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Everyone seems to be talking about the Glycemic Index or 'GI' as the latest healthy eating trend.

Is a low GI meal plan truly a healthy eating practice? We decided to ask our Healthy Eating Affiliate at the Canadian Health Network to tell us more about Glycemic Index.

Glycemic Index (or GI for short) was developed by researchers to determine how different foods containing carbohydrates affect our blood sugar levels. In healthy adults, insulin controls the blood sugar levels. But in some cases, insulin is not available or doesn't work well and glucose stays in the blood at higher levels than normal. This is called diabetes. Left untreated, this higher level of blood glucose can cause problems in the body such as blurred vision or high blood pressure. High blood sugar levels have also been linked to heart disease and obesity in the general healthy population.

Carbohydrates are found in lots of different foods: bread, pasta, rice, fruits, vegetables, sugars and sweets, milk products (e.g. milk, yogurt, ice cream) and legumes (e.g. dried peas, beans and lentils).

Foods can be divided into high, medium and low Glycemic Index. A food with a high Glycemic Index will raise blood sugar more than a food with a low Glycemic Index.

To see how your favourite food stacks up, check out The Glycemic Index Fact Sheet by the Canadian Diabetes Association.

A food's Glycemic Index is based on a comparison with a reference food, usually glucose- a sugar which raises the blood sugar quickly. Glucose gets a rating of 100%. The Glycemic Index then charts how other foods compare.

For example, pasta has a Glycemic Index of 41. This means that pasta raises your blood sugar less than half as much as glucose does.

Most foods that have a high GI are found in the "starchy" or grain products food group. These foods include bread, cereal, pasta, rice and potatoes. However, there are many low GI choices from within these groups including some types of bread (e.g. pumpernickel, 100% stone ground whole wheat breads), cereal (e.g. oatmeal, all bran, bran buds), rice (e.g. converted or parboiled) and potatoes (e.g. sweet).

Most fruits, vegetables and milk products have a low GI. Legumes such as chickpeas, beans and lentils also have a low GI and are an excellent source of fibre.

Studies (* footnote) have found that low GI foods have many health benefits, including:

• Prevention of type 2 diabetes
• Control of blood sugar
• Control of blood cholesterol levels

Use of the Glycemic Index is recommended in planning meals for people living with diabetes and those identified as being at high risk of developing type 2 diabetes.

Further studies are needed before recommendations about the use of Glycemic Index for the general healthy population can be made.

The term GI appears in many of the latest diet books. There are some studies that have found that including low GI foods in the diet, rather than those with a high GI, may result in short-term weight loss. However, there have been no studies to date that have looked at whether or not low GI foods can lead to long-term weight loss. Therefore, more research is needed before it is known if low Glycemic Index foods can help with long-term weight control.

Foods that are high in protein (e.g. meat, fish, poultry, cheese) and fat (e.g. butter, oil, margarine, cookies, pastries) may not raise your blood sugar very much, but they still contain calories. Eating too much of these foods can cause you to gain weight.

Also, eating too much fat can have a negative effect on your health by increasing your blood cholesterol.

Moderation is the key!

It is not necessary to completely give up all foods that have a high Glycemic Index.

Here are some tips you can follow to lower your GI:

• Select one low Glycemic Index food per meal
• Base two meals per day on low Glycemic Index food choices
• Include legumes (chick peas, beans and lentils) in your meals and recipes
• Because most fruits and vegetables and milk products have a low Glycemic Index, enjoy a variety of foods from these groups everyday, with an emphasis on low fat choices.
• Some low Glycemic Index foods (e.g. chocolate) are mostly fat and sugar and so add little to the nutritional value of your diet. Make choices based on overall nutrition and health value, not just on Glycemic Index.
• Remember…you can get too much of a good thing. So, watch your portion sizes, even when choosing foods with a low Glycemic Index.

A registered dietitian can help you select low Glycemic Index foods more often. You can find a dietitian in your area.

The Glucose Revolution by: Brand-Miller, Wolever, Colaguiri and Foster-Powell is a book that has reliable information about the Glycemic Index.

For more information about low, medium and high GI choices see the GI tool developed by the Canadian Diabetes Association at http://www.diabetes.ca/Section_Professionals/ng_glycemic.asp

*This growing interest is supported by scientific evidence, including data from epidemiological and clinical studies, which have linked low GI diets with improved outcomes such as a decreased risk of development of type 2 diabetes (Salmeron et al 1997a,b) and improvements in both metabolic control (Wolever et al 1992a, Jarvi et al 1995, Collier et al 1998, Jenkins et al 1987, Fontvieille et al 1988, Brand et al 1991, Giacco et al 2000, Gilbertson et al 2001) and quality of life (Gilbertson et al 2001) in individuals with established diabetes. As well, there is evidence for the GI concept in the control of cardiovascular disease risk factors such as blood lipids (Jenkins et al 1987; Jenkins et al 1988; Fontvielle et al 1988; Wolever et al 1992a; Wolever et al 1992b; Brand al 1991; Fontvieille et al 1992; Jarvi et al 1999; Liu et al 2000; Buyken et al 2001). There is also evidence that GI may play a role in prevention and management of obesity (Liljeberg et al 1999; Bouché et al 2002; Ball et al 2003). However, long-term studies are needed to clarify the role of the GI concept in weight regulation. Until there is more conclusive evidence, debate continues regarding the merits of low GI diets in the management of obesity (Pawlak et al 2002; Raban 2002).