Are sugar alcohol sweeteners like erythritol and xylitol good?

Sugar alcohols. The funny thing about sugar alcohols is that they reconstitute into actual sugar once digested. So a product can be marketed as "sugar-free" if it contains sugar alcohols, but after absorption there's sugar again. It's a marketing ploy. So yes, sugar alcohols can have bad effects on your body just like sugar. .
Erythritol is ideal . Sugar alcohols vary. Some have almost the same effect on blood sugar as regular sugar (maltitol). This is called glycemic index. Erythritol has the lowest glycemic index and calories per gram and is the best.