Grain Brain: The Surprising Truth about Wheat, Carbs, and Sugar--Your Brain's Silent Killers




Dietary Habits for an Optimal Brain

Hello, Fasting, Fats, and Essential Supplements

I fast for greater physical and mental efficiency.


THE SIZE OF OUR BRAIN IN COMPARISON to the rest of our body is one of the most important features distinguishing us from all other mammals. An elephant, for example, has a brain that weighs 7,500 grams, dwarfing our 1,400-gram brain. But its brain represents 1/550 of its total body weight, while our brain weighs 1/40 of our total body weight. So we can’t make any comparisons about “brain power” or intelligence just based on brain size alone. It’s the ratio of brain size to body size that’s key when considering the brain’s functional capacity.1

But even more important than our impressive volume of brain matter is the fact that, gram for gram, our brain consumes a disproportionately huge amount of energy. It represents 2.5 percent of our total body weight but consumes an incredible 22 percent of our body’s energy expenditure at rest. The human brain expends about 350 percent more energy than the brains of other anthropoids like gorillas, orangutans, and chimpanzees. So it takes a lot of dietary calories to keep our brains functioning. Fortunately for us, though, our large and powerful brains have allowed us to develop the skills and intelligence to survive extreme conditions like food scarcity. We can conceive of and plan for the future, a uniquely human trait. And having an understanding of our brain’s amazing abilities can help inform the ways in which we can optimize our diet for a healthy, functioning brain.


One critical mechanism of the human body that I’ve already covered is its ability to convert fat into vital fuel during times of starvation. We can break down fat into specialized molecules called ketones, and one in particular that I’ve already mentioned—beta-hydroxybutyrate (beta-HBA)—is a superior fuel for the brain. This not only provides a compelling case for the benefits of intermittent fasting to, as contradictory as this may seem, nourish the brain, but also serves as an explanation for one of the most hotly debated questions in anthropology: why our Neanderthal relatives disappeared between thirty and forty thousand years ago. While it’s convenient and almost dogmatic to accept that Neanderthals were “wiped out” by clever Homo sapiens, many scientists now believe that food scarcity may have played a more prominent role in their disappearance. It may be that the Neanderthals didn’t have the “mental endurance” to persevere because they lacked the biochemical pathway to utilize fat to feed the brain.

Unlike other mammals’, our brain can use an alternative source of calories during times of starvation. Typically, our daily food consumption supplies our brain with glucose for fuel. In between meals, our brains are continually supplied with a steady stream of glucose that’s made by breaking down glycogen, mostly from the liver and muscles. But glycogen stores can provide only so much glucose. Once our reserves are depleted, our metabolism shifts and we are able to create new molecules of glucose from amino acids taken from protein primarily found in muscle. This process is aptly named gluconeogenesis. On the plus side, this adds needed glucose to the system, but on the minus side, it sacrifices muscles. And muscle breakdown is not a good thing for a starving hunter-gatherer.

Luckily, human physiology offers one more pathway to power our brains. When food is no longer available, after about three days, the liver begins to use body fat to create those ketones. This is when beta-HBA serves as a highly efficient fuel source for the brain, allowing us to function cognitively for extended periods during food scarcity. Such an alternative fuel source helps reduce our dependence on gluconeogenesis and, therefore, preserves our muscle mass.

But more than this, as Harvard Medical School professor George F. Cahill stated, “Recent studies have shown that beta-hydroxybutyrate, the principal ketone, is not just a fuel, but a superfuel, more efficiently producing ATP energy than glucose. It has also protected neuronal cells in tissue cultures against exposure to toxins associated with Alzheimer’s or Parkinson’s.”2

Indeed, Dr. Cahill and other researchers have determined that beta-HBA, which is easily obtainable just by adding coconut oil to your diet, improves antioxidant function, increases the number of mitochondria, and stimulates the growth of new brain cells.

In chapter 5 we explored the need to reduce caloric intake in order to increase BDNF as a means of stimulating the growth of new brain cells as well as enhancing the function of existing neurons. The idea of substantially reducing your daily calorie intake does not appeal to many people, even though it’s a powerful approach to not only brain enhancement, but also overall health. But intermittent fasting—a complete restriction of food for twenty-four to seventy-two hours at regular intervals throughout the year—is more manageable, and I recommend and outline a fasting protocol in chapter 10. Research has demonstrated that many of the same health-providing and brain-enhancing genetic pathways activated by caloric restriction are similarly engaged by fasting, even for relatively short periods of time.3 This is counter to conventional wisdom that says fasting lowers the metabolism and forces the body to hold on to fat in a so-called starvation mode. Much to the contrary, fasting provides the body with benefits that can accelerate and enhance weight loss, not to mention boost brain health.

Fasting not only turns on the genetic machinery for the production of BDNF, but also powers up the Nrf2 pathway, leading to enhanced detoxification, reduction of inflammation, and increased production of brain-protective antioxidants. Fasting causes the brain to shift away from using glucose as fuel to using ketones manufactured in the liver. When the brain is metabolizing ketones as fuel, even the process of cell suicide (apoptosis) is reduced, while mitochondrial genes are turned on, leading to mitochondrial replication. Simply put, fasting enhances energy production and paves the way for better brain function and clarity.

Fasting in spiritual quests is an integral part of religious history. All major religions promote fasting as far more than a ceremonial act. Fasting has always been a fundamental part of the spiritual practice, as in the Muslim fast of Ramadan and the Jewish fast of Yom Kippur. Yogis practice austerity with their diets, and shamans fast during their vision quests. Fasting is also a common practice among devout Christians, and the Bible has examples of one-day, three-day, seven-day, and forty-day fasts.


What happens when you substantially reduce your carbohydrate intake and derive more of your calories from fat? I just finished explaining the benefits of fasting, which stimulates the brain to turn to fat for fuel in the form of ketones. A similar reaction takes place when you follow a diet low in carbohydrates and rich in healthy fats and proteins. This is the foundation of the Grain Brain dietary protocol.

Throughout our history we sought fat as a calorie-dense food source. It kept us lean and served us well in our hunter-gatherer days. As you already know, eating carbohydrates stimulates insulin production, which leads to fat production, fat retention, and a reduced ability to burn fat. What’s more, as we consume carbohydrates we stimulate an enzyme called lipoprotein lipase that tends to drive fat into the cell; the insulin secreted when we consume carbohydrates makes matters worse by triggering enzymes that lock fat tightly into our fat cells.

As I’ve also described, when we burn fat as opposed to carbohydrate, we enter ketosis. There’s nothing inherently bad about it, and our bodies have been equipped for this activity for as long as we’ve roamed Earth. Being in a mild ketosis state is actually healthy. We are mildly ketotic when we first wake up in the morning, as our liver is mobilizing body fat to use as fuel. Both the heart and the brain run more efficiently on ketones than on blood sugar, by as much as 25 percent. Healthy, normal brain cells thrive when fueled by ketones. Certain brain tumor cells, however, can only use glucose as fuel. Standard treatment for glioblastoma, one of the most aggressive types of brain tumor, is surgery, radiation therapy, and chemotherapy. But quite honestly, results from these approaches are fairly dismal. Taking advantage of the fact that glioblastoma cells can only use glucose, and not ketones, Dr. Giulio Zuccoli of the University of Pittsburgh School of Medicine reasoned that a ketogenic diet might actually prove effective in treating glioblastoma along with traditional treatments.4 And, in fact, he published a case report of treating a glioblastoma patient using a ketogenic diet with impressive results. If a ketogenic diet can prolong the life of a cancer patient, what can it do in a healthy individual?

A purely ketogenic diet is one that derives 80 to 90 percent of calories from fat, and the rest from carbohydrate and protein. Certainly this is extreme, but again, recognize that ketones are a far more effective fuel for the brain. In 1921, when the Mayo Clinic’s Russell Wilder developed the ketogenic diet, it was basically an all-fat proposition. In the 1950s, we learned about medium-chain triglycerides (MCTs), which act as precursors in the body for beta-HBA and can be consumed through coconut oil.

The diet protocol outlined in chapter 10 honors the main ketogenic principles of significantly reducing carbohydrates to the point that the body is pushed to burn fat while increasing dietary fat and adding nutrients to increase production of beta-HBA. You’ll limit your consumption of carbohydrates to just 30 to 40 grams a day during the four weeks, after which you can increase that amount to 60 grams. The degree of ketosis that you’re able to achieve can actually be measured with ketone test strips, which are typically used by diabetics and available at all pharmacies. They simply require a drop or two of urine and provide immediate information as to the level of ketosis that you’ve achieved. Look for trace to small levels of ketosis in the neighborhood of 5 to 15; most ketone test strips such as Ketostix use color charts, and light pink usually indicates the presence of small, trace amounts. This means that your body is effectively using ketones as energy. If you follow my protocol, you can expect to become slightly ketotic after approximately the first week on the plan, and you may want to test yourself to see this effect. Some people feel better at higher levels of ketosis.



“The high-carb diet I put you on twenty years ago gave you diabetes, high blood pressure, and heart disease. Oops.”

I love a cartoon that offers a nugget of wisdom in a matter of eyebrow-raising seconds, the time it takes to absorb the image and caption. The one above caught my eye years ago; I only wish more doctors were as smart as cartoonist Randy Glasbergen. Given all the science we’ve accumulated since this cartoon was first published in 2004, we can add “and set you up for brain disease” to this caption.

The painful reality in today’s doctoring world is that you’re not likely to get a lot of useful advice about staving off brain disorders during an office visit to your internist. Nowadays, you get fewer than fifteen minutes (if that) with a doctor who may or may not be trained in all the latest knowledge about how to preserve your mental faculties. What’s more disturbing is that many of today’s physicians, originally trained decades ago, don’t have a firm grasp of nutrition and its effects on your health. I don’t say this to pooh-pooh my industry; I’m merely pointing out a truth that’s largely a consequence of economics. My hope is that our next generation of doctors will be better equipped to swing the pendulum to the side of prevention rather than focus so much on treatment. Which brings me to my recommended supplements. (here for exact dosages and instructions on when to take each of these daily.)

DHA: As I mentioned earlier, docosahexaenoic acid (DHA) is a star in the supplement kingdom. DHA is an omega-3 fatty acid that represents more than 90 percent of the omega-3 fats in the brain. Fifty percent of the weight of a neuron’s plasma membrane is composed of DHA. And it’s a key component in heart tissue. I could write an entire chapter on DHA alone, but I’ll spare you that level of detail. Suffice it to say, DHA is one of the most well-documented darlings in protecting the brain.

I often ask doctors in my lectures what they think the richest source of DHA is in nature. I hear all kinds of answers—cod-liver oil, salmon oil, anchovy oil. Some guess flaxseed oil or avocados, but those don’t contain adequate DHA. The richest source of DHA in nature is human breast milk. Which explains why breast-feeding is continually touted as important for the neurologic health and long-term performance of a child.

Plenty of high-quality DHA supplements are available today, and there are more than 500 food products that are enriched with DHA. It doesn’t really matter whether you buy DHA that’s derived from fish oil or from algae. Opt for the algae-derived variety if you’re a strict vegetarian.

Resveratrol: The magic behind the health benefits of drinking a glass of red wine a day has a lot to do with this natural compound found in grapes, which not only slows down the aging process, boosts blood flow to the brain, and promotes heart health, but also curbs fat cells by inhibiting their development. You can’t get enough resveratrol in that glass of wine, though. Hence the need to supplement with higher doses to reap the benefits.

Because this so-called miracle molecule protects cells against a remarkable range of diseases, it’s frequently touted as an assistant in the body’s immune and defense system. Within the last decade we’ve come to learn just how this is possible, thanks largely to the work of Harvard’s Dr. David Sinclair, who discovered the supplement’s ability to activate certain genes called sirtuins, which affect longevity.5 In 2010, scientists at Northumbria University in the United Kingdom published a study in the American Journal of Clinical Nutrition that discussed exactly why resveratrol can be so effective in optimizing brain function.6 In it, they explained that they gave twenty-four students resveratrol and recorded marked increases in blood flow in the brain while they were performing mental tasks. And the harder the tasks, the greater resveratrol’s effect.

Whether or not this means we all should be taking resveratrol before embarking on a serious undertaking like a test or interview is up for debate. But for now we know that we could do our brains well with the addition of a modest dose every day. And note I said modest. Although earlier research hinted that very large doses would be required to reap any benefits (doses equating to drinking hundreds of bottles of wine), newer studies clearly demonstrate that lower doses (as small as 4.9 milligrams per day) confer positive effects.

Turmeric: Turmeric (Curcuma longa), a member of the ginger family, is the subject of intense scientific research, much of it evaluating the anti-inflammatory and antioxidant activities that stem from its active ingredient, curcumin. Turmeric is the seasoning that gives curry powder its yellow color, and as I mentioned earlier, it has been used for thousands of years in Chinese and Indian medicine as a natural remedy for a variety of ailments. In a report for the American Journal of Epidemiology, researchers investigated the association between curry consumption level and cognitive function in elderly Asians.7 Those who ate curry “occasionally” and “often or very often” scored much better on specific tests designed to measure cognitive function than did people who “never or rarely” consumed curry.

One of curcumin’s secret weapons is its ability to activate genes to produce a vast array of antioxidants that serve to protect our precious mitochondria. It also improves glucose metabolism. All of these properties help reduce risk for brain disease. Unless you make lots of curry dishes at home, you probably don’t get a lot of turmeric in your diet on a regular basis.

Probiotics: Stunning new research in just the last few years has shown that eating foods rich in probiotics—live microorganisms that support our intestine’s resident bacteria—can influence brain behavior and help alleviate stress, anxiety, and depression.8, 9, 10 These tribes of “good bacteria” that live in your intestines and help with digestion are enhanced and nourished by probiotics. They play a role in producing, absorbing, and transporting neurochemicals such as serotonin, dopamine, and nerve growth factor, which are essential for healthy brain and nerve function.

Understanding how this is possible requires a quick lesson in the science of your microflora–gut–brain communication.11 It’s true that your gut is your “second brain.”12 This is an area of active, fascinating research, a large volume of which in recent years has demonstrated an intimate communication highway between the brain and the digestive system. Through this two-way connection, the brain receives information about what’s going on in your intestines as the central nervous system sends information back to your gut to ensure optimal functioning.

All this transmission back and forth makes it possible for us to control our eating behavior and digestion, and even find restful sleep at night. The gut also sends out hormonal signals that relay to the brain feelings of fullness, hunger, and even pain from intestinal inflammation. In diseases and illnesses that affect the intestines, such as uncontrolled celiac, IBS, or Crohn’s disease, the gut can be a major influence on our well-being—how we feel, how well we sleep, what our energy level is, how much pain we experience, and even how we think. Researchers are currently looking at the possible role of some strains of intestinal bacteria in obesity, inflammatory and functional GI disorders, chronic pain, autism, and depression. They are also examining the role that these bacteria play in our emotions.13

So intricate and influential is this system that the health of our gut could be a much bigger player in our perception of overall health than we ever imagined. The information processed by the gut and sent up to the brain has everything to do with our sense of well-being. And if we can support this system just by consuming the gut’s most important collaborators—healthy gut bacteria—then why not? Although lots of foods—such as yogurts and some beverages—are now fortified with probiotics, these products can often come with too much sugar. Ideally, get your probiotics through a supplement that offers a variety of strains (at least ten), including Lactobacillus acidophilus and bifidobacterium, and contains at least ten billion active bacteria per capsule.

Coconut oil: As I’ve already described, coconut oil can help prevent and treat neurodegenerative disease states. It’s a superfuel for the brain and also reduces inflammation. You can drink a teaspoon of it straight or use it when you prepare meals. Coconut oil is heat stable, so you can cook with it at high temperatures. In the recipe section, I’ll give you some ideas for working with coconut oil in the kitchen.

Alpha-lipoic acid: This fatty acid is found inside every cell in the body, where it’s needed to produce the energy for the body’s normal functions. It crosses the blood-brain barrier and acts as a powerful antioxidant in the brain in both watery and fatty tissues. Scientists are now investigating it as a potential treatment for strokes and other brain conditions involving free radical damage, such as dementia.14 Although the body can produce adequate supplies of this fatty acid, our modern lifestyles and inadequate diets often require supplementation.

Vitamin D: It’s a misnomer to call vitamin D a “vitamin” because it’s actually a fat-soluble steroid hormone. Although most people associate it strictly with bone health and calcium levels—hence its addition to milk—vitamin D has far-reaching effects on the body and especially on the brain. We know there are receptors for vitamin D throughout the entire central nervous system; we also know that vitamin D helps regulate enzymes in the brain and cerebrospinal fluid that are involved in manufacturing neurotransmitters and stimulating nerve growth. Both animal and laboratory studies have indicated that vitamin D protects neurons from the damaging effects of free radicals and reduces inflammation. Let me state a few key findings:15

·   Reports have shown a 25 percent risk reduction in cognitive decline in individuals with higher levels of vitamin D (severely deficient individuals in one such study were 60 percent more likely to undergo cognitive decline over the six-year follow-up).16

·   A study done over seven years among 498 women showed that those with the highest intake of vitamin D had a 77 percent risk reduction for developing Alzheimer’s disease.17

·   When the mental states of 858 adults were evaluated between 1998 and 2006, there was substantial decline in mental function in those individuals with severe vitamin D deficiency.18

·   Multiple studies link low levels of vitamin D with risk for Parkinson’s and relapse in multiple sclerosis patients. (As an aside: Studies have shown that each 5 ng/mL increase in vitamin D levels in the blood correlates with a 16 percent reduction in relapses in MS.)19

·   Low vitamin D levels have long been shown in medical literature to contribute to depression and even chronic fatigue.20 Adequate vitamin D is needed by the adrenal glands to help regulate an enzyme necessary for the production of dopamine, epinephrine, and norepinephrine—critical brain hormones that play a role in mood, stress management, and energy. People with mild to severe depression have been known to experience turnarounds and improvements through supplementation alone.

Correcting insufficient levels of vitamin D can take several months of supplementation, but doing so will significantly improve your entire body’s chemistry—from bone health to brain health—and even its insulin sensitivity. My dietary protocol will also provide good sources of natural vitamin D found in nature, such as cold-water fish and mushrooms.