Kinda seems like two myths here.
1. Coffee doesn't have a net negative hydration effect.
2. Both coffee and yerba mate appear to contain "mineral salts". And you certainly piss drinking the latter just like you do drinking any liquid.
1. Coffee doesn't have a net negative hydration effect.
2. Both coffee and yerba mate appear to contain "mineral salts". And you certainly piss drinking the latter just like you do drinking any liquid.