As a daily drink, green tea shows small but consistent reductions in blood cholesterol, blood pressure and body fat, plus lower heart disease death and slower decline in thinking among the heaviest drinkers in population studies. The cancer picture is unsettled. Concentrated extract buys a little more effect at the cost of a real, uncommon chance of liver injury. (Full Review)
| Marker | Target | Why |
|---|---|---|
| ALT (alanine aminotransferase) | 10–26 U/L (men), 8–22 U/L (women) | Primary safety marker for extract liver injury |
| AST (aspartate aminotransferase) | 10–26 U/L | Confirms hepatocellular injury with elevated ALT |
| Alkaline phosphatase | 40–90 U/L | Distinguishes cholestatic from hepatocellular injury |
| Total bilirubin | 0.3–1.0 mg/dL | Marks clinically significant injury with elevated ALT |
| Ferritin | 50–150 ng/mL | Detects iron depletion from catechin-iron chelation |
| Apolipoprotein B | Below 80 mg/dL (below 60 for elevated cardiovascular risk) | Atherogenic particle count; most reliable benefit |
| LDL cholesterol | Below 100 mg/dL | The lipid endpoint reduced in randomized trials |
| HbA1c (glycated haemoglobin) | 4.8–5.3% | Captures the small glycemic benefit |
| Fasting glucose | 75–86 mg/dL | Detects near-term glycemic change ahead of HbA1c |
| hs-CRP (high-sensitivity C-reactive protein) | Below 0.5 mg/L | Tracks anti-inflammatory signalling from catechins |
| Blood pressure | Below 120/80 mmHg | Outcome with the most robust randomized evidence |
Cadence: Baseline panel before sustained high intake or any extract. Liver panel at 8 weeks, then every 6 months; lipids and HbA1c at 12 weeks, then annually; ferritin annually, or 6-monthly for menstruating women, vegetarians and blood donors; home blood pressure weekly for 12 weeks. Brewed tea alone: annual liver panel and ferritin.