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Diabetes Developments - A blog on latest developments in diabetes by David Mendosa

The Carbohydrate Brain Fuel Myth

May 11th, 2008 · 8 Comments

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We distort knowledge faster than things. Some things are so easy to assemble that “even a child can do it” in outer space. But even children know that information disassembles all too readily.

Children learn by playing the game of telephone that information gets garbled as it gets passed along. Too bad that medical writers don’t know that basic lesson.

That’s why that although I am also a medical writer about diabetes, I don’t ask you to trust me. Unlike almost everyone who prepares medical articles for the Internet, I link the primary sources so you can see that it’s not just my opinion or a secondary source that other medical writers at secondary sources like Reuters Health write.

In the children’s game of telephone cumulative errors from mishearing often result in what the last player hears isn’t anything like the way it started. This can amuse children. But it can lead us seriously astray. The brain fuel myth can lead those of us who have diabetes to a diet far too high in carbohydrates.

If the people who say that our brains need at least 130 grams of available carbohydrate per day to work properly were correct, then nothing you read here can make any sense. For about half a year I have been getting only about a third of that amount.

You can read — but don’t swallow — what Edutopia Magazine writes about our carbohydrate requirements. “To achieve and maintain normal brain function, adults and children need 130 grams of carbohydrates a day,” some freelance medical writer named Abby Christopher writes there.

She even quotes Diane Stadler, research assistant professor in the Oregon Health and Science University’s health promotion and sports medicine division to that effect. “Restricting carbs like [the Atkins Diet ] is going to have an effect on the brain,” Ms. Stadler told her.

Closer to home is a comment by a Certified Diabetes Educator to one of my articles here. “Remember that the brain does need 130 grams of carbs per day for healthy function,” she writes.

Even more grievous is the American Diabetes Association’s intermediate oversimplification. While the ADA isn’t as ridiculously wrong as the Edutopia Magazine article and that CDE, some people still believe what the largest diabetes charity organization tells us.

“The recommended dietary allowance (RDA) for digestible carbohydrate is 130 grams per day,” says the ADA’s latest position statement on its “Nutrition Recommendations. Why do we need so much carbohydrate?

The RDA is based, the ADA says,  “on providing adequate glucose as the required fuel for the central nervous system without reliance on glucose production from ingested protein or fat.”

Ah! So it’s at least 130 grams of glucose per day that our brain needs! And glucose just ain’t the same thing as carbohydrate.

Our bodies can convert protein into glucose, “but very slowly and inefficiently,” as Dr. Richard K. Bernstein wrote in Dr. Bernstein’s Diabetes Solution. The conversion of fat to glucose works much better.

“Fat is the perfect fuel, Dr. Michael Eades wrote on his blog. “Part of it provides energy to the liver so that the liver can convert protein to glucose. The unusable part of the fat then converts to ketones, which reduce the need for glucose.”

Dr. Eades continues. If “you’re following a low-carb diet…the protein you eat is converted to glucose….If you keep the carbs low enough so that the liver still has to make some sugar, then you will be in fat-burning mode….How low is low enough? Well, when the ketosis process is humming along nicely and the brain and other tissues have converted to ketones for fuel, the requirement for glucose drops to about 120-130 gm per day. If you keep your carbs below that at, say, 60 grams per day, you’re liver will have to produce at least 60-70 grams of glucose to make up the deficit, so you will generate ketones that entire time.”

In fact, I give the ADA credit for citing the primary source in its “Nutrition Recommendations.” That source is a report by the Institute of Medicine’s food and nutrition board titled Dietary Reference Intakes: Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. The National Academies Press in 2002 published this book. While the ADA fails to provide a link,  fortunately for those of us who like to go to primary sources you can find it online.

What is this Institute of Medicine and why should we trust it? The Institute of Medicine and its parent organization, the National Academy of Sciences, are hybrid governmental-private organizations. The U.S. government created these private organizations to advise it on scientific and technological matters. Among their functions they set the official recommended dietary allowances for the macronutrients and micronutrients in our diet.

The Institute of Medicine takes 17 dense pages — from page 277 to 293 — to consider the evidence for estimating the average requirement for carbohydrate. I’ve studied them and encourage you to study the source for yourself. I don’t need to copy or summarize its recommendations because Gary Taubes did it so well in his ground-breaking new book, Good Calories, Bad Calories, which I have written about here and in several other articles.

The IOM sets an “estimated average requirement” of 100 grams of carbohydrates a day for adults, Taubes writes, so that the brain can run exclusively on glucose, “without having to rely on a partial replacement of glucose by [ketone bodies].” It then sets the “recommended dietary allowance” at 130 grams to allow a margin for error. But the IOM report also acknowledges that the brain will be fine without these carbohydrates, because it runs perfectly well on ketone bodies, glycerol, and protein-derived glucose.

Many people don’t understand what ketone bodies (or “ketones”) are, confusing it with a dangerous condition called ketoacidosis. Dr. Eades, however, provides a clear explanation of why ketones are good.

“The liver requires energy to convert the protein to glucose,” he writes on his blog. “The energy comes from fat. As the liver breaks down the fat to release its energy to power gluconeogenesis, the conversion of protein to sugar, it produces ketones as a byproduct. And what a byproduct they are. Ketones are basically water soluble (meaning they dissolve in blood) fats that are a source of energy for many tissues including the muscles, brain and heart. In fact, ketones act as a stand in for sugar in the brain. Although ketones can’t totally replace all the sugar required by the brain, they can replace a pretty good chunk of it.”

No one should be surprised that it’s glucose rather than carbohydrates that our brains run on. For a century we have had evidence that our brains don’t need any carbohydrates. The arctic explorer Dr. Vilhjalmur Stefansson in 1935 wrote three articles about how “Eskimos Prove an All Meat Diet Provides Excellent Health” that you can read on my website starting with this article. Dr. Stefansson himself lived on an all-meat diet when he went to the arctic in 1906. Even before he wrote those articles, the Journal of Biological Chemistry reported on the experiments performed on him and a colleague at New York’s Bellevue Hospital in the article, “Prolonged Meat Diets with a Study of Kidney Function and Ketosis” by Walter S. McClellan and Eugene F. Du Bois (J. Biol. Chem. 87: 651-668, July 1930).

Just now we even have evidence that some of our brains work much better on a very low carbohydrate diet. British researchers reported on May 2 in The Lancet Neurology that a very low carb diet has proved highly effective in reducing seizures in children whose epilepsy didn’t respond to medication.

Does this make sense to you? Since I follow a very low-carb diet, I may be courting a nasty case of what Edutopia Magazine calls “Um…er…can’t remember…what was I going to say?”

But I go to the primary sources, and my brain seems to be working as well as ever, thank you. Hello? Can you hear me now?

This is a mirror of one of my articles that Health Central published. You can navigate to that site to find my most recent articles.

We distort knowledge faster than things. Some things are so easy to assemble that “even a child can do it” in outer space. But even children know that information disassembles all too readily.

Children learn by playing the game of telephone that information gets garbled as it gets passed along. Too bad that medical writers don’t know that basic lesson.

That’s why that although I am also a medical writer about diabetes, I don’t ask you to trust me. Unlike almost everyone who prepares medical articles for the Internet, I link the primary sources so you can see that it’s not just my opinion or a secondary source that other medical writers at secondary sources like Reuters Health write.

In the children’s game of telephone cumulative errors from mishearing often result in what the last player hears isn’t anything like the way it started. This can amuse children. But it can lead us seriously astray. The brain fuel myth can lead those of us who have diabetes to a diet far too high in carbohydrates.

If the people who say that our brains need at least 130 grams of available carbohydrate per day to work properly were correct, then nothing you read here can make any sense. For about half a year I have been getting only about a third of that amount.

You can read — but don’t swallow — what Edutopia Magazine writes about our carbohydrate requirements. “To achieve and maintain normal brain function, adults and children need 130 grams of carbohydrates a day,” some freelance medical writer named Abby Christopher writes there.

She even quotes Diane Stadler, research assistant professor in the Oregon Health and Science University’s health promotion and sports medicine division to that effect. “Restricting carbs like [the Atkins Diet ] is going to have an effect on the brain,” Ms. Stadler told her.

Closer to home is a comment by a Certified Diabetes Educator to one of my articles here. “Remember that the brain does need 130 grams of carbs per day for healthy function,” she writes.

Even more grievous is the American Diabetes Association’s intermediate oversimplification. While the ADA isn’t as ridiculously wrong as the Edutopia Magazine article and that CDE, some people still believe what the largest diabetes charity organization tells us.

“The recommended dietary allowance (RDA) for digestible carbohydrate is 130 grams per day,” says the ADA’s latest position statement on its “Nutrition Recommendations. Why do we need so much carbohydrate?

The RDA is based, the ADA says,  “on providing adequate glucose as the required fuel for the central nervous system without reliance on glucose production from ingested protein or fat.”

Ah! So it’s at least 130 grams of glucose per day that our brain needs! And glucose just ain’t the same thing as carbohydrate.


Our bodies can convert protein into glucose, “but very slowly and inefficiently,” as Dr. Richard K. Bernstein wrote in Dr. Bernstein’s Diabetes Solution. The conversion of fat to glucose works much better.

“Fat is the perfect fuel, Dr. Michael Eades wrote on his blog. “Part of it provides energy to the liver so that the liver can convert protein to glucose. The unusable part of the fat then converts to ketones, which reduce the need for glucose.”

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8 responses so far ↓

  • 1 dolores // Sep 18, 2009 at 6:05 am

    Mr. Mendosa, I have been type two for 18 years (since diagnosis) and eat potatoes, bread, rice, oatmeal etc. I am not on any meds and my blood sugar is between 5 and 6. I have not had an A1c done for a while but my monitor readings are pretty consistent. No complications. I am especially concerned about my eyes and go to the retina specialist twice a year but have no problems either with the retinas or with cataracts.

    Eskimos are not particularly long lived and their high fish oil diet makes them prone to nose bleed and possibly strokes. The first thing they do when they kill the larger game is to tear open the stomachs and eat the insides which are filled with carbs eaten by the grazing animals. They also relish certain shelfish which are high in carbs.

    If you read Atkins first book, he says his diet is absolutely the best for diabetics. His second book says that diabetics “lose” their healing on his diet but a couple of years of eating this way is good anyway. He then says his new “millet and meat” diet is absolutely the best for diabetics. He adds grains. Now what did he see among his diabetic patients that made him add grains to his diet. If you look at it, the diet is approaching a Pritikin diet.
    I think on a high fat and high protein diet, the blood sugar goes down and the insulin keeps going up. People are becoming more insulin resistant.
    Humans have between two and 15 genes coded for amylase–a starch digestor. The average person has about 6. Our nearest primate relatives have only 2. Some people cannot tolerate grains. Perhaps they are the people with only 2 genes coded for amylase.

    Dolores

  • 2 Joseph Loera // Oct 20, 2009 at 11:58 pm

    I am not a doctor but I did however take biology in college and am myself pursuing to be on a full neo paleo diet and I would like to add my 2 cents into this belief that carbs are not essential in the functioning habits of our brain. First of all as I am sure you know the brain is protected by what is known as the Blood Brain Barrier (BBB) and what this BBB does is help protect the brain from foreign substances that may be harmful to it such as low lipid fat soluble molecules. But glycogen is allowed to pass through the BBB to help fuel the brain. As we have seen, the human body is fuelled by glucose. Therefore all foods must be converted into glucose before they can be used as fuel. Carbohydrates are more easily converted into glucose than protein or fat, and are considered to be the body’s “preferred” source of energy, and the brain’s essential source of energy. Simple carbs are more easily converted into glucose because their molecular structure breaks down faster in the stomach and small intestine. Therefore these carbs raise glucose levels in the bloodstream quite rapidly (less than 30 minutes). This explains why diabetics, who occasionally suffer from an excessively low blood-glucose level, can quickly restore their balance by eating simple carb-foods, like sweets. Complex carbs, like starches, take longer to be converted into glucose because their molecular structure is much more complicated and usually (not always) requires quite a bit more time to metabolize into glucose (up to 2 hours). in conclusion simply cutting out carbs does not in fact completely keep your body from producing glucose for your brain it simply makes it harder for your body to fully and effectively convert from whatever the source being into glucose. I hope this somewhat helped you to fully understand that your an idiot.

  • 3 dolores // Oct 27, 2009 at 6:13 am

    I am sorry. It wasn’t clear to me exactly whom Joseph considers an idiot. So I must have missed the point he was trying to make.

    Dolores

  • 4 Joseph loera // Oct 27, 2009 at 6:21 am

    I have a tendency to ramble on in my old age, but don’t feel bad if you missed my point

  • 5 Hana Rous // Jan 25, 2010 at 4:51 am

    Anyone who says they studied biology at college level and thinks that starch takes 2 hours to convert into glucose, wasn’t paying attention. When I did demonstrations with kids at high school level( I was a teacher) We usually found that starch converted to glucose in a few minutes. I never had a 2 hour session in which to do this and we always completed it. However, the one critical thing was to remember to get the techs to cook the starch, because if you don’t, it doesn’t work at all. Starch molecules aren’t actually very complicated. Even when starch grains contain both amylose and amylopectin, they can be untangled and broken down so fast, the reaction is difficult to track. It begins pretty much instantly.

  • 6 jane // Jan 18, 2013 at 9:18 pm

    Certainly I found that when I got into ketosis by using the very low carb diet I was more mentally alert and energetic.
    My brain runs well off ketones!

  • 7 Pone // Feb 16, 2014 at 3:21 am

    David, do you know of a blood test or method by which we can calculate what is the actual daily glucose and ketones use in our bodies? The point of this is to understand our actual total metabolic needs, and then to understand in response to diet how much glucose we are using, and how many ketones we are using.

    What I know we have is the ability to make spot measurements on glucose and ketones. Even if you have average glucose with an A1C, does that actually tell you how rapidly your body is using that glucose?

  • 8 David Mendosa // Feb 21, 2014 at 2:31 pm

    Dear Pone,

    Good question. I wish I knew. Anyone else?

    Namaste,

    David

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