New food packaging symbol "G - Glycaemic Index tested" in Australia

A food packaging symbol "G - Glycemic index tested" for comparing the effect of different foods on blood sugar was launched in Australia on the 3rd of July 2002.

Please note: glycaemic is also spelled glycemic (especially in the US)

What is the Glycaemic index and why is it important?

The Glycaemic Index (GI) Symbol is designed to tell shoppers the GI rating of packaged food products in supermarkets. It ranks food products based on the speed at which they break down from carbohydrate to sugar in the bloodstream.

Food products containing certain types of carbohydrates which are broken down slowly by the digestive system result in a gradual release of glucose into the bloodstream. These foods have low glycemic indices and thus can have less of an impact on blood sugar levels and may help control established diabetes. In contrast, food products containing other types of carbohydrates that break down quickly have the highest glycemic indices.

Population based research has shown that diets made up mainly of high GI foods are associated with increased risk of coronary heart disease, type 2 diabetes and associated conditions (Liu, Willett et al., Am J Clin Nutr 2000; 71:1455-61).

Are there any problems associated with using the symbol as a guide to healthy eating?

Maybe, if you are not aware of the limitations associated with using the GI values.

The GI symbol will only appear on food products that meet certain nutrient criteria.
The food must not be high in fat, salt, sugar or calories and must contain significant amounts of fibre in order to be eligible for the symbol. High and intermediate GI soft drinks, cordials, syrups, confectionery, sugars are excluded. Jams, honey and other carbohydrate containing spreads are not necessarily excluded.

The GI symbol is being used by a fruit juice company in Australia "willd about juice" fruit juices.

However, some food products may simply state the GI value of the product without using the symbol because the product may not meet the GI symbol nutrient criteria - this may generate confusion for some consumers.

For example, the GIs of some fruits, vegetables and cereals can be higher than foods which are considered to be treats such as biscuits and cakes. This does not mean we should replace fruit, vegetables and cereals with treats because the former are rich in nutrients and antioxidants and the latter are not.

There are 2 main reasons why 'treats' may have a lower GI than healthy foods:

1. fat, protein and sugar content of treats:
Treats tend to be high in fat or sugar or both and can sometimes also contain protein.
Fat and protein can lower the GI of a food because they delay stomach emptying which delays digestion of the starches. For example, a boiled potato will have a higher GI than a fried potato, but yet a boiled potato is a healthier option. Also, different types of sugars can have different effects on blood glucose levels because of the way they are digested, absorbed and metabolised. Pure glucose when present in food will have a maximum effect on blood glucose, followed by sucrose (found in table sugar) and lactose (found in milk). Fructose when present in food will have the least impact on blood glucose. For example soft drinks can have a lower GI than most 'ripe' fruits because they contain mainly sucrose. In contrast, ripe' fruits may contain more glucose because the sugars and starches may have been broken down to glucose.But once again, the ripe fruits are a healthier option than soft drinks.
2. serving size
The GI is not based on the typical serving size of a particular food, but rather on 50g of carbohydrate found in that food. For example, 50g of carbohydrate is found in about 2 slices of bread OR 400g potatoes or 500ml of soft drink OR about 1kg of carrots - all these foods have a similarly high GI when eaten in these amounts. So, if a food has a medium to high GI, but is not ordinarily consumed in large quantities (carrots) then the value of the GI is not such an issue. In contrast, if a medium to high GI food can be consumed in large quantities (soft drinks, potatoes, rice, white bread) then the GI and total carbohydrate consumed is of concern.

The American Diabetes Association issued new nutrition guidelines for the treatment and prevention of diabetes and its complications in January 2002. The new guidelines outline strategies for controlling blood sugar levels, and they state that "the total amount of carbohydrate is more important than the source or type; the glycemic index may reduce post-meal blood glucose, but studies do not show sufficient evidence of long-term benefit for it to be recommended". For example, even though pasta has a low glycaemic index it is not advisable for people with diabetes or impaired glucose tolerance to have a large serve because the total amount of carbohydrate will be too high.

The verdict

In summary, the lower the GI of a food, the better the carbohydrate food is for everyone, especially if it also low in fat and/or added sugar, high in fibre and low in salt. The exception is if blood glucose falls below normal in people with diabetes. This is more likely if you are an insulin-dependent diabetic. A high GI food or drink will restore blood glucose levels more quickly. Follow up with a low GI food to maintain blood glucose levels.

It is not always possible to choose all lower GI foods. If you mix a low GI food with a high GI food, you will get an intermediate GI for that meal. Try to include a good proportion of ONE low GI food at each meal (MacDonald, Nutr Issues & Abstracts, 1995).

It is better to have 4-5 small meals a day containing at least one low GI food than to have fewer larger meals. These strategies will allow a slow diffusion of energy through the body, thus eliminating peaks and troughs of blood sugars, tiredness and alertness.

So what sort of carbohydrates are good to eat? Pasta, beans, lentils, chickpeas, oats, bread with 'bits' and seeds in it (e.g wholegrain), and whole pieces of fruit all have a
low GI. Cooking, mashing or juicing a food will increase the GI.

A high GI value is 70 or more
A medium GI value is 56-69
A low GI value is less than 55

To read more about the GI click here

 View a Table of Low Glycaemic Index Foods.

Other useful links:

http://abc.net.au/science/news/health/HealthRepublish_597411.htm

http://www.gisymbol.com.au (a website about the GI symbol)

http://www.glycemicindex.com ( a database website which will give you the GI of foods)