FOOD

Sugars: The Difference Between Fructose, Glucose And Sucrose

We're not just confused, we're also misinformed.

29/06/2016 7:43 AM AEST | Updated July 15, 2016 12:56
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Plus, why fruit is NOT bad for you.

"Fructose is the worst for you." "No way, sucrose is the devil." "I don't eat any sugar."

Sugar is confusing. While some people only use certain types of sugars, others dismiss them completely. But is this necessary, or even grounded?

To help settle the confusion, we spoke to Alan Barclay -- accredited practising dietitian, spokesperson for the Dietitians Association of Australia and Chief Scientific Officer at the Glycemic Index Foundation.

"All the sugars are used as a source of fuel, but there are subtle differences in the way they are digested and absorbed," Barclay said.

"In foods in Australia, the most common sugars are monosaccharides (glucose, fructose and galactose), but mostly these are occurring as disaccharides (which are sucrose, lactose and maltose)."

Monosaccharides and disaccharides are two kinds of simple sugars, which are a form of carbohydrate. Oligosaccharides and polysaccharides, on the other hand, contain more sugar combinations and are known as complex carbohydrates -- for example, whole grain breads, brown rice and sweet potatoes.

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Monosaccharides


Monosaccharides require the least effort by the body to break down, meaning they are available for energy more quickly than disaccharides.

"Monosaccharides don't require any digestion and can be absorbed into the mouth," Barclay said. "The problem there is they can cause dental caries which is one of the primary reasons why we need to be careful of how much added sugar we're consuming."

Glucose -- the body's main source of energy and is found in fruit such as pasta, whole grain bread, legumes and a range of vegetables.

Fructose -- this 'fruit sugar' found in foods such as fruit, honey, some vegetables and soft drinks.

Galactose -- this is a component of lactose (the 'milk sugar') and can be found in foods such as legumes, dairy products and dried figs.

Compare The Market
A chart outlining the fructose content of different fruit and veggies. Important note: eating fruit is better than eating none at all.

Disaccharides


"Disaccharides are again broken down in the mouth, depending on the bacteria in the mouth (if you're a frequent consumer of added sugars, it does change the bacteria in the mouth), but most of the digestion happens in the small intestine," Barclay said.

Sucrose -- referred to as 'table sugar' and chemically consists of glucose plus fructose. It is a common form of sugar found in sugarcane, some fruits and vegetables, and products which have been sweetened (e.g. cereal, ice cream, baked desserts and yoghurt).

Lactose -- referred to as 'milk sugar' and chemically consists of glucose and galactose. Lactose is found primarily in dairy products but is often added to bread and baked goods, lollies, cereals and processed snacks.

Maltose -- referred to as 'malt sugar' and chemically consists of two glucose molecules. Maltose is founds in cereals containing barley and 'malt products' such as malted milkshakes, lollies and beer.

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Lactose is an often forgotten type of sugar found in dairy products.

Now we know the different types of sugars -- is one sugar better or worse for us?

"All added sugars are devoid of vitamins, minerals and dietary fibre by definition, and all contribute unwanted calories for most people (athletes, for example, do need the extra calories)," Barclay told HuffPost Australia.

"Sugars are considered to be 'empty' calorie (or energy-dense, nutrient-poor) foods. From that perspective, other than a slight benefit from lactose, all the sugars are going to cause dental caries and will generally provide the same amount of kilojoules per gram."

This risk of dental caries -- as well as unhealthy weight gain -- is why the World Health Organisation recommends adults and children reduce their daily intake of "free" or "added sugars" typically found in soft drinks and confectionery to less than 10 percent of their total energy intake.

"Other than lactose, which is the least likely to break down in the mouth, all these sugars are going to contribute to dental caries and that's one of the primary reasons we have this guideline," Barclay said.

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Lollies provide too much sugar too quickly.

While different sugars have a slightly different effect in the body, there's no one 'hero' sugar.

"There are subtle differences in the way they affect blood glucose levels," Barclay said. "Glucose and maltose will raise blood glucose levels most rapidly of all the sugars and therefore increases insulin secretion. Whereas fructose will have the least effect on glucose and insulin, but it will raise triglyceride levels."

Quantity


Like anything regarding diet, it's all about the amount of sugar you consume.

"It comes down to the quantity you consume," Barclay told HuffPost Australia. "Most people don't eat something that's pure in one sugar or the other -- I think that's the biggest fallacy at the moment. Nobody consumes pure fructose."

Don't get too obsessed about the amount of added sugars in other foods if that other food is an all-round healthy choice.

This means that pitting one sugar against the other is not the right mentality to have towards sugar. Instead, see added sugar (that is, not whole fruit) as a 'sometimes' food.

"It's an area of much confusion. There's no need to avoid all sugars. The WHO guidelines make that quite clear," Barclay said.

"Really, the things people need to consume the least of are pretty obvious. It's sugar-sweetened beverages -- whether that's soft drink, flavoured mineral waters and energy drinks -- which shouldn't be daily foods or drinks."

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Fruit is not bad for you.

Fruit


Do you avoid fruit because it's high in fructose? Barclay urges people to move away from this attitude.

"Don't get too obsessed about the amount of added sugars in other foods if that other food is an all round healthy choice," Barclay said.

"Fruits are a core food and Australians only eat a piece a day on average which is appalling. The minimum recommended amount per day is two and anyone who suggests it contributes to obesity is wrong. We're eating so little of fruit, how could it possibly be contributing to obesity when two-thirds of the population are overweight or obese. It's absurd."

Fruit is a great source of dietary fibre and various vitamins and minerals, including vitamin C and potassium.

"Don't throw the baby out with the bathwater. It's an entirely unnecessary focus," Barclay said. "Don't worry about fruit, particularly whole fruit. It's not a problem for most of us because most of us hardly eat any."

Fructose chart provided by Compare The Market.

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