Drinking tea and red wine with plenty of kale could slash the risk of Alzheimer’s disease, a study suggests.
The products are rich in chemicals called flavonols, among many other nutrients which may support brain health.
Researchers at Rush University in Chicago tracked more than 900 older people for up to 12 years after asking them about their diets.
Those who consumed the most flavonols – around one cup of black tea a day – were half as likely to develop Alzheimer’s.
Olive oil, pears, oranges and broccoli were among the most beneficial foods to ward of the memory-robbing disease.
However, independent experts said there was no need for people to overhaul their diet because the findings are not definitive.
Lead author Dr Thomas Holland said: ‘More research is needed to confirm these results, but these are promising findings.
‘Eating more fruits and vegetables and drinking more tea could be a fairly inexpensive and easy way for people to help stave off Alzheimer’s dementia.
‘With the elderly population increasing worldwide, any decrease in the number of people with this devastating disease, or even delaying it for a few years, could have an enormous benefit on public health.’
In the first analysis of its kind the flavonols were broken down into four different types – kaempferol, isorhamnetin, myricetin and quercetin.
In particular kaempferol – abundant in leafy green vegetables like spinach, broccoli and kale as well as tea – slashed the risk of dementia by 51 per cent.
Diets packed with isorhamnetin – found in olive oil, red wine, pears and tomato sauce reduced the risk by 38 per cent, as did myricetin, found in tea, kale, oranges, tomatoes and red wine.
Quercetin, found in apples, had no effect.
In the study published in Neurology, 921 people with an average age of 81 filled out a questionnaire each year on how often they ate certain foods.
They were followed for an average of six years, up to 12 years, with annual checks to see if they had developed Alzheimer’s. Some 220 were diagnosed.
Those who consumed the most of 15.3milligrams (mg) per day – around the same amount in a cup of black tea – were 48 per cent less likely to be struck down by Alzheimer’s than those who consumed the least, of about 5.3mg per day.
This was after taking into account genetic pre-disposition and demographic and lifestyle factors.
Of the 186 people in the highest group, 28 were diagnosed with dementia (15 per cent). This compares to 54 (30 per cent) of the 182 in the lowest group.
The results were the same after researchers adjusted for health problems that could affect the risk of Alzheimer’s such as diabetes, a previous heart attack or stroke and high blood pressure.
Dr Holland said: ‘Our findings suggest dietary intake of flavonols may reduce the risk of developing Alzheimer’s dementia.
‘Flavonols are known to have antioxidant and anti-inflammatory properties.’
The Alzheimer’s Society says high levels of antioxidants may help to protect against some of the damage to brain cells associated with the disease.
Inflammation – in the form of a chemical change in the brain – is closely tied with Alzheimer’s, therefore a diet high in antioxidants is believed to help reduce the risk.
But not all experts are in agreement – Dr Ada Garcia, a lecturer in public health nutrition, University of Glasgow, said antioxidants are not a ‘magic pill’ against dementia.
She said: ‘The general public might interpret this study wrongly and think about the term “antioxidant” as a magic pill that will prevent the onset of dementia.
‘It is important to remember that consuming isolated flavonols or extracts of flavonol rich foods, for example tea extracts, will not work on isolation to reduce risk of disease.
‘High doses can also have negative effects on health.’
Professor Gunter Kuhnle, nutrition and food science at University of Reading, said: ‘There are a lot of misunderstandings regarding flavonols and flavonoids.
‘They do not act as antioxidants in the human body. This was believed decades ago, but a better understanding has shown that once they are taken up by the body, they can no longer act as antioxidant.’
Adults in the UK consume around 30mg of flavonols each day, Professor Kuhnle said. For US and European adults, the average daily intake of flavonols is about 16 to 20mg.
Those who eat high quantities are likely to also be eating other chemicals in abundance, which cannot be ruled out as the reason for the findings.
Dr Ana Rodriguez-Mateos, a lecturer in nutritional sciences, Kings College London, said it’s ‘more feasible’ the observed effects are related to other chemicals.
She said: ‘Flavonols tend to be present in foods in much lower amounts than other phytochemicals. The amount of flavonols in such foods are tiny.’
There is good evidence that a healthy lifestyle can help reduce your risk of developing dementia when you’re older, according to the NHS.
Dr James Connell, from Alzheimer’s Research UK, said: ‘While we don’t know whether flavonols could have any particular effect on dementia risk, a balanced diet with plenty of fruits and vegetables can help to support a healthy brain.’
More than six in ten people with dementia have Alzheimer’s, making it by the far the most common form of the disease.
There are more than 520,000 sufferers in the UK alone. Symptoms are wide-ranging and worsen over time, and include memory loss and confusion.
By 2050 around two million Britons will be living with Alzheimer’s and other types of dementia.
The Alzheimer’s Society say dementia is set to be the 21st Century’s biggest killer. With no way yet to cure it, ‘prevention is key’.
Alzheimer’s Research UK says the Mediterranean diet, which is rich in fruit, vegetables and olive oil, can support healthy brain ageing.
SOURCE: Daily Mail, Vanessa Chalmers