How The Body Metabolizes Sugar
By Royal Society of New Zealand
Sugar metabolism is the process by which energy contained in the foods that we eat is made available as fuel for the body. The body’s cells can use glucose directly for energy, and most cells can also use fatty acids for energy. Glucose and fructose are metabolised differently, and when they are consumed in excess they may have different implications for health.
Looking at glucose first – when food is consumed, there is a corresponding rise and subsequent fall in blood glucose level, as glucose is absorbed from the gastrointestinal tract into the blood and then taken up into the cells in the body.
Glucose in the blood stimulates the pancreas to release insulin, which then triggers uptake of glucose by cells in the body (e.g. muscle cells) causing blood glucose to return to base levels. Insulin will turn off fat burning and promote glucose burning as the body’s primary fuel source. Any excess glucose ends up being stored as glycogen in the muscles, and it can also be stored as lipid in the fat tissue.
Fructose is also taken up into the blood from the gut, but in this case, the liver serves as a pre-processing organ that can convert fructose to glucose or fat. The liver can release the glucose and fat into the blood or store it as glycogen or fat depots, which, if sugars are consumed in excess, may lead to fatty liver disease and also increase risk for diabetes and cardiovascular disease.
There are also some noted interaction effects between glucose and fructose, in that glucose enables fructose absorption from the gut, while fructose can accelerate glucose uptake and storage in the liver.
If the sugar comes with its inherent fibre (as with whole fruit) then up to 30% of this sugar will not be absorbed. Instead, it will be metabolised by the microbes in the gut, which may improve microbial diversity and help prevent disease. The fibre will also mean a slower rise in blood glucose, which has shown to have positive health effects.
It is easy to over-consume sugar
It is easy to over-consume sugar in juice and sweet drinks, as they contain mostly water and sugar. One glass of orange juice can contain concentrated sugar from five or six whole oranges. And while it is easy to drink that much sugar, you would be less likely to eat that many oranges in one go.
Fizzy drinks do not make you feel full as quickly as foods do. This makes them easy to over-consume. And a small fizzy drink contains nine teaspoons of added sugar, so drinking just one can means that you have almost reached your recommended maximum intake for that whole day.
Any sugar added in preparation of foods, either at the table, in the kitchen or in the processing plant. This may include sucrose, high fructose corn syrup and others.SugarScience Glossary
A broad term meaning any bodily process in which the liver is injured or does not work as it is supposed to. In this website we focus on liver diseases in which the diet hurts the liverSugarScience Glossary
Usually shortened to just diabetes. Sometimes called sugar diabetes. Look at Type 1 Diabetes and Type 2 Diabetes for more informationSugarScience Glossary
A type of fat in our body and our food. Three fatty acids are combined with another chemical called glycerol to form a triglyceride.SugarScience Glossary
Sugars are chemicals made of carbon, hydrogen, and oxygen found which taste sweet and are found in food. They are an important part of what we eat and drink and of our bodies. On this site, sugar is used to mean simple sugars (monosaccharides) like fructose or glucose, and disaccharides like table sugar (sucrose). Sucrose is two simple sugars stuck together for example (see Table sugar). Sugars are a type of carbohydrate. Carbohydrates are energy sources for our bodies Sugars enter the blood stream very quickly after being eaten.SugarScience Glossary
One of the three major groups of nutrients we eat. Much of this website is related to problems associated with too much fat storage in the body. Each gram of fat produces 9 calories of energy if burned by the body as fuel. Fat can be stored in many places in the body. We generally think of fat as under the skin (subcutaneous), but the fat that may be most damaging to us is the fat stored in the liver and around the organs of the abdomen (intrahepatic and visceral or abdominal or intra-abdominal)SugarScience Glossary
A sugar that we eat. Also called fruit sugar. Most fructose comes in sucrose (table sugar, cane sugar, beet sugar), or from high-fructose corn syrup.SugarScience Glossary
Glucose is a sugar we eat. It is found in starch. It is the main fuel for our bodies. It is the sugar measured when we have a blood test to measure the blood sugar.SugarScience Glossary
The largest internal organ. It weighs about three to four pounds and is located under the lower edge of the ribs on the right side. It helps us digest our food and remove toxins from our blood. "Hepat" in a word means liver, so an "hepato-toxin" is a liver poison or something that can cause damage to the liverSugarScience Glossary
The pancreas is an internal organ that helps us digest our food by making insulin and other chemicals.SugarScience Glossary
Insulin is a messenger released from the pancreas after eating, which shunts energy (glucose or triglycerides) from the blood into fat cells for storage. Insulin is given to some people with diabetes to lower the blood glucose; it leaves the blood and enters the fat cell for storage.SugarScience Glossary