I should add this is a mail order supplement. It is pharmaceutical grade. Many online vitamin companies sell only food grade or medical grade supplements. I thought medical grade and pharmaceutical grade were the same. Not so! EB-N6 is a 'medical food' and is far superior to OTC supplements. I was taking most of the OTC ingredients of EB-N6 formula already but there is no comparison between the two. If you to their website you can see their products or call them. I find the reps to be very helpful. I also found the OTC separate supplements to cost more than the complete EB-N6. Good luck!