Wednesday, October 12, 2011

Very high GI in whole grain bread: Canadian Living response


Do you remember my post from last week about the glycemic index of whole grain bread being similar to that of white bread?  Well, this morning I received a very nice reply from Canadian Living (I am still waiting for a response from Liberte regarding the sugar in their yoghurt):
Thanks for getting in touch with your concerns about our writer's whole grain bread recommendation in the September 2011 issue of Canadian Living. I shared your email with our registered dietitian, writer Cara Rosenbloom, and thought I'd in turn share our rationale for including whole grain bread in that feature on foods that boost your brainpower.

As you know, the GI values for foods all come from www.glycemicindex.com – the definitive database of the GI value of thousands of foods tested by researchers at University of Sydney. If you search the database for "bread," there are 315 different entries. There is a range of glycemic index (GI) values for whole grain bread -- some have a higher GI than others (up to 71) - but the vast majority of whole grain breads have a GI between 36 and 54, which is considered low. Those are obviously the breads we'd recommend. White bread usually has a GI of 70 -100, which is considered high. 

Of course, it you take just two outlying examples from the database (in this case, a whole grain bread that has a GI of 69, and a white bread with a GI of 71), they can look similar. At the other extreme, you can compare a whole grain bread with a GI of 34 with a white bread with a GI of 89. The idea that whole grain and white bread have similar GI levels is true for some brands of bread, but false for many others. As with any science, the same literature can be interpreted many ways. But, in general, whole grain breads do have a lower GI than white breads, so we stand by our initial recommendation. 

Thanks again for sharing your concerns about out nutrition feature. We do appreciate your perspective!
I hope you aren't thinking at this point that I got my facts all wrong.  I totally disagree with that the vast majority of whole grain breads listed on www.glycemicindex.com have a lower GI.

I have also scrolled through the 315 different entries, and in fact, the ones with the very low GI readings are not even bread on their own, but whole meals and sandwiches.   For example, 37g of "Greek lentil stew with a bread roll, home made" is one of the 315 low GI entries.  

When we are told to eat more whole grains, my understanding is not that we are being asked to seek out specialty grains like spelt, buckwheat or einkorn.  

The vast majority of whole grain breads available to us in the stores on a day to day basis are not the specialty low GI ones.   

It is widely understood (albeit mistakenly so) that regular whole grain bread in the grocery store is a better nutritional choice than white bread.

Have you ever heard a nutritional expert advising the public to stay away from commercially produced whole grain sandwich loaves - the kind that are served in cafeterias and institutions?  The kind my husband's diabetic inpatients are served on a daily basis?

When they tell us to "eat more whole grains", do you understand that to mean that products marked "whole wheat" are nutritionally acceptable?  

Because that's the message I'm hearing from the nutritional authorities.

So, this is the response I sent:
Thank you for your detailed response to my email.  Your point about varying GI's is well taken, and I do understand the difficulties involved in making blanket statements about whole grain bread as a category.  Also, as someone who has baked a lot of bread, I am fully aware of the possible GI impact of the ingredients that are used in different recipes.  Many recipes add sweeteners, powdered milk, refined white flour and even mashed potatoes to the dough to improve the flavour and the texture of the crumb. 
This makes it very difficult to assign one average GI reading to a food category as broad as whole grain bread.
However, I think you would agree that the vast majority of whole grain bread consumed is in the form of the common sandwich loaf.  This is what one would typically see in cafeterias, hospitals, schools, old age homes and all other institutions. It is also the kind of bread that most children would eat, when they eat whole grain bread.  As much as I or other health-conscious consumers would be naturally drawn to coarser artisanal loaves, which may indeed have a lower GI, it is simply not what the majority of people consume.
I know that Wonderbread is a particular brand name, but it is a popular one both in the US and here in Canada.

This is what the Harvard Medical Schools GI index listing shows:

Wonder™ bread, average
73±2
30
10
Whole wheat bread, average
71± 2

Furthermore, www.glycemicindex.com lists the following range of whole wheat breads*.  As you can see, these all in a close range in the high end of the GI scale.

Food Name GI serve (g) carb/serve (g) GL
Wholemeal (whole wheat) bread (Hovis, UK) 68 30 11 7
Wholemeal (whole wheat) bread 69 30 13 9
Wholemeal (whole wheat) bread (Sainsbury's, UK) 71 30 11 8
Wholemeal (whole wheat) bread 72 30 12 9
Wholemeal (whole wheat) bread 74 30 14 10
Wholemeal (whole wheat) bread (Hovis, UK) 74 30 11 8
Wholemeal (whole wheat) bread 75 30 13 9
Wholemeal (whole wheat) bread (Tip Top Bakeries, Australia) 77 30 12 9
Wholemeal (whole wheat) bread (Tip Top Bakeries, Australia) 78 30 12 9
Wholemeal (whole wheat) bread 85

It seems to me that the two examples I originally sent you were not outliers, and in fact, are fairly representative of many of the items listed above.
This is why I would disagree with Ms. Rosenbloom that the GI impact of the vast majority of whole grain breads is much lower.
Sincerely,
Philippa

* Try this yourself by searching for "bread whole wheat" on www.glycemicindex.com.


2 comments:

  1. Their response was infuriating! Good for you, for not letting them off the hook. The kinds of numbers game they're playing is part of how we all got into this mess.

    Keep fighting the good fight!

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  2. This comment has been removed by a blog administrator.

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