Drinking three cups of tea a day can keep you mentally alert in old age.

It is the perfect excuse to have another cup of tea.

Research suggests that regularly having the drink keeps the mind sharp in old age.

US researchers analysed six studies on the effect of caffeinated drinks on memory and mental alertness, with the biggest involving more than 7,000 men and women.

Those taking part in the studies logged how often they drank tea or coffee and did a memory test that is normally used in the initial stages of diagnosing Alzheimer’s disease.

Up to ten years later, they resat the test and any fall in score was noted.

In all of the studies that included tea, the brain stayed sharper in those who drank the beverage, the journal Advances in Nutrition reports.

In one study, of almost 1,500 men and women in Singapore, drinking more than four cups a day cut the odds of memory failing by three-quarters.

Even just one to three cups of Ceylon tea a day had an effect, reducing the chances of cognitive decline by 43 per cent.