The good, the bad and the sugary

By Anna Tiley

This year my flatmates decided to go on a 40 day sugar ban. Being a self-confessed sugar addict I thought they were crazy and decided to opt-out (how could I honestly survive so long without Biscuit Mondays and Cake Fridays at my lab?). They eventually managed to brave through the challenge and it really highlighted just how much sugar can be found in our everyday foods.

Sugar hasn’t always been a major ingredient in food. Conventional sugar extracted from the sugar cane plant used to be the major sweetener and was expensive to obtain. Then the 1950’s saw the discovery of high fructose corn syrup (HFCS) which was easier and cheaper to make. This form quickly began to replace conventional sugar and companies which previously couldn’t afford to sweeten things began to add it to their products.


The increase in consumption of HFCS has been linked to a rise in obesity; however, there have been speculations about whether this correlation is significant.

More recently, scientists have been looking at the difference between conventional sugar and HFCS. Conventional sugar comprises only of glucose while HFCS is 40% glucose and 60% fructose. Both of these molecules are chemically very similar in structure but are processed differently by our bodies.

Glucose is generally used by our tissues as a source of energy and the rest is stored by the liver as glycogen for use later on. Fructose on the other hand is almost completely metabolised in the liver by an enzyme known as ketohexokinase (KHK) to make fructose 1-phosphate. This molecule can then be stored as fat which builds up around the stomach.

Fructose has therefore been linked to high fat levels. One study compared wild type mice to mutant mice lacking the KHK gene. Both mice were given a diet high in fat and fructose, and their health was monitored.

The wild type mice developed severe fatty livers and liver inflammation. However, the mutant mice, which were unable to process fructose into fat, were relatively healthy and only developed mild fatty liver disease.

Many countries have already tried to reduce sugar consumption by taxing sugary foods and removing sweet snacks from schools. However, the global increase in obesity and the related diseases cannot be down to sugar alone. Despite HFCS consumption decreasing, obesity levels continue to rise. Therefore other factors such as lifestyle may also be to blame.

Further reading:

Metabolic syndrome: F stands for fructose and fat

Public health: The toxic truth about sugar