Drinking tea or coffee may reduce risk of dementia, study suggests

Drinking tea or coffee may help preserve brain function and reduce dementia risk, a large US study has suggested.

Researchers said those who had the highest daily intake of caffeinated coffee had an 18% lower risk of developing dementia compared to those with the lowest such intake. People who drank the most tea appeared to have a 16% reduced risk.

The study, published in the Journal of the American Medical Association (JAMA), ​also found that those who consumed the most tea and coffee also showed a slower rate of cognitive decline compared to those who drank the least. But decaffeinated coffee was not associated with lower dementia risk or better cognitive performance.

Experts from Harvard University examined data on 131,000 health workers in the US, who were tracked for an average of 43 years. "We observed the most favourable associations were at moderate intake levels - the strongest associations were seen at about two to three cups per day of caffeinated coffee and about one to two cups per day of tea," study leader Dr Daniel Wang of Harvard Medical School said ​in a statement.

But the study does not prove caffeine ‌helps protect the brain. Researchers also concluded the effect of caffeine, if any, was small, and there are ‌other better ways to protect cognitive function as people age.

Lifestyle factors linked with lower risks of dementia include physical exercise, a healthy diet and adequate sleep, according to previous research. Study has 'important limitations' Commenting on the study, Dr Susan Kohlhaas from Alzheimer's Research UK, said the research "doesn't prove that coffee or tea protect the brain".

Professor Tara Spires-Jones, at the UK Dementia Research Institute, agreed there were "important limitations.