Free fatty acids have more potent effects on gastric emptying, gut hormones, and appetite than triacylglycerides.
OBJECTIVE
The effects of fat on gastric emptying (GE), gut hormones, and energy intake are dependent on digestion to free fatty acids (FFAs). In animals, small intestinal oleic acid inhibits energy intake more potently than the triacylglyceride (TG) triolein, but there is limited information about the comparative effects of FFA and TG in human beings. We compared the effects of FFA and TG on GE, gut hormone secretion, appetite, and energy intake in healthy males.


METHODS
Nine men (age, 23 +/- 2 y; body mass index, 22 +/- 1 kg/m(2)) were studied on 3 occasions to evaluate the effects of (1) 40 g oleic acid (FFA, 1830 kJ), (2) 40 g macadamia oil (TG, 1856 kJ; both 600-mL oil-in-water emulsions stabilized with 4% milk protein and labeled with 15 MBq (123)I), or (3) 600 mL 4% milk protein (control, 352 kJ), administered intragastrically, on GE, plasma cholecystokinin (CCK) and peptide-YY (PYY) levels, appetite perceptions, and subsequent energy intake.


RESULTS
GE of FFA was much slower than that of TG (P < .05), with greater retention of FFA, than TG, in the proximal stomach (P < .001). Hunger was less (P < .05), and fullness was greater (P < .05), after FFA when compared with control and TG. Increases in plasma CCK and PYY levels were greater after FFA than TG or control (P < .05). Energy intake tended to be less after FFA compared with TG (control, 4754 +/- 610 kJ; TG, 5463 +/- 662 kJ; FFA, 4199 +/- 410 kJ).


CONCLUSIONS
FFAs empty from the stomach more slowly, but stimulate CCK and PYY and suppress appetite more potently than TG in healthy human beings.
Little
Tanya J
TJ
University of Adelaide Discipline of Medicine, Royal Adelaide Hospital, Adelaide, South Australia, Australia.
Russo
Antonietta
A
Meyer
James H
JH
Horowitz
Michael
M
Smyth
Douglas R
DR
Bellon
Max
M
Wishart
Judith M
JM
Jones
Karen L
KL
Feinle-Bisset
Christine
C
D000284:Administration, Oral; D000328:Adult; D001066:Appetite / Q000187:drug effects*; D001067:Appetite Depressants / Q000008:administration & dosage / Q000494:pharmacology*; D001628:Beverages; D002766:Cholecystokinin / Q000097:blood; D004311:Double-Blind Method; D002149:Energy Intake / Q000187:drug effects; D005230:Fatty Acids, Nonesterified / Q000008:administration & dosage / Q000494:pharmacology*; D005746:Gastric Emptying / Q000187:drug effects*; D005768:Gastrointestinal Hormones / Q000097:blood*; D041981:Gastrointestinal Tract / Q000187:drug effects* / Q000378:metabolism; D005772:Gastrointestinal Transit / Q000187:drug effects; D006801:Humans; D039106:Macadamia / Q000737:chemistry; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage; D019301:Oleic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D019894:Peptide YY / Q000097:blood; D010938:Plant Oils / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D012016:Reference Values; D013997:Time Factors; D014280:Triglycerides / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*
D001067:Appetite Depressants; D005230:Fatty Acids, Nonesterified; D005768:Gastrointestinal Hormones; D008894:Milk Proteins; D010938:Plant Oils; D014280:Triglycerides; D019894:Peptide YY; D019301:Oleic Acid; D002766:Cholecystokinin