toward your daily total. It dissolves in water, so it works as a quick morning cup.

The bottom line

Green tea coffee is a reasonable way to get some of green tea's catechins and L-theanine without giving up your coffee. Expect the energy to come mostly from the coffee. The catechin and caffeine pairing may support a small rise in energy use, and L-theanine may support a smoother, more focused feel for some people, but neither is a weight loss treatment. Keep your total caffeine in check, avoid high dose extracts on an empty stomach, and talk to your doctor first if you have liver problems, take regular medication, or are pregnant.

Frequently asked questions

Can you mix green tea and coffee?

Yes. Mixing green tea and coffee is generally fine for healthy adults. The main thing to watch is total caffeine, since both drinks contain it. Most functional blends use green tea extract, which adds catechins without changing the taste much.

Does green tea extract in coffee burn fat?

Studies suggest green tea catechins combined with caffeine may slightly increase energy use and fat burning in the short term. Long term trials show small and inconsistent effects on weight, so it is best seen as a minor helper, not a fat burner.

How much caffeine is in green tea coffee?

Most of the caffeine comes from the coffee, typically around 80 to 100 mg in an 8 oz brewed cup. Green tea extract may add a little, and other ingredients such as guarana add more. Check the label and count everything toward the 400 mg daily guideline for healthy adults.

Does L-theanine reduce coffee jitters?

Small trials found L-theanine with caffeine may improve attention and help some people feel more relaxed and alert. Results are mixed on jitters specifically, and many studies used more L-theanine than a cup of tea provides.

Is green tea extract safe every day?

Green tea in drink amounts is considered safe for most healthy adults. Concentrated extracts are different: high EGCG doses from supplements have been linked to raised liver enzymes and rare liver injury, so avoid high dose products, take them with food, and ask your doctor if you have liver concerns.

Who should avoid green tea coffee?

People who are pregnant or nursing, have liver disease, heart rhythm problems, anxiety disorders, high blood pressure or low iron, take medications such as nadolol, or are sensitive to caffeine should talk to a doctor before using green tea coffee.

What is the difference between matcha coffee and green tea extract coffee?

Matcha is powdered whole green tea leaf, so it has a strong grassy taste and a visible green colour. Green tea extract is a concentrated powder made from the leaf, used in small amounts, so it usually tastes like regular coffee.

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