Neither eating a “conventional diet” or a modified “Mediterranean diet” over years will reduce your probability of developing dementia, according to a 20-year, large-scale Swedish study published Wednesday in the journal of Neurology.
This is valuable knowledge in the context of preventative strategy, given the aging of the global population.
That does not mean diet and all-cause dementia development are definitely unrelated. They may be, but if there’s a link their study didn’t find it.
The only solid fact about all-cause dementia – and diet too – is that the data are all over the place. The team itself points out that different studies have had different outcomes.
Dementia itself is not a specific disease or even a bunch of them. It is a catchall term for mental impairment that impacts day-to-day life. It may ensue from brain damage, including due to substance abuse or even pollution, disease, etc., or just changes in the brain.
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There is also no definition of what the Mediterranean diet is, but for the purposes of the study the team defined specific daily intakes of vegetables and legumes, fruits, vegetable fats (including but not confined to olive oil), dairy, red and processed meats, wine, fish and seafood, nuts and seeds, and saturated fatty acids, even allowing for around 12 grams a day of sweets.
Usually the “Mediterranean diet” relies heavily on olive oil as a fat. But the team points out that it’s rare in the Scandinavian realm – if they’d stuck to that, they wouldn’t have had much of a study group. The subjects were recruited among non-demented individuals in Malmö born between 1923 and 1950, with an average age of 58. Hence, they called it adherence to a “modified” Mediterranean diet.
On the same grounds, the team also excluded sofrito – a “typical Mediterranean” sauce that Nordics aren’t much aware of. In fact, neither are Mediterranean people, that being a delight of Mesoamerican cuisine, but duly noted. By “conventional diet,” they mean adherence to “conventional dietary recommendations.”
The study excluded people whose conditions could have skewed the data, such as diabetics, or people who reported change in relevant dietary habits before their baseline examination.
“Previous studies on the effects of diet on dementia risk have had mixed results,” points out co-author Isabelle Glans. “While our study does not rule out a possible association between diet and dementia, we did not find a link in our study, which had a long follow-up period.”
Inevitably, the work had to rely on self-reporting on adherence to the Mediterranean or conventional diet, and lifestyle (smoking, activity, and so on) by the study participants.
Out of 28,000 people, one can assume that at least some lied – though a 2019 study on mendacity published in PLOS One found that lying in general is the fief of specialists, as it were: a survey of 3,000 participants found that 5 percent of respondents were responsible for over half the lies reported within the previous 24 hours. So, out of the vast Swedish study group, we can assume that most were reliably reporting their long-term eating and lifestyle habits.
The subjects had not been diagnosed with dementia when their study period began. By its end, 1,943 people, or 6.9 percent, had been, which is very roughly in keeping with general population data for the age group.
Or, as said, there may be a link that hasn’t been identified. Some studies indicate, for instance, that long-term carbohydrate and/or sugar-high consumption may increase the risk of cognitive impairment, even if the consumer doesn’t have diabetes.
In an editorial accompanying the paper, Nils Peters of the University of Basel explains that diet alone may not strongly impact the development of dementia, but could well be one of multiple factors that together may influence the course of cognitive function – such as regular exercise, vascular risk, smoking, alcohol and possibly diet. He also points out that the diagnosis of dementia was not based on specific cognitive testing, but on medical information gathered during follow-up.
What is the bottom line? A Mediterranean diet – or in this case, a modified Mediterranean diet – may not reduce your probability of developing cognitive decline; neither will a conventional diet based on government eating recommendations. But it’s now accepted that intense fruit and vegetable consumption more or less à la Mediterranean diets are inversely related to all-cause mortality. Yes, you will die one day, but if you eat lots of fruit and veg, you likely will feel better before you do.