I finally went to Amazon.com yesterday and skimmed through the book Grain Brain. The author, Dr. Perlmutter, is an award-winning, practicing neurologist. The book was a number one New York Times bestseller. Perhaps he has something to say.

Grain Brain: The Surprising Truth About Wheat, Carbs, and Sugar – Your Brain’s Silent Killers, by David Perlmutter and Kristin Loberg, September 2013

With “grain” in the title, I assumed the book was about avoiding gluten, a protein found in some grains. Was Perlmutter going to argue that gluten impacts neurological function? The full title, which I just saw now, is telling me it isn’t about gluten, not exclusively. It’s about carbohydrate.  So, is he arguing that dietary carbohydrate impacts neurological function? Any food with carbohydrate in it? Quinoa? Rice? Beans? Apples? Carrots? Lemons? Potatoes? Just about all plant foods contain carbohydrate.

Here’s what I found from Amazon’s “Look Inside”

Modern grains are silently destroying your brain. … I’m referring to all the grains that so many of us have embraced as being healthful – whole wheat, whole grain, multigrain, seven-grain, live grain, stone-ground, and so on.

I will demonstrate how fruit and other carbohydrates could be health hazards.

… An extremely low-carbohydrate but high-fat diet is ideal (we’re talking no more than 60 grams of carbs a day – the amount in a serving of fruit). This may also sound preposterous, but I’ll be recommending that you start swapping out your daily bread with butter and eggs. You’ll soon be consuming more saturated fat and cholesterol and re-thinking the aisles in your grocery store.

In the days leading up to your new way of eating, you’ll want to take an inventory of your kitchen and eliminate items that you’ll no longer be consuming. Start by removing the following … All forms of processed carbs, sugar and starch: corn, yams, potatoes, sweet potatoes.

The following can be used in moderation (“moderation” means eating small amounts of these ingredients once a day or, ideally, just a couple times weekly):
– Carrots and parsnips.
– Legumes (beans, lentils, peas).
– Non-gluten grains. (Avoid oats entirely.)
– Whole sweet fruit: Berries are best; be extra cautious of sugary fruits such as apricots, mangoes, melons, papaya, prunes, and pineapple.

I’m going to rescue you from a lifetime of trying to avoid eating fat and cholesterol and prove how these delicious ingredients preserve the highest functioning of your brain. … Our bodies thrive when given “good fats,” and cholesterol is one of these. And we don’t do so well with copious amounts of carbohydrates, even if those carbs are gluten-free, whole grain, and high in fiber.

Eating high-cholesterol foods has no impact on our actual cholesterol levels, and the alleged correlation between higher cholesterol and higher cardiac risk is absolute fallacy.¹

You will be starting a daily supplement regimen for life. [Perlmutter sells supplements on his site.]

Yes, Perlmutter is saying that any intake of carbohydrate, beyond the 60 or so grams in a piece of fruit, impairs brain function. It’s evident that Dr. Perlmutter’s food journey and mine have led to drastically different diets. (At least he allows small amounts of beans. On a Paleo diet, you have to avoid them at all costs, even fresh green beans.)

Here’s a comment by srj, who claimed to be a physician. It’s representative of other comments which call into question Perlmutter’s treatment of the evidence:

“I quit reading about half way through the book because in almost every case he badly misinterpreted the studies he quoted. As an example, reference 25 in Chapter 4 (Title: Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance) compared people on a high glycemic diet, a low glycemic diet (whole grain) and a very low carbohydrate (high fat/meat) diet. This study did show a slight improvement in metabolic syndrome components in the low carb diet over the low glycemic diet, but the low carb diet raised cortisol and CRP (C-Reactive Protein) levels considerable. Previous studies have shown a 5-fold (that’s 500%!) increase in cardiovascular mortality with the higher levels of cortisol and CRP and thus the conclusion of the study authors was that the low carb diet was too dangerous to recommend. The only part of the study reported by Dr. Perlmutter was that that the metabolic syndrome parameters were better – nothing about the cortisol and CRP elevation which was far more important.”

I’m surprised at the assurance with which Perlmutter advances his ideas. Dr. David Katz, founding director of Yale University’s Prevention Research Center, criticized Grain Brain, saying many of its claims were “wildly preposterous,” particularly the one where Perlmutter says the ideal diet “is close to that of the Paleo diet: 75% fat, 20% protein, and 5% carbs.” Katz, citing work of researcher and “The Paleo Diet” author Lorin Cordain, said that humans during the Paleolithic Era ate mostly plants with a scattering of seeds and nuts. … “What the hell could they possibly have eaten that would be that fatty?”²

Maybe we’re all a little guilty of focusing on science that supports our preconceptions and glossing over that which challenges them. It’s our prerogative. Most of us aren’t writing books, selling products, and collecting consulting fees. Don’t you think that someone who is presenting himself as an authority, who claims to be science-based, who is urging millions of people to adopt a controversial diet, would be more even-handed with the evidence? I do. The reason I support eating a whole-food, plant-based diet is because I’ve read the studies, not because I’ve read a book by someone claiming to have read the studies for me.

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¹ This particular claim has been exhaustively researched by a blogger who goes by Plant Positive. He refers to people who reject the lipid hypothesis, as Perlmutter does here, as cholesterol deniers. He’s amassed a trove of evidence that defends the lipid hypothesis, that defends the correlation between serum cholesterol and heart disease, i.e. the lower your cholesterol, the lower your heart disease risk.
² James Hamblin’s skepticism is wholly transparent in his Atlantic article, “This Is Your Brain On Gluten.“)