The common alternatives for xanthan gum in some food uses are the following 9 ingredients: cornstarch, psyllium husk, sodium carboxymethyl cellulose (sodium CMC), agar agar, gum arabic, Locust bean gum, konjac gum, gelatin and carrageenan.

Among the above replacements, only psyllium husk, guar gum and locust bean gum are defined as dietary fiber which has the benefits of (1):

Lowering blood glucose/blood pressure/cholesterol levels
Improving laxation
Reducing energy intake
The difference between xanthan gum and the substitutes are mainly in five aspects:
 

Cornstarch
Native corn starch is separated from corn and used widely as a thickening agent in fresh food or food for short-time storage due to the limited application caused by, e.g. the insolubility in water, unresistant to acid, heat or shear. Therefore, native corn starch is sometimes made to modified corn starch for specialized uses.

Following are some advantages of xanthan gum than corn starch:

Usage: Less amount is needed to obtain a desired viscosity. Xanthan gum does not need to be heated to thicken while corn starch does.
Stability: maintain a more stable viscosity.
Clarity: provide a transparent solution while corn starch makes the solution cloudy.
Psyllium husk
Psyllium husk, the seed coat from the psyllium seed, which can be used as a source of fiber and also can replace xanthan gum as a thickener or binding agent in gluten-free baking.

Sodium carboxymethyl cellulose
A cellulose derivative or the sodium salt of CMC, to improve the solubility of CMC in water, made from the natural cellulose after alkalinization and etherification. It is another popular thickener (not a gelling agent) in food with the properties of thickening, suspension, emulsification and stabilization. Learn more about Sodium CMC

Agar agar
A polysaccharide extracted from the red algae of the class Rhodophyceae, insoluble in cold water, commonly used as a gelling agent in jelly and can replace gelatin. Learn more about Agar Agar

Gum arabic
A water-soluble polysaccharide comes from stems and branches of acacia senegal and acacia seyal, mainly used in chocolates, candies and chewing gum. Learn more about Gum arabic

Locust bean gum
It is the endosperm of the seed of the carob (locust) tree, this polysaccharide is commonly used as a thickener (can also be acted as a gelling agent but with a high concentration) in ice cream. Learn more about LBG

Konjac gum and Konjac glucomannan
Water-soluble polysaccharides with the strongest viscosity, made from the root of the konjac plant, used as a thickening and gelling agent commonly in meat products, pastas and noodles. Learn more about Konjac

Gelatin
Commonly made by cooking collagen from the skin and bones of fish, beef and pig and mainly used to produce a gel in yogurt, pudding and ice cream. Not suitable for vegetarians as originated from animals. Learn more about Gelatin

Carrageenan
Extracted from red algae, with both thickening and gelling properties. This ingredient can be divided into three types: Kappa, Iota, and Lambda according to the source of red algaes and classified into two grades (semi-refined and refined) based on the different manufacturing processes. It is mostly used in meat. Learn more about Carrageenan