---
type: Concept
title: Tea Antioxidants
description: The catechins (led by EGCG), tannins, vitamins, and aromatic oils that
  give tea its healthful reputation and its characteristic astringency.
tags:
- tea
- antioxidants
- chemistry
- health
resource: raw/tea-guide.md
timestamp: '2026-07-16T15:54:42Z'
citadel_version: 0.3.0
---

Beyond [caffeine](caffeine.md), the tea leaf is chemically rich, and much of its reputation as a healthful drink rests on its content of antioxidants.[^s1] Tea is a notable source of catechins, a family of plant antioxidants of which the most studied is epigallocatechin gallate (EGCG).[^s2][^s8] Catechins are most abundant in the less oxidised teas, since oxidation converts many of them into other compounds — one reason green [tea](../objects/tea.md) is so often singled out for its supposed benefits.[^s3]

Shading works the opposite direction: covering the bushes before harvest — the technique behind [matcha](../objects/matcha.md) and gyokuro — blocks most sunlight and halts the light-driven conversion that would otherwise turn [L-theanine](l-theanine.md) into catechins, so shaded teas carry markedly fewer catechins and taste less bitter.[^s13]

Tea also contains tannins, the astringent compounds that lend the brew its characteristic dryness and grip on the palate and that contribute to the colour of darker infusions.[^s4] Tannins bind readily with proteins and with iron, which is why tea can taste smoother when softened with milk and why very strong tea is sometimes discouraged alongside iron-rich meals.[^s5] Those same tannins can also stain tooth enamel over time, especially with strong, frequent brewing.[^s9] A few simple habits limit the effect: rinsing with water after a cup, not letting a strong tea sit on the teeth all day in slow sips, keeping up a normal brushing routine, and, for some drinkers, a splash of milk to soften it further.[^s10] The iron-binding effect is strongest against non-heme iron — the plant-based iron in foods like beans, lentils, and leafy greens — so anyone told they are low in iron, or prone to deficiency, does best to drink tea between meals rather than alongside an iron-rich one, which sidesteps most of the binding.[^s11][^s12]

The leaf further supplies small amounts of vitamins, minerals, and aromatic oils.[^s6] The interplay of caffeine, catechins, and tannins gives each style of tea its particular balance of stimulation, sweetness, and astringency.[^s7]

## See also
- [Tea](../objects/tea.md)
- [Caffeine](caffeine.md)
- [L-Theanine](l-theanine.md)

## Sources
[^s1]: [raw/tea-guide.md](../../raw/tea-guide.md), lines 131-132 — antioxidants behind tea's healthful reputation (ingested 2026-07-16)
[^s2]: [raw/tea-guide.md](../../raw/tea-guide.md), lines 132-134 — catechins, led by epigallocatechin gallate (EGCG) (ingested 2026-07-16)
[^s3]: [raw/tea-guide.md](../../raw/tea-guide.md), lines 134-137 — catechins most abundant in less-oxidised teas (ingested 2026-07-16)
[^s4]: [raw/tea-guide.md](../../raw/tea-guide.md), lines 139-141 — tannins' astringency and colour contribution (ingested 2026-07-16)
[^s5]: [raw/tea-guide.md](../../raw/tea-guide.md), lines 141-143 — tannins binding protein and iron (ingested 2026-07-16)
[^s6]: [raw/tea-guide.md](../../raw/tea-guide.md), lines 145-146 — vitamins, minerals, and aromatic oils (ingested 2026-07-16)
[^s7]: [raw/tea-guide.md](../../raw/tea-guide.md), lines 146-148 — the interplay giving each tea its balance (ingested 2026-07-16)
[^s8]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 13 — catechins and EGCG corroborated, concentrated in green tea (ingested 2026-07-16)
[^s9]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 53 — tannins can stain tooth enamel, especially with strong, frequent brewing (ingested 2026-07-16)
[^s10]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 57 — habits that limit staining: rinsing, avoiding all-day slow sips, brushing, and milk (ingested 2026-07-16)
[^s11]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 61 — iron-binding strongest against non-heme iron from beans, lentils, and leafy greens (ingested 2026-07-16)
[^s12]: [raw/tea-health-faq.md](../../raw/tea-health-faq.md), line 65 — advice to drink tea between meals when low in iron or prone to deficiency (ingested 2026-07-16)
[^s13]: [raw/tea-processing-and-cultivars.md](../../raw/tea-processing-and-cultivars.md), lines 115-117 — catechins fall under shading since less L-theanine converts into them (ingested 2026-07-16)
