Do Carbs Cause Alzheimer's?

by Charlotte Andersen for SHAPE.com

Imagine a piece of whole-grain toast slathered in butter- which part of that do you consider to be healthy? For many years the answer has been the whole-grain bread, but Grain Brain, a new book published this past Tuesday by neurologist David Perlmutter, M.D., argues that we'd all be better off chucking the bread and just eating a stick of butter for breakfast.

Perlmutter says that contrary to popular belief, while we definitely require protein and fat, "the human requirement for dietary carbohydrate is none, none whatsoever." Not only do we not need them, he says that they're killing us, calling carbs "the brain's silent killers."

The book is based on his years of extensive research and private practice as a neurologist in Florida. After years of frustration trying to help patients with all types of cognitive impairments, he finally came to the conclusion that modern medicine tends to focus on treating symptoms, not the underlying disease process. So rather than focus simply on treating Alzheimer's, autism, and other diseases, he came up with a radical diet based on lots of fats, some protein, and almost no carbohydrates to try to prevent the onset of these illness.

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Much of Perlmutter's book focuses on the way he says the human body evolved to eat. "The brain thrives on a fat-rich, low-carbohydrate diet, which unfortunately is relatively uncommon in human populations today," he says. As evidence, he points out how many people struggle with celiac disease or a gluten sensitivity today-up to 30 percent of the population, according to his research. He adds that it is likely that 100 percent of humans have some reaction to gluten because a compound called zonulin is activated when exposed to gluten, and this increases gut permeability. In turn, increased gut permeability can cause all kinds of health issues ranging from mild inflammation to debilitating digestive disorders to autoimmune problems to dementia, he says.

Many experts disagree with Perlmutter, however. "Grain Brain is a misleading and sensationalist title for a book that distorts current science and contributes, sadly, to public confusion about what constitutes a healthy diet," says Cynthia Harriman, director of food and nutrition strategies for the Whole Grains Council. She challenges Perlmutter's numbers, saying that it's closer to 7 to 10 percent of the population with a known gluten intolerance, and even these people can safely and healthfully eat non-gluten-containing grains such as amaranth, buckwheat, corn, and oats (as long as they're certified gluten-free). For the rest of us, "leading medical researchers in the area of gluten intolerance and celiac disease attest that there is no need for 90 percent or more of our population to avoid any grains," Harriman says.

Another one of Perlmutter's contentions is that increased carb consumption is linked to diabetes and becoming a diabetic will double your risk for Alzheimer's disease, for which there is no treatment. "Elevated blood sugar attaches to proteins in the body, and this process dramatically increases the production of both free radicals and chemicals involved in inflammation. Both of these are strongly involved in damaging the brain in Alzheimer's as well as Parkinson's and multiple sclerosis," he says.

While the link between diabetes and cognitive impairment is well documented, the link between grains and cognition may be more complicated, says David R. Jacobs, Ph.D., a professor of nutritional epidemiology at the University of Minnesota School of Public Health. In a 2010 study, he examined 29,192 women over the age of 50 and found that whole-grain intake (as reported on a food frequency questionnaire) increased the women's ability to complete a follow-up questionnaire about their health. He also found that elderly women who ate more whole grains had less "frailty," although since the study wasn't specifically examining that, he says it needs more research.

Jacobs adds that focusing on just one isolated part of a grain-like gluten-misses the bigger picture of "the synergistic effect of the individual constituents within the whole grains," noting that whole grains contain fiber, antioxidants, phytochemicals, and other compounds that are thought to act together to provide protective health benefits. "Whole grains generally are part of a healthy diet," Jacobs concludes.

However, Harriman points out that other than Perlmutter's mistake of generalizing the problems of gluten intolerance to the population as a whole, there is much in the book she finds worthwhile, such as the key roles of physical activity and sleep, the essential contribution of good fats, the value of the Mediterranean Diet (which Perlmutter cites as "very similar to my dietary protocol"), and the importance of avoiding inflammation and choosing carbohydrates with a low glycemic impact. "Don't let Grain Brain scare you away from appropriate-sized portions of healthy forms of whole grains, and enjoy a balanced diet including a delicious variety of real, whole foods," she advises.

RELATED: 6 Common Gluten-Free Myths

Perlmutter says that if there is one thing he wishes he could teach all medical professionals, it's that "nutrition matters more than you could imagine. Time to hit the books and realize that food is our most important health ally." Which is a statement most experts could probably agree with.

What do you think? Tell us your thoughts on Grain Brain in the comments below or tweet us @Shape_Magazine.

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