The many faces of sugar

Understanding the family of carbohydrates behind your everyday food

Sugar is not a single substance, it is a whole family of carbohydrates, some naturally in fruit and dairy, some added to processed foods, some hidden inside grains and vegetables, some tied up in fibre. Each type behaves a little differently once inside your body. Some rush in quickly, others drift in slowly and some are not digested at all.

This blog is here for you to understand sugars a little better, and without a single wagging finger.

Meet the family

When we say "sugar", we are really talking about a family of carbohydrates. They differ in size, meaning how many sugar units are joined together, and that changes how they are digested, absorbed and used for energy.

There are three broad groups.

Monosaccharides: single sugars

These are the simplest sugars. One unit only, small enough to be absorbed straight into your bloodstream without further digestion.

Glucose: the sugar your body ultimately uses for fuel. Most carbohydrates end up as glucose after digestion. Found in small amounts in honey and fruit.

Fructose: the natural sugar in fruit and honey. Handled a little differently by the body, taking a detour through the liver before it can be used.

Galactose: usually found alongside glucose in lactose (milk sugar).

Disaccharides: pairs of sugars

Two monosaccharides linked together. Your body needs to snip them apart before they can be absorbed.

Sucrose = glucose + fructose. This is table sugar, and what you will find in sweetened drinks, sauces, biscuits and most sweet treats.

Lactose = glucose + galactose. The natural sugar in milk, yoghurt and cheeses.

Maltose = glucose + glucose. Forms during starch breakdown, and shows up in malted products, some cereals and beers.

Polysaccharides: long chains of sugars

Many sugar units linked together in long chains. Some of them we digest, and some of them we do not, which is where things get really interesting.

Starch: the storage form of glucose in plants. Found in grains, potatoes, maize, rice, oats and legumes. Digested into glucose over time.

Glycogen: the storage form of glucose in animals and humans. Held in the liver and muscles as a back up energy reserve.

Fibre: long chains of sugars that we do not digest at all.

Fibre is technically a polysaccharide, but its magic is that we cannot digest it. Which sounds like a failure until you understand what it actually does inside us.

Soluble fibre forms a soft gel in your gut. It slows digestion, feeds your gut microbes, and helps flatten the rise in blood sugar after a meal. Found in oats, psyllium, and the pectin in apples and citrus.

Insoluble fibre adds bulk to your stool and keeps things moving nicely. Found in wheat bran and vegetable skins.

Resistant starch is a special kind of starch that behaves like fibre. It resists digestion in the small intestine, then arrives in your large intestine to feed your gut microbes. Found in slightly underripe bananas, legumes, and in rice or potatoes that have been cooked and then cooled.

Why the packaging matters

Here is one of the most important and exciting ideas in modern nutrition.

The same sugar can behave completely differently depending on the "packaging" it comes in.

Take an apple. It contains fructose and glucose, roughly the same sugars you would find in a fizzy drink. But when you eat an apple, those sugars are locked inside the fruit's cell walls. They are surrounded by fibre, water, vitamins and antioxidants. The sugars moves out slowly as your body breaks the fruit down. Your blood sugar rises gently. Your body handles it much easier.

Now take the same apple, blend it into juice and strain out the fibre. Suddenly the same sugars are free, unbound and ready to hit your bloodstream almost immediately. The cell walls are gone. The fibre is gone. The fruit is gone, in a sense.

This concept is called the food matrix, and it is why nutrition scientists increasingly say that how the food is structured is also very important along side what a food contains. An apple is not the same as apple juice. A whole grain is not the same as refined flour. The sugars may look similar on paper, but the packaging is completely different, and your body responds accordingly.

What this means for your plate

Once you understand the family of sugars and the power of the food matrix, here are a few practical takeaways.

Whole fruit is not the same as fruit juice. Enjoy your fruit whole, with the skin where possible. Save juice for occasional treats.

Whole grains carry their own fibre. Oats, brown rice, wholewheat bread, quinoa and barley all release their sugars more slowly than their refined cousins. Choose them more often.

Cooked-and-cooled starches. Cooking rice or potatoes and then cooling them (even briefly) creates resistant starch, which behaves more like fibre than glucose!

Read labels for free sugars. Anything ending in "-ose" (sucrose, glucose, fructose, dextrose, maltose) is a form of sugar. So are syrups, honey, agave, and fruit juice concentrates.

Give your fibre some love. Most South Africans eat far less fibre than recommended. Aim for 25 to 30 grams a day, from a variety of vegetables, legumes, whole grains, nuts, seeds and fruit.

A note on the "healthy" sugars

Our ethos at Sally-Ann Creed® is centred on education, not fearmongering. We do not want to promote restriction or label foods as "good" or "bad", or even simply "healthy" and "unhealthy".

However, it is helpful to understand that some sugars marketed as more natural or healthier can still affect blood glucose in a similar way to ordinary table sugar. Honey, coconut sugar, maple syrup and agave may differ slightly in taste, processing and micronutrient content, but they are still sources of added sugar.

This does not mean that you need to avoid them completely. It means that they are best enjoyed mindfully and in context, rather than assumed to have no effect on blood sugar.

The graph below provides an example of this. This blood-glucose curve from one participant in a study compared the same amounts of honey and glucose. In this example, honey produced a lower glucose response than pure glucose (not table sugar), and both caused a considerable rise in blood glucose.