Book Review of Grain Brain: Extraordinary claim not backed up by evidence

[ This is my book review of David Perlmutter’s (2013) Grain Brain: The Surprising Truth about Wheat, Carbs, and Sugar–Your Brain’s Silent Killers.

And hey, if you want to believe in silly dietary notions despite all the peer-reviewed evidence, I already there’s no talking you out of it!  This is a god damned religion.  Check out the comments at my Amazon book review here.

At worst, strange diets can lead you to a Darwin Award, but more likely simply a shorter, less healthy quality of life.

Alice Friedemann  author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report ]

Update February 2014: Diabetes is usually triggered by eating too many sugary and high-fat foods that cause insulin to spike, desensitizing cells to its presence. As well as causing obesity, insulin resistance can also lead to cognitive problems such as memory loss and confusion. To investigate whether beta-amyloid might also be a cause of cognitive decline in type 2 diabetes, scientists fed 20 rats a high-fat diet to give them type 2 diabetes. These rats, and another 20 on a healthy diet, were then trained to associate a dark cage with an electric shock. Whenever the rats were returned to this dark cage, they froze in fear – measuring how long they stayed still is a standard way of inferring how good their memory is.  As expected, the diabetic rats had weaker memories than the healthy ones – they froze in the dark for less than half the time of their healthy counterparts. You can read all the details at NewScientist in Are Alzheimer’s and diabetes the same disease? 28 November 2013 by Jessica Griggs

Update December 2013: The Atlantic Monthly has just published an article about this book called “This Is Your Brain on Gluten” by James Hamblin. Below are some excerpts:

1) “In the Paleolithic Era, human life expectancy was around 30 years… humans did not live past their 50s. I wonder often why these are the times we cite as a standard of health. The paucity of old age should in itself explain why Alzheimer’s and cardiovascular disease were basically nonexistent”

2) Dr. David Katz is an epidemiologist who has published two editions of a nutrition textbook for healthcare professionals called Nutrition in Clinical Practice. Perlmutter estimates the Stone Age diet was 75% fat, a claim Dr. Katz finds “wildly preposterous. Anthropological research… suggests that in the age before cooking oil, humans ate mostly plants with a scattering of seeds and nuts. Virtually nothing in the natural world is that concentrated of a fat source, except maybe for the brain. Maybe if they just ate the brains of animals? They didn’t have oil. They only started adding oil to the diet after the Dawn of Agriculture. What the hell could they possibly have eaten that would be that fatty?’”

I have an excellent example of how absurd Perlmutter is to say our diet used to be 75% fat. In the amazing chronicle of Lewis and Clark Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West, venison and elk meat was so lean (per 3.5 ounces: 4% fat, versus 35% fat in beef), that even though each expedition member ate up to 9 pounds of meat a day,…they were still hungry (p 165). Later in the book, Lewis remarks “that he didn’t care what kind of meat he got, whether elk or dog or horse or wolf, so long as it was fat”. Sacagawea brought the men some roots to eat which was a welcome addition to “the virtually all-meat diet…which if not complemented by other food might lead to scurvy, … the men of the expedition at various times did suffer from scurvy. It was an age in which almost nothing was known about a balanced diet.” A diet that sounds a lot like what Perlmutter is recommending!

3) Dr Katz goes on to say that Perlmutter’s “book is filled with a whole bunch of nonsense, that’s why it’s a bestseller. …That’s how you get on the bestseller list. You promise the moon and stars, you say everything you heard before was wrong, and you blame everything on one thing. You get a scapegoat; it’s classic. Atkins made a fortune with that formula. we now have Perlmutter saying it’s all grain. There’s either a scapegoat or a silver bullet in almost every bestselling diet book. The recurring formula is: Tell readers it’s not their fault. Blame an agency; typically the pharmaceutical industry or U.S. government, but also possibly the medical establishment. Offer a simple solution. Cite science and mainstream research when applicable; demonize it when it is not.

Dr. Katz gives Perlmutter too much credit for the few scientific citations he has — if he had read the papers cited (I read all of the original papers), he would have discovered that they do NOT support Perlmutter’s claims about whole grains and dementia (which is what my review below focuses on since it would take a book to refute every piece of nonsense — See #10 below).

4) Perlmutter’s advice is POTENTIALLY LETHAL. Hamblin asks: “What is the worst that can come of avoiding gluten and limiting carbs? That depends entirely on what you replace those calories with. I read the book with an eye for the most dangerous claim. What stuck out to me was Perlmutter’s case for cholesterol. He basically says that we can’t have too much. Beyond that, Perlmutter says that cholesterol-lowering statin medicines like Lipitor, which are prescribed for a quarter of Americans over 40, should actually be vehemently avoided. Cholesterol is necessary for the brain in high levels, he says, and lowering it is contributing to dementia. Dr. Katz replies: “..can we totally ignore both dietary cholesterol and LDL? Absolutely not…Ignoring LDL could absolutely result in heart attacks and strokes”. Katz acknowledges that dietary cholesterol may be an innocuous part of an overall healthy diet. “The problem is that people are going to get their dietary cholesterol from things other than fish and eggs; they’re going to get it from meats and dairies. The problem with diets like that is if you eat more of A, you’re probably going to eat less of B. So people who are eating more meat and dairy and high-fat, high-cholesterol foods are eating fewer plants–they’re not eating beans; they’re not eating lentils. So yes, I think it’s entirely confabulated and contrived, and potentially dangerous on the level of lethal.”

5) “We do not have reason to believe that gluten is bad for most people. It does cause reactive symptoms in some people. Peanuts can kill some people, but that does not mean they are bad for everyone. Diets consistently shown to have good long-term health outcomes—both mental and physical–include whole grains and fruits, and are not nearly as high in fat as what Perlmutter proposes. I hope people don’t give up on nutrition science, because there is a sense that no one agrees on anything. An outlier comes shouting along every year with a new diet bent on changing our entire perspective, and it’s all the talk. That can leave us with a sense that no one is to be believed. When a person [like Perlmutter] advocates radical change on the order of eliminating one of the three main food groups from our diets, the burden of proof should be enormous. Everything you know is not wrong.”

At the New York Times, this book was the #1 best seller in the Dining list and #9 in the Advice, How-To & Miscellaneous list in November 2013.

Dr. Oz endorses this book on the front cover with the blurb “An innovative approach to our most fragile organ” and on the back cover he says “Dr. Perlmutter is an absolute leader in the use of alternative and conventional approaches in the treatment of neurological disorders. I have referred patients to him with wonderful results”.

Dr. Perlmutter was practically unknown until Dr. Oz discovered him.  He is touted as a “board certified neurologist”.

One of the few references I could find to his past was his presentation of “Mitochondrial Therapy – A Powerful Approach to Brain Functional Enhancement” at the 17th Annual World Congress on Anti-Aging and Regenerative Medicine in  2009. This presentation explored “the body of science validating the use of specific oral supplements targeting mitochondrial functional preservation and enhancement including coenzyme Q10, acetyl L-carnitine, and N-acetyl cysteine and intravenous therapy with glutathione”.

Whole grains cause dementia?

The title “Grain Brain. The Surprising Truth About Wheat, Carbs, and Sugar – Your Brain’s Silent Killers”, and front cover blurb “carbs are destroying your brain. And not just unhealthy carbs, but even healthy ones like WHOLE GRAINS can cause dementia, ADHD, anxiety, chronic headaches, depression, and much more”  lead you to expect new scientific discoveries have found a connection between eating whole grains and all sorts of other major diseases.

Wow! This is such an incredible claim.  And there is not one shred of evidence in the book to back it up.

#1 If whole grains caused dementia etc., it would be headline news in medical journals, the New York Times, and TV news.  

But it isn’t.

#2  Perlmutter provides no evidence to support his idea. None.

Perlmutter hasn’t published peer-reviewed papers about anything –not in his field of neurology our outside of his field in nutrition.

To prove his point, he often cites what he calls a Mayo clinic paper in Grain Brain, TV, radio, and internet articles. He says that “Relative Intake of Macronutrients Impacts Risk of Mild Cognitive Impairment or dementia”, shows people favoring carbohydrates in their diet had an 89% increased risk of developing dementia. But those who ate the most fat had a 36% reduction in risk.

Not true.  In this study:

  • No one developed dementia.
  • Mild Cognitive Impairment (MCI) is a controversial diagnosis. It just means someone has mild problems with language, thinking, memory and judgment. Many physicians think these are normal symptoms of aging.  MCI often goes away.  Most people diagnosed with MCI do not go on to develop dementia or Alzheimer’s.
  • The words “whole grain” or “whole wheat” do not appear in this study.  No effort was made to distinguish healthy whole grains from refined carbohydrates.
  • This was an observational study.  It can only show a correlation between two things, not cause-and-effect.  There could be other factors in the participants’ lives that explain the results.
  • The subjects self-reported their dietary intake. Its well-known people aren’t good at this.

There are only 7 peer-reviewed references in Grain Brain that have anything to do with both carbohydrates and dementia.  Not one of these papers mentions whole grains or whole wheat. Two of the papers apply only to the 1% of the population with Celiac Disease.  Five of these 7 papers apply only to people with celiac disease or gluten sensitivities (at most 6 to7% of the U.S. population).

Perlmutter says that because 70% of our brains are fat, we should be getting 50-60% of our calories from fat.  That’s more than twice what the Mayo Clinic and every other expert says.  They all recommend 20-35% of total daily calories from fat, 45-65% of your daily calories from carbohydrates, and 10-35% of calories from protein (Zeratsky, Mayo Clinic Staff, U.S. Dept of Health and Human Services).

Goodbye nutrition, hello cardiology.

I know people are really angry that sugar and white flour may be as bad as fat, but that doesn’t mean going to the other extreme and eating so much fat you’ll get a heart attack.

Perlmutter cites studies to show fat prevents dementia, but if you actually read these studies (free and available online), it backfires.  He advises not eating much fruit, yet the conclusion of one of the papers “Dietary Patterns and Risk of Dementia: The Three-city Cohort Study” concluded “Frequent consumption of fruits and vegetables, fish, and omega-3 rich oils may decrease the risk of dementia and Alzheimer disease”.

At his website he cites “Evidence-Based Guideline of the German Nutrition Society: Carbohydrate Intake and Prevention of Nutrition-Related Diseases”.  Oops again. Perlmutter spends a lot of time trying to show that carbohydrates (and therefore whole grains) lead to diabetes, which leads to dementia), but this paper says the opposite: “a high dietary fibre intake, mainly from whole-grain products, reduces the risk of obesity, type 2 diabetes, cardiovascular disease and colorectal cancer”.

#3 On the other hand, there is a lot of evidence showing that whole grains are really good for you

Thousands of peer-reviewed studies in scientific journals over many decades show whole grains can reduce heart disease and certain types of cancer, among other diseases..

The main cause of death in America and most of the world is heart disease. One of the few health claims the FDA allows is “Diets rich in whole grain foods and other plant foods, and low in saturated fat and cholesterol, may help reduce the risk of heart disease.” (FDA Health Claim).

The March 2008 issue of Consumer Reports says that eating whole grains is the #1 action you can take to improve your health (besides quitting smoking).

According to the World Health Organization Global Burden of disease 2010 study, the 16th leading cause of early death and disability is not eating enough whole grains (The Lancet).

In 2004 (Nutrition Research Reviews 2004), Dr. Joanne Slavin of the University of Minnesota published a comprehensive article that reviewed and compiled scores of recent studies on whole grains and health, to show how whole-grain intake is protective against cancer, cardiovascular disease, diabetes and obesity.

In 2010, the American Society for Nutrition brought researchers together to review the evidence of whole grain health benefits. Current scientific evidence shows that whole grains play an important role in lowering the risk of chronic diseases like coronary heart disease, diabetes, and cancer, and also contribute to body weight management and gastrointestinal health. The findings were published as a supplement to The Journal of Nutrition in 2011.

#4 The Mediterranean diet has lots of whole grains

People eating a Mediterranean diet are among the longest-lived on earth and they’ve been studied for decades. Italy has the 4th longest lifespan in the world!

These diets have lots of carbohydrates and lower dementia, heart attacks, blood pressure, cancer, and strokes.

U.S. News and World report has ranks diets from best to worst.  All of the top diets recommend whole grains ( Mediterranean diet, Mayo Clinic, DASH, and TLC).  Diets were ranked by 22 experts including many physicians and nutrition professors based on: how easy to follow, short and long-term weight loss, nutritional completeness, safety, and prevention of  diabetes and heart disease. The Paleo diet came in last, and Atkins was also very close to the bottom.  This is actually a Paleo book, and I don’t have time to debunk all the myths of this practically-a-religion-diet, but if you’re interested, I highly recommend Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live.

#5 We already know what the causes of dementia and Alzheimer’s are from tens of thousands of studies. Whole grains have nothing to do with it.

The risks are: Being over 65, genetic (5%), female (women live longer), severe or repeated head trauma, lack of exercise, smoking, high blood pressure, high blood cholesterol, poorly controlled diabetes, not enough fruits & vegetables, lack of social engagement. You’re at lower risk the more education you have, a good job, have mentally challenging hobbies like reading or playing a musical instrument, and lots of social interactions.

#6 Grains are the basis of civilization. Over the past 10,000 we evolved to eat grain. So did dogs.

Our genetics have even changed to adapt to eating grains — those with ancestors from a farming region have up to 7 times as many amylase genes to digest starch as a hunter-gatherer gene (Perry, Hancock).  Cochran’s book The 10,000 Year Explosion: How Civilization Accelerated Human Evolution makes the case we evolved faster the past 10,000 years to adapt to agriculture than we did the previous 6 million years.
One of the top peer-reviewed science journals in the world, Science, has a 2013 article titled “Diet Shaped Dog Domestication”. DNA from wolves and dogs was compared and it was clear that dogs had evolved to digest starch 5 times better than wolves.


#7 Even before agriculture most people ate a lot of carbohydrates

In California, half the diet of most hunter-gatherer tribes was acorns. Tribes across America depended heavily on acorns, as well as tribes across the Eurasian continent. Acorns are 43% carbohydrate.
Bits of starch grains have been found on the grinding stones from 30,000 year old sites in Italy, Russia, and the Czech Republic, where our ancestors made flour from ground up plants, combined it with water and made a pita bread on stones heated in fires. Our ancestors were smart to grind roots so the flour could be stored or carried, since often game animals were seasonal and no meat was to be had many times of the year.

Eating carbohydrates could go back for millions of years. Fossil hominids had such sturdy premolar teeth it’s believed they were probably used to open seeds and chew starchy underground tubers and bulbs. Even Neanderthals ate starch, which we know from studying the plaque on their teeth.

Anthropologist Frank Marlowe studied the eating patterns of 478 groups around the globe. He found that no matter where you live, at least a third of your diet is going to come from plants (and in many places nearly all of your diet), so the idea our ancestors were mainly carnivorous is not true.

#8 Did Perlmutter single-handedly disprove decades of peer-reviewed studies about whole grains, the causes of dementia and Alzheimer’s, and that high fat diets do NOT lead to heart disease? 



#9 Testimonials are not proof. Only peer-reviewed science in top-tier journals counts

Testimonials are NOT SCIENCE –and Dr. Perlmutter MUST know this if he has an advanced degree. Only peer-reviewed science counts. Most of Perlmutter’s “proof” are the testimonials of his own patients.

#10 Comparing whole grains to refined carbohydrates is like comparing wild Alaskan King Salmon to deep-fried Spam (sorry Hawaii)

If Perlmutter had read any nutrition textbooks, or even done a simple internet query, he would have quickly and easily discovered how healthy whole grains are.  How could he possibly say that whole grains are as bad as refined carbohydrates like white flour for your health?  He doesn’t have any evidence for that in his book or at his websites.

Whole grains are alive.  They’re seeds – full of all the nutrition a baby plant needs to grow. They’re like mini-vitamin pills, one of the densest sources of nutrition on the planet. Bread wasn’t called the staff of life for nothing.

White flour is unhealthy, nutritionally bankrupt, stripped of all fiber, most protein, vitamins and minerals.  Why isn’t that a crime?

White flour has had the bran and germ removed so it’s just a starch. It no longer behaves like flour, so up to 30 chemicals are added (many of them banned in Europe). White flour has no fiber, up to 88% of 21 vitamins and minerals are removed (they’re mostly in the missing bran & germ), all the essential healthy oils, phytochemicals, and most of the protein too.

David Kessler, former head of the FDA, writes in The End of Overeating: Taking Control of the Insatiable American Appetite that more than any other product, baked goods have more sugar, salt, and fat than other products to hide these sour, bitter chemical flavors.


#11     7 Billion people can’t be wrong!

4.6 Billion people get most of their calories from carbohydrates.  The other 2.4 Billion of us, the wealthiest third, get about half our calories from carbohydrates.

Meat, seafood, dairy products, fresh produce, and fruit are expensive.  They need refrigeration, which will only last as long as fossil fuels provide reliable electricity 24 x 7.   After that, all 7 billion of us will get most of our calories from grains and legumes (carbohydrates), just like we have for ages.

Civilization depends on grains and legumes because they can be stored for many years and outlast bad harvests.  As climate change makes growing food less reliable, we’ll be more dependent on grains than past civilizations were.

#12 Why are not just quacks, but a tiny number of legitimate nutrition professors attacking whole grains?

When you look into it, the only criticism a few actual experts make is that whole grains have a high glycemic index.  They are criticized by their colleagues, much as climate scientists dismiss climate change deniers, because they only have this one argument. They totally avoid mentioning that whole grains have fiber, protein, vitamins and minerals that don’t exist in white flour.  Instead, they say whole grains and white flour are equal because they both have a high glycemic index.

But that’s not true.  You don’t eat bread or cereal alone.  Sandwiches have butter, lettuce, tomatoes, ham; cereal has nuts, milk, and/or fruit. The additional ingredients, or any other food eaten with bread or cereal lowers the glycemic index.
I can’t prove it, but I suspect industrial food companies are funding scientists to speak out against whole grains.

Why?  The basis of processed food is cheap ingredients. Fat, sugar, salt and white flour are almost as cheap as water. Michael Moss writes about this in Salt Sugar Fat: How the Food Giants Hooked Us .  The multi-billion dollar food industry also hates whole grains because they have a shorter shelf-life than white flour.
So if there’s anyone who makes money off of attacking whole grains, it would be the processed food industry.

They’d do it by making lucrative engagements available to scientists who criticize whole grains by paying them a lot to speak at conferences and on TV and radio shows.

You can find many examples of how this is done in Bending Science: How Special Interests Corrupt Public Health Research and Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming

I also wonder who paid Amazon to give 19 Amazon Vine Reviewers free copies of Grain Brain a month before the book was published.  On the main amazon page for Grain Brain, the first three customer reviews are all by Amazon Vine reviewers (and they each gave the book five-stars).  The odds are really good that these early Amazon Vine reviews would stay at the top, where everyone  seeS them, because the “Most Helpful Customer Reviews” are shown first, and people are most likely to vote for the reviews at the top.  My review has been found helpful by 239 of 318 people and gotten 37 mostly angry comments that attack me with straw man and ad hominem fallacies, with a good measure of hostile vituperation. But so far, no comments have provided any peer-reviewed evidence.

#13 Perlmutter knows other factors are to blame

Most of Grain Brain is about getting exercise, sleep and other topics.   But not grains and brains.



It’s too much work to separate the wheat from the chaff in this book.

The only way to protect yourself from quacks is to know what we know and how we know it by reading books and articles based on peer-reviewed science.

There are a lot of good books at the library, or free information at medical websites like the Mayo Clinic, the U.S. Dept of Health and Human Services publication  Dietary Guidelines for Americans 2010, or nutrition textbooks like Nutrition for Health and Health Care that are based on evidence from peer-reviewed science.


FDA Health Claim §101.77   Health claims: fruits, vegetables, and grain products that contain fiber, particularly soluble fiber, and risk of coronary heart disease.

Hancock, A. M., et al. “Colloquium Paper: Human Adaptations to Diet, Subsistence, and Ecoregion are Due to Subtle Shifts in Allele Frequency,” Proceedings of the National Academy of Sciences 107:8924–8930 (2010).

Mayo Clinic staff. Healthy diet: do you follow dietary guidelines? Get the scoop on dietary guidelines for key nutrients, such as carbs, protein, fat, sugar, and salt.

Perry, G., et al. Diet and the evolution of human amylase gene copy number variation. Nature genetics 39 (2007).

The Lancet. Global Burden of Disease Study 2010.  December 2012.

U.S. Dept of Health and Human Services.  Dietary Guidelines for Americans 2010.

Zeratsky, K. to monitor how much fat I eat each day, which should I focus on—fat grams, calories, or percentages.


What the Whole Grains Council had to say about this book:

Celiac disease and gluten intolerance are real and serious issues. People with celiac disease (1-2% of the population) or non-celiac gluten intolerance (estimated at about 6% of the population) can indeed have medical issues not only with their digestive systems but with other organs including the brain, and these people will benefit from removing the four gluten grains – wheat, barley, rye and triticale – from their diets.

Even the 7-10% of people with a reaction to gluten, however, can continue to enjoy all the non-gluten grains: amaranth, buckwheat, corn, millet, oats (if certified as non-contaminated), quinoa, rice, sorghum, teff, and wild rice. The rest of the population can enjoy these ten grains along with the four gluten grains. Leading medical researchers in the area of gluten intolerance and celiac disease attest that there is no need for 90 percent or more of our population to avoid any grains.

Put simply, there is no evidence for the idea we should all avoid all grains. Perlmutter must realize this himself, since Grain Brain contradicts its main premise that all grains are injurious to brain health, and recommends eating, in moderation, “amaranth, buckwheat, rice (brown, white [sic], wild), millet, quinoa, sorghum, teff and [gluten-free] oats.”

In fact, evidence for the health benefits of whole grains is well-documented at the whole grains council website – and was touted by Grain Brain’s author in his earlier book The Better Brain which included foods like whole grain couscous, oatmeal, spelt pasta, and quinoa-stuffed peppers throughout its menu plans. In an interview promoting The Better Brain on CBN-TV, for instance, Perlmutter advocated replacing junk food with “real food such as unprocessed whole grains and fruits and vegetables.” He does not acknowledge or explain his flip-flop in Grain Brain, giving us no clue why he has now turned against what he previously acknowledged to be sound science.

While Grain Brain goes off the deep end in imagining that the very real health problems of the 7-10% of the population with gluten intolerance or celiac disease somehow extend to all of us, the book rightfully details many important components of good health that Oldways and the Whole Grains Council have long supported. These include the key roles of physical activity and sleep; the essential contribution of good fats; the value of the Mediterranean Diet (which Perlmutter cites as “very similar to my dietary protocol”); and the importance of avoiding inflammation and choosing carbohydrates with a low glycemic impact.

Our advice? Don’t let Grain Brain scare you away from appropriate-size portions of healthy forms of whole grains (yes, a whole grain cookie is still a cookie!). Enjoy a balanced diet including a delicious variety of real, whole foods, an approach followed in traditional diets backed up by proven science, like those championed by Oldways. What are the Health Benefits?

If you liked my review, vote you found it helpful at amazon

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