If you’ve ever been to Argentina or Uruguay, you may have noticed pretty much everyone walks around with a hot water bottle, a small round vessel called mate that contains green yerba mate leaves and a metal straw called bombilla. They sip yerba mate all day long, pouring more hot water as needed. That is the “proper” (i.e. traditional) way of consuming yerba mate, although the demands of modern life have driven the production of convenient teabags that you can pop in your mug. Yerba mate is highly regarded for its stimulant effects and antioxidant content. Another benefit that is probably less known is that it’s very good at keeping…