Grinding your oats and raising the GI

[rookie000]

I have been grinding my oats and barley to put in my weightgainer shakes. I grind it to make it go down easier. I am wonder if by grinding the oats and barley if I am raising the GI? I noticed that Barley flower has a significantly higher GI then raw barley. I am assuming the same would go for oats. So Am i infact loosing my low GI properties by grinding it????making it easier to digest???

[shortz]

I dunno why it would change, but then again, I would only be guessing. I am not familiar with the processing of certain foods. It would be interesting to here an answer.

[YellowJacket]

Grinding your oats obviously makes it easier to mix and thus digest. Ive been asked this question numerous times and I have come to the conclusion that yes, it was effect the GI of your oats, but not significantly enough to really matter... I have only one study that shows this and will post it...

Particle size of wheat, maize, and oat test meals: effects on plasma glucose and insulin responses and on the rate of starch digestion in vitro.

Heaton KW, Marcus SN, Emmett PM, Bolton CH.

University Department of Medicine, Bristol Royal Infirmary, UK.

When normal volunteers ate isocaloric wheat-based meals, their plasma insulin responses (peak concentration and area under curve) increased stepwise: whole grains less than cracked grains less than coarse flour less than fine flour. Insulin responses were also greater with fine maizemeal than with whole or cracked maize grains but were similar with whole groats, rolled oats, and fine oatmeal. The peak-to-nadir swing of plasma glucose was greater with wheat flour than with cracked or whole grains. In vitro starch hydrolysis by pancreatic amylase was faster with decreasing particle size with all three cereals. Correlation with the in vivo data was imperfect. Oat-based meals evoked smaller glucose and insulin responses than wheat- or maize-based meals. Particle size influences the digestion rate and consequent metabolic effects of wheat and maize but not oats. The increased insulin response to finely ground flour may be relevant to the etiology of diseases associated with hyperinsulinemia and to the management of diabetes.

[BBAddict]

Thanks, YJ. I was just reading this and wanted to post an answer saying yes, but I didn't have any evidence to back it up! It makes sense that mechanically breaking down a fiber prior to ingesting it would increase the rate of absorption. After all, it's very similar to what is done to make quick oats.

[shortz]

So not chewing would make it digest slower too then, right? Wouldn't chewing it up have a similar effect as grinding it up?

[YellowJacket]

So not chewing would make it digest slower too then, right? Wouldn't chewing it up have a similar effect as grinding it up?

A very valid point, thus is the primary reason why I think it does change it, but only very slightly and not a change I would consider too significant. Also, gringing it into a fine powder would be finer than chewing (unless you do so for 3 minutes like mom says :) )

[rookie000]

cooking it as well would raise the GI and lower digestion time...Right?