<prompt> Translate the following text to EnglishIdadi ya masomo ambayo yameonyesha athari, ama na kujitolea au randomized washiriki, ni kiasi lakini kuongezeka, na athari mbalimbali kutoka ndogo kwa kiasi kikubwa sana kupunguza hatari ambayo kuwa na umuhimu mkubwa wa afya ya umma.  <response>: The number of studies that have demonstrated effects either with volunteer or randomized participants is modest but increasing, and the effects range from minimal to very sizeable reduction in risks that have significant public health importance. 