Rethinking Dietary Approaches for Brain Health

Abstract

David Perlmutter: The major thesis of Grain Brain is that both carbohydrates and glucose are detrimental to brain health. Well-respected and peer-reviewed journals have published reports that higher levels of blood glucose are specifically damaging and detrimental to the brain in general, and more specifically, to the hippocampus, which mediates memory function. A recent article in Neurology reported that elevations of blood glucose and glycated hemoglobin [HbA1c] translate into two things: memory compromise and shrinkage of the hippocampus.2 Another recent article in The New England Journal of Medicine demonstrated that even mild elevations of blood sugar translate dramatically into an increased risk for developing dementia.3 It is a profound correlation to recognize that even subtle elevations of blood glucose—well below levels to be considered diabetic—may already be damaging the brain. If we understand that elevated blood glucose and glycation of proteins relate to an increased risk for cognitive dysfunction, as well as brain shrinkage, what should a dietary evaluation look like? A study in the Journal of Alzheimer’s Disease, demonstrated that individuals who consumed higher amounts of carbohydrates in their diets had about an 89% increased risk for developing dementia, in contrast to people whose diets were highest in fat and whose risk was reduced by 44%.4 We live with this notion that a calorie is a calorie, but, at least in terms of brain health—and I believe for the rest of the body as well—there are very big differences between our sources of calories in terms of the impact on our health. Carbohydrate calories, which elevate blood glucose, are dramatically more detrimental to human physiology—and specifically to human health—than are calories derived from healthful sources of fat. The diet that I recommend—high in fat and low in carbohydrates—has simply been what we have eaten for a million years, so it has a bit of a track record. The notion that this is a revolutionary new diet has to be put into context. In reality, the diet that people are now consuming, which is dreadfully high in carbohydrates and low in fat, as our governmental institutions are recommending, is the biggest challenge to human physiology that we have ever experienced, and this is very, very worrisome. In terms of gluten consumption, we have come a long way from our understanding that celiac disease exists, and we now recognize that, according to top researchers, non-celiac gluten sensitivity also exists, which may affect 30% of humanity. Marios Hadjivassiliou [MD, department of neurology, Royal Hallamshire Hospital, Sheffield, United Kingdom] has said, so poetically, that gluten sensitivity may at times be a pure neurologic disease that is basically extraintestinal, and that we do not need to have intestinal issues to define gluten sensitivity. In fact, we are now seeing literature that points the finger clearly at gluten sensitivity as a culprit in a variety of neurologic problems, including depression, cognitive dysfunction, seizures, and even headaches. According to the work of Alessio Fasano [MD, chief of pediatric gastroenterology and nutrition at MassGeneral Hospital for Children, Boston, Massachusetts], gluten stimulates the production of zonulin, and zonulin makes the bowel hyperpermeable, which allows proteins access to the bloodstream, where they might normally have been excluded.5 More importantly, what Dr. Fasano’s research has revealed is that the same mechanism is involved—gluten-stimulating zonulin—in increasing the permeability of the blood–brain barrier. While clinicians may be concerned about patients having leaky bowels, I can promise that having a leaky brain is certainly of much more concern. What is so compelling about Dr. Fasano’s work is that, according to Rethinking Dietary Approaches for Brain Health