My diet:
Comparison

Xanthan Gum vs Guar Gum

The short answer
Use xanthan gum for gluten-free bread and hot or acidic sauces; it's more stable and gives more stretch. Guar gum is cheaper and better in cold foods like ice cream and smoothies.
Side by sideXanthan GumGuar Gum
Safety score88/100 Generally safe86/100 Generally safe
Best forBread, sauces, dressingsIce cream, smoothies, cold sauces
Made fromBacterial fermentationGuar beans
Heat & acid stabilityVery stable ✓ BetterBreaks down in acid
Thickening powerStrongStronger (cold) ✓ Better
PriceHigherLower ✓ Better
Gut toleranceGoodGood; feeds gut bacteria ✓ Better

Swapping one for the other

Swap 1:1 in most recipes. In yeast bread, use about 1.5 times as much guar gum as xanthan. Avoid guar in very acidic recipes like lemon curd.

Common questions

Can I use both together?

Yes. Many gluten-free blends use both: xanthan for structure, guar for moisture.