I was taught at school 18:11 Aug 10, 2011
many years ago never to use "the fact that" because it is unecessarily wordy and clumsy. It is challenging. You could do it with a "because", but to really do it effectively you have to rearrange everything and at a word or two to smooth it out.
"This is borne out by the vast number of drug treatmens accounting for around 40-50% of the total which still today are based on active ingredients originating directly in the plant kingdom".
As for the baggaglio terapeutico this is just the therapeutic substances which doctors have metaphorically collected and carry around with them in their luggage. Medicines or drugs. I don't think you want the "available". Obviously I am sure you will quote your source if you use this and sleep soundly Claire :) | 
The translation workplace 
