"If you could make just three simple changes in your life to prevent, or even reverse, memory loss and other brain disorders, wouldn't you?"

So asks Dr. David Perlmutter, in promotion of his PBS special Brain Change, coming soon to your regional affiliate. Three changes. Simple ones. Wouldn't you?

The 90-minute special is a companion to Perlmutter's blockbuster book on how gluten and carbs are destroying our brains.

In November it became a New York Times number one bestseller. Since its September release, as Perlmutter told me, "It's never not been on the bestseller list, frankly."

"Is it still number one?" I asked. A pause over the phone as he checked. In modern interview style, we were both also on our computers.

"As of next week it's number six ... darn."

The book is Grain Brain: The surprising truth about wheat, carbs, and sugar; your brain's silent killers. It promises straightforward dietary solutions to prevent the illnesses we most hate and fear.

Why wouldn't you make three simple changes?

***

"The question is, how far will you take the Paleo diet?" Perlmutter asked in a recent video on his YouTube channel. "Here we are at a Chinese grocery store in San Francisco — and this is part of the Paleo diet."

He holds up a large frog.

"How far will you go?"

That is Perlmutter's kind of joke. He is not joking when he says that carbohydrates, even the whole-grain carbs that many of us think of as the good ones, are the cause of almost every modern neurologic malady. That includes dementia, decreased libido, depression, chronic headaches, anxiety, epilepsy, and ADHD.

"It may seem draconian," he says, "but the best recommendation I can make is to completely avoid grains."

"All of the neurodegenerative diseases are really predicated on inflammation. Who knew?"

"Most grain foods, whether we're talking about quinoa, amaranth, the very popular grains of the day, the reality is they still are associated with a carbohydrate surge. They have a fairly high glycemic index, meaning that after 90 to 120 minutes, your blood sugar is going to go up, and that is detrimental to the brain."

Humans consume calories in the form of three macronutrients: carbohydrates, protein, and fat. Perlmutter describes the current U.S. diet as 60 percent carbs, 20 percent protein, and 20 percent fat. His ideal is close to that of the Paleo diet: 75 percent fat, 20 percent protein, and 5 percent carbs. He allows for up to 50 to 80 grams of carbs daily, which is about one serving of fruit. The heart of the diet is "good fats like olive oil, avocado, wild fish, organic nuts and nutrient-dense vegetables."

***

David Perlmutter practices in Naples, Florida. He holds a medical doctorate from the University of Miami School of Medicine. He is both a board-certified neurologist and a fellow of the American College of Nutrition — the only person, he says, to have both credentials. He is the medical director of the Perlmutter Health Center and the Perlmutter Hyperbaric Center. His practice is endorsed by Mehmet Oz, "America's Doctor" (Oprah-appointed), who says he has referred patients to Perlmutter "with wonderful results. He is on the cutting edge and can help change the way we practice medicine."

Oz's endorsement also wanders across the jacket of Grain Brain: "An innovative approach to our most fragile organ."

In large letters at the top of his website, Perlmutter describes himself as an Empowering Neurologist. To my knowledge and his, this is another distinction unique to Perlmutter. This is presumably not to imply that neurologists without this qualifier are not empowering, but that in a specialty plagued by powerlessness in the face of many incurable and barely untreatable diseases, he offers power.

In his 2013 book Do You Believe in Magic?, University of Pennsylvania pediatrician Paul Offit wrote about the idea that there is really no such thing as alternative medicine; there is only what is proven to work and what is not. His book meticulously debunks alternative medical myths with science. Offit recounts hundreds of years of history of physicians peddling hope: Max Gerson's miracle cancer prevention diet in the 1980s, William Koch's 1940 cancer-curing glycoxide which turned out to simply be water, and Burzynski's "urine cure." (Dr. Stanislaw Burzynski claims to have discovered a unique peptide with anti-cancer properties, which he then, according to his website "began extracting from human urine, since it was far easier to obtain large amounts of healthy human urine versus healthy human blood. Burzynski began setting up collection containers at state parks, religious institutions, and even prisons. Today, Burzynski synthesizes the chemicals to help your body naturally produce these peptides in his massive 46,000 square foot manufacturing facility in Stafford, Texas").

Offit's book spent zero weeks at the top of the bestseller list.

Over the last 40 years, people have become addicted to gluten, Perlmutter's narrative goes. In combination with carbs, gluten's influence on our diets explains why we get dementia — and every other common neurologic problem. "Inflammation is the cornerstone of Alzheimer's disease and Parkinson's, multiple sclerosis — all of the neurodegenerative diseases are really predicated on inflammation. Who knew?"

"Who knew" is Perlmutter's one vocal tic. He says it where a celebrity diet guru might say "It's just that simple."

Publicists started to contact me about this book in August. I was reluctant. As the book spent week after week at the top of The New York Times bestseller list, it became clear that people cared about this idea. Wouldn't you like to speak with Dr. Perlmutter about his new book?

Well, Perlmutter has been practicing medicine for decades and has seen all kinds of tragedy. He took the same Hippocratic Oath I did in medical school. I agreed that there was something to his basic tenet that "diet is fundamentally important in reducing the degeneration of the body, and particularly the brain." But then he calls gluten "a modern poison" and earnestly, imploringly likens eating it to drinking gasoline. Okay, let's talk.

***

"Why do you think this book has seen such an enormous response?" I ask. "It is now being published in 15 countries."

"It's not because of the marketing," Perlmutter said, quickly. His speech is almost completely devoid of pauses. "I think it's because of the empowerment. I think people are finally getting this message that's so darn important for brain health. This is information that people have not gotten from the mainstream medical community. People say 'what you're promoting here is really outside the box. Is that your mission?' I try to explain that, no, my mission is to make this inside the box. To make the box bigger. So that mainstream medical professionals will begin to discuss the importance of these factors. Because it's already there. In the peer-reviewed literature. It's been there for decades. There's nothing proprietary about this. Every peer-reviewed article is available in the "Science" section of my website."

The idea of medicine being integrative was once implicit.

In fact it is. There are full-text PDFs of articles from The New England Journal of Medicine, Neurology, and many other credible peer-reviewed sources — the sort that are typically behind paywalls. His website hosts what appear to be every journal article that might support his argument.

"This is where we are," he continued, taking the discussion toward Alzheimer's without prompting. "This is what our most well-respected peer reviewed journals are telling us: that this is a preventable disease. More than 50 percent of Alzheimer's cases didn't have to happen, and this is a disease for which there is no treatment. Why do I say that? Because it was actually published, by Dr. Deborah Barnes at UCSF. I'll send you the link."

The link appears in my inbox. The sender is David, sans title or surname.

"You write about not just Alzheimer's, but also anxiety, depression, chronic headaches, ADHD, etc. How do you see carbs and gluten fitting into so many different pathologies?"

"The biggest issue by far is that carbohydrates are absolutely at the cornerstone of all of our major degenerative conditions," he says. "That includes things like Alzheimer's, heart disease, and even cancers. What we know is, that even mild elevations in blood sugar are strongly related to developing Alzheimer's disease. That was published August 8, 2013, in the New England Journal of Medicine. Even mild elevations in blood sugar compromise brain structure and lead to shrinkage of the brain. That's what our most well-respected, peer-reviewed journals are telling us."

The New England Journal of Medicine article appears in my inbox, in which researchers conclude, "Our results suggest that higher glucose levels may be a risk factor for dementia, even among persons without diabetes."

"So, we control our blood sugar based on, oddly-enough, our food choices," Perlmutter says. "Who knew? We need a low-carbohydrate diet that decreases your risk for diabetes, which will double your risk for Alzheimer's. It's really very straightforward. The empowering part of that is this is what our most well-respected science is telling us. It's been kept from us. We've been basically told, do whatever in the heck you want. Eat whatever you like. Then you'll have a magic pill that we're going to develop for you to treat all of your maladies. That doesn't exist for Alzheimer's disease."

I was getting twinges of conspiracy. Who is keeping this from us? I asked him if everyone should be off gluten.

Capillaries supplying blood to brain cells PLOS/Wikimedia "The gastroenterologists don't seem to realize that gluten insensitivity far exceeds their area of focus. According to the work of Dr. Marios Hadjivassiliou in England, there are a large number of people who have reactions to gluten that have absolutely nothing to do with the gastroenterologist. Manifestations can occur anywhere in the body. The work of Dr. Alessio Fasano at Harvard indicates that perhaps all humans have some negative reaction to gluten. Gluten induces this cornerstone of brain degeneration: inflammation. It causes leakiness of the blood-brain barrier."

The blood-brain barrier is a network of endothelial cells that prevents substances in our blood from getting into our brain tissue. Some molecules can cross it, and some can't, in order to maintain a favorable environment for the brain. Undue leakiness is not a desirable property in one's blood-brain barrier.

I asked for some clarity on that. "We don't have clinical studies linking gluten to Alzheimer's, ADHD, or —"

"With all due respect, we do. That information is well established. It was actually published by the Mayo Clinic, that gluten can in fact be related to risk for dementia. So I would beg to differ with you on that point. Gluten, certainly in patients with celiac disease, is strongly associated with risk for dementia. As was described in the Proceedings of the Mayo Clinic, it was a treatable cause of dementia. So I think that's pretty revolutionary and exciting."

That study didn't appear in my inbox. I asked him for it later, and he promptly sent me a 2006 case series that identified 13 patients in a review of Mayo Clinic records from January 1, 1970, to December 31, 2005. That is an interesting correlation — the study's authors called it a "possible association" — but is far from well-established causation that gluten is a mechanism for dementia in people with celiac disease, much less all people.

"So, we have data from celiac disease patients that gluten is the mechanism for dementia?"

"We have absolute data from Dr. Hadjivassiliou that I've just sent to you that indicates, as a matter of fact, definite cognitive issues in patients who do not have celiac disease, but simply have gluten sensitivity. That information is well established in the literature and has been there for a long time."

Hadjivassiliou has documented correlations between neurologic symptoms and the presence of gluten antibody patterns "similar to those seen in celiac disease." He also wrote in a "Personal View" published in The Lancet Neurology in 2010, "Celiac disease, or gluten-sensitive enteropathy, is only one aspect of a range of possible manifestations of gluten sensitivity." He believes neurologic symptoms are a largely unrecognized manifestation.

"If all of this has been around for such a long time and is well established in the literature," I say, "Why again do you think we're seeing this massive interest in your book?"

"I'm sure many other books have hinted around it. I think Dr. William Davis' wonderful book Wheat Belly kind of mentioned the brain a little. This is the first book that has really put it all together specifically in terms of brain issues."

***

Chris Kresser is an integrative medicine practitioner and author of Your Personal Paleo Code. Integrative is an increasingly popular adjective that usually means focusing not just on pills and procedures but on lifestyle, diet, and prevention. The idea of medicine being integrative was once implicit; that practitioners now feel the need to explicitly state it is probably telling. Kresser has seen a flood of patients who have read Grain Brain and came to him asking what to make of it. He wrote recently on his website about how he responds.

"Just because a low-carb diet can help treat neurological disorders, doesn't mean the carbs caused the disorder in the first place."

Kresser tells his patients that initial studies on low-carb diets and mental health have shown promise. He notes scientific articles that look at why low-carb diets are sometimes effective in managing epilepsy, rat models that have shown positive effects in Parkinson's, and a small study that showed some cognitive improvement in patients with dementia. "It's important to realize," Kresser says, "that just because a low-carb diet can help treat neurological disorders, doesn't mean the carbs caused the disorder in the first place."

Kresser also tells concerned patients about cultures that do just fine on carbohydrate-based diets. "The Hadza of north-central Tanzania and the Kuna of Panama obtain a high percentage of their total calories from foods that are high in natural sugars, such as fruit, starchy tubers and honey, yet they are remarkably lean, fit and free of modern disease." He also mentions the Kitava in the Pacific Islands, whose diet heavy in yams, banana, and papaya is 69 percent carbohydrate; the Tukisenta in the Papua New Guinea highlands, whose diet is over 90 percent carbs; and the Okinawans, whose diet is "mostly from sweet potato."

Better-known still are the Greeks, in particular from the islands like Crete, and other Mediterranean diets that are grain-centric.

"All of these cultures," Kresser notes, citing Swedish researcher Staffan Lindeberg's book Food and Western Disease (and, I would add, Dan Buettner's The Blue Zones) "are fit and lean with practically non-existent rates of neurological disorders and other modern chronic disease."

***

When Dr. Robert Lustig appeared on The Colbert Report earlier this year, he likened the toxicity of sugar to that of alcohol. Lustig is a pediatric endocrinologist at UCSF and the author of Fat Chance: Beating the odds against sugar, processed food, obesity, and disease . He may be most widely known for his 90-minute lecture on sugar, that has been viewed on YouTube more than 4 million times, in which he "intend[s] to debunk the last 30 years of nutrition information in America." The villain in his narrative is fructose. He is one of the physicians Perlmutter cites for support in Grain Brain.

"There is no doubt in my mind," Lustig told me last week, "that insulin resistance drives dementia. We have causative data in animals, and we have causative medical inference data in humans. Basically, Alzheimer's is a metabolic syndrome of the brain."

I asked him about the moniker "diabetes type 3" that some people, including Perlmutter, have begun using.

"I think that's a mistake, because diabetes specifically has to do with urination. But think about it this way. In the entire body, where are mitochondria the most dense?"

"The brain."

"Exactly." Phew. "If anything affects how our mitochondria function, it's going to be felt in the brain first. We know that metabolic syndrome is defective mitochondrial function. I have no doubt that at least one form of dementia — the most common form; the one that's gotten worse over the past decades — is due to our diet. There is no question that refined carbohydrates play a role in this. The question is, what role, and is it the starch or the sugar? I think the jury is out."

As for Perlmutter's other claims, Lustig is hesitant to comment. He's not yet read the book. "I can't say that Dr. Perlmutter is right, wrong, or anything else. It may be they have some data of which I'm unaware. Considering that my partner is a pediatric gastroenterologist who deals with this every day, I think I'm pretty up-to-date."

Lustig says that at this point gluten is a grab bag. "I have taken kids off of gluten, but in no way, shape, or form do I think this is a panacea."

"Of all the lessons in this book," Perlmutter writes, "the one I hope you take seriously is the following: Respect your genome."

He goes on to argue that fat is the preferred fuel for the human body, and has been for two million years. In the last 10,000 years, agriculture made carbohydrates the most abundant form of calories. His arguments consistently harken reverently back to "the hunter-gatherer days."

"In our hunter gatherer days obviously there were times when we didn't have food, and that would create a small stress to our genome," he said in a talk this summer. "When we didn't have calories, life-sustaining protective genes would be activated, increasing antioxidant coverage, reducing inflammation, and ultimately actually being good for the brain."

The thrifty gene hypothesis was proposed by geneticist James Neel in 1962. Our bodies are preparing us for a fast that, in this time of abundance, never comes. Instead our thrifty genes lead us to diabetes and obesity. Perlmutter explains how our bodies were meant to fast. When we go without food, in the initial stages, we create sugar from glycogen that is stored in our livers and the muscles. After we fast for a few days, we start to mobilize fat, creating ketones. "When the brain is powered by ketones," Perlmutter reasons, "it functions a lot better, allowing us, when we're calorie-deprived, like in our hunter-gatherer days for example, to remain clever."

"We're not the fastest animal in the forest," Perlmutter says, "nor are we the strongest; but we're probably the most clever. Although you could, these days, argue that point." A wry smile.

In the Paleolithic Era, human life expectancy was around 30 years. Even accounting for childhood deaths and tramplings by wooly mammoths or wooly rhinoceri, 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, shouldn't it?

Dr. David Katz is the founding director of Yale University's Prevention Research Center. He is an epidemiologist who has published two editions of a nutrition textbook for healthcare professionals called Nutrition in Clinical Practice. The third edition, nearing publication, will have nearly 10,000 citations. He is also the author of the nutrition book Disease Proof: The remarkable truth about what makes us well . Like Perlmutter, he also cites this era as a gold-standard. Though apart from that — and a first name and medical degree — the two have little else in common.

"There actually is an argument to give the Paleo diet serious consideration," he says. "And the argument, I think, is nicely demonstrated by zoological parks. Have you ever been to a zoo?"

"Yes."

"Ever wonder how they figure out what to feed the animals?"

"Yes."

"You think they do randomized clinical trials to figure out what to feed the lions and the zebras? No, right? They know something about what lions and zebras were eating when they found them. So for every other species on the planet, knowing something about their native diet does help figure out what to feed them. It does stand to reason that the same would be true of us."

"It's a revolutionary idea. The book tells you exactly how to grow new brain cells."

"Of course," Katz added, "Everything about the Paleolithic Era is subject to debate. Most of us don't know what we had for breakfast yesterday, let alone what people were doing 100,000 years ago. Yeah, I've read the same thing that the average life expectancy was between 20 and 40 and, consequently, the diseases of old age didn't happen because old age didn't happen. There's nothing about their diet that we know to be protective against things like Alzheimer's. That's just silly."

Perlmutter has estimated that the Stone Age diet was 75 percent fat, a claim Katz finds "wildly preposterous." Anthropological research, he pointed out the work of Loren Cordain, 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?'"

Conspiracy

A November appearance on Fox & Friends is emblematic of the tonality of much of Perlmutter's press tour. It begins with unambiguous incredulity, "We have been lied to."

"People have been fed this notion that they can do whatever they want," Perlmutter told me. "Live their lives come what may, and then suddenly when you find yourself walking into a room and you can't remember why, or you lost your keys or forgot your WiFi password or whatever that there's going to be some kind of pharmaceutical fix for that. It doesn't exist. It's not even anywhere close. The traction of this book is because people are learning that, and they want to get a second chance. You can grow back your memory center. You can get new cells in your brain. It's a revolutionary idea. The book tells you exactly how to grow new brain cells."

Who wouldn't want to grow new brain cells? The study he sent me to substantiate this claim was published in Neurology, the specialty's preeminent journal. The Berlin-based researchers concluded that even in people without diabetes, "chronically higher blood glucose levels exert a negative influence on cognition, possibly mediated by structural changes in learning-relevant brain areas. Therefore, strategies aimed at lowering glucose levels even in the normal range may beneficially influence cognition in the older population." They assess this appropriately as "a hypothesis to be examined in future interventional trials."

"This isn't just for the elderly," Perlmutter continued seamlessly. "There are 6.5 million children in America carrying a diagnosis of ADHD. Two-thirds of them are receiving mind-altering medications, the long-term consequences of which we do not understand. Yet we fully understand that dietary choices have a huge role to play in how the brain works. Specifically in terms of risk for ADHD. That's the kind of stuff that no one is willing to talk about. People are desperate for the other side of the story."

"I keep getting this message of a third party creating a narrative."; I said. "You mentioned earlier a pill being promised. Who is pulling these strings, doing this misleading?"

"I don't think it stretches the imagination to see who's promising us the pill. That doesn't take a lot of cognitive effort to figure out in whose interest it would be for us to think that the answer is going to come in a pill." He alludes to the pharmaceutical industry. He then turns to government.

"Government doctrine in 1992 indicated that we need to be on a low-fat diet. That's saying in the same breath, high carb. Immediately, within 10 years, the rates of diabetes in America went up three-fold."

The number of people diagnosed with diabetes in the U.S. has nearly tripled in the last twenty years, according to the CDC. In 1992, 7.5 million people had a diagnosis. By 2002, the number was 13.6 million. By 2011 it was 20.9 million.

"That doubles your risk for Alzheimer's disease. We were told, "Eat more whole grain goodness. Eat more of what the U.S. Department of Agriculture is producing for you, and that will be good for you. Nothing could be further from the truth. Diets that are high in fat lower cardiovascular risk factors and are absolutely associated with a reduced risk for dementia. This was published in The Journal of Alzheimer's Disease in January of 2012, research from the prestigious Mayo Clinic. People on a high-fat diet had a 44 percent risk reduction for developing dementia. Those on a high carb diet, which the government continues to recommend, had an 89 percent increased risk."

That study is interesting and available in full text.

"So I'll let you figure out the conspiracy issues in terms of what we're being told."

***

"I find the whole thing a little bit sad, to be honest with you," Katz told me. "In several ways. Beginning with the fact that I actually like Dr. Perlmutter. He does some really interesting and innovative work in the area of neurodegenerative diseases. He"\'s cutting edge and is doing stuff that's a little bit out there. But he generally does this carefully and has actually provided some useful guidance we've applied in my own clinic; and I have a long-standing relationship with him — or at least his clinic — and we've corresponded and I generally think very highly of him. So I find it sad to be in a position to say that I think so much of his book is a whole bunch of nonsense."

Katz paused.

"Now, he's absolutely right that we eat too much sugar and white bread. The rest of the story, though, is one just completely made up to support a hypothesis. And that's not a good way to do science."

This launches the discussion of what science is — the critical point that confronts every mainstream media health and science writer. Most recently and famously we have heard about it in criticism of the works of Malcolm Gladwell and Jonah Lehrer (outside of the latter's self-plagiarism debacle). The law of good science is that you can't say "I've got an idea and I'm going to fall in love with it and selectively cite evidence to support it."

"I also find it sad that because his book is filled with a whole bunch of nonsense, that's why it's a bestseller; that's why we're talking."

"You're only being a good scientist," Katz said, "if you say, "I'm going to try to read the literature in as unbiased a manner as I possibly can, see where it leads me, and then offer the advice that I have based on that view from an altitude." I don't see that going on here, and again, I think it's kind of sad because I think the public is being misled."

"I also find it sad that because his book is filled with a whole bunch of nonsense, that's why it's a bestseller; that's why we're talking. Because 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've got Rob Lustig saying it's all fructose; we've got T. Colin Campbell [author of The China Study, a formerly bestselling book] saying it's all animal food; 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 apparent: Tell readers it's not their fault. Blame an agency; typically the pharmaceutical industry or U.S. government, but also possibly the medical establishment. Alluding to the conspiracy vaguely will suffice. Offer a simple solution. Cite science and mainstream research when applicable; demonize it when it is not.

"It makes me sad that somebody like you is going to reach out to me, so you can get what I'd like to think are sensible comments about a silly book. If you write a sensible book, which I did — it's called Disease Proof , and it's about what it really takes to be healthy, brain and body — nobody wants to talk about that. It has much less sex appeal. The whole thing is sad."

The worst that could happen

Perlmutter is not new to practicing medicine. He talks again and again about experiences seeing patients in the early stages of Alzheimer's, or fielding questions from children of patients about what they can do to protect themselves. Years of saying, "I fix this" and conceding there&'s little that can be done — that prospect was the reason many of my classmates did not go into neurology. At the end of our interview, Perlmutter mentioned that his elderly father has Alzheimer's disease.

"5.4 million of us [in the U.S.] have been diagnosed with Alzheimer's disease. That turns out to be a lot of influence on the rest of us. Our parents, our loved ones are getting this more and more frequently, and people are so concerned that they're going to end up like mom or dad. You know, I'm dealing with this every single day. Virtually every day, children of a patient will say "I don't want to end up like that. What can I do? Now the book provides those answers."

Perlmutter in fact dedicates the book to his father, who is in an assisted-living facility across the street from his son's clinic.

To my father, who at age 96, begins each day by getting dressed to see his patients — despite having retired more than a quarter century ago.

Perlmutter writes about how his father often does not recognize him.

The common defense of writers like Lehrer and Gladwell, and celebrity physicians like Mehmet Oz, is that they make people care to learn about subjects they otherwise would know nothing about. The message may be salacious, but the end result is a net positive. People might fail to consider their diet entirely if they aren't told it is destroying their brain. Is this book a problem? 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.

"Nothing could be further from the truth than the myth that if we lower our cholesterol levels, we might have a chance of living longer and healthier lives," Perlmutter writes . He recommends disowning the notion that LDL is bad cholesterol and HDL is good cholesterol; rather, both are generally good. LDL is only bad when it is oxidized, and it only becomes so in the presence of the sort of oxidative stress brought about by carbs and gluten. Avoid those, and cholesterol is innocuous.

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.

I took this to Katz, too.

"Is there a weight of evidence that says we can totally ignore both dietary cholesterol and LDL? Absolutely not," he said. "You can legitimately say we're starting to rethink some things, but ignoring LDL could absolutely result in heart attacks and strokes. Perlmutter is way ahead of any justifiable conclusion."

The medical community's understanding of the danger of cholesterol is changing. Many cardiologists are starting to think that independent of other considerations, the level of LDL in our blood may not be as important as it previously seemed. In November, the American Heart Association and the American College of Cardiology released new guidelines that redefined the use of statins. While they continue to recommend that people at high risk for heart disease and people with LDL levels above 189 take a statin, the long-standing goal of lowering one's LDL level to 70 is no longer deemed worthwhile to monitor.

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."

***

Even as someone who was seriously skeptical of Perlmutter's story, after reading his 336 pages — and watching his whole YouTube channel and most every TV appearance — I have found myself hesitating around grain. His message is so ardently and unwaveringly delivered. That is how one-sided pop-science works, though. Katz wrote a tongue-in-cheek case that the 1974 advent of the Post-it note was the cause of the obesity pandemic, to show how easily correlations can be spun. If I read 336 pages on the evils of Post-its, I might set our office supply room on fire.

It comes with the certainty that you are doing something to save yourself from cognitive decline and mental illness.

Having talked to all of these people and read their work, here is how I walk away from this. Oxidative stress will increasingly be the target of medical treatments and preventive diets. We'll hear more about the role of blood sugar in Alzheimer's and continue to focus on moderating intake of refined carbohydrates. The consensus remains that too much LDL is bad for you. 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. I agree with Katz that the 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. The scientific community on the whole is not as capricious as the bestseller list might make it seem.

When a person advocates radical change on the order of eliminating one of the three macronutrient groups from our diets, the burden of proof on them should be enormous. Everything you know is not wrong. Perlmutter has interesting ideas that I would love to believe. I'd love it if a diet could deliver all that he promises. There is value in belief. It's what the Empowering Neurologist literally markets. His narrative comes with the certainty that you are doing something to save yourself from cognitive decline and mental illness, which is probably the most unsettling of disease prospects.

With that belief also comes guilt; an idea that something could've been done to prevent a mental illness, when in fact it was bigger than us. To think that every time you eat any kind of carb or gluten, you are putting your mental health and cognitive faculties at risk is, to me, less empowering than paralyzing.

Empowerment comes in many forms. It is important to believe you're doing what's right.