Explainer: Is all sugar bad for you?

It’s probably safe to say that we all crave a sugary snack from time to time. Whether it’s chocolate, ice cream or a soft drink, most of us have our way of getting a sweet fix. But there’s a growing pile of evidence that too much sugar is not good for you.

So, is all sugar equally bad?

Sweet science

To understand the negative impacts sugar might have on our bodies, let’s start with the basics. What is sugar?

Sugars are carbohydrates (biomolecules made up of carbon, hydrogen and oxygen atoms) which the body breaks down into glucose. Glucose is a monosaccharide, meaning it is a sugar which can’t be broken down into smaller carbohydrates.

Glucose is the main source of energy for the body’s cells.

Many of the sugars in our diet are disaccharides – formed by the chemical joining of two monosaccharides. Sucrose, what we might refer to as table sugar, lactose, found in milk, and fructose, found in fruits, some vegetables and honey, are all examples of disaccharides.

So, if sugar is our bodies’ main energy source, how can it be bad for you at all?

Too much of a good thing

“If sugars come from a natural source, this is one category,” Dr Filippe Oliveira, a lecturer in obstetrics and gynaecology at Monash University, tells Cosmos. “Another is what we call added sugars – sugars added to foods and drinks by either a person or a manufacturer.”

Oliveira notes that there could be a number of reasons for doing this. One is that it tastes good (what other reason could you need?). Sugar can also be used to increase a product’s shelf life, like jams and preserves. It can also be used to enhance the appearance of food, such as a cake’s icing or other sugary ornaments.

“So there are different reasons why people would consider adding sugar. But we don’t really need added sugar in our diet. We should be fine with natural sugars.”

“When we eat carbohydrates, our digestive system will break down those larger complex molecules into smaller and smaller pieces, eventually into a glucose molecule,” Oliveira explains. “Glucose molecules are then absorbed through the walls of our small intestine and then they go into our bloodstream. Then once it’s in our blood, it can be used by our cells for energy.

“Every single cell in our body needs energy to function. Glucose is a relatively fast, easy way to get energy. It allows us to just go about our daily activities. But, just like everything, balance is the key. Too much or too little glucose can cause problems. Our body has some mechanisms to regulate the amount of glucose in our bloodstream.”

Don’t risk it for the sugar biscuit

Having high levels of sugar in your blood can cause serious long-term health problems.

When there are high levels of blood sugar, the pancreas pumps out the hormone insulin which regulates blood sugar levels. Over time, though, cells can stop responding to constant insulin, causing insulin resistance.

The pancreas keeps pumping out more insulin, but eventually can’t keep up with rising blood sugar levels.

High blood sugar is damaging and needs to be moved into the cells quickly. The liver and muscles can store some, but when they’re full, the liver sends excess blood sugar into fat cells. This causes weight gain and can have serious health repercussions from obesity and dental problems to prediabetes and type 2 diabetes.

How to avoid sugary health problems

So, we thought sugar was good. Now we’re saying sugar is bad, right?

It’s not so simple.

“As a scientist, we avoid using ‘good’ or ‘bad,’ or ‘better’ or ‘worse,’” Oliveira says. “But for the sake of simplicity, I would say there are usually good and bad sugars.”

Oliveira warns against stigmatising and judging individuals and focusing on the nutritional quality of different types of sugar.

“We might consider a ‘good’ sugar typically coming from whole, unprocessed food such as fruits or vegetables, or dairy products. These sugars are accompanied by fibre, vitamins and other nutrients that contribute to a balanced diet.

“On the other hand, if you think of ‘bad’ sugars. They often refer to added sugars found in processed or sugary foods or beverages and they are not naturally present in the food.”

These, Oliveira says, should be avoided where possible. But he’s no party pooper.

Though he’s lactose intolerant and can’t have chocolate, Oliveira, like anyone else, finds sugary foods enjoyable to eat.

“It’s about balance. It’s about making an informed decision that you are eating something that it’s not just natural sugar. People add sugar that you don’t necessarily need. But, yes, it is pleasurable. It’s nice to eat and it gives people some sense of calmness and gives people some sense of relaxation. So, yeah, I do consume added sugars from time to time, but I’m conscious of it.”

Cosmos recently launched in its Debunks podcast a four-part series about vices. In Episode 3, “Should you avoid sugar?” the team spoke to experts and health professionals to help us understand whether sugar is bad for you, or if there’s more to it.

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