Know2eat

Green tea

Camellia sinensis

Also known as green tea, sencha, matcha, gunpowder tea

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Leaves of Camellia sinensis heated soon after picking to stop enzymatic browning, which leaves the catechins largely intact. The USDA entry is for brewed tea, so it reflects what is extracted into the cup rather than the dry leaf.

Almost every discussion of green tea and health has a dose problem hiding in it. Brewed tea delivers catechins in the range of a few hundred milligrams a day for a heavy drinker; green tea extract capsules deliver similar or much larger amounts of EGCG in a single dose, sometimes on an empty stomach. Those are different exposures with different risk profiles, and the research literature mixes them freely.

Heart HealthEnergy & MetabolismWeight Management

Potential health benefits

Best supported: Moderate

Ordered by how well the human research supports them — strongest first. A rating describes the state of the evidence, not how impressive the food is. How we rate evidence.

Blood lipid profile

Heart Health
Moderate evidence

Meta-analyses of randomised trials report small reductions in total and LDL cholesterol with green tea. Many included trials use concentrated catechin extracts at doses well above several cups of brewed tea, reviews report substantial heterogeneity, and the average effect is modest.

Moderate evidence. Several human studies point the same way, with real caveats.

4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Alertness and energy

Energy & Metabolism
Limited evidence

Trials combining caffeine and L-theanine report modest short-term changes in attention and alertness tasks. Most use isolated compounds in doses chosen by the researchers rather than brewed tea, and results for theanine on its own are weak.

Limited evidence. Early human work, or mostly lab and animal research.

3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Body composition

Weight Management
Limited evidence

Meta-analyses of green tea catechin trials report very small average weight differences, generally around a kilogram or less over several months, mostly using high-dose extracts often combined with caffeine. The effect is too small to be worth building a plan around, and the extract doses carry their own liver caution.

Limited evidence. Early human work, or mostly lab and animal research.

4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Healthy blood pressure

Heart Health
Limited evidence

Reviews report small average reductions in blood pressure with green tea, of a size easily swamped by differences between trials. Trials are short and again lean on extracts rather than brewed tea.

Limited evidence. Early human work, or mostly lab and animal research.

3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

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Key nutrients

Nutrient content per 100 grams
NutrientAmount% DV
Macronutrients
Calories1 kcal0%
Protein0.22 g0%
Total fat0 g0%
Carbohydrate0 g0%
Fibre0 g0%
Total sugars0 g—
Water99.9 g—
Fats
Saturated fat0 g0%
Monounsaturated fat0 g—
Polyunsaturated fat0 g—
Cholesterol0 mg0%
EPA (omega-3)0 g—
DHA (omega-3)0 g—
DPA (omega-3)0 g—
Linoleic acid (omega-6)0 g—
Vitamins
Vitamin A0 µg0%
Vitamin C0 mg0%
Vitamin D0 µg0%
Vitamin E0 mg0%
Vitamin K0 µg0%
Thiamin (B1)0.0070 mg1%
Riboflavin (B2)0.058 mg4%
Niacin (B3)0.03 mg0%
Vitamin B60.0050 mg0%
Folate0 µg0%
Vitamin B120 µg0%
Choline0 mg0%
Minerals
Calcium0 mg0%
Iron0.02 mg0%
Magnesium1 mg0%
Phosphorus0 mg0%
Potassium8 mg0%
Sodium1 mg0%
Zinc0.01 mg0%
Copper0.0040 mg0%
Manganese0.184 mg8%
Selenium0 µg0%
Other measured compounds
Beta-carotene0 µg—
Alpha-carotene0 µg—
Lycopene0 µg—
Lutein + zeaxanthin0 µg—
Caffeine12 mg—
Ash0 g—

Nutrient values are per 100 g of the USDA reference entry named on this page and vary with variety, growing conditions, storage and preparation.

Source record: Beverages, tea, green, brewed, regular (USDA FoodData Central, FDC ID 171917).

% DV uses the FDA Daily Values for adults and children aged 4 and over. A dash means no Daily Value has been established for that nutrient.

Bioactive compounds

Compounds present in meaningful amounts. Presence is banded rather than quantified, because whole-food levels vary enormously with variety, growing conditions, storage and preparation.

How preparation changes things

Only effects with real support are listed. If a preparation method is missing, it is because nothing dependable is documented — not because it makes no difference.

  • brewedChanges catechin and caffeine extraction

    Hotter water and longer steeping pull more catechins and more caffeine into the cup, along with more tannin and bitterness. Around 80 °C for two to three minutes is the usual compromise; boiling water makes a more astringent and more caffeinated cup.

  • with foodReduces non-heme iron absorption

    Drinking tea with a meal reduces absorption of non-heme iron from that meal; leaving an hour either side largely avoids the effect.

Things to know

Allergies, interactions and intake concerns. Every food gets this section — a reference where everything is uniformly good is not a reference.

  • Too much

    High-dose green tea extract and rare liver injury

    Concentrated green tea extract has been linked to rare but serious liver injury, with risk appearing to rise above roughly 800 mg of EGCG a day and when taken on an empty stomach; a genetic susceptibility has been identified in some cases. European authorities acted on this specifically for supplements. Brewed tea is not implicated in the same way, and the distinction between the drink and the capsule is the whole point.

  • Interaction

    Tannins reduce absorption of non-heme iron

    Tea polyphenols bind non-heme iron in the gut and can substantially reduce how much is absorbed from a meal. For anyone iron-deficient, or relying on plant sources of iron, the practical fix is drinking tea between meals rather than with them.

  • Interaction

    Reduces absorption of some medicines

    Green tea catechins inhibit intestinal drug transporters and have been shown to markedly reduce plasma levels of the beta-blocker nadolol, with similar concerns raised for other transporter substrates. Very high intakes also supply enough vitamin K to matter to warfarin dosing.

  • Worth knowing

    Caffeine, sleep, anxiety and pregnancy

    Green tea contains caffeine, less than coffee per cup but enough to disturb sleep and worsen anxiety in sensitive people. Pregnancy guidance in most countries caps total caffeine at around 200 mg a day from all sources.