The science of carbs

Low carb, no carb, loads of carbs
“Carbs” or “carbohydrates”, which is the real name of this group of compounds outside of the fitness and health industry, brings out the strongest of emotions in people. I have even seen people who seem more upset of someone consuming carbohydrates than they are over the Syrian war, world poverty, or climate change. I think Lily Allen put it well in her song “The Fear”:

Now I’m not a saint but I’m not a sinner
Now everything is cool as long as I’m getting thinner

Sad, but true.

Anyhow back to the carbohydrates, our friends, foes, or whatever side of the picket line you are because no one seems to be straddling it. This is a short explanation to what a carbohydrate actually is. I actually doubt that most of you can explain what it is despite having very strong opinions on it.


It’s a heart-potato, it definitely is (image credit: Lumbar).

What is a carbohydrate?

A carbohydrate can be defined in a few different ways; let’s start with the basic chemical description which states that a carbohydrate is a compound with the formula Cm(H2O)n (with a few exceptions).

In normal language this means that you have some number of carbon atoms and add any number of units of H2O to those. It does not mean that you add liquid water (H2O) to a bunch of coal (carbon) but it means that some H (hydrogen) and some O (oxygen) have attached to the carbon atoms to form a large molecule. The carbon has become hydrated (hydro = water in Greek), thereof the name: carbohydrate.

The biochemical way of defining a carbohydrate, which is the most interesting for most of us, is that it is a type of sugar (a saccharide). Despite this definition only the short chained carbohydrates are generally referred to as “sugars” for example: sucrose (white and brown sugar) and glucose (“blood sugar”).

The biochemical definition of a carbohydrate is a repetition of a unit of (CH2O)n where n is larger than three (n here just means how many times the CH2O-part is repeated). By keeping n above three you can exclude things like formaldehyde (CH2O) from this group and make the definition more biologically relevant. Formaldehyde is a nasty thing in high concentrations, trust me, I have had some in my eyes. You can use formaldehyde for preservation of tissues. The weird glass jars in old films, with dead things in, would in real life contain formaldehyde. It is anyhow what I would use if I would to pickle some dead tissue.


Not particulary deadly (image credit: Nesnad)

It should be noted that we are now talking about liters of highly concentrated formaldehyde. The tiny amounts of formaldehyde present in vaccinations for example do not affect you at all. There is the same amount of formaldehyde in a vaccination shot as it is in a pear and you know for sure that you won’t die from eating a pear, unless you are severely allergic. Even too much water may kill you.

There are long and short chained carbohydrates

Carbohydrates can be divided into four groups: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. As you probably have guessed the groups define the length of the molecule. Monosaccharides (glucose and fructose) are made up of one unit (CH2O)1, disaccharides (lactose, sucrose) of two (CH2O)2, and so on.


Hydrolysis of lactose. This means that the disaccharide lactose molecule is split into two monosaccharide sugars (image credit: Yikrazuul)

The exoskeleton (shell) of insects is made up of a polysaccharide called chitin; this is a molecule that does not exist in many other animal groups (except for some mollusks, crustaceans, and cephalopods) and is therefore often a target for insecticides.


A cockroach with a chitin exoskeleton (image credit: Nesnad)

Generally polysaccharides are often storage molecules such as cellulose in plants, glycogen in our muscles (getting us ready for a sprint), and starch in potato-tubers for example.


Starch or “Amylose” (image credit: NEUROtiker)

Some carbohydrates are processed fast and some slow

The length of the chain and how branched it is approximately determines how fast the carbohydrate is broken down in your body and hence how fast your blood sugar rises. Already in your mouth there is an enzyme called amylase that starts breaking down long-chained starch into smaller units called maltose. Test it yourself! A potato or bread will become sweeter the longer you chew.

The carbohydrates are eventually absorbed in the small intestine. If you eat a normal Western diet full of mono and disaccharides most of the absorption will be in the upper part of the small intestine. If you eat more healthily with more oligo- or polysaccharides in your diet, the main part of the absorption will take place further down in the intestine. Further down is good.

There is no real energy difference between simple and complex carbs; it has only to do with the speed of uptake. It simply takes longer to dissemble a house with 20 floors than one with one or two floors.

Your internal pet intestinal bacteria love to grow on carbohydrates and it is thought that you will support a healthier internal zoo by eating more slowly digested carbohydrates. Do that if you want to try to live long.


A happy belly (and happy inhabitants of your belly) will improve your health (image credit: Henry Vandyke Carter)

Complex and simple carbohydrates are terms that are often used interchangeable and very confusingly. Many nutritionists cannot tell a monosaccharide from a polysaccharide and often just make it up as they go along. “Complex carbs” may end up including any old food where fibers and vitamins are included such as fruits even though they basically only contain the monosaccharides fructose and glucose. The proper definition is: simple = mono and disaccharides, complex=the rest.

It isn’t that complex after all.

Science Safely!

...enjoys all food (except fried liver and Swedish cheese-cake).

…enjoys all kinds of food (except fried liver and Swedish cheese-cake).

Fundamentals of Biochemistry: Life at the MolecularLevel Loose Leaf – January 18, 2012. by Donald Voet  (Author), Judith G. Voet (Author), Charlotte W. Pratt (Author)

Molecular Biology of the Cell, 4th edition. Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter. New York: Garland Science; 2002. ISBN-10: 0-8153-3218-1ISBN-10: 0-8153-4072-9

Posted in Animals, Biology, Chemistry, Medicine, Plants and tagged , , , , , .



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