Do You Need Sugar To Live?

There is so much confusion when it comes to carbs. We live in a world with all sorts of conflicting nutrition advice, and carbohydrates are at the front and center of nutrition controversy.

Not all carbohydrates – or all carbohydrate-rich foods – are equal in terms of the nutrition they provide or how the body uses them. There’s differences in types of carbohydrates, how they are digested and absorbed, and how they’re used by the body.

Sucrose is a type of simple carbohydrate called sugar. Specifically, sucrose is a disaccharide, meaning its made of two monosaccharides. In the case of sucrose, its made of the monosaccharide glucose, and the monosaccharide fructose. Other disaccharides include maltose, which is 2 glucose molecules fused together, and lactose, which is a glucose and galactose fused together.

Individual sugar units can combine into much more complex, often branched, structures called polysaccharides, which typically consist of hundreds or thousands of glucose molecules fused together.

These carbohydrates are found in grains and vegetables, and can be broadly categorized into digestible and indigestible types. Digestible polysaccharides include starch and glycogen. Starch is the storage form of glucose found in plant tissues, and glycogen is the storage form of glucose in the muscle & liver in humans and animals.

But Fun Fact about glycogen - when you eat meat, you don’t actually consume glycogen because it has already been broken down when then the animal died. Indigestible polysaccharides mostly consists of fiber, which only comes from plants. Cellulose is an example of a fiber that is composed entirely of glucose molecules. But unlike the glucose found in starch or glycogen, the glucose molecules in cellulose are fused together in a way that makes it impossible for our gut enzymes to break them down.

Certain foods contain two types of fiber, both of which are important for you. Insoluble fiber is a type of polysaccharide that cannot be broken down in our body. It can’t be absorbed into your bloodstream, so it provides 0 calories to you. It passes unchanged through our digestive tract, and I’ll later explain why this is so important. Soluble fiber, on the other hand, dissolves during digestion, turning into a gel-like substance. It’s not digestible, but some components of it can be broken down by our gut bacteria in the colon, and what those bacteria do with it becomes very important.

For example, soluble fiber, is metabolized by gut bacteria into short-chain fatty acids like butyrate, which gets absorbed into the bloodstream. And that’s a good thing, because butyrate has anti-inflammatory properties. But let’s for a second, say you eat a carrot, which, yes, contains fiber, but it also contains starch.

You’re crunching on that carrot, the saliva in your mouth starts to break down the starch molecules into smaller starch molecules, because of an enzyme called…salivary amylase. This is why if you eat a cracker, and chew it long enough before swallowing, it tastes sweet on your tongue, because the starch gets broken down to maltose.

So after that the carrot goes into your stomach, where you have some acid sitting there, which deactivates the salivary amylase enzyme that is mixed in with those little carrot chunks. Then it makes its way to the first section of your small intestine, called the duodenum. Most of the starch is broken down into disaccharides there….maltose. Why? Because the pancreas secretes an enzyme here, called pancreatic amylase.

You also have other enzymes located in the small intestine that break down the disaccharides into sugar’s most simplest form, monosaccharides, mainly glucose and fructose, and lactose if you consume milk-products. The monosaccharides get absorbed from the intestine, into the blood, which immediately goes to your liver, by way of your portal vein. The liver will convert fructose and galactose into glucose.

The human body is very efficient when it comes to absorbing sugars. The body uses glucose to provide energy for all sorts of functions, and that’s why the body carefully monitors blood glucose levels. It’s called glucose homeostasis, and it’s controlled by the pancreas and liver.

When it comes to controlling blood glucose levels, the pancreas secretes two important hormones, insulin and glucagon. When blood glucose increases, such as after eating carbohydrates, insulin is released from the pancreas. Insulin lowers blood glucose by stimulating the uptake of glucose by tissues, including the process of converting extra glucose into glycogen in the liver and muscles. When blood glucose is low, glucagon is released from the pancreas, which has the exact opposite effects of insulin, in order to raise blood glucose levels.