The "Grain Brain" diet, popularized by Dr. David Perlmutter in his bestselling book, promises a revolutionary approach to brain health. It posits that carbohydrates and gluten are the root cause of various neurological disorders, advocating for a very-low-carbohydrate, high-fat diet as the solution. This article critically examines the claims made by the "Grain Brain" diet, comparing them with scientific evidence and expert opinions.
The Promises of "Grain Brain"
Dr. Perlmutter claims that his "Grain Brain" program will lead to increased confidence and self-esteem, a more youthful feeling, and greater control over one's life. Furthermore, he suggests the diet will improve insulin sensitivity, lower diabetes risk, facilitate fat loss, and even treat Alzheimer's disease. These are bold claims that warrant careful scrutiny.
Diet Overview
The "Grain Brain" diet is a four-week plan that focuses on reducing carbohydrate intake to fewer than 60 grams per day while emphasizing high fat consumption. It discourages calorie counting but provides limited guidance on carbohydrate counting. The diet identifies gluten as a primary culprit in brain health issues, asserting its role in conditions like ADHD, chronic headaches, dementia, and Alzheimer's. The diet promotes the consumption of meat and oils to achieve ketosis, suggesting ketosis is safe due to evolutionary adaptation.
Examining the Key Claims
Several key claims in "Grain Brain" have been subjected to scrutiny:
Carbohydrate and Dementia Risk
The book argues that carbohydrate consumption increases dementia risk by causing insulin resistance and diabetes, which in turn promote dementia. While it is true that insulin resistance, diabetes, and elevated blood sugar levels may increase dementia risk, there is limited evidence that carbohydrate itself causes insulin resistance. In fact, a large scientific trial demonstrated that a calorie-controlled, low-fat, high-carbohydrate diet combined with exercise significantly reduces the risk of developing diabetes. The "Grain Brain" diet's claim lacks substantial evidence.
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High Cholesterol and Brain Health
"Grain Brain" suggests that high levels of blood cholesterol, including LDL cholesterol, are beneficial for the brain. This claim is not only likely incorrect but also potentially dangerous. Research indicates that high blood cholesterol in midlife is strongly associated with an increased risk of Alzheimer's disease. Moreover, studies examining cholesterol-increasing genes and the impact of cholesterol-lowering statin drugs on dementia risk do not support the claim that high cholesterol protects against dementia.
Gluten and Brain Disorders
The book asserts that gluten is a major cause of numerous brain conditions, including dementia, depression, ADHD, schizophrenia, anxiety, epilepsy, movement disorders, and migraine. It cites a study that reported higher levels of anti-gluten antibodies in people with brain illnesses of unknown cause. However, the same study found that people with known brain illnesses, including epilepsy, movement disorders, and dementia, had the lowest rate of gluten antibodies. This undermines the sweeping claims made in "Grain Brain".
Scientific Accuracy Assessment
An overall scientific accuracy score of 0.8 was given to "Grain Brain," indicating that its key claims are poorly supported by evidence. The book tends to cite references accurately when making mainstream scientific claims, but accuracy deteriorates when supporting more questionable claims. For example, the book inaccurately stated that an exercise intervention in elderly people caused an "1,800 percent improvement" in cognitive function when the study reported only a "modest improvement."
The "Atkins Diet" Connection
The "Grain Brain" diet has been compared to a backdoor approach to the Atkins low-carbohydrate method. While the Atkins Diet openly recommends a diet primarily composed of meat, poultry, cheese, butter, fish, and eggs, "Grain Brain" subtly steers readers away from starchy foods, suggesting they are unhealthy. However, it's important to recognize that populations throughout history have thrived on diets rich in grains and starchy vegetables, and these foods do not inherently cause type-2 diabetes.
Inflammation and Carbohydrates
The claim that dietary carbohydrates are packed with inflammatory ingredients is largely unfounded. Inflammation is a response to injury, and the primary sources of repetitive injury in dietary diseases like atherosclerosis are meat, cheese, and eggs. Studies have shown that whole-grain bread consumption is associated with lower levels of inflammatory markers, while red meat consumption is associated with higher levels.
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The Role of Whole Grains
While wheat can be problematic for individuals with Celiac disease, whole grains have historically been a major source of calories, protein, vitamins, and minerals for billions of people. Meta-analyses have shown that consuming whole grains is associated with a reduced risk of type-2 diabetes and heart disease.
The Importance of Diet Quality
It is essential to note that the Western diet, loaded with meat, fat, and empty calories, contributes to weight gain and diabetes. Steering people away from healthy components of the diet, such as grains and starchy vegetables, in favor of unhealthy foods like meat, dairy, fish, and eggs, can worsen matters.
The MIND Diet as an Alternative
The Mediterranean-DASH Diet Intervention for Neurodegenerative Delay, or MIND diet, offers a more balanced approach to promoting brain health. The MIND diet emphasizes plant-based foods while limiting animal and high saturated fat foods. Studies have shown that higher MIND diet scores are associated with a slower rate of cognitive decline and a reduced risk of Alzheimer's disease.
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