Atherosclerosis ('furring' of the arteries) affects the functioning of blood vessels, narrowing and eventually blocking them, causing conditions like heart attack and stroke. The Mediterranean diet, which is rich in tomatoes and tomato-based products, has been shown to be associated with a reduced risk of blood vessel damage. In this double blind, placebo-controlled randomised study, the investigators will investigate whether a food supplement containing a standardised extract of tomato improves blood vessel function in both healthy people (aged 40-80), and people with a history of cardiovascular disease. The food supplement is on sale to the public, and the investigators are testing the standard dose. Approximately 72 people will take part at the Clinical Pharmacology Unit at the ACCI Building, Cambridge University Hospitals NHS Trust.