Medscape recently interviewed Dr. David Perlmutter, Associate Professor at the University of Miami School of Medicine, about his theory that carbohydrate and gluten consumption may cause or contribute to dementia. Dr. Neal D. Barnard, Adjunct Associate Professor of Internal Medicine at the George Washington University School of Medicine, doesn't agree. Here's why.
Grain and the Brain: A Lesson From Japan
It seems that many people are looking for a whipping boy on whom to blame our expanding waistlines, our diabetes epidemic, and our continuing need for cholesterol and blood pressure medications. Apparently they have found him: bread. It's not that grease-laden eggs-and-bacon breakfast, those fat-drenched chicken wings, or that sausage-and-cheese pizza that have caused our problems; it's that darn slice of bread.
Some clinicians and writers are going a step further. They are now flogging that whole-wheat whipping boy for triggering Alzheimer disease. But scientific evidence tells a very different story.
Grain-blaming started with the observation that high blood sugar levels are linked with Alzheimer disease. That's true enough. People with diabetes are at elevated risk of developing dementia. So some have reasoned that because carbohydrates release natural sugars during digestion, the way to lower blood sugar must be to avoid carbs. They assumed that might protect the brain, too.
But here they have stepped on a scientific landmine. Avoiding healthy carbohydrate-containing foods turns out to be the last thing you would want to do for diabetes, obesity, or Alzheimer disease.
Take a lesson from Japan. In the 1960s and 1970s, Japan's dietary staple was rice. The Japanese diet was, of course, very high in carbohydrate, and yet diabetes was rare -- affecting a mere 1%-5% of adults older than 40 years. In the ensuing years, westernization occurred rapidly. Meat displaced rice in Japanese meals and fat intake quickly climbed, while carbohydrate consumption plummeted. What was the result? By the 1990s, diabetes prevalence had risen dramatically. Clearly, carbohydrate was not the problem. The influx of fatty foods had elevated blood sugars and sparked a diabetes epidemic.
Americans have undergone a similar shift, albeit more gradually. In 1909, according to records from the US Department of Agriculture, American meat intake was 123.9 lb per person per year. Over the next century, meat intake soared, peaking at over 201.5 lb per person per year in 2004. That's an average rise of more than 75 lb -- every person, every year. In the same interval, per capita cheese intake rose from less than 4 lb per year to nearly 34 lb. Grain intake went in the opposite direction: It fell substantially. Although it has partially rebounded in recent years, our consumption of flour and cereal products is far below 1909 levels.
So it is not bread, rice, or grains in general that have caused blood sugars to rise or diabetes to become an epidemic. Just the opposite: The transition to a diet heavily based on animal products, especially meat and cheese, aided and abetted by fryer grease and sugar, is the real culprit in the current epidemics of obesity; diabetes; and, as we will see, Alzheimer disease.
We can't blame a lack of exercise either. Careful studies show that exercise patterns have not changed nearly enough to account for the dramatic rise in obesity. The real problem is on the input side of the calorie equation.
But, you ask, aren't carbs fattening? The answer is no, and this is not rocket science. Carbohydrates have only 4 calories per gram. Fats have 9. So skipping meat and cheese and their load of fat is a great step for slimming down. In fact, the butter slathered over your morning toast is far denser in calories than the bread itself. Ditto for the cream cheese on a bagel, the meat sauce on your spaghetti, and the shortening baked into a cookie. Low-carb diets cause weight loss only when you leave out so many foods that your calorie intake falls. There is nothing magical or healthy about avoiding carbohydrates.
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Cite this: Neal D. Barnard. Is Avoiding Grains a Mistake? - Medscape - Feb 26, 2014.