如果你早餐刚吃了谷类食物或者中饭只嚼了一块三明治，你也许不想读这篇文章，因为根据文中的医生所言，谷物有损你的大脑健康。

It's tempting to call David Perlmutter's dietary advice radical. The neurologist and president of the Perlmutter Health Center in Naples, Fla., believes all carbs, including highly touted whole grains, are devastating to our brains. He claims we must make major changes in our eating habits as a society to ward off terrifying increases in Alzheimer's disease and dementia rates.

And yet Perlmutter argues that his recommendations are not radical at all. In fact, he says, his suggested menu adheres more closely to the way mankind has eaten for most of human history.

What's deviant（不正常的）, he insists, is our modern diet. Dementia, chronic headaches, depression, epilepsy and other contemporary scourges are not in our genes, he claims. "It's in the food you eat," Perlmutter writes in his bestselling new book, Grain Brain: The Surprising Truth About Wheat, Carbs, and Sugar – Your Brain's Silent Killers. "The origin of brain disease is in many cases predominantly dietary."

Perlmutter's book is propelled by a growing body of research indicating that Alzheimer's disease may really be a third type of diabetes, a discovery that highlights the close relationship between lifestyle and dementia. It also reveals a potential opening to successfully warding off debilitating brain disease through dietary changes.

Perlmutter says we need to return to the eating habits of early man, a diet generally thought to be about 75 percent fat and 5 percent carbs. The average US diet today features about 60 percent carbs and 20 percent fat. (A 20 percent share of dietary protein has remained fairly consistent, experts believe.)

Some in the nutrition and medical communities take issue with Perlmutter's premise and prescription. Several critics, while not questioning the neurological risks of a high-carb diet, have pointed out that readers may interpret his book as a green light to load up on meat and dairy instead, a choice that has its own well-documented cardiovascular health risks. 

"Perlmutter uses bits and pieces of the effects of diet on cognitive outcomes -- that obese people have a higher risk of cognitive impairment, for example -- to construct an ultimately misleading picture of what people should eat for optimal cognitive and overall health," St. Catherine University professor emerita Julie Miller Jones, Ph.D., told the website FoodNavigator-USA.

Grain Brain does delve deeply into the neurological effects of dietary sugar. "The food we eat goes beyond its macronutrients of carbohydrates, fat and protein," Perlmutter said in a recent interview with Next Avenue. "It's information. It interacts with and instructs our genome with every mouthful, changing genetic expression."

Human genes, he says, have evolved over thousands of years to accommodate a high-fat, low-carb diet. But today we feed our bodies almost the opposite, with seemingly major effects on our brains. A Mayo Clinic study published earlier this year in the Journal of Alzheimer's Disease found that people 70 and older with a high-carbohydrate diet face a risk of developing mild cognitive impairment 3.6 times higher than those who follow low-carb regimens. Those with the diets highest in sugar did not fare much better. However, subjects with the diets highest in fat were 42 percent less likely to face cognitive impairment than the participants whose diets were lowest in fat.

Further research published in the New England Journal of Medicine in August showed that people with even mildly elevated levels of blood sugar -- too low to register as a Type 2 diabetes risk -- still had a significantly higher risk of developing dementia. 

"This low-fat idea that's been drummed into our heads and bellies," Perlmutter says, "is completely off-base and deeply responsible for most of our modern ills."

This fall, the federal government committed $33.2 million to testing a drug designed to prevent Alzheimer's in healthy people with elevated risk factors for the disease, but "the idea of lifestyle modification for Alzheimer's has been with us for years," Perlmutter says, and it's cost-free.

The author hopes his book and other related media on the diet-dementia connection will inspire more people to change the way they eat. "Dementia is our most-feared illness, more than heart disease or cancer," Perlmutter says. "When you let Type 2 diabetics know they're doubling their risk for Alzheimer's disease, they suddenly open their eyes and take notice.