Constructing a Cognitive Portfolio

Does the fruit-always-better-than-the-juice pan out, though, in terms of brain protection? We have the juice study—what about whole fruits and vegetables?

Using the largest twin registry in the world, researchers concluded last year that “greater fruit and vegetable consumption may lower the risk of dementia and Alzheimer’s disease.” The reason it’s so useful to study twins is that if one gets Alzheimer’s and the other doesn’t, it can give us special insight into environmental and dietary influences, since genetically, twins are so similar. “These findings emphasize the importance of including a greater proportion of fruits and vegetables in the diet for cognitive health.” But which ones are the best?

In 2005, the Harvard Nurses Study reported that high consumption of particularly cruciferous and green leafy vegetables were related to less cognitive decline. But it took until 2010 before dozens of plant foods were tested—all the way down to rutabagas. Now, this was done in Norway. They don’t eat a lot of plant foods in Norway. For example, the average daily bean consumption: 1.3 grams a day. That’s like one bean; maybe half a kidney bean.

They found nearly all plant foods associated with better cognitive performance, including white potatoes, which was a pleasant surprise, and mushrooms. “The only negative cognitive association was [with increased intake] of white bread.” If you look at the data, they actually found negative results with another group of plant foods; not just white bread, but also cakes, pies, and cookies. Just because we’re eating a plant-based diet doesn’t mean it’s a healthy plant-based diet.

Whole fruits appeared to beat out fruit juice; there was a nice dose response with fruits and veggies. The more you eat, the better, especially that first pound every day; apparently, a nice steep rise in benefit before it plateaus out a bit.

And perhaps the most interesting finding: different foods seemed to boost different areas of the brain. For example, total vegetable consumption had the strongest positive associations with executive function, perceptual speed, global cognition, and semantic, or fact-based memory, whereas total fruit intake was more consistently associated with visuospatial skills and autobiographical memory.

So, yes, while carrots and cruciferous cabbage-family vegetables seemed to win out above the rest, we have to eat a variety of whole healthy plant foods, because they each tend to shore up different cognitive domains.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by veganmontreal.

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