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How Sugar Affects the Body

Sugar is a naturally occurring carbohydrate that can be found in many common foods such as fruits, vegetables, grains and dairy products. All carbohydrates are macronutrients. The amount of total sugars in the foods we consume varies depending on the type of food, if it’s manufactured and what’s added to it or not. 

Many of the natural foods we consume on a daily basis (like fruits, grains, vegetables and dairy) also have high amounts of fibre, antioxidants and essential minerals along with containing proteins and calcium (in the case of dairy products). 

It is the entire make up of these foods that effects how our bodies digest it and how much energy we get from it. Consuming too much of anything (alcohol, salt, protein, fat), including sugar, can have unwanted effects on the body. 

What happens to the body when we eat food that contains sugar?

Each part of the body has different ways of dealing with all foods and nutrients for digestion, including sugar.  

The Mouth

Sugar digestion starts its journey in our mouths when our bodies start producing an enzyme called salivary amylase that helps start breaking down the foods we chew along with any sugars in those foods. Once food travels through the esophagus into the stomach, stomach acid makes the salivary amylase inactive.

The Stomach

Once the food and sugars make their way to the stomach the digestive system starts to become more active by breaking down foods into their basic nutrient components. During this process (called digestion) starches and sugars start breaking down by both mechanical (chewing) and chemical (enzymes) processes.  

Stomach acid and gastric juices consist of digestive enzymes and hydrochloric acid along with other substances (like pancreatic secretions) that help to break down foods, split up proteins and kill bacteria. Once the stomach has done its job, food we’ve eaten has been broken down into monosaccharides like glucose, fructose, and galactose for distribution and use throughout the body. 

The Small Intestine

As broken down food travels through our digestive system, the body starts to absorb different nutrients (like Glucose, Fructose and other Monosaccharides) for use as energy or is stored as glycogen in our liver and muscles. This stored glycogen acts as a reserve of readily available glucose that can be easily used as an energy source should the body require it. 

Glucose is transported from the intestinal lumen (the insides of our intestines) across the epithelium (a layer of cells that line hollow organs and glands) and into our blood for distribution throughout the body. 

Different Monosaccharides are transported to the epithelium via a range of different transporters. Glucose and Galactose, for example, are carried by the transporter SGLUT-1 and fructose is carried by the transporter GLUT5.

The Liver

The liver is one of the major pathways for fructose absorption in the body and how it’s broken down will differ depending on the exercise condition, gender, our health status and the availability of other energy sources in the body. 

Once fructose has made its way through the stomach, into the small intestine and then into our blood it will be metabolised by our liver for use as an energy source, enzymatically converted to glycogen or converted to lactic acid. 

The Brain

Glucose is a primary source of energy for all the cells in our body and because our brains are the most energy-demanding organ in our body, it uses almost half of the body's sugar energy. 

If the brain doesn’t get enough glucose to function the body goes into a state of Hypoglycemia (brain fuel deprivation) which triggers physiological symptoms such as sweating, dizziness, a feeling of shakiness or trembling, being quick to irritation, tearfulness or moodiness (hangry) and feeling lethargic. In severe cases functional brain failure can result if the brain doesn’t receive the required amount of glucose needed to function.

The quickest way to treat hypoglycemia is to consume 15-20 grams of fast acting carbohydrates (like fruit juice, honey or glucose tablets). It’s worth noting that Hypoglycemia is more common in sufferers of Diabetes and is very different to what many call the ‘3pm or afternoon slump’. 

Finding the right combinations of healthy foods that suit your lifestyle and tastes is always an interesting challenge for those who wish to monitor their intake of calories and carbohydrates to help their bodies perform at peak energy levels throughout the day.  


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