Your “Healthy” Diet Could Be Quietly Killing Your Brain
A new book challenges convention with the latest science on brain health.
Posted Oct 09, 2013
I recently stumbled onto a book that opened my eyes in many ways to the misinformation plaguing Americans regarding healthy eating, particularly where it concerns brain health. The book, Grain Brain, by Dr. David Perlmutter, is mind-blowing—no pun intended—and disruptive to some long-standing beliefs about what our bodies require for optimal health.
The book is also not without serious consideration for cardiovascular system, citing study after study to reaffirm that it’s not fat and cholesterol, but carbohydrates and certain fats—and not the fats that you would think—that are the true enemies of heart and vascular health. Guidelines to eating for above-average health and longevity are not without nuance, but Grain Brain lays out an easy-to-understand roadmap packed with the latest science in a colloquial writing style, never once doubting the ability of its audience to keep up.
As the only doctor in the country who is both a board-certified neurologist and Fellow of The American Board of Nutrition, he deftly covers a topic rarely discussed: How what we eat affects the health of our brain. And considering that deaths from Alzheimer's increased 68 percent between 2000 and 2010, the timing of Grain Brain couldn’t be better.
After reading it, I couldn't wait to sit down with him for a Q&A. (My questions are in bold.)
You’ve stated that carbs of any kind, from natural sugars in fruit to the complex carbs in quinoa and a whole wheat bagel, are detrimental to the brain, to the point that the most serious degenerative brain disorders, including Alzheimer’s disease, are now being referred to as “Type 3 diabetes”. What’s the science behind this?
Carbohydrate consumption leads to blood sugar elevation obviously in the short term, but also, in the long term as well. Persistently challenging the pancreas to secrete insulin to deal with dietary carbohydrate ultimately leads to insulin resistance, a condition directly associated with increased risk for dementia. What’s worse, insulin resistance is the forerunner of type 2 diabetes, a condition associated with a doubling of Alzheimer’s risk. In a recent report in the Journal of Alzheimer’s Disease., Mayo Clinic researchers showed that individuals favoring carbohydrates in their diets had a remarkable 89% increased risk for developing dementia as contrasted to those whose diets contained the most fat. Having the highest levels of fat consumption was actually found to be associated with an incredible 44% reduction in risk for developing dementia.
So-called “complex carbs” may actually represent a more significant threat to health than simple sugar in that they may not only raise blood sugar, but keep it elevated for a more prolonged period of time. Foods can be evaluated by their glycemic index which measures not only how high blood sugar will be elevated by the consumption of a particular food, but also takes into account how long it will have this effect. So the higher the glycemic index, the more damaging are the effects of elevated blood sugar. Whole grain bread for example has a dramatically higher glycemic index when compared to pure table sugar.
Ultimately, continued challenges of our bodies with high glycemic index foods leads to elevation of fasting blood sugars. This is of paramount importance as recently published in New England Journal of Medicine. In this report, researchers found that a fasting blood sugar even in the range that most doctors would consider to be normal, levels far below what would qualify for the diagnosis, are powerfully associated with developing dementia.
In your book you challenge some of the most commonly accepted dogmas regarding nutrition, namely that both saturated fat and cholesterol are not only benign, but imperative to brain health. If someone is suffering from brain dysfunction, would you actually recommend that they consume more red meat, whole eggs, coconut oil as treatment?
Two forms of fat that are vitally important for brain health are cholesterol and saturated fat. In the Mayo Clinic study mentioned above, it was found that those individuals consuming the most saturated fat experienced a 36% reduction in risk for developing dementia. And this comes on the heels of data now indicating that saturated fat consumption has absolutely no relevance in the area of cardiovascular risk as recently described by Dr. Glen Lawrence in the journal, Advances in Nutrition.
Saturated fat is a fundamental building block for brain cells. It’s certainly interesting to consider that one of the richest sources of saturated fat in nature is human breast milk.
Similarly, cholesterol is vital for a well functioning brain. Cholesterol functions as a brain protective antioxidant. It is the raw material from which our bodies make vitamin D, a fundamental player in preserving brain function. In addition, cholesterol is the precursor for the sex hormones estrogen, progesterone and testosterone – all of which contribute to healthy brain function. While the brain constitutes about 2-3% of our total body weight, an impressive 25% of the body’s cholesterol is found in the brain. So when the FDA last year began requiring consumer warnings on certain cholesterol lowering medications related to memory decline and other cognitive issues, it wasn’t surprising. Indeed, it has now been shown that in the elderly, those folks whose cholesterol levels are the highest may have as much as a 70% risk reduction for dementia.
So yes, I am absolutely an advocate for grass-fed beef, pasture raised eggs, and coconut oil is on the top of my list. Getting these life sustaining, brain nurturing fats back on the plate while substantially reducing carbohydrates paves the way to brain preservation, enhancement of function and reducing the risk for Alzheimer’s disease – a disease for which there is no treatment whatsoever.
In general, the public knowledge base and thus decision-making behaviors are far more influenced by advertisement than with current science. The widespread demonization of cholesterol has been incredibly monetized as you well point out. My mission is to offer up the other side of this debate to the public forum so caveat emptor can more appropriately apply.
You reference many studies that challenge conventional wisdom about heart health, most interestingly that people with high cholesterol and low cholesterol tend to have just as many heart attacks and die just as frequently. Should a diagnosis of “high cholesterol” from ones internist be alarming? Are there any cases in which it should be controlled by medicine or diet?
Over the past decade we have witnessed a changing landscape in terms of refinement of the cholesterol markers as they relate to cardiovascular risk. Whereas cholesterol itself was first targeted, emphasis soon moved to LDL as it was given the name “bad cholesterol,” despite the fact that LDL’s role is to deliver life sustaining cholesterol to every one of our body’s cells. I’ll say parenthetically that whatever marketing team attached the “bad “ surname to LDL must have been well rewarded! We then saw emphasis move to the importance of so-called “particle size” as being an important marker of cardiovascular risk – and rightfully so, size really does matter.
Now the focus of attention has gone back to LDL in recognizing that it truly represents a potent risk factor when it has become oxidized. Oxidation represents the damage that can occur to proteins by the action of chemicals called free radicals. So, measurement of oxidized LDL is now showing up on comprehensive heart disease blood panels, and with good reason. The empowering science here is that LDL gets oxidized when it is bound to sugar, a process called glycation. And this process is directly related to fasting blood sugar and therefore relates to a person’s choice to consume carbohydrates – or not. In evaluating cholesterol in and of itself, I do not define any upper limit in terms of cardiac liability.
A recent report correlated higher intake of omega 3 fish oils—which we know from Grain Brain to be very healthy and protective to the brain—with a greater incidence of acquiring prostate cancer. I was always under the assumption that the more omega 3's you could consume, the better (while minimizing omega 6's, their pro-inflammatory cousin). What's your take on the study?
The study had actually nothing to do with taking fish oils or any supplement for that matter. And yet spinmeisters would have you believe that this report dealt with people taking supplements compared to those who did not. What the study showed was that those men whose one time measurement of the omega-3 DHA was higher than others were found to have a miniscule increased risk for developing prostate cancer. The explanation that the public did not get was that because most men get their DHA from fish consumption as opposed to supplementation, and that the vast majority of fish consumed is farm raised, eating farm raised fish poses a risk for developing prostate cancer. And that is certainly no surprise.
My grandmother is 96 years old and has never even heard of gluten. Because of the seemingly overnight hysteria surrounding this grain protein, some have written it off as a fad. How do you refute this?
In writing Grain Brain, I reviewed more than 250 peer-reviewed references, many of which specifically address this issue and are discussed in great detail. Gluten free isn’t new or a fad. It’s the diet that humans have consumed for more than 99.9% of our existence on this planet. I would direct your readers to recent publication by my friend and colleague Dr. Alessio Fasano from Harvard. I welcome the hysteria as it is directing attention to an absolutely fundamental issue in our modern nutrition.
If someone is not suffering from celiac disease, and generally feels okay after consuming bread—even 100% whole grain bread—how do you convince them that wheat is as detrimental as you claim in the book?
I must and should defer to the most well respected peer-reviewed literature that now indicates that gluten consumption leads to the amplification of a specific protein called zonulin which increases permeability of both the gut and blood brain barrier as described by Dr. Fasano in the above reference. Gut permeability activates inflammation and inflammation is a cornerstone of some of the most pernicious brain disorders including Alzheimer’s disease, multiple sclerosis, and Parkinson’s disease. What is so compelling in a very positive light is that this occurs in all humans and may be the key to a vast number of human maladies including a vast number of other inflammatory disorders as well as autoimmune diseases, and even cancer.
In addition, the gluten issue aside, whole grain bread has an incredibly high glycemic index and this poses an equally powerful threat to brain health.
What’s your daily diet like? What's currently in your fridge?
I really love to eat and maintain the diet described in Grain Brain. I generally start my day with a three egg omelet made with kale or spinach and covered with olive oil. I drink a cup of coffee with breakfast along with water. At lunch I might have steamed vegetables, salmon, a green salad and an iced tea. And at dinner I again load up with above ground vegetables by themselves or along with wild fish or grass fed beef. I drink one or two glasses of wine each week, but statistically I should drink more. That’s a work in progress.
As to your second question, there’s not much in my fridge at home as we try to keep food as fresh as possible and as of this writing, my wife and I are traveling.
Grain Brain is available now in bookstores and on Amazon.com.