Tea Components, Mental Stress and Blood Pressure

Caffeine and (mental) stress can increase blood pressure. In a typical everyday and/or work environment they commonly coincide. Tea has the reputation of being a relaxing drink. L-theanine is an amino acid found almost exclusively in tea. In a previous study it was shown that caffeine increased blood pressure, while theanine antagonised these effects. In the current study the effect of theanine to a placebo on blood pressure are directly compared.

Inclusion criteria

• Apparently healthy males and females
• Women taking the contraceptive pill
• 18-45 years of age
• BMI 20-30 kg/m2
• Normal or corrected vision
• Low caffeine consumers (<100mg/day)
• Non smokers and having been a non-smoker for > 6 months
• Fluent English
• Normotensive (>90/60 <140/90 mmHg)

Exclusion criteria

• Significant current or medical history of cardiovascular disease
• Low or high STAI trait score in the opinion of the PI
• Known sensitivity to caffeine or theanine
• Colour blindness
• Alcohol consumption above 14/21 units female/male resp. per week
• Weight loss diet > 10% of bodyweight in the previous year
• Anyone with a dependency on PI or staff of Department of Epidemiology and Public Health or being an employee of Unilever
• Reported participation in another biomedical study < 3 months before screening