Understanding Glucose: The Body’s Energy Source

Our nutritional choices are influenced by billion-dollar marketing campaigns aimed at making money for the food industry – campaigns for fizzy drinks, fast food and sweets. These are usually justified under the guise of what matters is how much you eat – processed foods and sugar aren’t inherently bad? But science is demonstrating the opposite: processed foods and sugar are inherently bad for us, even if we don’t eat them in caloric excess.

Glucose is our body’s main source of energy. We get most of it from the food we eat, and it’s then carried in our bloodstream to our cells. Its concentration can fluctuate greatly throughout the day, and sharp increases in concentration – I call them glucose spikes – affect everything from our mood, our sleep, our weight, and our skin to the health of our immune system, our risk for heart disease, and our chance of conception.

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Both fructose and insulin levels are hard to monitor continuously. Glucose levels are the only measure we can track from the comfort of the couch, and the good news is that when we flatten our glucose curves, we also fatten our fructose and insulin curves. This is because fructose exists only hand in hand with glucose in foods and because insulin is released by our pancreas in response to glucose.

Among the things plants can make from glucose is starch. A living plant needs a supply of energy at all times. However, when it’s not sunny out, either because it’s cloudy or because it’s dark, photosynthesis cannot take place and provide the plant with the glucose it needs to survive. In order to solve this problem, plants make extra glucose during the day and pack it away into reserves for later use.

Glucose’s natural tendency is to dissolve into everything around it, like children let loose into a playground at playtime. Kids race and dash in random directions, generally uncontrollably and unpredictably, but can be rounded up by their teacher and sit (mostly) quietly behind their desks when class begins again.

Similarly, plants have a solution to round up glucose. They enlist tiny helpers called enzymes – teacher’s aides, if you will – that grab glucose molecules by the hand and attach them to each other: left hand with right hand, left hand with right harvested and processed to create paper, from Egyptian papyruses onward.

Plants concentrate fructose into fruit – apples, cherries, kiwis and more – that they dangle from their branches.

The purpose of fructose is to make fruit taste irresistible to animals. Why do plants want their fruit to be irresistible? Because they hide their seeds in them. It’s key to propaga-tion: plants hope that animals will eat their fruit and their seeds will go unnoticed until they come out their eater’s other end. That’s how seeds spread far and wide, thereby ensuring the plants’ survival.

Most of plants’ fructose is used in this way, but some, with the help of another enzyme, links up, for a time, with glucose. The result is a molecule called sucrose. Sucrose exists to help plants compress energy even further (a sucrose molecule is slightly smaller than a glucose and fructose molecule side by side, which allows plants to store more energy in a tighter space). For plants, sucrose is an ingenious temporary storage solution, but for us, it has a huge significance. We use it every day, under a different name: table sugar.

Starch, fiber, fructose and sucrose – the various forms glucose can take – exist thanks to photosynthesis.

Your cells, like all animal and plant cells, need energy to stay alive – and glucose is their prioritised energy source. Each of our cells uses glucose for energy according to its specific function. Your heart cells use it to contract, your brain cells to fire neurons, your ear cells to hear, your eye cells to see, your stomach cells to digest, your skin cells to repair cuts, your red blood cells to bring oxygen to your feet so you can dance all night long.

Every second, your body burns eight billion billion molecules of glucose. To put that into perspective, if each glucose molecule were a grain of sand, you’d burn every single grain of sand on all the beaches of the earth every ten minutes.

A slice of bread is made, for the most part, from flour. Flour is made by grinding wheat kernels and wheat kernels, as you know, are filled with starch. Any food made from flour contains starch. Pie crust, cookies, pastries, pasta – all are composed of flour, so all are composed of starch. When we eat, we break starch down into glucose, using the same enzyme that plants use to do this task: alpha-amylase.

Starch is turned into glucose extremely quickly in our body. In general, the process happens mostly in our gut, where it goes unnoticed. The alpha-amylase enzymes snap the bonds of the chain, and glucose molecules are freed. There they are, running around in the playground once again.

When we chew starch long enough, we give the enzymes the time they need to begin their work. That process begins in our mouth, and we can taste it. Hence the power of this experiment.

Fruit, in contrast, tastes sweet from the get-go. ‘This is because it already contains unchained glucose molecules, which taste sweet, as well as fructose, which tastes even sweeter, and their combined form, sucrose, which is sweeter than glucose but not as sweet as fructose.

Source : Glucose Revolution: The Life-Changing Power of Balancing Your Blood Sugar by Jessie Inchauspé

Goodreads : https://www.goodreads.com/book/show/58438618-glucose-revolution