Sugars are the basic units of carbohydrate, synthesised by plants, via photosynthesis, from water and carbon dioxide.
Glucose is the most common of the monosaccharides (simple sugars), with the chemical formula C6H12O6. Six molecules each of water (H2O) and carbon dioxide (CO2) form one glucose molecule and six molecules of oxygen (O2). Another monosaccharide is fructose, which has the same chemical formula as glucose, but with different molecular structure. Fructose typically occurs bound to glucose as the disaccharide sucrose (C12H22O11), which exists in abundance in crops such as sugar beet and sugar cane. Lactose, found in milk, is a disaccharide of glucose and galactose; maltose is a disaccharide comprising two molecules of glucose.
All carbohydrates are saccharide polymers (polysaccharides), consisting of hundreds, and even thousands, of linked monosaccharides. Carbohydrates that are made up of one kind of simple sugar are called homopolysaccharides; an example is starch, which consists of multiple units of glucose. Those that contain two or more types of monosaccharide are heteropolysaccharides; for example, agarose, in the cell walls of red seaweed.
Only simple sugars can be absorbed, so our digestive systems must break down complex carbohydrates into monosaccharides. The more complex they are, the more energy it takes to digest them. The simpler they are, the less energy it takes to digest them, which is why sugar is such an economical form of energy and very fattening.
We need a certain amount of glucose in our blood, and the level is monitored by the liver and the hormone insulin, produced by the pancreas. Excess glucose is stored as glycogen, the animal equivalent of the plant kingdom’s starch. When we spend energy, the liver breaks down glycogen into glucose and releases it into the blood stream.
If there’s a great excess of glycogen, it’s converted to fat, which is stored mainly in the liver and skeletal muscles.
The sweet foods we eat, like biscuits, cake, chocolate, and ice cream, contain a lot of added sugar. The sugar in these foods is sucrose, harvested from sugar cane and sugar beet and added during processing or preparation.
The NHS recommends that an adult consumes no more than about 30g of sugar per day. For reference, there’s 30g of sugar in:
Many processed foods that we don’t always think of in terms of sugar can have a surprisingly high sugar content.
For example, from one particular brand:
However, the sugar content of these foods is not necessarily all added sugar.
When it comes to processed foods, you can choose the low-sugar option. For example, reduced sugar products from the same brand:
Cutting out – or cutting down on – sweets is an obvious step to take if you want to reduce your sugar intake. But if you have a sweet tooth, how can you get your sugar fix in a healthier form?
Fruit is a tasty and healthy alternative to foods with added sugar. Although fruits contain sugar (an apple 10g, a banana or peach 12g, an orange 14g) in the form of fructose, glucose, and sucrose, digestion of the sugar is slowed down by the food’s soluble fibre, giving fruits a low glycaemic index (GI) rating. A low GI indicates low potential for a spike in blood sugar levels.
Fibre is a type of carbohydrate that humans can’t digest. Unlike other carbohydrates, fibre passes right through our digestive systems and is not broken down into simple sugars. Soluble fibre absorbs water, bulking out the contents of the intestines and slowing the rate of digestion. This has the effect of making us feel full for longer, and it prevents blood sugar levels from spiking.
Another food that’s high in fibre is oat bran, which can be sweetened with fruit for a healthy, low- calorie breakfast. Fruits like blackberries, strawberries, blueberries, and raspberries contain a high proportion of fructose, which has a sweeter flavour than any other kind of sugar. This means that the fruit will provide more sweetness per overall weight in sugar.
The natural sweetness of fruit can liven up a glass of still or sparkling water. By adding a few crushed raspberries or blueberries, or a slice of orange or lime, you can create a bright, fresh drink that’s full of sweet, fruity flavour. Or you could put a few pieces of fruit in your refillable bottle.
Milk contains lactose, a disaccharide of one glucose molecule and one galactose molecule. As milk is digested, an enzyme called lactase breaks down the lactose into simple sugars (glucose and galactose).
Like fruit, milk has a low rating on the glycaemic index, meaning that sugars will be digested slowly. However, in the case of milk, this isn’t due to the presence of soluble fibre, but in some part to the presence of fat. It also has a lot to do with the fact that lactose itself is not a quickly digested sugar and has little effect on blood sugar levels.
But still, in 100ml of cow milk, there’s 5g of lactose, which means that a 200ml portion of milk provides about one third (10g) of your recommended daily sugar. There are, however, some good substitutes for real (i.e. mammal’s) milk. Each type of plant-based milk has its own flavour, and each contains a different amount of sugar.
Oat milk, for example, contains 2.8g of natural sucrose per 100ml. In soy milk, there’s just 0.4g of sugar: sucrose, stachyose (a tetra-saccharide made up of two galactose, one glucose, and one fructose), and raffinose (a trisaccharide, composed of one molecules each of galactose, glucose, and fructose). Almond milk contains no sugars at all.
Bear in mind that some plant-milk products contain added sugars. For low-sugar plant milks, choose unsweetened products.
Reducing your sugar intake is only part of a healthy diet. One element of nutrition that’s often overlooked is hydration. Water plays an important role in every bodily function – including circulation, digestion, and cognition – and dehydration can have a detrimental impact on health, mood, and productivity.
So grab a glass or bottle, and REFILL! Again and again and again and again, and again, and again …