Sickly sweet?
It’s not surprising that humans enjoy sweetness. The first food we consume – breast milk – is sweet as well as providing an important source of energy for life and growth. However, although lactose is sweet, it’s less than half as sweet as the sucrose that dominates so many of the foods in our diet for the rest of our lives.
Sugars
Common sugars exist as simple sugars known as monosaccharides such as glucose (also called dextrose), galactose and fructose (also called levulose), or as disaccharides such as lactose (glucose and galactose), sucrose (glucose and fructose) and maltose (two molecules of glucose). Note that these, and other members of the sugar family, end in –ose.
Breast milk contains a collection of some important oligosaccharides that help set up healthy bacteria in the infant’s colon. Oligosaccharides have three to ten sugars joined together. Polysaccharides may have hundreds or even thousands of linked sugars.
Sugars added to foods can lead to many health problems. In the mouth, sugars attract harmful bacteria that can cause dental decay. The major damage occurs if sugary foods stick to the teeth. The acidity of sweet drinks also damages tooth enamel, making it especially easy for harmful bacteria to cause decay. This problem applies to sweet drinks, whether sweetened with sugar or any of the artificial or substitute sweeteners.
In most other aspects of health, the damage from sugar is related to how much we consume. Most people actively seek out some sweet foods. Food companies are well aware of the fact that sugar makes many foods more attractive, so they add it to an increasing range of processed foods, including many that we would never have traditionally been associated with sweetness.
Sweet drinks are the single greatest source of sugar in the typical Australian diet, accounting for just over half of total sugar consumed. The next biggest source includes obviously sweet foods such as cakes, biscuits, desserts, sweet pastries, confectionery and breakfast cereals. But sugar is also added to products where you might not expect it, such as tomato and barbecue sauces, various Asian sauces, pasta sauces, salad dressings, chutneys, relishes and canned soups. Some breads also contain added sugar.
The ingredients on food labels list sugar in various ways, including not only the dominant sucrose, but also glucose, dextrose, maltose, fructose, dextran, maltodextrin, caramel, cane juice, corn syrup (used mainly in the United States), golden syrup, molasses, treacle and cane juice crystals.
Foods purporting to be healthy may include agave syrup, barley malt, carob syrup, coconut sugar, date syrup, fruit juice concentrate, maple syrup, muscovado, palm sugar, panela sugar, rapadura, and rice malt syrup. These are all more expensive forms of sugar, but they’re basically just sugar and have the same potential for health problems as common sugar. Brown sugars and brown cane sugars such as molasses, rapadura, panela and muscovado sugars may contain some minerals, but the quantities are negligible.
Honey
Although honey is basically sugar, some types of minimally-processed honeys contain some oligosaccharides. Whereas the sugars in these honeys are broken down in the small intestine and could be as damaging as regular sugar, the oligosaccharides pass to the colon where they may have potential benefits. These include reducing the presence of harmful bacteria while simultaneously stimulating the growth of beneficial bacteria.
Research into these possible advantages of minimally processed honey continues, although the greatest benefit may be that food companies are unlikely to ever put much honey into ultra-processed foods. There’s no mystery to this: sugar is a cheap ingredient that’s easy to use. Check the label of products such as breakfast cereals that include ‘honey’ and you’ll find the major sugar present is not honey. Indeed, I checked a range of products and found four, six and even ten times as much sugar added as honey. One popular product of honey cereal is half sugar. Better to make yourself a bowl of porridge and add a small spoonful of honey!
Sugar substitutes
Substitutes for sugar such as saccharine, cyclamates and aspartame have been around for many years. Newer sweeteners include sucralose, in which the usual structure of the sugar molecule has been ‘tweaked’ so that it is about 600 times as sweet as the regular sugar from which it originated. Unlike many of the artificial sweeteners, sucralose doesn’t taste bitter and can be used in baked goods.
A new cloud has formed over sucralose and many of the other newer sugar substitutes.
Although the research has only been done in rodents, a paper published in a journal noted for its high quality reporting shows several of the sugar substitutes change the balance of bacteria in the colon. Potentially harmful bacteria increase while the ‘good’ bacteria numbers fall. At least in the animals used, the changes can lead to increased inflammation. Research in humans shows that long-term inflammation can cause problems for weight control and type 2 diabetes.
At this stage, the sweeteners that show this problem include sucralose, saccharin and, although to a lesser extent, aspartame and stevia.
Other problems have also been identified with sugar substitutes. When we taste sugar, the pleasure centres in the brain go into action, and the brain sends signals to the systems that manipulate metabolism, letting the small intestine know that sugar is about to hit it and will need to be broken down and absorbed. The body’s satiety mechanisms also start working to regulate how much we should eat by producing a hormone commonly called GLP-1. Although this satiety system may fail for many people, GLP-1 has well-known protective effects on the cardiovascular system and anything that diminishes it is a potential problem.
When we consume sugar substitutes, the signals from the tastebuds to the brain work as they would if we had consumed sugar. However, no sugar arrives and this may confuse the ability to regulate satiety. One effect is to blunt the body’s production of GLP-1.
So far, there is no research showing if the potential adverse effects only occur with large quantities of sugar substitutes consumed over a long period. However, independent scientists studying these effects suggest that we should stop thinking that sugar substitutes are completely safe. Before you rush back to sugar, they don’t recommend that either.
Take home message. Ideally, we should wean ourselves off too many sweet foods and avoid sweet drinks. It can be done. As an example, when most people give up adding sugar to tea or coffee, they find an unexpected sweet cup unpalatable. I’ve also yet to see someone who is truly thirsty refuse straight water. As usual, I don’t recommend any food needs to be totally forbidden (except with a genuine allergy), so most of us can still enjoy sweet foods as an occasional treat.
Dr Rosemary Stanton OAM
