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For years, scientists have been studying how food affects our bodies. We now know more than ever that everything we eat has a direct impact on our body. The food that we eat affects trillions of cells and bacteria within us. You rarely hear about glucose unless you have diabetes, however, it is important to understand how this ubiquitous source of energy is vital for life and its effects on the body.  

Hundreds of years ago, it was a common assumption that plants made themselves out of dirt, they called them ‘soil eaters’. In the 17th century, scientists found that plants make their own ‘food’ from carbon dioxide (from the air) and water (from the soil) and energy (from sunlight) to make a never-before-seen substance that we now know is glucose. Without glucose, there would be no plants or life on earth.  

Plants can either break down glucose to use as energy or use it for growth. Glucose particles are so small that plants can use them in many ways to sustain their health.  There are four different forms of glucose which are: starch, fructose, sucrose, and fibre. They are like siblings with different characteristics.  


Is a strong long chain of glucose that can be stored in small amounts within a plant, but mostly in its roots. Root vegetables such as beetroot, potatoes, carrots, celeriac, and parsnip are all starches. Seeds such as corn, oatmeal, wheat, beans, peas, lentils, or chickpeas also hold starch for energy to grow. Whenever plants need glucose (energy), they use an enzyme that travels to the roots and releases glucose molecules from their starch chains.  


Is another form of glucose. Generally, we know that glucose tastes sweet, however, fructose is 2.3 times sweeter. Plants use fructose to make their fruits irresistible to animals that help them survive by spreading their seeds. Plants store their excess of fructose and glucose in a smaller form called sucrose to compress energy even further. We use this molecule every day in a kitchen staple, table sugar.    


Is a form of glucose that works like grout between the bricks of a house. It allows plants to grow tall and strong without falling over. It is mostly found in trunks, branches, flowers, and leaves but fruits and roots have fibre as well.  


All forms of glucose are carbohydrates, referring to the way they are made by joining carbon and water in a process called photosynthesis. The human body cannot photosynthesise and make glucose out of air, water, and sunlight, we can make glucose from the food we eat. Our liver performs a process called gluconeogenesis. Furthermore, when glucose is limited, many cells in our body switch to using fat for energy and that is called metabolic flexibility.   

In modern society, carbohydrates are the primary and quickest energy source for the body, however, they are not biologically necessary to survive. Scientists found that prehistoric diets included foraged plants and meat from animals, what people ate depended on where they lived, showing how adaptable humans were to the food supply around them. In today’s world, our food supply is very different to what nature had planned for us. We are no longer hunter gatherers in the way our ancestors were. The food industries have created a market for confectionery and sweet foods. Humans have evolved to feel pleasure when we taste something sweet. For instance, when we eat a dessert, a chemical called dopamine floods our brain, the same way that it is released during sexual intercourse, watching television, scrolling on social media, drinking alcohol or smoking. Sweets and dopamine feel forever rewarding and make it very difficult for the brain to curb craving the instant reward. 

What happens to the body when glucose spikes? 

The main purpose of glucose in the human body is to be turned into energy. As glucose enters the blood stream, it travels into our cells and straight to the mitochondria (the powerhouse using glucose and oxygen) and creates a chemical version of electricity to give each cell the power to function properly. 

The mitochondria can only use as much glucose as the cells need for energy. If there is more glucose than necessary, some tiny molecules (with large consequences) called ‘free radicals’ are released. These tiny molecules are seriously dangerous in their nature as they damage everything they touch and can set off a dangerous chain reaction. Free radicals can randomly modify our DNA, creating mutations that activate harmful genes which can lead to the development of cancer. We can tolerate a moderate amount of free radicals in our cells, but when there are too many, our body goes into a state of oxidative stress; which is a driver of heart disease, type2 diabetes or general aging.  

Fructose increases oxidative stress more than glucose. When a glucose molecule bumps into another type of molecule, it causes a reaction that is known as glycation. Once a molecule is glycated, it is damaged forever, and the long-term consequences vary from minor ageing signs such as wrinkles to major conditions such as heart disease or Alzheimer’s. Fructose molecules glycate molecules 10 times faster than glucose, causing more damage. Extract sucrose added to processed foods is the chemical copy of the one found in fruits, but even more concentrated. As sucrose is fructose and glucose together, sugary foods full of sucrose like cookies, biscuits and chocolate, because of their fructose content, make us age faster than starchy foods such as pasta, rice, and cereals where the fibre content prevents from glucose spike.  Extract sucrose added to processed foods is the chemical copy of the one found in fruits, but even more concentrated. As sucrose is fructose and glucose together, sugary foods full of sucrose like cookies, biscuits and chocolate, because of their fructose content, make us age faster than starchy foods such as pasta, rice, and cereals where the fibre content prevents from glucose spike. 

The combination of free radicals, oxidative stress and glycation leads to a state of inflammation; a protective reaction by the body’s immune system to defend against invaders. However, chronic inflammation is very harmful as it turns the immune system against the body. Redness and/or swelling may occur on the outside, but internally tissues and organs are slowly getting damaged. The World Health Organisation (WHO) calls inflammation-based diseases ‘the greatest threat to human health’.  

Insulin – the antidote to excess glucose 

It is vital to remove any excess glucose out of the blood stream as quickly as possible to remain healthy and prevent free radicals. When we eat food, our glucose levels increase and the pancreas releases insulin to keep glucose out of circulation and protect our cells from damage.  

Insulin is a powerful hormone affecting various cells, including muscles, red blood cells, fat and other hormones such as estrogen or cortisol. Without insulin we would die. People with type1 diabetes must inject insulin to make up for what their pancreas cannot produce. Insulin helps the body to use glucose for energy or for it to be stores as glycogen in 3 main storage units: the liver, our muscles and fat reserves (adipose tissues).  

Fructose unfortunately cannot be turned into glycogen (energy) and stored in the liver or muscles; it is only stored as fat. The fat our body creates from fructose first accumulates in the liver, leading to conditions such as non-alcoholic fatty liver, or secondly, it fills up fat cells around the hips, face, and thighs (subcutaneous fat) and between our organs (visceral fat). Ironically, many processed foods that are ‘fat free’ contain a lot of sucrose that has fructose content which gets turned into fat immediately after digestion.  

If insulin is high for a long period, it can lead to the development of insulin resistance. When cells in our muscles, fat and liver don’t respond well to insulin and can’t easily absorb glucose from the blood, the pancreas makes even more insulin to help glucose enter the cells.  

Society has complicated views about fat, but fat can be very useful in the short term. The body uses fat to supply storage for excess glucose and fructose floating in the blood, protecting the body from oxidative stress, free radicals, and glycation. But in the long-term, the more glucose spikes we have, the more insulin is released which leads to insulin resistance and the root cause of obesity, type2 diabetes and Polycystic Ovary Syndrome (PCOS).  

How to avoid glucose spikes and flatten insulin level 

  1. Start your day with a savoury meal rather than sweet. This helps keep your glucose levels steady during the day.  
  2. Always add vegetables to your meal and eat that first, because fibre reduces the rate of absorption of glucose. 
  3. Before eating, have a tablespoon of vinegar (any kind except balsamic) in a glass of water or drizzled on your vegetable starter. Acetic acid in vinegar slows the breakdown of carbohydrates.  
  4. Eat whole fruits only, not juiced, and eat more fibre.  
  5. Eat sweet foods at the end of a meal instead of in the morning or as a snack on their own.  
  6. Use your muscles and go for a minimum of 10 minutes’ walk or do house chores after a meal so your body uses glucose for energy and doesn’t store it.