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If the thought of your brain suffering over a bowl of savory pasta or plate of sweet French toast seems far-fetched, brace yourself. You probably already knew that processed sugar and carbs weren’t all that great for you, especially in excess, but so-called healthy carbohydrates like whole grains and natural sugars? Welcome to the whole grain truth. In this part, we’re going to explore what happens when the brain is bombarded by carbohydrates, many of which are packed with inflammatory ingredients like gluten that can irritate your nervous system. The damage can begin with daily nuisances like headaches and unexplained anxiety and progress to more sinister disorders such as depression and dementia. We’ll also look at the role common metabolic challenges like insulin resistance and diabetes play in neurological dysfunction, and see how we likely owe our obesity and Alzheimer’s epidemics to our undying love for carbs and stark disdain for fat and cholesterol. By the end of this part, you’ll have a new appreciation for dietary fat and an educated apprehension when it comes to most carbohydrates. You’ll also learn that there are things you can do to spur the growth of new brain cells, gain control of your genetic destiny, and protect your mental faculties. CHAPTER 1 The Cornerstone of Brain Disease What You Don’t Know About Inflammation The chief function of the body is to carry the brain around. —THOMAS A. EDISON IMAGINE BEING TRANSPORTED BACK to the Paleolithic era of early humans who lived in caves and roamed the savannas tens of thousands of years ago. Pretend, for a moment, that language is not a barrier and you can communicate easily. You have the opportunity to tell them what the future is like. From a cross-legged perch on a dirt floor in front of a warm fire, you start by describing the wonders of our high-tech world, with its planes, trains, and automobiles, city skyscrapers, computers, televisions, smartphones, and the information highway that is the Internet. Humans have already traveled to the moon and back. At some point, the conversation moves to other lifestyle topics and what it’s like to really live in the twenty-first century. You dive into describing modern medicine with its stupendous array of drugs to treat problems and combat diseases and germs. Serious threats to survival are few and far between. Not many people need to worry about crouching tigers, famine, and pestilence. You explain what it’s like to shop at grocery stores and supermarkets, a totally foreign concept to these individuals. Food is plentiful, and you mention things like cheeseburgers, French fries, soda, pizza, bagels, bread, cinnamon rolls, pancakes, waffles, scones, pasta, cake, chips, crackers, cereal, ice cream, and candy. You can eat fruit all year long and access virtually any kind of food at the touch of a button or just a short drive away. Water and juice come in bottles for transportability. Although you try to avoid brand names, it’s hard to resist because they have become such a part of life—Starbucks, Wonder Bread, Pepperidge Farm, Pillsbury, Lucky Charms, Skittles, Domino’s, Subway, McDonald’s, Gatorade, Häagen-Dazs, Cheerios, Yoplait, Cheez-It, Coke, Hershey’s, and Budweiser. They are in awe, barely able to picture this future. Most of the features you chronicle are unfathomable; they can’t even visualize a fast-food restaurant or bread bar. The term “junk food” is impossible to put into words these people understand. Before you can even begin to mention some of the milestones that humans had to achieve over millennia, such as farming and herding, and later food manufacturing, they ask about the challenges modern people deal with. The obesity epidemic, which has gotten so much attention in your media lately, comes first to mind. This isn’t an easy matter for their lean and toned bodies to grasp, and neither is your account of the chronic illnesses that plague society—heart disease, diabetes, depression, autoimmune disorders, cancer, and dementia. These are totally unfamiliar to them, and they ask a lot of questions. What is an “autoimmune disorder”? What causes “diabetes”? What is “dementia”? At this point you’re speaking a different language. In fact, as you give them a rundown of what kills most people in the future, doing your best to define each condition, you are met with looks of confusion and disbelief. You’ve painted a beautiful, exotic picture of the future in these people’s minds, but then you tear it down with causes of death that seem to be more frightening than dying from an infection or being eaten by a predator higher up on the food chain. The thought of living with a chronic condition that slowly and painfully leads to death sounds awful. And when you try to convince them that ongoing, degenerative disease is possibly the trade-off for potentially living much longer than they do, your prehistoric ancestors don’t buy it. And, soon enough, neither do you. Something seems wrong with this picture. As a species, we are genetically and physiologically identical to these humans that lived before the dawn of agriculture. And we are the product of an optimal design—shaped by nature over thousands of generations. We may not call ourselves hunters and gatherers anymore, but our bodies certainly behave as such from a biological perspective. Now, let’s say that during your time travel back to the present day, you begin to ponder your experience with these ancestors. It’s easy to marvel at how far we’ve come from a purely technological standpoint, but it’s also a no-brainer to consider the struggles that millions of your contemporary comrades suffer needlessly. You may even feel overwhelmed by the fact that preventable, non-communicable diseases account for more deaths worldwide today than all other diseases combined. This is tough to swallow. Indeed, we may be living longer than our ancient relatives, but we could be living much better—enjoying our lives sickness-free—especially during the second half of life when the risk of illness rises. While it’s true that we are living longer than previous generations, most of our gains are due to improvements in infant mortality and child health. In other words, we’ve gotten better at surviving the accidents and illnesses of childhood. We haven’t, unfortunately, gotten better at preventing and combatting illnesses that strike us when we’re older. And while we can certainly make a case for having much more effective treatments now for many illnesses, that still doesn’t erase the fact that millions of people suffer needlessly from conditions that could have been avoided. When we applaud the average life expectancy in America today, we shouldn’t forget about quality of life. When I was in medical school decades ago, my education revolved around diagnosing disease and knowing how to treat or, in some cases, cure each disease with a drug or other therapy. I learned how to understand symptoms and arrive at a solution that matched those symptoms. A lot has changed since then, because we are not only less likely to encounter easily treatable and curable illnesses, but also better able to understand many of our modern, chronic diseases through the lens of a common denominator: inflammation. So, rather than spotting infectious diseases and addressing sicknesses with known culprits, such as germs, viruses, or bacteria, doctors are faced with myriad conditions that don’t have clear-cut answers. I can’t write a prescription to cure someone’s cancer, vanquish inexplicable pain, instantly reverse diabetes, or restore a brain that’s been washed away by Alzheimer’s disease. I can certainly try to mask or lessen symptoms and manage the body’s reactions, but there’s a big difference between treating an illness at its root and just keeping symptoms at bay. Now that one of my own kids is in medical school, I see how times have changed in teaching circles. Doctors in training are no longer taught just how to diagnose and treat; they are equipped with ways of thinking that help them to address today’s epidemics, many of which are rooted in inflammatory pathways run amok. Before I get to the connection between inflammation and the brain, let’s consider what I think is arguably one of the most monumental discoveries of our era: The origin of brain disease is in many cases predominantly dietary. Although several factors play into the genesis and progression of brain disorders, to a large extent numerous neurological afflictions often reflect the mistake of consuming too many carbs and too few healthy fats. The best way to comprehend this truth is to consider the most dreaded neurological ailment of all—Alzheimer’s—and view it within the context of a type of diabetes triggered by diet alone. We all know that poor diet can lead to obesity and diabetes, but a busted brain? ALZHEIMER’S DISEASE—TYPE 3 DIABETES? Flash back to your moment with those hunters and gatherers. Their brains are not too different from yours. Both have evolved to seek out foods high in fat and sugar. After all, it’s a survival mechanism. The problem is that your hunting efforts end quickly because you live in the age of plenty, and you’re more likely to find processed fats and sugars. Your caveman counterparts are likely to spend a long time searching, only to come across fat from animals and natural sugar from plants and berries if the season is right. So while your brain might operate similarly, your sources of nutrition are anything but. In fact, take a look at the following graphic that depicts the main differences between our diet and that of our forebears. And what, exactly, does this difference in dietary habits have to do with how well we age and whether or not we suffer from a neurological disorder or disease? Everything. The studies describing Alzheimer’s as a third type of diabetes began to emerge in 2005, 1 but the link between poor diet and Alzheimer’s has only recently been brought to light with newer studies showing how this can happen. 2, 3 These studies are both convincingly horrifying and empowering at the same time. To think we can prevent Alzheimer’s just by changing the food we eat is, well, astonishing. This has many implications for preventing not just Alzheimer’s disease but all other brain disorders, as you’ll soon discover in the upcoming chapters. But first, a brief lesson on what diabetes and the brain have in common. Evolutionarily, our bodies have designed a brilliant way to turn the fuel from food into energy for our cells to use. For almost the entire existence of our species, glucose—the body’s major source of energy for most cells—has been scarce. This pushed us to develop ways to store glucose and convert other things into it. The body can manufacture glucose from fat or protein if necessary through a process called gluconeogenesis. But this requires more energy than the conversion of starches and sugar into glucose, which is a more straightforward reaction. The process by which our cells accept and utilize glucose is an elaborate one. The cells don’t just suck up glucose passing by them in the bloodstream. This vital sugar molecule has to be allowed into the cell by the hormone insulin, which is produced by the pancreas. Insulin, as you may already know, is one of the most important biological substances for cellular metabolism. Its job is to ferry glucose from the bloodstream into muscle, fat, and liver cells. Once there, it can be used as fuel. Normal, healthy cells have a high sensitivity to insulin. But when cells are constantly exposed to high levels of insulin as a result of a persistent intake of glucose (much of which is caused by an overconsumption of