Before we discuss Grain Brain, I think it's important to look at Dr. Perlmutter's credentials. Dr. Perlmutter is a board certified neurologist and Fellow of the American College of Nutrition. He currently sees patients at his practice in Naples, Florida and is an Associate Professor at the University of Miami School of Medicine.
In Grain Brain, Dr. Perlmutter makes the case that consumption of grains and a high carbohydrate diet are detrimental to brain health and seem to be a primary cause for a number of neurological problems. He goes over the effects of gluten, high blood glucose, and insulin levels on brain function thoroughly. I think most people buy in to these concepts save for gluten, but one concept they will not buy in to is the health promoting effects of cholesterol on the brain and how detrimental it is to try and lower your cholesterol. He covers this in detail, and it was something he covered in depth in Power Up Your Brain as well.
The amount of research he goes over in Grain Brain is impressive. While a lot of that data is epidemiological, meaning you can't use it to draw conclusions, he uses the research in the way that it's meant to be used. He uses the data to identify the important relationships and provides the mechanisms by which the relationships may exist. It doesn't hurt that his clinical experience confirms much of his reasoning, which he points out in a few case studies throughout the book. Let's look at some of the general mechanisms he discusses in Grain Brain.
Dr. Perlmutter fingers diet as the primary cause of more or less all of the common brain diseases we are seeing today including Alzhimer's disease, Parkinson's disease, anxiety, depression, schizophrenia and more.. He describes how a high carbohydrate diet, gluten consumption, and the avoidance of dietary cholesterol are related to brain disease in great detail. The two primary mechanisms by which diet can negatively affect brain health are inflammation and free radical production. If you don't have a thorough understanding of how these processes are interrelated, this book will give it to you. The research even points to blood glucose levels in the normal range as being detrimental to brain health and he describes why very well. Let's just say that by the time you have diabetes or pre-diabetes, you have done significant damage already.
While most of the book is related to brain health, he discusses several instances where patients have resolved terrible neurological problems by removing gluten from their diet. The science has identified the vagus nerve as the conduit through which the bacteria in your gut communicate with your brain(1). If pathogenic bacteria are able to hijack the vagus nerve, bad neurological problems are sure to ensue. The vagus nerve helps control heart rate, blood pressure, and other aspects of the autonomic nervous system, specifically by calming the nervous system down, so to speak.
One thing I find very refreshing about Grain Brain is that Dr. Perlmutter squashes the notion that you can be overweight and healthy at the same time. While it is possible to be overweight and have numbers that are perfectly fine on a comprehensive metabolic panel, the effects on the brain are noticeable from the get go. Here is a quote directly from Grain Brain:
"In a joint research project between UCLA and the University of Pittsburgh, neuroscientists examined brain images of ninety-four people in their seventies who had participated in an earlier study of cardiovascular health and cognition...What these researchers found was that the brains of obese people-defined by having a body mass index above 30-looked sixteen years older than their healthy counterparts of normal weight. And those who were overweight-defined by having a body mass index between 25 and 30-looked eight years older than their leaner counterparts."
While this quote is pretty shocking, many of the findings in other studies he references match or surpass it. This is not to say that this damage is irreversible, it is completely reversible with the proper dietary and lifestyle modifications which are included in the book as an easy to follow program.
The discussion on cholesterol in Grain Brain is fantastic and should be required reading. One thing Dr. Perlmutter does in Grain Brain that he didn't in Power Up Your Brain is take on statin drugs. Given his discussion on how important cholesterol is for the brain, his take makes sense. However, he also discusses how statin drugs, although anti-inflammatory, can actually increase inflammation and free radical production.
When I started reading Grain Brain and up until about halfway through I did not buy in to his recommended carbohydrate consumption. At this point I still think his recommendations on carbohydrates are too low. His description of how glucose enters the cell is pretty simplistic and does not take in to consideration that insulin is only necessary for glucose to enter cells when at rest. However, as I read on I began to buy in a little more. When the discussion in the book began I was adamant that he was wrong, but after providing his case I'm not so sure. If you are trying to mitigate the risk of having elevated blood glucose, he may be spot on. At this point, however, my A1c and fasting blood glucose levels are in line with his recommendations. Since I have not had my fasting insulin levels checked, which he recommends, there is the potential that I am wrong.
It's funny, I really liked Power Up Your Brain. I read it as I was beginning my shift to a more Paleo way of life. What drew me to the Paleo Diet is the evolutionary approach to health. Not the mistaken notion that we are not evolved to eat certain things so much as the way we evolved has a dramatic impact on what is optimal for human health today. Dr. Perlmutter uses the same approach in Grain Brain and you don't have any of the "gotcha" scientific misrepresentations that many make about Paleo. Most of these issues were settled a few years ago but new books by hacks seem to want to rehash these issues. It's great to have people like Dr. Perlmutter on board because he is obviously a better source of information than the guy your Uncle Eddie knows who heard from another guy that gluten is only bad for celiacs. He has the scientific references and clinical experience to back up his assertions and I am thankful he invests his time in writing books to help people that aren't his patients.
The grand question is will Grain Brain make a difference? I'm a bit cynical about how big of an impact this will have. It is estimated that 90% of Americans are for the labeling of GMOs, yet somehow California is unable to pass a bill requiring the labeling of GMOs. This is because corporations have essentially unlimited funds to mislead a populace that is uninformed at best and stupid at worst. I bought and read this book on the day it was released and I will buy a few more copies for people I want to read it to help push it up the NY Times best seller list. If it gets to the top, the discussion on cholesterol will at least annoy some vegans I know.
Overall I give Grain Brain a 9 out of 10. I still think the discussion on carbohydrate metabolism is off and potatoes and low fructose fruits are probably perfectly fine to consume within a sane level of total daily carbohydrates (150g or so). Everything else in the book is great and I think most people would be healthier and happier trying his 4 week program.