1 September 2008

GI Symbol News with Alan Barclay

Alan Barclay

‘Are there guidelines covering manufacturers making the claim on food labels and in advertising that their product has a low glycemic load (GL)?’
Yes there are guidelines for cut-offs. Back in 2003, Prof Jennie Brand-Miller and colleagues suggested that the following cut-offs be used to describe the glycemic load (GL) of individual foods:

  • Low GL ≤ 10
  • Medium GL 11-19
  • High GL ≥ 20
But as far as I have been able to ascertain, manufacturers aren't necessarily using these specific cut-offs as the basis for making their low GL claims on food labels at this point in time. There are in fact no government regulations about making GL claims anywhere in the world. Yet.

Nutrition claims are regulated by Food Standards Codes and so far no country has a code that defines GL, how to measure it, and what the cuts-offs should be. There are a number of likely reasons why this is so but this is where the story can get very technical. Perhaps the key reason is that when it comes to low GL diets, you aren’t just looking at carbs or GI. You are looking at a mixed bag.

This is because low GL diets can be protein- and fat-rich, and contain high or moderate GI foods, but with little carbohydrate in them such as the original Atkins Diet. Or they may be higher in low GI carbohydrate, and lower in fat and protein, like the Low GI Diet.

If you look at specific food examples, high fat, higher GI foods with relatively little carbohydrate per serve such as many savoury snack foods, can have a low GL, as can carb-rich foods with a low GI such as most fruits and legumes, and then there are those foods that come somewhere in between such as most cereal based foods. As I said earlier, it's inherently a mixed bag.

‘Are low GL claims more useful than low GI ones?’
In our experience most people find the GI is a much simpler tool to use than the GL day to day in the supermarket. And the evidence published to date in scientific journals suggests that low GI diets are generally healthier than low GL diets – for most of us. In addition, if you use the GI as it was intended – to select the food with the lowest GI within each food group or category – then in most cases, you get the product with the lowest GL anyway, as foods are grouped according to their macronutrient content (amongst other things), so they generally have a very similar carbohydrate content anyway.

This is why the GI Symbol program focuses on the GI of healthy foods within specific food groups/categories to help people make healthy choices easy choices in the supermarket.

Email us for more information: alan@gisymbol.com

Dr Alan W Barclay, PhD
CEO, Glycemic Index Ltd
Phone: +61 2 9785 1037
Mob: +61 (0)416 111 046
Fax: +61 2 9785 1037
Email: mailto:alan@gisymbol.com
Email: alan@gisymbol.com
Website: www.gisymbol.com.au


Anonymous said...

I'm confused. I read the term glycemic load (GL) which I kind of understood after reading the article. However in terms of the cut-offs of the GL, what unit we are talking about here, eg Low GL ≤ 10. What does the 10 stand for and how do you calculate it.

Selma Janet said...

I too am confused. Are DL & GI are two different measures???

GI Group said...

A couple of years ago in GI News, we published a glossary of terms. Here are the definitions for glycemic index and glycemic load.

"Glycemic Index (GI)
Different carbohydrate foods can behave quite differently in your body. Some break down quickly during digestion and release glucose rapidly into the bloodstream; others break down gradually as you digest them and slowly trickle glucose into the blood stream. The glycemic index or GI, a relative ranking on a scale of 0 to 100, is how we describe this difference. After testing hundreds of carbohydrate foods around the world, scientists have found that foods with a low GI will have less effect on your blood glucose than foods with a high GI. High GI foods tend to cause spikes in your glucose levels whereas low GI foods tend to cause gentle rises. To make a fair comparison, all foods are compared with a reference food and tested following an internationally standardised method.

Glycemic Load (GL)
How high your blood glucose actually rises and how long it remains high when you eat a meal containing carbohydrate depends on both the quality of the carbohydrate (its GI) and the quantity of carbohydrate in the meal. Researchers at Harvard University came up with a term to describe this: glycemic load. It is calculated by multiplying the GI of a food by the available carbohydrate content (carbohydrate minus fibre) in the serving (expressed in grams), divided by 100.

GL = GI/100 x available carbs per serving."

hermin said...

GI vs GL. yes, they're so similar, but slightly different - i'd call them "look-alike sisters" (but
not close enough to be called "twin sisters" :)

but they do have a difference. Let's take Australian mangoes as an example: (GI = 51, GL = 7.7)

imagine you have a 50 gram glucose (that's the naturally present sugar in your body). What if
you had mangoes instead of glucose drink? if you ate some mangoes which will give you 50 g carbohydrate, then your blood sugar would increase by 51% as much as that of pure glucose.

That's what they mean by "GI 51".

This means, if you have a mango (which contains 15.1 g carbs in it), how much glucose are you bringing into your body?

If that amount of carbs had come from pure glucose, then you would have got 15.1 g glucose.
But mangoes only give you 51% of that amount (remember their GI is 51?)
So, by eating one mango, you would get (51% x 15.1) grams glucose = 7.7 g glucose. In other words, the GL is 7.7.

If you use the GI Group's equation above, you'll get

GL = 51/100 x 15.1 = 7.7

hope this helps :)

hermin said...

another "trick" to remember the difference between GI and GL:

GI = glycemic INDEX = quality. i mean, an "INDEX" will give you an idea about the strength of something, the intensity of something, the quality of something.

Another example is the popular Body Mass INDEX (BMI). Say someone's BMI is 22, that doesn't mean they have 22 kg fat, does it? Instead, that means they are slimmer than another
person with a BMI of 35. So, body mass INDEX doesn't refer to an amount, but a characteristic (slim/fat) or QUALITY. The same principle applies to glycemic INDEX - it's about a characteristic/ quality (how QUICK the full fat milk rises blood sugar levels).

GL = glycemic LOAD = quantity.
when you say you have a huge "workLOAD", that means you have to do a huge amount (QUANTITY) of work. The same goes for glycemic LOAD - it's about the quantity/the amount... how MUCH "homework" your glass of milk is giving your

hope this also helps! :)

GI Group said...

>>> What does the 10 stand for and how do you calculate it?

Glycemic load or GL combines both the quality and quantity of carbohydrate in one ‘number’. The formula is:

GL = (GI x the amount of carbohydrate) divided by 100.

Take a single apple as an example. It has a GI of 40 and it contains 15 grams of carbohydrate.

GL = 40 x 15/100 = 6 g

What about a small baked potato? Its GI is 80 and it contains 15 g of carbohydrate.

GL = 80 x 15/100 = 12 g

So we can predict that our potato will have twice the metabolic effect of an apple. You can think of GL as the amount of carbohydrate in a food ‘adjusted’ for its glycemic potency.