For millions a strong coffee is the perfect start to the day.

But today, new research suggests coffee could also protect against dementia.

Drinking between three and five cups a day could cut the chance of developing Alzheimer's disease by up to 20 per cent, scientists said.

Nutrition can play an important role in preserving memory and thinking skills, especially during the phase of Alzheimer's disease before symptoms of dementia occur.

This is according to a report published by the Institute for Scientific Information on Coffee, who are funded by major European coffee companies such as illycaffe, Nestlé and DE Master Blenders.

However, experts from leading charities Alzheimer's Research UK and Alzheimer's society today warned the research does not conclusively prove drinking coffee can prevent Alzheimer's, because no clinical trials have been carried out.

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Experts found that those who drink between three and five cups of coffee a day could cut the chance of getting Alzheimer's disease by up to a fifth thanks to the ingredients the beverage contains (file picture)

The number of cases of dementia is set to triple by 2050, totalling 115.4 million worldwide, and Alzheimer's disease will make up the majority of these cases, according to World Health Organisation predictions.

The new report presents new research explaining how diet can affect the development of the disease.

A Mediterranean diet, consisting of fish, fresh fruit and vegetables, olive oil and red wine, has been associated with a reduced risk for development of Alzheimer's disease, it argued.

Research suggests that compounds called polyphenols are responsible for this protective effect; compounds also found in high quantities in coffee.

Other studies cited in the report found regular, life-long moderate coffee consumption is associated with a reduced risk of developing Alzheimer's disease.

Dr Iva Holmerova, vice chairman of Alzheimer Europe, said: 'The findings presented in this report are very encouraging.

'Coffee is a very popular beverage enjoyed by millions of people around the world and I'm pleased to know that moderate, lifelong consumption can have a beneficial effect on the development of Alzheimer's disease.

'Cognitive decline is a feature of ageing, and although some changes can be expected in all of us, there is some evidence that diet and lifestyle may be related to cognition.'

A recent study, suggested that moderate coffee consumption was associated with a lower risk of developing dementia over a four year follow-up period, however the effect diminished over longer follow up period.

Caffeine helps prevent the formation of amyloid plaques and neurofibrulary tangles in the brain - two hallmarks of Alzheimer's Disease, it said.

In addition to this, both caffeine and polyphenols reduce inflammation and decrease the deterioration of brain cells - especially in the hippocampus and cortex, areas of the brain involved in memory.

The report, released by the Institute for Scientific Information on Coffee, suggested that moderate coffee consumption was associated with a lower risk of developing dementia over a four year period (file picture)

Dr Arfram Ikram, from the Erasmus Medical Centre Rotterdam, presented his findings at the symposium.

He said: 'The majority of human epidemiological studies suggest that regular coffee consumption over a lifetime is associated with a reduced risk of developing Alzheimer's disease, with an optimum protective effect occurring with three to five cups of coffee per day.'

But Dr Simon Ridley, of Alzheimer's Research UK, the UK's leading dementia research charity, said clinical trials are needed to prove a link between drinking coffee and a reduced risk of developing Alzheimer's disease.

He said: 'Although some studies have suggested a possible link between coffee consumption and lower dementia risk, there is currently not enough evidence to be able to draw firm conclusions about its effects.

'Many studies that have investigated these links have been observational studies, which are not able to tell us definitively whether coffee can prevent or reduce the risk of Alzheimer's.

'While many of us enjoy a cup of coffee now and again, we'd need to see clinical trials to know whether the drink could prevent Alzheimer's disease.

'With half a million people currently living with Alzheimer's in the UK and that number set to increase, we must invest in research to find ways of preventing the disease.

'In the meantime, current evidence suggests that we can lower our risk by eating a healthy, balanced diet, doing regular exercise, not smoking, and keeping blood pressure and weight in check.'

Jess Smith, of Alzheimer's Society, echoed comments that the evidence is not conclusive.

She said: 'The evidence is not conclusive that drinking coffee will help to protect against Alzheimer's disease.

'Some research suggests that caffeine and antioxidants in coffee may be beneficial but studies in people show mixed results - more research and clinical trials are needed to see if positive effects occur in people over the long term.

'There is no single way to reduce your risk of dementia.

'Exercising frequently, as well as eating a healthy balanced diet, avoiding smoking, not drinking in excess, and managing other health conditions can play a role in reducing your risk of dementia.'

Meanwhile Professor John Hardy, Professor of Neuroscience, UCL, added: 'This type of study needs both replication and assessment for the possibility/probability of confounding variables to do with other aspects of lifestyle.'

The report also highlighted the role nutrition can play in preserving cognitive function, especially during the pre-clinical phase of Alzheimer's, before symptoms of dementia occur.

It found that a Mediterranean diet, consisting of fish, fresh fruit and vegetables, olive oil and red wine, has been associated with a reduced risk of developing Alzheimer's.

The research and key findings were originally presented at the Alzheimer's Europe Annual Congress in Glasgow last month before being officially released today.

Alzheimer's affects one person in 20 over the age of 65, amounting to 26 million people worldwide.

In Britain alone, 850,000 people are affected by dementia, with 60 per cent of those suffering from Alzheimer's.