Top Belgian detective Hercule Poirot was convinced fish was good for his “leetle gray cells.” But according to the latest research, he was wrong. The real brain food is anything rich in polyphenols, the micronutrients most commonly found in plant-based foods.
In fact, eating a polyphenol-rich diet reduces your risk of ever developing dementia or Alzheimer’s as you get older.
Medical research has shown time and again that a healthy diet is one of the best ways of warding off cognitive decline—especially since discovering the vital role our gut and the microbiome of bacteria play in brain health. But what does a healthy diet look like, and what should we be avoiding?
Up to now, it’s all been a little unscientific, say researchers from the University of Barcelona who have harnessed metabolomics—a new technology that measures small molecules called metabolites in our blood—to determine the definitive brain-healthy diet, or so they hope.1
They took blood samples from 842 people who didn’t have dementia and tracked their health for 12 years. Those who didn’t develop dementia had higher levels of metabolites generated from polyphenol-rich foods, while those who had started to show early signs of the disease had more metabolites from processed foods and artificial sweeteners.
Even harnessing the latest science still threw up anomalies. For instance, red wine was protective, while alcohol in general wasn’t. Cocoa and coffee also reduced the risk of dementia, but other caffeinated drinks were on the danger list.
Another group of researchers also looked at the influence of diet on dementia—but they used MRI scans to monitor for any brain shrinkage (atrophy) over an 18-month period while participants ate a variety of healthy diets.2
The researchers, from Ben-Gurion University in Israel, put 284 people on one of three diets: a general ‘healthy’ diet, a Mediterranean diet that included eating walnuts, or a ‘super’ Mediterranean diet that also included drinking three to four cups of green tea a day and a daily shake of Mankai duckweed to replace the evening meal.
So, two of the three diets being assessed were rich in polyphenols. And after just 18 months, scans showed the brain had atrophied dramatically in people over 50 who were eating a standard ‘healthy’ diet. But there was hardly any deterioration in the brains of those on either Mediterranean diet, and those on the ‘super’ Med diet had the least shrinkage of all.
So, we’re much closer to understanding what a brain-healthy diet looks like, even if there are anomalies, such as caffeine and alcohol. The answer? More research, the scientists say. Of course, as Poirot might say.
Foods rich in polyphenols, ranked by the amount in each half-cup serving.
* All vegetables contain polyphenols and should be part of any healthy diet. Aim for five to eight servings a day. Here are the vegetables and other foods with the highest polyphenol content per serving.
Mol Nutr Food Res, 2021; 65(23): e2100606
Am J Clin Nutr, 2022; nqac001