Avocado on whole wheat bread isn’t just a staple at trendy brunch spots. It could also be part of a diet to combat Alzheimer’s and dementia.
Scientists who studied the diet and cognitive abilities of more than 3,000 Britons over 70 years have discovered which foods eaten in childhood and young adulthood affect brain function later in life.
They found that diets consisting of unprocessed or less processed leafy greens, beans, whole fruits, and whole grains were the most protective.
Experts linked this to the high concentration of antioxidants and mono- and polyunsaturated fats in these foods, which boost blood flow to the brain and fight harmful substances in the brain.
They found that only seven percent of people who followed such a diet at a young age showed low cognitive ability over the course of the study, which can be a precursor to dementia.
Experts found that diets consisting of unprocessed or less processed leafy greens, beans, whole fruits and whole grains were most protective for our cognitive health
It is currently thought that around 900,000 Britons suffer from the memory-robbing disorder. But scientists from University College London estimate that this number will rise to 1.7 million within two decades as people live longer. It is a 40 per cent increase on the previous forecast in 2017.
In stark contrast, 92 percent of people who ate a lot of salt, added sugars and refined grains such as white bread experienced decreased cognitive ability in older age.
Scientists based their findings on a long-running British study that began in 1946 and followed the diet and health of 3,059 Britons aged four to 75.
During the study, participants’ diets were assessed at five points and their cognitive abilities were tested seven times.
Cognitive ability is a term that describes the strength of a person’s memory and thinking speed.
While cognitive decline occurs naturally as we age, it can also be a sign of conditions such as dementia. A quarter of people with low cognitive ability in the study also showed signs of dementia.
The authors of the new study, who presented their findings at the annual meeting of the American Society for Nutrition in Chicago, acknowledge that the advice to eat more fruits and vegetables is not new.
However, they added that this research suggests that eating these foods at a young age has a longer-lasting protective effect on the brain than previously thought.
Researcher Kelly Cara, a nutrition expert at Tufts University in Boston, said: “These initial findings generally support current public health guidelines that it is important to develop healthy dietary patterns early in life to support and maintain health throughout life.”
‘Our findings also provide new evidence suggesting that improvements in dietary patterns up to middle age may influence cognitive performance and help mitigate or reduce cognitive decline in later life.’
She added that while the findings still need to be peer-reviewed, they do suggest a clear pattern in which foods appear to protect the brain.
“Diets rich in unprocessed or minimally processed plant foods, such as leafy greens, beans, whole fruits, and whole grains, may offer the most protection,” she said.
‘Adjusting dietary intake, regardless of age, to eat more of these foods and to better adhere to current dietary recommendations will improve our health in many ways, including our cognitive health.’
Additionally, researchers found that dietary patterns appear to develop in childhood and continue into later life, for better or for worse.
Fruits and vegetables are generally high in antioxidants. These antioxidants fight unstable atoms called ‘free radicals’ that are thought to damage cells.
Foods rich in monounsaturated fats help lower bad cholesterol levels in the blood. Examples include avocados, peanut butter, and nuts such as almonds.
Polyunsaturated fats have similar benefits and also provide omega-6 and omega-3 fatty acids, essential fats that your body needs. Examples of foods high in polyunsaturated fats include fatty fish such as salmon, some nuts, and tofu.
The researchers rated the diet of the Britons in the study as high or low quality based on the US government’s dietary guidelines.
It recommends that adults generally eat at least two and a half cups (US kitchen measure) of vegetables, two cups of fruit, 170 grams of grains, about 155 grams of lean or vegetable proteins such as beans, and 27 grams (two tablespoons) of oils each day.
An example of this would be an adult who eats in one day 88 grams of broccoli, two medium carrots, 33.5 grams of kale, 210 grams of apples, about four slices of whole wheat bread, and a chicken or fish fillet, plus 27 grams of oil for cooking or salad dressing.
However, the exact amounts vary by food and the calorie intake needs of the individual adult, which differ for men and women.
The NHS guidelines for a healthy diet are broadly similar and encourage adults to eat five portions of a variety of fruit and vegetables every day, starchy carbohydrates such as bread or pasta (preferably wholegrain), 30g of fibre a day, some low-fat dairy products and for protein some beans, pulses, fish, eggs, lean meat (including two portions of fish a week, one of which is fat) and small amounts of unsaturated oils and spreads.
Adults are recommended to consume less than 6 grams of salt and 20 grams of saturated fat for women and 30 grams for men per day.
Authors of the new study noted that the long-term nature of the study meant that there were some gaps and inconsistencies in data collection.
In the UK, an estimated 944,000 people have dementia, while in the US the figure is estimated at around seven million.
Alzheimer’s is the leading cause of dementia, affecting approximately six in ten people with the condition.
This is thought to be caused by a build-up of amyloid and tau in the brain, which clump together, forming plaques and tangles that make it harder for the brain to function properly.
But they can also be a sign of dementia, the memory-destroying condition that affects nearly 1 million Britons and 7 million Americans.
Eventually, the brain can no longer process this damage and symptoms of dementia develop.
The second most common form of dementia is vascular dementia, which involves reduced blood flow to the brain, for example in a stroke.
Memory problems, problems with thinking and reasoning, and language problems are common early symptoms of the condition, which worsen over time.
An analysis by Alzheimer’s Research UK found that 74,261 people will die from dementia in 2022, compared to 69,178 the year before, making it the biggest cause of death in the country.