Over the course of nine years, people who adhere to a Mediterranean diet are up to 23 percent less likely to develop dementia than people who adhere less well to that healthy diet. This risk reduction was independent of the hereditary predisposition to dementia. The connection rolls out of a large British study that appeared last week in the scientific journal BMC Medicine. It is a solid indication of the importance of a healthy diet in reducing the risk of dementia.
The Mediterranean diet is high in fruits and vegetables, whole grains and legumes, plenty of olive oil, fish and nuts, and low in red meat, dairy and processed foods such as sweets and processed snacks. There are indications that eating according to this eating pattern inhibits cognitive decline. But whether it plays a role in slowing down the disease dementia is not yet clear.
The scientists used the data of more than 60,000 people over sixty who had donated all kinds of medical data and biological samples to the UK Biobank since 2009. Between 2010 and 2012, they had ticked five times on a questionnaire with 238 types of food and drink what they had eaten and drunk in the 24 hours before that measurement. That was representative of their eating pattern in the years that followed, a sample five years later showed.
The researchers used two different score lists to determine to what extent the eating pattern of the participants corresponded to the Mediterranean diet. Participants could score a point per food component if it fell within the healthy Mediterranean diet – for example, one point for at least 400 grams of vegetables per day, at least three pieces of fruit per day, nuts at least three times a week, a glass of soft drink at most once a day, and sweets or pastries less than twice a week.
Alcoholic drink
Wine is a debated part of the Mediterranean diet. With seven or more drinks per week, participants scored a point, and on one of the score lists that was even allowed to be another alcoholic drink. That is remarkable, because the idea that a glass of wine a day is healthy has been abandoned for years. Not drinking alcohol is better.
Hospital and death records up to March 2021 showed that 882 participants developed dementia. The researchers divided the participants into three groups: with a low, an intermediate or a high score. In the group that adhered best to the Mediterranean diet, the risk of dementia was 14 to 23 percent lower than in the group that adhered to it least.
The link also seems to apply to people with a hereditary predisposition to dementia. This needs to be investigated further, previous studies found opposing effects.
A disadvantage of the study is that it only included white British and Irish over-60s from higher socio-economic classes. This is because the measure used for the hereditary risk of dementia only applies to people with a European genetic makeup. The results are therefore not translatable to people with other backgrounds.
Similar effects
It is also not yet clear from the study whether a healthy diet causes the lower risk of dementia. But the results are consistent with those of a other recent study, who found similar effects of two healthy and similar eating patterns, including the Mediterranean, in a completely different way. In it, American scientists examined the brains of 581 people over the age of eighty who had been given annual food questionnaires in the ten years before their death. The researchers counted the accumulations of the proteins beta-amyloid and tau in those brains. These are characteristic of the most common form of dementia, Alzheimer’s disease.
It is not yet clear how a healthy eating pattern could have a beneficial effect on the development of dementia
The healthiest eating group had protein deposits as if they were 12 to 18 years younger than the least healthy eating group. In particular, the brains of people who ate green leafy vegetables at least seven times a week as part of their healthy diet had fewer protein deposits, these researchers found.
It is not yet clear how a healthy eating pattern could have a beneficial effect on the development of dementia. It may be because a healthy lifestyle keeps the heart and blood vessels in good condition. The link between a Mediterranean diet and a lower risk of cardiovascular disease has often been demonstrated.