When I think of ‘sugar’ I am thinking of white table sugar! Of course this is not the only type of sugar in our foods and drinks. As a dietitian and nutritionist though, I never really focus on one component of food. I assess the total quality of food — both the nutritional and sensory qualities. From a health point of view sugar creates confusion. I was recently asked “doesn’t our body deal with all sugars the same?” Let’s start answering this question by looking at where we find sugar in food.
Sugar is a part of the larger nutrient group called carbohydrates. Carbohydrate is a natural component of whole foods and is found in:
- cereal foods such as bread, breakfast cereals, rice and pasta;
- starchy vegetables including potato, sweet potato;
- legumes and lentils such as baked beans, chickpeas and kidney beans;
- fruit — fresh, dried, preserved and canned;
- milk and yoghurt.
These foods also supply a wide range of vitamins, minerals, phytonutrients such as antioxidants, protein, fat and fibre. The less processed or refined a food is, the more nutrients the food will contain.
Processed foods and highly refined sources of sugar offer fewer nutrients with high kilojoule (calorie) contents. I refer to these as occasional foods, drinks and ingredients:
- cakes, sweet biscuits, desserts, ice-cream and snack bars e.g. muesli bars;
- savoury biscuits and snack foods such as potato crisps;
- chocolate and lollies;
- soft drinks, vitamin drinks, sports drinks, cordial and sweetened ice-blocks;
- white sugar, raw sugar, honey, molasses and maple syrup.
Due to the high fructose content of fruit juice (plus added sugars), I include fruit juice in the occasional category too. The nutritional profile of occasional foods can be improved by using wholemeal and wholegrain flours, replacing butter with unsaturated oils, using herbs and spices in preference to salt and adding fruit as a sweetener.
Three main types of carbohydrate
There are three main groups of carbohydrates monosaccharides, oligosaccharides and polysaccharides. Saccharide is the Greek word for sugar.
- Monosaccharides (mono meaning one) consist of a single unit of sugar, for example glucose, galactose or fructose.
- Oligosaccharides (oligos meaning few) consist of at least two sugars (disaccharides), such as sucrose or cane sugar, which is made from one unit of fructose and one of glucose. Other disaccharides that you might be familiar with are lactose (glucose and galactose), which is only found in milk and maltose (two units of glucose) and found in potatoes, cereal products and malt.
- Polysaccharides are made from hundreds or thousands of monosaccharide units. In plants cellulose and starch are the most abundant polysaccharides.
Carbohydrate supplies our main source of energy for the body, with glucose being the only fuel supply for our brain. The type of carbohydrate and the presence of other nutrients such as fat and protein and fibre in foods affect how our body digests and utilises sugar.
Not all sugars are equal in this regard.
The digestion and metabolism of carbohydrate has been a focus of research for body weight management and the prevention and management of chronic disease such as diabetes. One significant finding has been the glycemic index. This system rates how quickly a carbohydrate is digested and absorbed as sugar into our blood stream. We will explore the glycemic index next week.