Guar gum (a natural vegetable gum) is a great addition to homemade protein shakes (gives them that thick, rich quality), and may be very beneficial to one's health.

I use a 1/4 tsp in my shakes (tried a teaspoon once and couldn't pour it out of the glass very easily).

Although it has some carbs, they are all made up of insoluble fibre.

Below is a link to a study that shows guar gum may have a beneficial effect on blood sugar levels.

guar gum study