Green Tea
Overview
Green tea provides catechins (especially EGCG), L-theanine, and other polyphenols in a low-calorie brewed beverage. These intrinsic compounds support antioxidant defenses and are widely studied for cognitive and metabolic relevance, alongside small amounts of manganese, fluoride, and potassium from the leaf and brew matrix.
Within the BRAIN Diet framework, green tea is best used as a polyphenol beverage rather than a calorie or protein source. In Green Mediterranean Diet trials, added green-tea polyphenols contributed to greater visceral adiposity reduction than a standard Mediterranean diet alone [1], and the same trial programme linked the green-Mediterranean pattern to attenuated brain atrophy with glycemic control as part of the neuroprotective signal [2].
Key Nutritional Highlights
- EGCG and related catechins dominate the polyphenol profile; brew strength, leaf dose, and steep time strongly affect extraction.
- Green-tea polyphenols in the Green Mediterranean Diet were associated with greater visceral adiposity reduction than standard Mediterranean diet alone [1].
- Brain MRI follow-up in DIRECT PLUS linked the green-Mediterranean pattern to attenuated brain atrophy, with glycemic control contributing to the neuroprotective signal [2].
- L-theanine is a tea-specific amino acid often discussed alongside catechins for calm, non-sedating focus.
- Can reduce non-heme iron absorption when taken with meals; spacing from iron-rich meals or adding vitamin C may help.
Food Context
Synergies
- Can reduce non-heme iron absorption if taken with meals; space ≥1 hour from iron-rich meals or add lemon (vitamin C) to mitigate this.
Preparation
- Steep at lower temperatures (roughly 70–80 °C) to preserve catechins and limit bitter tannin extraction.
- Unsweetened brews fit best within polyphenol-forward dietary patterns; cup strength varies widely by leaf type and steep time.
Recipes
1 recipe containing this food
Matcha Mitochondria Smoothie
Mitochondrial energising smoothie rich in polyphenols, magnesium, and antioxidants
Nutrient Tables (per 100 g)
Core nutrients
| Nutrient | Amount per 100 g | % RDA per 100 g |
|---|---|---|
| Energy | 0 kcal | — |
| Protein | 0 g | — |
| Total fat | 0 g | — |
| Carbohydrates | 0 g | — |
Bioactive compounds
Values below are often from specialist compositional databases or literature, not the standard USDA panel. Asterisks (*) refer to source notes at the bottom of this section.
| Compound / class | Amount per 100 g | Notes |
|---|---|---|
| EGCG | 30 mg * | Dominant catechin in many green teas; very sensitive to leaf dose, time, and temperature. |
| L-Theanine | 6 mg * | Tea-specific amino acid; often co-discussed with catechins for calm focus. |
Note: Bioactive-compound values vary substantially by cultivar, species, cocoa or oil percentage, processing, and brand formulation. Show quantitative values only where a defensible source exists; otherwise prefer qualitative presence statements or ranges in source notes.
- * EGCG: Order-of-magnitude for a typical brewed green tea beverage scaled to per 100 g liquid; cup strength and cultivar dominate variance (USDA brew panels are not a full polyphenol spec).
- * L-Theanine: Approximate per 100 g brewed beverage; shade-grown teas can be higher.
Functional metrics
| Metric | Score | Notes |
|---|---|---|
| Total catechins (brewed proxy) | Varies by product | Pool includes EGCG, EGC, ECG, and EC; brewing dominates extraction. |
Note: Functional-metric values depend strongly on assay method, processing, and product formulation. Use these as contextual metrics, not strict like-for-like nutrient equivalents.
Substances
Substances in this food: editorial (Overview / literature) plus analytical (nutrition table).
4 substances in this food
EGCG (Green Tea Catechin)
Polyphenol; antioxidant; gut barrier/LPS modulation; supports microbiome
L-Theanine
Calming amino acid from tea; increases alpha waves; sleep-friendly
Manganese
Cofactor for MnSOD (SOD2); mitochondrial antioxidant defense
Potassium
Electrolyte for nerve transmission, muscle function, and blood pressure regulation
References
[1] In Green Mediterranean Diet trials, added green-tea polyphenols contributed to greater visceral adiposity reduction than a standard Mediterranean diet alone. Zelicha et al. 2022. The effect of high-polyphenol Mediterranean diet on visceral adiposity: the DIRECT PLUS randomized controlled trial
[2] Brain MRI follow-up in DIRECT PLUS linked the green-Mediterranean pattern to attenuated brain atrophy, with glycemic control contributing to the neuroprotective signal. Pachter et al. 2024. Glycemic control contributes to the neuroprotective effects of Mediterranean and green-Mediterranean diets on brain age: the DIRECT PLUS brain-magnetic resonance imaging randomized controlled trial