That "The average minimum amount of carbohydrates needed to fuel the brain is 130g/day. .................the acceptable macronutrient distribution range for carbohydrates is 45 to 65% of calories."

Yes, it is true because it is written in my Nursing school nutrition book. (ATI Nutrition For Nursing Version 3.1) Also, similar sentences are found in two (at least) other texts I have that are required reading.

Now I don't really believe that is true because as I previously understood it, before I started going to school, was that the minimum amt. of glucose(carbs) the body(brain) needed was something like 1tsp(5g) if I can remember correctly (correct me if I am wrong). And the body can make that all by itself thank you very much, thereby making carbs a non essential nutrient. So I don't really have a point here, except I guess that one shouldn't trust the textbooks. But I don't really know how to explain to my classmates why the info in the books is wrong. Is it wrong? Any advice?

(By the way, I do remember my microbiology book did say that their was no need for dietary carbohydrate. I borrowed the book though so I no longer have it.)

It is sorta wrong. The brain needs around 130 g of glucose per day, that is true. (I think the 5g is glucose needed per hour, so 5 g times 24 is 120g).
This amount of glucose can come from dietary carbs, but it can also come from dietary protein (gluconeogenesis) and a little even from fat (glycogenesis).

When the nursing nutrition book says people have to get it from dietary carb, they are taking one step beyond the physiology and voicing an opinion, not a physical fact.

Dr. Michael Eades and Mark Sisson's blog posts on the need for carbs are pretty good. Maybe you could use the ideas in them. They both have searches - sorry I don't have a handy list of the best posts on that.

The wording makes it sound like the brain requires that much glucose from our diet. It does not. The liver can produce all the glucose the brain requires out of the substrates like glycerol and some amino acids, all of which can come from the diet or the body's own fat and protein reserves. The liver also recycles certain substrate and converts them back into glucose. But, if we eat at least 130g of glucose per day, then the brain will use that much but not much more.

But why does the brain use that much when we eat glucose? Well, we could speculate that glucose is toxic above normal, and since the brain is the organ that consumes the most amount of fuel per weight, then it follows that the brain is the best organ for the job of disposing glucose as quickly as possible. I mean, why would it prefer glucose if when it runs on ketones, it does so 30% more efficiently? Or rather, when it runs on glucose, it burns 30% more fuel.

If we eat more than 130g of glucose per day, what happens with the surplus that the brain does not use? Well, it is used to replenish glycogen stores, to fuel other anaerobic activity, and to make us fat. Considering that glycogen stores are very small and quickly replenished, and that we do very little anaerobic activity, then it's logical to conclude that most of the surplus glucose we eat serves to make us fat. However, I learned that glucose is not converted to fat very well, probably only 20% of it. However more, glucose is converted to glycerol which is then used to bind fatty acids inside fat cells thereby allowing fat to accumulate above normal needs.

Also, glucose fed to worms shortens their life. So, when we eat glucose, and when our blood glucose rises above normal because of that, then perhaps it shortens our lives as well. I'm only guessing here but I'm pretty sure on this one.

Finally, regardless of how much glucose the brain uses, if we eat mostly refined and easily digestible carbs (which convert in glucose and other simple sugars), and if we eat at least 86g per day for twenty years, then we will suffer at least one disease of civilization if not more. Do I really care how much glucose my brain uses at this point?

There is no need to eat carbs to maintain a proper level of glucose in the blood. The body makes its own glucose without any problem.

Patrick

Thanks everyone! So helpful....
So does anyone know how many teaspoons is 130g of glucose?

Oh, and during our lecture my know nothing teacher talked about "dangerous fad diets like Atkins" and how if you don't eat enough carbs you will go into ketoacidosis which is very life-threatnening. I had to try really hard to keep quiet on that one! The problem is that our main text says the exact same thing so disputing it would have been very difficult.

So wait a minute, why does the brain need any glucose at all if it can run on ketones?

And I was surprised to find out that they add ketones into TPN (nutrition you get through a vein) and the reasoning is to prevent ketoacidosis. Huh?

Some cells in our brains absolutely need glucose, they can't use anything else. That's kind of weird about the ketones, maybe you could ask about that. Make it seem like you're concerned about the dangerous ketone.

About 5g per teaspoon. Incidentally, 5g is about the entire glucose content of your blood right now. The ketosis/ketoacidosis debate has already been done a million times. Simply refer those people to the Wikipedia entry on ketosis for a summary.

Do the smart thing. Keep your mouth shut. Pass the course. Move on. You won't win points by contradicting your teacher, and probably humiliating him too, in front of his class.

But if you want to be a smart ass, like I would have been then, ask why should we rely on such a small fuel tank of glucose when we have access to literally unlimited fuel within our fat tissue? And why does the liver convert this fat into ketones, and why does the brain (and the heart and probably all other tissues as well) run 30% more efficiently on ketones if ketosis is so bad for our health? And why does fasting induce a ketotic state if ketosis is so bad for our health? I mean, doesn't that mean our body is trying very hard to provide us with adequate fuel and this fuel is ketones? And why am I returning to good health, and losing fat, and gaining strength, and lifting the mind fog, by cutting out sugar from my diet if ketosis is so bad for my health? And why do we suffer emaciation and neurosis when we eat a high carb diet but not enough calories (Ancel Keys, 1950, semi-starvation experiment)? And why does fresh meat cure scurvy, and why does an all meat diet sustain us in perfect health indefinitely (Stefansson, 1920s, the all meat clinical trial)? And, and...

But of course somebody's gonna call you names long before you get to Stefansson.

I've been living on less than 50 g of carbohydrate daily for over 6 months. For the first three months, on less than 30 g.

My brain seems to be functioning just fine according to my wife, adult stepsons, and coworkers.

-Steve

Oh whoops, my mistake....it is Acetate that is in the liquid nutrition and it is to "prevent metabolic acidosis".

Still.....huh? I've never eaten acetate - only drawn on it.

Thanks for the clarifications everyone. It is so unnerving that every book I have to read talks about how glucose is needed for cell energy. And then there is that awful, awful government food pyramid to memorize. Well, I'm off to take my online nutrition exam! Wish me luck....I'll tell them what they want to hear.

Good girl! You can start to try to educate people AFTER you have the degree after your name. Good luck ... a lot of us here will be pulling for your success!!

They're just sucking up.

Hi Steve ... how many of your colleagues will listen when, or if, you promote a low-carb life-style? Is it an easy sell, or a no sell? Do any of them have, or take, time to actually do some research into diet? Do any of them actually care to learn about diet, or do they just pass their patients on to traditionally taught dietitians and nutritionists?

Last quarter I took molecular biology, I was surprised to see a whole section on how the body can make all the glucose it needs. When we talked about fiber the professor said he didn't understand why people think they need so much fiber when it passes through the body unchanged.

I thought is was great progress.

I don't understand why that class and my immunology texts both list saturated fat as a carcinogen?