12:19 Nov 6 

Definition of "-fold": thousand-fold - by three orders of magnitude; "this poison is a thousand-fold more toxic"
thousand times
http://www.thefreedictionary.com/thousand-fold
(The above seems also to be corroborated by Chamber's Dictionary.)
However, you can equally say "n-fold less toxic", e.g.:
The EPA revised the reference dose for 1,3,5-TNB from 0.00005 to 0.03 (i.e., determined to be a thousand-fold less toxic).
http://www.epa.gov/superfund/sites/fiveyear/f2006070001099.p...
e.g.:
In all binding studies the spermine concentration
that elicited half-maximal increase in binding was 2- to
5-fold lower than that observed in our electrophysiological
assay (29-32), and in cultured hippocampal neurons the
spermine concentration producing half-maximal increase in
NMDA-induced current was 10-fold lower (47).
http://www.pnas.org/content/87/24/9971.full.pdf

This concentration is several hundred fold below the lowest dose that elicited antibody production in the submitted study (0.5 mg/kg/day).

The above seems to indicate that the use of "-fold" qualified by less or more is as legitimate in English as it appears to be in German.