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Black and Oolong Tea
Most people treat black tea as the health afterthought behind green. That's backwards. Black and oolong are green tea's catechins welded into new molecules that do the same cardiovascular work: a small drop in blood pressure, a small drop in LDL, arteries that relax within an hour of the cup. Across half a million British drinkers, two cups a day tracked with about a tenth fewer deaths over a decade Inoue-Choi 2022. The cost is hot water and three minutes.
Do ยท Daily Evidence Moderate Chapter Food

It's one plant, sorted by how long the leaf sat in air. Green tea is heated fast to lock in pale compounds called catechins. Black and oolong are left to oxidise, and an enzyme welds those catechins into bigger red molecules called theaflavins. When theaflavins reach the cells lining your arteries they switch on nitric oxide, which tells the vessel wall to relax; peak widening lands one to two hours after the cup 1.

The other half of the cup is the caffeine-theanine pair. A cup carries 35 to 60 milligrams of caffeine, about half a coffee, plus L-theanine, an amino acid near-unique to tea that takes the edge off the buzz. You get even alertness without the crash.

Give people three cups a day against a matched placebo and the pressure drops. After six months, black-tea drinkers ran about 2 mmHg lower systolic and diastolic on a 24-hour cuff 2; a pooled review of 13 trials points the same way 3. Daily black tea also drops LDL by roughly five milligrams per decilitre, more in people already at risk 4.

The survival signal is the headline. Two-plus cups a day tracked with a 9 to 13 percent lower death rate, concentrated in heart disease and stroke, holding whether people added milk, added sugar, or metabolised caffeine fast or slow 5. In Japan, oolong pointed the same direction 6.

The arc is slow and mostly invisible.

  • First week: the two-o'clock wall comes later or not at all, and the cup becomes a quiet pause the theanine seems to deepen.
  • A month in: a few millimetres off your systolic at the next check-up; sleep untouched if you stayed off afternoon cups.
  • A decade in: the cohort signal starts to apply to you, and the event that didn't happen in your sixties is the whole point.
The fine print โ€” when to skip it, and what people get wrong

Milk cancels the vessel benefit per cup โ€” casein binds the polyphenols before your gut absorbs them 7. The mortality benefit survived milk in the UK data, so it isn't ruinous, but black gives you more.

Scalding-hot tea is a carcinogen. Drinking it at 65ยฐC or hotter tracked with about 90 percent higher oesophageal cancer risk 8. It's the heat, not the tea. Let the cup cool two or three minutes.

"Green is the healthy one; black is watered-down." No. Black tea's theaflavins are converted catechins that protect cholesterol about as well; the mostly-black UK data lines up with mostly-green Japan.

"Decaf doesn't count." Most theaflavins survive decaffeination; you lose the alertness, keep the cardiovascular load.

Pregnant or breastfeeding: stay under about 200 mg caffeine a day across all sources; two or three cups fit 9.

Insomnia, anxiety on caffeine, or arrhythmia: stop at noon, switch to decaf, or ask your cardiologist.

References
  1. 1Grassi D, Mulder TPJ, Draijer R, Desideri G, Molhuizen HOF, Ferri C (2009). Black tea consumption dose-dependently improves flow-mediated dilation in healthy males. Journal of Hypertension. link
  2. 2Hodgson JM, Puddey IB, Woodman RJ, Mulder TPJ, Fuchs D, Scott K, Croft KD (2012). Effects of black tea on blood pressure: a randomized controlled trial. Archives of Internal Medicine. link
  3. 3Ma C, Zheng X, Yang Y, Bu P (2021). The effect of black tea supplementation on blood pressure: a systematic review and dose-response meta-analysis of randomized controlled trials. Food & Function. link
  4. 4Wang D, Chen C, Wang Y, Liu J, Lin R (2014). Effect of black tea consumption on blood cholesterol: a meta-analysis of 15 randomized controlled trials. PLOS One. link
  5. 5Inoue-Choi M, Ramirez Y, Cornelis MC, Berrington de Gonzalez A, Freedman ND, Loftfield E (2022). Tea consumption and all-cause and cause-specific mortality in the UK Biobank: a prospective cohort study. Annals of Internal Medicine. link
  6. 6Mineharu Y, Koizumi A, Wada Y, Iso H, Watanabe Y, Date C, Yamamoto A, et al. (2011). Coffee, green tea, black tea and oolong tea consumption and risk of mortality from cardiovascular disease in Japanese men and women. Journal of Epidemiology and Community Health. link
  7. 7Lorenz M, Jochmann N, von Krosigk A, Martus P, Baumann G, Stangl K, Stangl V (2007). Addition of milk prevents vascular protective effects of tea. European Heart Journal. link
  8. 8Islami F, Poustchi H, Pourshams A, Khoshnia M, Gharavi A, Kamangar F, Dawsey SM, et al. (2019). A prospective study of tea drinking temperature and risk of esophageal squamous cell carcinoma. International Journal of Cancer. link
  9. 9ACOG (2010). Moderate caffeine consumption during pregnancy (Committee Opinion No. 462). link
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  • โ€” An adjacent topic in the handbook.
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