Monday, October 3, 2011

Did you know white and wholegrain bread have the same GI?

No?  Well, you're not alone.  Canadian Living doesn't either.

The September 2011 issue features an article titled "Feed your brain:  Mind-mending miracle foods for breakfast, lunch and dinner" on page 51.

Unfortunately the author's recommendation to eat whole grain bread is flawed, and I felt compelled to send the following letter to the Editor:
Cara Rosenbloom advised eating whole grain bread in the September 2011 issue (Health is Happiness) because it is less refined than its white counterpart, stating that the higher fibre and protein content would slow down the stream of energy.  I would like to point out that any difference in glucose release between the two is normally so small as to be negligible.  This can be easily verified by referring to a glycemic index table.

Also, although it is true that the brain's main source of fuel is glucose, it is a common misconception to believe that this glucose comes only from carb-rich foods.  In fact, while carbohydrates can provide a quick source of fuel that can be helpful in times of famine, the human body can technically thrive on a diet that is totally devoid of carbohydrates because of a metabolic process named gluconeogenesis.  Far from being an uncommon process, it is widely used by animals as well as plants, fungi, bacteria and microorganisms to generate glucose from non-carbohydrates.
It's really easy to compare the glycemic index of different foods, and if you didn't know it already, you might be really surprised to learn that the glucose load from whole grain bread is virtually the same as that of white bread.  This is what I found on

Remember that this is typically one slice of bread.  Most people eat two slices in a sandwich.  And a can of pop has about 26g of sugars.

Just because it's made with whole grain, it's not going to give you a slower energy release.  Some whole grain bread can even give you a more rapid energy release, depending on the ingredients it's made with.  Suffice it to say that I totally disagree with Ms. Rosenbloom.  Not that I'm defending white bread, mind you.

I recommend staying away from both.

As for the comment about the brain's main source of fuel being glucose, this is something I already wrote about in May:  It is true that glucose fuels the brain.  However it is not true to imply that when we eat glucose, it makes its way there via a direct path and that this makes carbohydrates good for our brain function.  If it did, people would be far more susceptible to hypoglycemia than they normally are.  And it would be the really-bad-for-you kind of hypoglycemia, not just a shaky feeling.  Don't believe me?  Go back and read my post, and feel free to check out the references I provided.

Bottom line: Canadian Living isn't the only guilty party.  After all, Mother Earth News published something very similar, which is why I wrote that post in May.  Given the extent of the misinformation, and the fact that it's commonly propagated by people with nutritional credentials that make them appear to be experts in the field, it's not entirely surprising to me that so many people believe carbs from whole grains are good for you, essential even for optimum brain function.

But I do think the registered dieticians who write these erroneous articles are doing the public a disservice, and it's time to set the public straight. 

It would be very nice to see my letter published, though I'm not going to pin too much hope on it happening.  I'm sure their letters department is inundated with reader comments.


  1. A friend of mine considers whole-wheat bread to be a "slow-carb" and thus good for his weight loss plan. I'm going to show him this data.

    I like the new layout. It's nice to see all your groovy posts laid out magazine style. :)

  2. Thanks, CMP. I like the cleaner lines of this new dynamic template too, though I wish it was a little customizable. And it seems to be reorganizing the tabs at the top of the page of its own volition. Hopefully another version will come out soon.