Caffeine is a bitter substance derived from the leaves, fruit and seeds of various plants and acts as a natural pesticide against threatening insects.

Caffeine is of course found in high amounts in the seeds of the coffee plant and the leaves of the tea bush but it’s also commonly found in:

• kola nuts – used to flavour cola drinks

• guarana berries - which contain about twice the amount of caffeine as coffee beans

• cacao pods – used to make chocolate products

The effects of caffeine on...

Your blood pressure figures are an indication of how much pressure your blood is exerting against the walls of your arteries.

Blood pressure is usually represented by two figures and they indicate the highest and lowest pressure the blood exerts during the heart beat cycle.

The higher figure is known as the systolic pressure – this is the peak force the blood exerts against the artery walls when the heart contracts and pushes the next pulse of blood out through your circulation.

The lower figure is...