1. One of the most popular teas that can be taken on a regular basis is teas with mountain ash. Rowan contains a large amount of diverse nutrients, such as beta-carotene, carotene and ascorbic acid (which is especially a lot in mountain ash). Such tea normalizes the work of the kidneys, helps from constipation and vitamin deficiency, hemorrhoids and rheumatism — and this is only part of the useful properties of this wonderful drink.