Fructose is a sugar that’s abundant in nature – you’ll find it in fruit, berries and honey. It has provided humans with carbohydrate energy for millions of years. As a product today it stands out from the crowd of alternative sweeteners, being sweeter than sugar (it depends on the temperature, the colder the better), providing the same amount of calories, but having only one-third the GI (19). This means you can use less fructose to achieve the same level of sweetness, and as a result, consume fewer calories and experience a much smaller rise in your blood glucose levels.
Photo: Ian Hofstetter
The most recent study published in the American Journal of Clinical Nutrition (2006;84:1374–9) found that a 4-week high fructose intake by a small group of healthy men did not lead either to an increase in body fat or insulin resistance. But there’s no doubt that fructose consumption per capita has increased in recent decades as it is more widely used by manufacturers for sweetening beverages and foods. Here are answers to some of the questions we are most frequently asked about fructose.
How come fructose has a low GI?
Fructose (GI 19) is absorbed and taken directly to the liver where it is immediately metabolised.
The food industry will lower the GI by using fructose or adding fat
It hasn't happened in Australia to date. For example, there are over 100 products in the GI Symbol Program. Manufacturers could use fructose if they wanted to, but to date there’s only one, a low kilojoule sports water, with 3 per cent fructose in it. And if a food was high in fat, it wouldn’t be able to carry the symbol as products with the GI symbol must meet a host of strict nutrient criteria including calories/kilojoules, total and saturated fat, sodium (salt) and where appropriate fibre and calcium. For more information: http://www.gisymbol.com.au/
What’s high fructose corn syrup (HCFS) and why is it a problem?
Corn syrup solids’ are often found on the labels of American foods. They are the most common form of sweetener in North America because they are cheaper than cane sugar. They are made from corn starch by enzymatic or chemical treatment. Further treatment produces HCFS solids which are very sweet and contain roughly 50 percent glucose and 50 per cent fructose. They are the main source of sweetness in soft drinks made in the United States and Canada. Although the name implies they are high in fructose, they yield the same number of fructose molecules as cane sugar during digestion and absorption.
I have fructose malabsorption. How can I eat a balanced diet since a lot of fruit and veggies seem to be ruled out?
If you have fructose malabsorption it means that the small intestine is impaired in its ability to absorb fructose which then passes through to the large intestine where bacterial fermentation can cause symptoms such as bloating, wind, pain, diarrhoea and/or constipation says IBS specialist dietitian Sue Shepherd. The good news is that foods with more fructose than glucose tend to be the problem, as are foods with a lot of fructose (regardless of the amount of glucose). To make sure you are eating a balanced diet, see a dietitian. And if you want recipes, check out Sue Shepherd’s website. She has self published two ‘Irresistible for the Irritable’ cookbooks that will be helpful: http://www.coeliac.com.au/
Is it true that if fructose is consumed after eating a large meal that overly raises the blood glucose or with high glycemic foods, it no longer has a low glycemic value as it takes on the value of the high glycemic foods?
This is not correct. Fructose mixed with a high GI meal gives you something intermediate between the two.