Ba. Nuck et al., INABILITY OF THE HUMAN FECAL MICROFLORA TO METABOLIZE THE NONABSORBABLE FAT SUBSTITUTE, OLESTRA, Journal of industrial microbiology, 13(5), 1994, pp. 328-334
Olestra is a non-caloric fat substitute under review by the Food and D
rug Administration. It consists of a mixture of octa-, hepta- and hexa
esters of sucrose formed with long chain fatty acids. Previous studies
showed olestra is not hydrolyzed by mammalian lipases and is not abso
rbed. The objective of this study was to evaluate the potential for co
lonic microflora to metabolize olestra after continued exposure. Neat
and emulsified C-14-[fatty acid] olestra was incubated for 72 h in bot
h minimal and organically-enriched anaerobic media inoculated with fec
es from seven subjects who had consumed olestra (9 g per day) over a 3
-4 week period. C-14-sucrose and C-14-glucose served as positive contr
ols. Production Of (CO2)-C-14, (CH4)-C-14, C-14-volatile fatty acids (
VFAs) and C-14-long chain fatty acids (LCFAs) was determined. In addit
ion, the ester distribution and fatty acid composition of olestra were
examined before and after incubation. Significant quantities of (CO2)
-C-14 and C-14-VFAs were generated from the C-14-sugars, indicating th
at the microflora were active under the incubation conditions, Further
more, free oleic acid was extensively hydroxylated and hydrogenated. i
n contrast, no degradation products (gas, VFAs, LCFAs) or changes in t
he olestra resulting from bacterial activity were detected. These resu
lts indicate that under anaerobic conditions the colonic microflora of
the humans, consuming olestra, did not metabolize olestra.