Daily. Sadly, this works out to be 25p per day on the H&B website. Of course, if you know it works, it would be worth it, but I suspect I will just have to buy a big packet and decide for myself.
I still have half a jar of acidophilus and two vitD sprays (3 for 2 offer - don't work for me) and B6 and magnesium (seem ok - will probably use all of them.)