For many of us, the day doesn’t properly begin until that first cup of tea or coffee. But your morning brew could be doing more than just waking you up. A major study suggests that regular tea and coffee drinkers may also have a lower risk of developing dementia.

Researchers at Harvard University analysed data from more than 131,000 health professionals and found a clear link. Those who drank the most coffee each day had an 18% lower risk of dementia compared with those who drank the least.

Tea drinkers saw similar benefits, too. People who regularly enjoyed a classic ‘builder’s brew’ were found to have a 16% reduced risk.

The long-term study – which followed 86,000 women and 45,000 men over an average of 43 years – also found that regular tea and coffee drinkers tended to perform better in tests of cognitive function than those who rarely drank them.

Coffee’s health credentials have been hotly debated in recent years. Some studies have linked it to poorer sleep, higher blood pressure and higher anxiety levels; these concerns have fuelled a wave of TikTok trends, with users attempting to cut back on their caffeine intake.

In the UK, adults are advised to limit caffeine consumption to a maximum of 400mg per day, roughly equivalent to two strong cups of coffee or six cups of breakfast tea.

If you’re pregnant, the Food Standards Agency recommends slightly less: no more than 200mg.

Alongside finding a link between reduced dementia risk and higher caffeine intake, the researchers were also able to pinpoint the number of cups of tea and coffee each day that could offer associated benefits for brain health.

The Harvard team asked the health workers to fill out questionnaires about their diet every two to four years, including questions about how much caffeinated coffee, decaffeinated coffee and tea they drank.

Alongside this, they got the study group to perform regular cognitive tests – tasks designed to measure how well different parts of the brain are working, such as speed, working memory, attention and decision-making.

During the 43-year follow-up period, the researchers identified 11,033 cases of dementia, an umbrella term for a range of progressive, often degenerative conditions that affect the brain. There are many kinds of dementia, but the most common in the UK is Alzheimer’s disease.

From their findings, the researchers estimated that drinking around two to three cups of caffeinated coffee each day, or one to two cups of tea per day, was linked with the lowest risk of dementia compared to people who abstained entirely.

The health workers who consumed the most tea and coffee also showed a slower rate of cognitive decline compared to those who drank the least.

Overall, the authors said that the most "pronounced association" was among people who drank a "moderate" amount of tea or coffee, with "no additional advantages" among people who consumed more.

Lead author, Yu Zhang from the TH Chan School of Public Health at Harvard University, told the Press Association: "Dementia is one of the most important and challenging public health problems worldwide, and there are still very limited effective treatments.

"So identifying modifiable lifestyle factors that may be linked to dementia risk is critical.

"Coffee and tea are widely consumed globally, so even modest associations could have meaningful population-level implications."

However, Dr Susan Kohlhaas, executive director of research at Alzheimer’s Research UK, urged readers to approach these findings pragmatically: "This research doesn’t prove that coffee or tea protect the brain. This study shows an association, not a cause-and-effect relationship," she said.

"People who drink coffee or tea may also differ in other ways that affect brain health, even after careful adjustment, and the study relied partly on self-reported diagnoses.

"It was also conducted in relatively similar groups of health professionals, which limits how widely the results can be applied."

In recent years, researchers have been taking a closer look into certain foods that might reduce your risk of developing dementia if consumed regularly and in moderation.

For example, a large Swedish study tracking nearly 28,000 people for 25 years recently found an unexpected link between eating full-fat cheese and brain health.

Among adults who didn’t already have a genetic risk for Alzheimer’s, those who added the fridge favourite to their diet (in moderation) had a noticeably lower risk of developing the disease.

Other studies have looked at the impact of wider diet patterns, finding that sticking to a Mediterranean diet – an eating style inspired by European coastal regions that’s loaded with fruits, vegetables, wholegrains, oily fish and some dairy – could reduce dementia risk by up to 23%.

Your age, genes and exposure to air pollution can all increase your likelihood of developing dementia, but the NHS say you can generally reduce your risk by:

Eating a balanced diet

Maintaining a healthy weight

Exercising regularly

keeping alcohol within recommended limits

Stopping smoking

Keeping your blood pressure at a healthy level

Added to this, additional research studies have linked prioritising good oral health, including regular flossing to remove levels of harmful bacteria in your mouth, with a significantly lower risk of cognitive decline.

There’s also strong emerging evidence correlating higher risks of dementia with untreated depression, hearing loss, loneliness (although new research suggests this doesn’t speed up memory decline) and sitting down for large portions of the day.