1. What is glucose?
Glucose is an organic compound or, more precisely, a simple sugar which consists of a single molecule. It is the simplest form of carbohydrates, which are mainly used as a source of energy in the human body – hence it is often said that the brain needs sugar to work properly. However, glucose is not only used by the brain, but by the entire human body, which is why under standard physiological conditions glucose is essential for its correct functioning.
Glucose is found in everyone’s blood, regardless of their eating habits – it is even present in people who do not eat sugar at all or are following the keto diet. Any type of carbohydrate we consume (even if it is complex, like wholegrain flour starch) is decomposed into its primary building blocks during digestion, down to individual molecules of glucose – the only form in which it can be used by the body.
Glucose is so essential to the human body that even if it is not supplied with food, it can be generated from other substrates, such as protein. This is why people on a keto diet (which excludes all sources of carbohydrates) do not have a “zero” blood sugar level, but a physiological concentration of glucose in the body.
2. The dose makes the poison – when does glucose become toxic?
As you can see, glucose is essential for maintaining the right homeostasis of the body. However, this does not mean that the more blood sugar you have, the better. According to the old saying that everything is poison and nothing is poison, it is factors such as the amount of carbohydrates in your food, your eating habits and the amount of exercise you get that determine the way glucose affects you.
This is because too much glucose is toxic to the human body. Imagine adding sugar to a glass of lukewarm water one spoonful at a time. Initially, at first glance, the properties of the liquid do not change, but over time, the water gradually becomes thicker and turns into syrup. After the solution becomes saturated with sugar, some crystals will stop dissolving at all, and after a few days you will observe sugar being precipitated from the solution in the process known as crystallization.
If you extrapolate this experiment to the human body, you can easily imagine that blood with an excessive concentration of sugar will no longer be able to fulfil its functions, such as the transport of oxygen and nutrients to the organs and tissues.
3. From glucose to glycation
Prolonged increased blood sugar levels will result in glycation. Glycation is a phenomenon whereby the body becomes oversaturated with glucose, leading to the precipitation of sugar particles. They are very “sticky” and thus likely to adhere to other particles, such as protein, which have the function of enzymes and lipids. After a sugar particle binds to an enzyme, the enzyme can no longer fulfil its role.
Glycation not only inhibits enzyme function, but also promotes the development of disease. Glycation products are responsible for capturing and embedding cholesterol particles in blood vessels, which leads to atherosclerosis. Recent research also associates glycation processes with neurodegenerative lesions and carcinogenesis.
4. Insulin to the rescue
Fortunately, you do not need to avoid carbohydrates like the plague or be on the keto diet until your last days. Your body has developed a mechanism to cope with blood sugar level swings. It involves the production of a hormone known as insulin, which works to decrease the blood sugar level. Insulin enhances the transport of glucose from the blood to body cells – the more effective the transport, the quicker the blood sugar level will return to normal and the cells will be able to use the fuel they receive faster.
However, as is the case with any complicated and multi-process machine, this mechanism sometimes breaks down. The breakdowns can be of a mechanical nature (like in type I diabetes, where pancreatic cells fail to produce insulin and it must be supplied from the outside) or they may result from excessive wear.
The more often your blood sugar level becomes excessive, the more insulin you produce. The more insulin there is in the bloodstream, the more reluctant your cells become to react to it. This is known as insulin resistance – a condition where body cells become resistant to the effects of the hormone at some point in time.
5. How to calculate the glycemic load?
Can we help the body to enhance this mechanism? Of course! The effectiveness of this process largely depends on how fast blood sugar levels increase after a meal. Products rich in simple carbohydrates, sugar or glucose-fructose syrup do not take long to be digested – glucose is served “on a silver platter”, causing blood sugar levels to skyrocket quickly and abruptly.
Not so in the case of complex carbohydrates. To transform them into glucose, the body must break down plenty of chemical molecular bonds during digestion. This is a slow process, thanks to which not all glucose particles are released into the bloodstream at once. Rather than that, they are released gradually, preventing the post-meal rise in blood sugar levels.
How to tell if a product will cause a mild or a steep increase in blood sugar levels? This is what the glycemic index and glycemic load indicate. The quicker the blood sugar level rises after you eat a certain product, the higher its glycemic index.
The glycemic index is expressed as a score, with pure glucose being the point of reference with a glycemic index of 100. Foods are divided into three groups, depending on their glycemic index:
- products with a low glycemic index (up to 55);
- products with a medium glycemic index (from 56 to 70);
- products with a high glycemic index (above 70).
The glycemic index itself is not enough, though, since quality is equally important as quantity. After all, the glycemic index of a glass and of a teaspoon of sugar is the same, but the body will react completely differently to both doses.
To calculate the glycemic load, you need to know the carbohydrate content of a food portion. The amount of carbohydrates in grams should be multiplied by the value of the glycemic index and then divided by one hundred.
GL = (GI x amount of carbohydrates in grams)/100
If the result is above 20, it means that the product has a high glycemic load and should only be eaten occasionally.
6. Slow down glucose!
Choosing products with a low glycemic index and load is not the only way to reduce the post-meal glucose spike and to keep the blood sugar curve under control. Physical activity is an immensely important factor affecting blood sugar levels (especially in modern times).
Muscles need glucose to function. They can absorb it “fresh” from the blood, as well as from glycogen, which is a reserve glucose store in your body. The harder your muscles work, the more glucose they consume to meet their demand. This is essential in the context of today’s ubiquitous sedentary lifestyle – people who work at a desk and are not physically active, relying on their cars for mobility, are more prone to developing insulin resistance, as their muscle cells do not consume glucose on an ongoing basis.
This is also one of the factors why so many elderly people suffer from diabetes – as we age, we naturally tend to exercise less and physical exercise also becomes difficult for many due to pain or various health conditions. Elderly people often see their physical activity level drastically reduced, while their eating habits tend to remain unchanged.
7. The big three behind effective blood glucose level regulation
Besides regular physical exercise – such as practicing sports, going for regular walks, cycling or walking while going about your daily business – you can significantly limit your post-meal blood sugar spike by having correctly balanced meals.
Protein, dietary fiber and fat are the big three of nutrients which significantly slow down the absorption of glucose from the digestive tract to the bloodstream. This is why nutritionists advise against snacking and promote having wholesome balanced meals. A chocolate bar, pastry or other types of sweet treats will raise your blood sugar levels much faster if consumed on their own than they would if preceded by a vegetable-rich salad (dietary fiber) with salmon (protein) and olive oil (fat).
In this respect, what also matters is the order in which you consume particular products in your meal. If you start your meal with a salad as an appetizer or have a handful of nuts before eating fruit, you will reduce the glycemic load of the meal and will be able to better control your blood sugar levels.
8. Glucose and sports
As you already know, glucose is the fuel for your muscles. Without it, your workout will not be effective – just like driving a car with an empty gas tank. This is why athletes, especially those practicing endurance sports, consume carbohydrates before and during training sessions and championships.
This, however, does not mean that you need to flood your body with huge amounts of glucose to work out efficiently. Your daily habits are key as they determine whether your body will be able to effectively absorb, transport and use glucose in its cells. A stable blood sugar level throughout the day will be enough to ensure you have plenty of energy to work out and will also make you more sensitive to insulin – the hormone responsible for transporting glucose from the blood to the muscles.
From the perspective of sports nutrition, to increase the availability of glucose to your muscles, you should have a snack rich in simple sugars before you exercise. Foods such as dried fruit are a good idea and can be used in healthy snack bars or you can also try some home-made jam or marmalade, which will be the perfect oatmeal topping.
After a workout, make sure you replenish your glycogen reserves – if you only work out once a day, have one serving of (complex) carbohydrates in your post-workout meal – choose bread, groats, rice or pasta. If you work out more than once a day, your post-workout meal should be much like the one you had before your training session – make sure it is easily digestible, relatively low in dietary fiber and a good source of simple carbohydrates (e.g. dried and fresh fruit, jam, marmalade).
A correctly balanced diet, limited intake of sugar and regular physical activity will help you to control your blood sugar levels. Treat it like an investment into your later life, to guarantee not only correct glucose and insulin metabolism, but also a good overall health condition.
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Resources:
1. Fizjologia żywienia, red. nauk. Krauss H. PZWL Wydawnictwo Lekarskie, Warszawa 2019.
2. Wierusz-Wysocka B, Araszkiewicz A, Schlaffke J., Końcowe produkty glikacji — nowy biomarker cukrzycy i jej powikłań?, Diabetol Klin. 2013;2(3):96–103.
3. Joanna Suliburska, Justyna Kuśnierek. Czynniki żywieniowe i pozażywieniowe w rozwoju insulinooporności, 2010.
4. Anita Bean, Żywienie w sporcie. Kompletny przewodnik. Wydawnictwo Zysk i S-ka, Poznań 2014.