The effect of drinking milk containing conjugated linoleic acid on fecal microbiological profile, enzymatic activity, and fecal characteristics in humans.
BACKGROUND
The primary objective was to determine whether consumption of conjugated linoleic acids (CLAs) affected the fecal microbiota composition, fecal enzyme activity or fecal composition.


METHODS
Human subjects consumed (1 L/day) cows' milk (4% fat) containing (5 mg/g fat) cis-9, trans-11 CLA (CONT), (32 mg/g fat) cis-9, trans-11 CLA (NAT) and (32 mg/g fat) trans-10, cis-12 CLA and cis-9, trans-11 CLA (SYN) for 8 weeks, in addition to their normal diet. Milk feeding periods were separated by 4 week washout periods. Fecal samples were obtained at the beginning (day 0) and the end (day 56) of each milk feeding period. Fecal samples were analysed for microbiological profile, enzyme activity, pH and short chain fatty acid content.


RESULTS
Samples taken at day 0 and day 56 indicated that the numbers of lactobacilli and bifidobacteria significantly decreased after consumption of all experimental milks; total aerobes, total anaerobes, enterobacteria, and enterococci + streptococci did not change. At day 56, the activities of beta-glucosidase, nitroreductase, and urease enzymes had decreased compared to samples taken on day 0 for all treatments. beta-glucuronidase activity did not change. Fecal pH and ammonia content did not change.


CONCLUSIONS
It was concluded that observed changes could have been attributed to increased milk intake; no differences could be attributed to consumption of the different CLAs.
Farnworth
Edward R
ER
Food Research and Development Centre, Agriculture Canada, Saint Hyacinthe, Quebec, Canada. farnworthed@agr.gc.ca
Chouinard
Yvan P
YP
Jacques
Helene
H
Venkatramanan
Sudha
S
Maf
Akier A
AA
Defnoun
Sabrina
S
Jones
Peter J H
PJ
D000328:Adult; D000818:Animals; D001644:Bifidobacterium / Q000254:growth & development*; D018592:Cross-Over Studies; D005232:Fatty Acids, Volatile / Q000032:analysis; D005243:Feces / Q000737:chemistry / Q000201:enzymology / Q000382:microbiology; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006949:Hyperlipidemias; D007536:Isomerism; D007778:Lactobacillus / Q000254:growth & development*; D044243:Linoleic Acids, Conjugated / Q000008:administration & dosage* / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D008892:Milk / Q000737:chemistry*; D009601:Nitroreductases / Q000378:metabolism; D050177:Overweight; D014510:Urease / Q000378:metabolism; D001617:beta-Glucosidase / Q000378:metabolism
D005232:Fatty Acids, Volatile; D044243:Linoleic Acids, Conjugated; D009601:Nitroreductases; D001617:beta-Glucosidase; D014510:Urease