Rubidium 

Rubidium: The typical daily dietary intake of rubidium is 1 to 5 mg. Foods high in rubidium include coffee, black tea, fruits, vegetables (especially asparagus), poultry and fish. Rubidium is a relatively nontoxic element and has not show to be of toxicological concern from the nutritional point of view. Rubidium deficiency apparently depresses growth and life expectancy in goats.