BS”D
Please be very careful with practitioners as well – some of them really are MLM salespeople in disguise. Start by asking your own physician or a family friend who is a physician as to what, if anything, you need.
And don’t pay more than high end drugstore prices for any supplement (Landau’s was my upper limit when I lived in the US b/c I wanted the “haimishe hechsher” but ask your rov what hechsher is needed on any given supplement).