Flow Mediated Dilation in Response to Black Tea

Epidemiological studies indicate that regular consumption of three cups of black tea per day reduces the risk of stroke or myocardial infarction. In a number of previous nutrition intervention studies tea has been shown to improve vascular function as assessed by Flow Mediated Dilation in various populations. The current confirmatory study tests a specific black tea against a placebo in a population of in non-tea drinking hypertensive subjects.

Inclusion criteria

• Males and post menopausal (> 1 year) females, not on hormone replacement therapy
• Aged >18 and < 65 years
• Body mass index (BMI) of >=18.0 and =<35.0 kg/m2
• Hypertension as previously diagnosed by primary care or hospital physician.

• If untreated, office BP between 140/90 mmHg and 160/100 mmHg on screening
• If treated, a controlled blood pressure (<160/100) on stable medication for at least 4 weeks

Exclusion criteria

• Tea drinkers: having typically consumed > 1 cup of black tea per week.
• Current smoker or has stopped smoking less than 6 months before start of study
• Self reported alcohol intake of >21 units/week
• Established cardiovascular disease other than hypertension
• Clinically significant arrhythmia
• Diabetes mellitus
• Chronic Kidney Disease > stage 2
• 10-year cardiovascular risk equivalent to 20% or greater using the QRisk2 calculator
• Abnormality of laboratory blood tests considered clinically significant
• Any other significant intercurrent condition/disease