Reincarnation, to answer your original question, yes those data do look odd. It's hard to fathom that cake, donuts, ice cream and Mars Bars would really be lower GI than brown rice and brown bread, or why white pasta comes out so low, similar to eating an egg!
Remember that rice and bread are never eaten on their own, but with fats and proteins, which would reduce the net GI. So a more relevant comparison might be between ice cream or Mars Bars, and risotto or cheese sandwiches .
The white pasta is still a mystery though. I would not rely on these data as being accurate, until we know more.
The data is pretty accurate, it comes from an authoritative source and is pretty much identical to all the other data I have seen. If you find these values odd, it is frankly because of your limited understanding of the subject not because there is really something odd going on
Remember that sugar (sucrose) itself has only a medium GI of 58. This is because only half of it is glucose, the other half is fructose which hardly raises blood glucose at all (that doesn't make it any healthier, of course). Moreover, things like chocolate bars ice cream or even donuts contain loads of fat which slows down the absorption of the sugars, further lowering the GI.
The relatively low GI of pasta is not a mystery at all but intrinsic to its cooking properties. Have you ever tried to make pasta from soft wheat without the use of eggs? It is impossible; you can try to form pasta but it will start to fall apart as soon as you put it into the boiling water. Durum wheat has two special properties allowing to make pasta from it without the use of any binder: firstly, it has very hard and dense starch granules which take much longer to soak up water than other starches and secondly, it is very rich in protein which forms networks during the processing of the pasta and effectively traps the starch granules within a dense protein matrix. This is the reason why pasta keeps both its shape during cooking and why it provides some resistance to our digestive enzymes. Hence the GI of firm pasta cooked al dente is lower than that of soft, overcooked pasta. Parboiled rice also has a lower GI than ordinary or even brown rice for similar reasons.
Edited by timar, 29 July 2014 - 09:42 AM.