A few days ago I decided to buy Bob's Red Mill Xanthan gum - best decision ever! I have seen it in many recipes before but it is pricey (about $11-12 for .5 lb) so I never bought it. I kept seeing it in recipes this week so I decided to just go ahead and purchase it at my local grocery store, Wegmans (I have seen it at WalMart too).
It seriously thickens up your protein shakes and gives them the consistency of a milkshake or even ice cream! A little bit goes a LONG way and you only have to use about 1/2 tsp in your protein shake to really thicken it up. Even though the xantham gum is pricey it will last you a really long time.
Xanthan gum is a corn derivative but I did some research on Bob's Red Mill brand and learned that they have a company policy that requires their providers to be certified organic and use non-GMO seeds. So, this brand does not use genetically modified corn. If you have sensitivity to corn another great option to thicken up your shakes is glucomanan which is also an excellent form of fiber.
Have you used xanthan gum before? What did you think?