<Tr> <Td> No evidence for biological action in mammals, but essential in some lower organisms . (In the case of lanthanum, the definition of an essential nutrient as being indispensable and irreplaceable is not completely applicable due to the extreme similarity of the lanthanides . Thus Ce, Pr, and Nd may be substituted for La without ill effects for organisms using La, and the smaller Sm, Eu, and Gd may also be similarly substituted but cause slower growth .) </Td> </Tr> <Table> <Tr> <Td> </Td> </Tr> </Table> <P> The following play important roles in biological processes: </P> <P> RDA = Recommended Dietary Allowance; UL = Tolerable Upper Intake Level; Figures shown are for adults age 31 - 50, male or female neither pregnant nor lactating </P>

How many minerals are in the periodic table