Green Tea Extract: Benefits and the Liver Caution

What it is

A concentrated leaf preparation standardised for catechin content, chiefly epigallocatechin gallate (EGCG). It is not the same thing as drinking green tea — concentration changes both the effect and the risk profile.

What the research covers

EGCG is among the better-characterised dietary antioxidants, studied for oxidative stress markers, metabolic measures and cardiovascular endpoints. The natural L-theanine content of tea is separately studied for calm attention.

Effects are generally modest and the literature is large rather than conclusive.

The caffeine content people miss

Green tea extract carries naturally occurring caffeine. The amount in a supplement serving is small — well below a cup of coffee — but it is not zero.

This is why describing a green-tea-containing formula as “stimulant free” is imprecise, and why it is a useful test of how carefully a given product page was written.

The liver caution

Concentrated green tea extract has been associated with rare cases of liver injury, generally at high doses and often in multi-product stacks rather than from drinking tea.

The practical implications are simple: stay at label servings, do not stack multiple green-tea-containing products, and avoid it entirely if you have existing liver disease. Anyone developing yellowing of the skin or eyes, or dark urine, should stop and seek medical advice.

The reasonable position

A legitimate, well-studied antioxidant ingredient that belongs in a formula at sensible doses, with one genuine safety caveat that most marketing omits.

Keep reading

• Zinc, Magnesium and Testosterone: What the Claims Really Say
• Ashwagandha for Men: What the Research Shows
• Bacopa Monnieri: The Memory Evidence Examined
• Ginkgo Biloba: What the Evidence Actually Says
• Rhodiola Rosea and Mental Fatigue

Found this useful? The rest of the series is on the Horsewood blog.